The Diamond Geyser

So I've inhaled some nanodiamonds...

2010-04-27T04:36:00.005+01:00

Silence is golden - unfortunately this does not apply to blogging, but with the coming of Golden Week here in Japan I have had some quieter moments to throw in my 2 yens worth on the recent offerings from the diamond community.

Continuing the bio theme that has been running for the last few posts, the paper 'Pulmonary toxicity and translocation of nanodiamonds in mice' by Yuan et al. has recently caught my attention. It examines the effect of nanodiamonds on the pulmonary system of mice.

Yuan et al. inserted nanodiamonds of 4nm and 50nm in size into the lungs of mice and found minimal biochemical reaction to their presence. The nanodiamonds were quickly ingested after 1 day in vivo via phagocytosis by the macrophages in the lungs of mice, and after 28 days Yuan et al. could no longer find nanodiamonds in the lungs of the mice (nor the liver or spleen). The team put the disappearance of the nanodiamonds down to the nanodiamond-filled macrophages migrating up the mucociliary escalator to the pharynx, i.e. the nanodiamonds were naturally expelled via ciliary action, arriving at the pharynx and then were coughed or spat out by the unlucky mice.

Yuan et al. predict the excellent biocompatibilty of nanodiamonds in the lungs of mice and their ability to be naturally expelled from the lungs will allow the development of a nanodiamond-based pulmonary drug delivery system. The full paper can be found here.

Nanodiamonds are a neuron's best friend

2010-01-14T18:07:00.007Z

Have a look below and you'll see I've been whining about having to write a paper. Here it is finally! If you stumbled across Symposium J of the MRS Fall 2009 meeting in Boston there's a chance you may have already seen me do a talk on this work. The paper entitled "The use of nanodiamond monolayer coatings to promote the formation of functional neuronal networks" is currently available online in the journal Biomaterials.

It feels a bit wrong writing about my own paper, so let me just say we report an interesting observation of nanodiamond monolayers being an exceptional platform for supporting the attachment and growth of functional neuronal networks. The above image is taken from this work and is a confocal microscopy image of neurons and glia cells growing directly on top of nanodiamond layers, without using the usual coating of extra cellular matrix proteins to initiate neuronal growth. With further investigation, the ND monolayers could be a promising biomaterial for chronic brain implants.

Give it a peruse! I'd be very interested in any comments anyone has.

UNCD Horizon from ADT

2009-10-15T11:17:00.003+01:00

ADT have once again added to their repertoire of diamond products, with the latest addition to the family being the world's smoothest commercially available vapour-deposited diamond. Using chemical-mechanical planarisation (CMP - a standard industry polishing technique) ADT have reduced the roughness of their UNCD wafers from 10nm to 1nm.

ADT hope the outstanding smoothness of their new material will pave the way for more efficient RF devices, and the material is already being used to fabricate nanophotonics for applications ranging from bio-chemical sensing to optical information processing.

The artwork for this post is the UNCD Horizon wafer patterned with the ADT logo, courtesy of Dr. Warren McKenzie, University of New South Wales. To find out more about UNCD Horizon (and other ADT products, including all-diamond AFM tips) follow the Advanced Diamond Technologies Ltd. link on the group list to the right hand side.

Nanodiamonds for gene delivery

2009-09-01T22:50:00.005+01:00

I said in my last post I was looking forward to Dean Ho's next nanodiamond (ND) application, but I didn't expect it to come so soon.

This time, Ho's group are using NDs for gene delivery into cells, where NDs are increasing the gene insertion efficiency 70 times. This has been achieved by using the superlative biocompatibility of NDs, along with their ability to be easily chemically functionalised with any desired chemical. Exploiting these two properties of NDs have resulted in dramatic improvements on existing gene insertion techniques.

"A low molecular weight polymer called polyethyleneimine-800 (PEI800) currently is a commercial approach for DNA delivery," said Xue-Qing Zhang, a postdoctoral researcher in Ho's group and the paper's first author. "It has good biocompatibility but unfortunately is not very efficient at delivery. Forms of high molecular weight PEI have desirable high DNA delivery efficiencies, but they are very toxic to cells."

Zhang et al. functionalised NDs with PEI800 using amine groups as covalent linkers. The 70x improvement of gene insertion efficiency is in comparison to the convention approach of using PEI800, and the NDs have allowed PEI800 to retain its function and biocompatibility whilst increasing gene insertion efficiency. Zhang et al. believe this use of NDs to be a rapid, scalable, and broadly applicable gene therapy strategy, and with further work hope the technology will treat diseases ranging from inherited disorders to acquired conditions and cancer.

"There's a long road ahead before the technology is ready for clinical use," Ho said, "but we are very pleased with the exciting properties and potential of the nanodiamond platform."

As a diamond engineer, diamond's biological applications are those which excite me most, yet most diamond engineers I have met come from physical backgrounds. Where do these bio-inspired ideas come from? The answer is simple; Ho is from a Physiological Science background, so has a plethora of problems to address - rather than a pile of nanodiamonds that need using. I need to find me a doctor...

The full paper can be found here in ACS Nano.

Savlon? No thanks, I've got nanodiamonds

2009-07-30T17:08:00.005+01:00

I've finished my paper (sigh of relief) so I'm going to report on what's been flooding the diamondnet: nanodiamonds for insulin delivery.

You may remember back in October last year I wrote a piece on Dean Ho and his remarkable use of nanodiamonds (embed in polymer films) to deliver chemotherapeutic drugs to post-operated tumour sites. This time, wounds in general are the target.

Insulin has recently been identified as an agent for fighting bacterial infection, hence if you have a wound a bit of insulin would not go unwanted - that is if it's infected. Shimkunas et al. have adsorbed insulin onto nanodiamonds that is only released when the local pH increases above usual physiological levels. This happens during infections, allowing targeted delivery of insulin to wounds. Ho hopes to incorporate the ND-insulin complexes into gels for direct application on wounds.

So what will be next for Ho's lab? Nanodiamond is one of the best adsorbers of proteins at the nanoscale: Its oxygen terminated surface (unless otherwise treated) gives proteins high binding affinities to nanodiamonds above other nanoparticles, and their curvature and size is (controversially) thought to allow proteins and enzymes to adsorb and remain in their native and functional states. As a biologically minded but physically trained scientist, I wait with baited breath to see which protein will be given the next ND treatment.

I'm nearly back, I promise

2009-07-28T11:49:00.008+01:00

It's been ages hasn't it! Well it's going to be a bit longer I'm afraid. I'm currently writing up a paper (watch this space) and blogging has taken a back seat for the last few months.

Meanwhile, I thought I'd share some tools I've recently found that make science a lot easier. The first one I feel a bit embarrassed to mention, as I think I'm a late adopter on this one:

Scopus. It's better than Google Scholar, Science Direct and WoS put together in my opinion.

Secondly, this one's Mac-only I'm afraid, but its caught on like wild-fire in the lab. Papers. Get it now.

And finally, I've been hunting high and low for something to replace my illegible paper logbook that looks like a 5-year old's scrapbook. If you're like me, you think the concept of printing out a graph and sticking it in an actual book (what are they again?) is a bit out of date. If you're showing similar symptoms I'd recommend Journler to you. It's like an organised diary that you can attach any file, folder, website, email, video or you-name-it to. Get it while it's free.

Thank you to my readers who have been checking back on the blog while I've been AWOL.

Metal matrices and diamond injections

2009-05-28T10:29:00.002+01:00

Today is just a quick roundup of some of the latest diamond news. I have some deadlines looming...

A project called ExtreMat has just come into my attention, where Professor H. Peter Degischer and Co. are in the process of fabricating new materials for extreme environements. Degischer is using 100µm diamond particles coated in silver and connected with tiny silicon bridges to create a new composite material for extreme application.

"We examined some metal matrix composites and their interfacial bonding which are promising for use in nuclear reactor heat sinks, rocket engines or in power electronics. The characterisation of these heterogeneous materials falls within our area of competency", says Degischer, Head of the Institute of Materials Science and Material Technology at the TU Vienna. The team hope the material to be resistant to very high heat fluxes and temperatures, physico-chemically aggressive media, complex mechanical loads and highly energetic radiation field.

The second news item reminds me of a previous post I wrote on Nanodiamond printing. A team of researchers at Northwestern University have developed a tool called the Nanofountain Probe that functions in two different ways. Firstly, the probe acts like a fountain pen. The drug-coated nanodiamonds serve as the ink, allowing researchers to create devices by "writing" with it. The second mode functions as a micro syringe for single cell application, permitting direct injection of biomolecules or chemicals into individual cells.

The research was led by Horacio Espinosa, a Professor of mechanical engineering, and Dean Ho, an assistant Professor of mechanical and biomedical engineering, both at the McCormick School of Engineering and Applied Science at Northwestern University. Their results were recently published online in the scientific journal Small.

Thinner than theory: Diamond nanorods

2009-05-20T15:59:00.007+01:00

How thin can diamond nanorods be? Theory would lead you to believe that 2.7nm is the smallest possible diamond-diameter, however Shang et al. from the University of Ulster have recently shown diamond nanorods (DNRs) can be grown to the ultrathin size of 2.1nm.

Below 2.7nm thickness DNRs are thought to be energetically unstable. Shang et al. have ascribed the existence of their thinner-than-theory DNRs to a tapered graphene sheath around the DNR, which they claim could be responsible for the system's low free energy, and thus stability.

As well as housing the DNR, Shang et al. also speculate that the graphene sheath could act as a 'high pressure reactive nanocell' that self-assembles and catalyses DNR growth during PECVD. The group suggest that the curvature of a piece of graphene (seeded onto a surface) could possibly give rise to a surface tension or additional pressure that creates a thermodynamic nano-climate in favour of DNR growth over carbon nanotubes (CNTs) or amorphous carbon.

Upon measuring the threshold field emission of the DNRs, Shang et al. found them to compare favourably to most nanostructured emitters (CNT, ZnO, CNx, GaAs, GaN, AlN, BCN, etc.); however they did fair worse than oriented high density multiwall CNTs. The group measured 1mA/cm2 at 1.9V/µm, and performed admirably against the metric of field emission for flat panel displays.

The full paper, which employs a host of imaging techniques to characterise the DNRs, can be found here.

When Semi Turns To Super

2009-04-28T10:28:00.009+01:00

I haven't posted much on Boron-doped diamond (BDD) superconductivity yet as I'm fairly unacquainted with it, so it was a pleasant surprise recently to see the cover of Nature Materials devoted to an initiating review of 'Superconducting group-IV semiconductors', by Blase et al.

It's a review so I'll leave the scientific details for you to discover, but I would like to point you in the direction of a good figure on the 'evolution of the electronic density of states and band structure with increasing p-type doping'.

Also in the news, here is a recent interview with the De Beers Group Managing Director Gareth Penny from the IDEX website.

$6.1 million and 50 nanometers

2009-04-20T12:11:00.006+01:00

This week I'm killing two birds with one post by highlighting some recent stories from the diamond community. Last week the University of California, Santa Barbara, (UCSB) received a $6.1 million grant from DAPRA and AFOSR to develop diamond as the material of choice for quantum computing processing. The project will cover all corners of quantum computing, bringing together physicists, electrical engineers, material scientists and computer scientists to deliver the complete diamond-computing package.

"We are extremely excited by the rapid pace of discoveries in this emerging area of science and technology. This vital support offers extraordinary collaborative research opportunities for students to engage at the frontiers of the field in areas spanning fundamental physics to materials science," said David Awschalom, principal investigator for both projects and Professor of Physics and Electrical and Computer Engineering at UCSB.

On the other side of the pond, Dr. David Moran from the University of Glasgow has recently unveiled his group's most recent creation - the smallest diamond transistor in the world. The diamond gate measures only 50nm, which halves the previous record held by NTT (Japan).

Dr. Moran explains, “by developing a diamond transistor technology, we aim to tap into the truly amazing properties of this exciting material which could prove fundamental to the development of several next generation technologies. These require a very fast and ideally high-power transistor technology that needs to be able to operate in adverse weather/temperature conditions. This is where a diamond transistor technology would excel.”

Ultralong spin coherence in quantum-grade diamond brings quantum computing a step closer

2009-04-08T11:14:00.011+01:00

Quantum computing is at the forefront of popular diamond research at the moment - and rightly so. This month's Nature Materials (AOP) has presented a letter from the EQUIND project entitled, 'Ultralong spin coherence time in isotropically engineered diamond', which describes an important step that has been taken into improving the viability of using diamond as a processor for quantum information.

The paper is reporting the longest-ever, room-temperature spin dephasing in N-V centres observed in the solid state, with dephasing times weighing in at 1.8 ms. This long dephasing time is the mainstay of quantum computing and will possibly allow coherent coupling between spins separated by a few nanometers in a quantum information processor. This impressive time has been achieved by almost eradicating all other non-zero spin states in diamond (during its growth), in order to minimise any unwanted interactions between the purposeful N-V centres and other paramagnetic impurities.

The 'quantum grade' single crystal diamond was grown at E6 under the direction of Daniel Twitchen, where the non-zero spin states were minimised by depleting the content of carbon 13 atoms in the diamond lattice from 1.1% to 0.3%. Other impurities such as nitrogen and hydrogen were also minimised resulting in long-lived quantum states.

Nanodiamonds in blue

2009-04-06T12:53:00.005+01:00

Nanodiamonds can come in a variety of colours. Red and green NDs are made by knocking N-V and N-V-N centres into diamond via ionic bombardment and annealing, however blue nanodiamonds are not so easy. Mochalin and Gogotsi from Drexel University have now managed to light up nanodiamonds in blue, but without using the conventional ion bombardment approach.

"When we started this work, we did not intend to produce a fluorescent material, we just explored ways to make hydrophobic nanodiamond that could be easily mixed with motor oils and hydrophobic polymers," says Mochalin. "Octadecylamine is used as a strongly hydrophobic protective coating for boilers. It was a natural choice for us to bind it to nanodiamond. Somewhat surprisingly, this modification resulted not only in highly hydrophobic nanodiamond, but also rendered it fluorescent. And the fluorescence was so bright that it could be detected with bare eyes under a laboratory UV lamp even at high dilutions."

Mochalin and Gogotsi functionalised the nanodiamonds using conventional amine chemistry and are now working to uncover the mechanism for this fluorescence. The full paper, published in JACS can be found here.

Light sensitive p-type surface conduction channels on diamond

2009-03-11T14:19:00.011Z

Last September I wrote a post on the work of Rezek et al., which described the illumination-induced charge transfer between Polypyrrole (PPy) and an H-terminated diamond surface. I left you on the edge of your seats by saying 'there is much work that needs to be done to uncover the possible transfer mechanism between the two substances', so without much further ado...

Cermák et al. have recently fabricated a device in order to gauge the influence of charge transfer between PPy and diamond on H-terminated surface conductivity. The device consists of a contacted and passivated thin strip of H-terminated diamond, upon which there is a non-passivated, covalently bonded PPy cluster. Cermák et al. report that, upon exposure to visible light, the device shows linear IV characteristics with resistivities being an order of magnitude lower than that of dark measurements. Switching the light source on and off, the device has demonstrated a 1 second response time, and a strong dependence on the wavelength of the light source has been reported.

The group ascribes the effect down to exciton creation at the PPy/diamond interface. Since the energetic positions of the trap states of PPy and diamond are similar, holes excited in the PPy can move from the PPy into the diamond, enhancing the p-type surface conduction in the diamond. Unfortunately the conductivity of the PPy-device is 4 orders of magnitude lower than its equivalent solely H-terminated device because of the removal of H-termination during PPy covalent bonding; however, a consolation prize of the large differences in light/dark conductivities is gained.

The full, rather emotionally written paper can be found here!

STED microscopy of N-V centres with nanometric resolution

2009-03-04T11:26:00.003Z

The optical detection of N-V (nitrogen-vacancy) centres in diamond is limited by diffraction and resolution is limited to half the wavelength of light used. However in the latest issue of Nature Photonics, Rittweger et al. report sub-Angstrom precision at pinpointing N-V centres in type IIa CVD diamond - 3 orders of magnitude below the conventional diffraction limit.

Rittweger et al. have used stimulated emission depletion (STED) microscopy to image the N-V centres. STED resolves close-spaced objects by ensuring only one object fluoresces at one time. Employing stimulated emission on the optically-active objects allows them to be transiently switched off, allowing STED to achieve nanometric resolution and Angstrom precision.

The group observed outstanding photostability in the N-V centres, indicating that N-V centres engrained in nanodiamonds will be excellent fluorescent markers for biological nanoscopy. Rittweger et al. now hope to investigate the effects of magnetic and microwave fields on STED microscopy, which may lead to great simplifications in magnetic imaging at the nanoscale.

The full paper can be found here.

Tense atmosphere at E6 after 50% pay cuts announced

2009-02-26T16:57:00.006Z

Following their 150-strong sit-in at the E6 plant in Shannon, the E6 diamond factory workers have been told they are now subject to a week-on week-off rostering system, equating to a 50% pay cut. The management, who announced the new scheme to 400 meeting attendees yesterday, are not subject to the same pay cuts.

"If management are not willing to take the hits like us, why should we? If we have to take a 50% cut in wages, so should they. Half a manager's salary is a damn size more than half mine, so they can afford to take a cut. Let's be fair about it, that's all we ask.... If there have to be cuts to get us through the hard times, these cuts must be spread fairly across the company including management," one worker said.

The company plans to let go 70 more workers, depending on the availability of funds for new redundancy packages.

Sit-in protest at E6 Shannon factory

2009-02-23T11:23:00.004Z

Workers at the Element Six diamond processing facility in Shannon, Ireland, held a sit-in protest this Friday in objection to the 3-weeks-on-1-week-off rostering system proposed by the E6 management. The workforce believe that the measure is being introduced in an unfair manner, in that the management grades are not subject to the same rostering.

The protest ended after the company agreed to defer the introduction of the short time hours, and enter discussions with workers representatives.

Harder than Diamond?

2009-02-20T11:51:00.012Z

The hardest material in the world is diamond, right? Apparently not. Pan et al. at the Department of Physics in Shanghai have recently finished some first-principle calculations to show that wurtzite boron nitride may be some 18% stronger than diamond.

The group proposes that the lattice undergoes a volume-conserving, bond-flipping, structural phase transformation during indentation, and that this mechanism significantly increases the strength of the material above diamond's record value. Pan also demonstrates that Lonsdaleite (hexagonal diamond) also can utilise the same bond reconfiguration mechanism and will produce a superior indentation strength that is 58% higher than diamond.

For now this is only theory and experiments will be needed to test Pan's calculations. The catch is in order to prove the theory, single crystals of each material will be needed and so far there are no known ways to isolate or grow such crystals of either material.

The full paper can be found here.

Multiple conduction paths in boron ∂-doped diamond structures

2009-02-05T15:00:00.006Z

Diamond layers grown by PECVD have exceptional carrier mobilities, the problem is there are very few carriers in diamond to show off this notable accolade. To get around this problem you can introduce dopants into diamond that inject carriers into the crystal. Boron acts as such a dopant; however the p-type acceptor state it forms requires an activation energy of 0.37eV to release its carriers, meaning few holes are present at room temperature. This activation energy can be reduced by increasing the concentration of Boron up to 10^18 atoms cm-3, however carrier mobility greatly suffers as the conduction adopts a quantum-like tunneling mechanism.

∂-doped structures have thrown a life-line into this vicious doping circle. By only doping a very thin layer (ideally 1-2nm) of diamond, it is hoped that carriers can experience the low activation energy but also the high carrier mobilities promised by the intrinsic diamond sandwich layers. Tumilty et al. have now carried out impedance spectroscopy measurements in order to non-destructively characterise these boron-butties.

Tumilty have found that the ∂-doped structures exhibit 3 differing conduction paths. The lowest resistance path has been ascribed to the ∂-doped layer itself, whilst the other conduction paths indicate more complex conduction mechanisms around the ∂-layer.

The full paper can be found here.

Diamond WMD Sensors

2009-02-03T21:57:00.003Z

Advanced Diamond Technologies Inc. (ADT) have won a 3-year $4.8 million contract from the Defense Threat Reduction Agency (DTRA) to develop sensors that detect biological and chemical agents in water. ADT hopes to exploit the superlative binding stability of biomolecules with diamond and fabricate MEMS (micro electrical mechanical systems) devices (cantilever arrays), which will integrate electrical, mechanical, and thermal functionalities together to detect the presence of bacterial and other threats in real-time. ADT with use their own UNCD films to build the sensors.

“Smooth, electrically conducting diamond film has many potential advantages for biosensors. By using MEMS technology, we can miniaturize the devices making it economically feasible for people to carry a sensor in their wallet or as a piece of jewelry which would allow them, for example, to determine if water is safe to drink. In the case of military personnel or first responders, detectors could be integrated into uniforms or personal protective equipment," said John Carlisle, ADT’s chief technical officer.

The full press release can be found on the ADT site.

Nanodiamonds indicate the cause of the Younger Dryas Event

2009-01-21T21:02:00.006Z

13 thousand years ago an unexplained event occurred in the Northern Hemisphere - deglacial warming was interrupted by a short (thousand year) ice age, which came to be known as the Younger Dryas event. The cause of the Younger Dryas Event has remained a mystery, puzzling generations of scientists trying to pin down the instigator of the big freeze, until now that is.

By analysing sedimentary cores in Canada and other localities across North America, Kennett et al. at the University of Oregon have found concentrations of nanodiamonds, supporting a recently hypothesised theory that multiple cometary airbursts barraged North America at the onset of the Younger Dryas Period. These airburts could have triggered massive environmental changes, abrupt extinctions and severe repercussions for plants, animals and humans in North America.

Nanodiamonds (NDs) are associated with comet impacts either by arriving inside impacting meteorites or forming through shock metamorphism upon re-entry. The anthropolgy group in Oregon found subrounded, spherical and octahedral crystallites, ranging in size from 2 to 300 nm that were distributed within carbon spherules, suggesting they crystallised from the amorphous carbon matrix.

Is there anything nanodiamonds can't do? The paper can be found in Science, here.

E6 rostering dispute passed onto Labour Relations Commision

2009-01-21T18:46:00.004Z

The E6 saga has taken a turn for the worse following a meeting between Siptu (Services, Industrial, Professional and Technical Union) and Element Six management last Friday. No progress has been made in the standoff between disgruntled E6 workers and the credit-crunched E6 management since they exposed their plans to reduce working hours for the Shannon-based workers. With no agreement being met, the matter has been referred to the Labour Relations Commission for discussion tomorrow. Workers say they will participate in talks to finalise a redundancy package for the 150 staff only when the short-time plan is “off the table”.

Workers warn E6 of mass walkout

2009-01-07T12:21:00.007Z

The new year has begun with uncertainty for the workers of the E6 factory in Shannon Ireland, whom are still turning up for work in spite of the '3 weeks on, 1 week off' rostering system proposed by E6 which started this week. Workers have warned that a mass walkout will occur if colleagues who are not rostered to work are not allowed to enter the plant and carry out their duties. E6 still stands by the rostering system being an 'interim measure' until redundancy packages are negotiated.

Aside, if you have an iPhone you can now add a The Diamond Geyser to your home screen, complete with a custom Diamond Geyser icon.

Diamond X-Ray Lenses

2009-01-06T14:08:00.005Z

The X-Rays produced in synchrotrons such as the Diamond Light Source (pictured above) need precise focusing and phase alignment. X-Ray optics, called Kinoform lenses, are computer-generated phase optics that, upon illumination, deliver an image of the mathematically desired object. Diamond lends itself to be an ideal material for Kinoform lenses; it has a low absorption of radiation, a relatively large decrement of refractive index and a high thermal conductivity - allowing it to withstand the high power loads from synchrotron sources.

Unfortunately the difficulty of sculpting diamond into the invariably complicated patterns of Kinoform lenses has lead Silicon to be used in its place, however a group from the Brookhaven National Laboratory have recently made a Kinoform lens out of diamond. Isakovic et al. have developed a precise sculpting process that involves a 3-step O2/Ar etch, designed to give high aspect ratios and low surface roughness. Isakovic et al. found the diamond lenses performed better than the Si lenses, and they demonstrated angular control of the focal spot. The full paper can be found here.

Happy New Year!

Happy Christmas!

2008-12-23T16:29:00.003Z

I'm in an archaic village somewhere in Hampshire, but have managed to find some very expensive internet to wish you all a very Happy Christmas and a Happy New Year. See you 2009!

"Three weeks on - one week off" for disgruntled Element Six workers

2008-12-11T10:16:00.004Z

Element Six workers are having a tough few weeks. Following the announcement of 150 redundancies at the Shannon plant (see below), the workers have now been told there are plans to introduce a three-week working month and a rostering system for the remaining workforce on January 5th, 2009.

The letter describing the "three week on - one week off" scheme was due to be sent this week, however as of last night it has not been sent and it is thought the company has bowed to union pressure and has put the plan on hold.

Downturn hits diamonds as Element Six lets go 150 employees

2008-12-02T16:34:00.008Z

The Mayor of Clare today described the loss of 150 jobs at Shannon-based industrial diamonds company, Element Six, as a hammer blow to the entire West of Ireland economy. Element Six,currently employs 620 people at the plant to manufacture and distribute industrial diamonds and super-hard materials, and said the jobs cuts are necessary due to a 50% fall in sales.

“While I recognise that the company has confirmed the redundancies are part of a group-wide cost-saving programme in the organisation, it must be pointed out that the company’s General Manager last year indicated its operations were under ‘active review’. The fact that the company turned pre-tax profits of just over $2m last year, well ahead of 2005's $9m loss, shows that rising operating costs coupled with the global economic downturn is having a real impact on major multinationals,” stated Mayor Taylor Quinn. She said she believed the 50% fall in sales experienced by the firm had been further compounded by the loss of the Shannon to Heathrow service. The Mayor also indicated that the ending of the service had resulted in the region becoming a less competitive and attractive location for existing and potential investors.

Buried conductive channels in single crystal diamond

2008-11-26T12:08:00.007Z

Olivero et al. at the University of Torino, Italy, have become the first group to fabricate three-dimensional conductive micropaths in single crystal diamond. The micropaths have been made by bombarding single crystal diamond with a high energy (6 MeV) focused ion beam of C3+ ions, which deposits its energy in concentrated paths ~2.7µm below the surface to form conductive graphitic channels.

Whilst the conductive channel is dug into the diamond, the overlying region of diamond remains relatively undamaged. At MeV kinetic energies, ions have low collision cross-sections, hence pass through the diamond incurring only minor collisions which do not transfer much energy. Only after the ions lose enough of their energy in these glancing collisions does their collision cross-section increase sufficiently for them to deposit the bulk of their energy and graphitise the diamond.

Contacts to the surface from the buried conduction paths have been realised by using small dome-shaped metallic masks in the path fabrication stage. The masks' dome-like shapes give the ion beam an increasingly lengthy path to penetrate as it traverses the mask, meaning the conductive graphite path is deposited nearer and nearer to the surface as the mask thickness increases.

As a result of the ion implantation, 200nm swellings at the diamond surface have been reported and resistivities of 0.9 Ωcm have been achieved for the graphite paths. The resistivity of graphite is 1.4x10-3 Ωcm, which suggests the conducting medium is not constituted of an ordered sp2-bonded phase, and hence the group will be working to optimise the implantation process and improve the electrical characterisation of the buried channels.

The article in press can be found here.

Diamond Dialysis

2008-11-23T20:27:00.003Z

Kidney failure means going to a hospital three times a week to be hooked up to an expensive dialysis machine for a few hours. William Fissel at the Cleveland Clinic and colleagues from the University of Ohio have taken the first steps to making an implantable dialysis machine, made possible by the exceptional biocompatibilty of diamond.

Being only being 300mm wide, Fissel's invention is small enough to implant in the body. It consists of successive layers of diamond film that are puckered with nanopores of decreasing size, which filter toxic molecules from the blood stream. The nanopores have widths of less than 20nm and, in order to prevent protein clogging, the device employs an electric field across the pores to steer proteins away from the tiny holes. Fissel says the the diamond device can operate at normal blood pressures and will be more efficient than conventional dialysis membranes.

The full patent can be found here.

BAE Systems buy a 50% share of Diamond Detectors Ltd.

2008-11-17T21:06:00.008Z

Diamond Detector's Ltd. (a spin off of Element 6) make diamond devices for detecting particle, X-Ray and deep-UV radiation. BAE Systems have just secured a 50% holding in it, investing £2 million in Diamond Detectors Ltd.

"We welcome on board a strategic investor that has a requirement for the products under development at Diamond Detectors Ltd," says Brendon Grunewald, Head of E6 Ventures. "This second round of funding will support the company as it moves into full product commercialisation".

Having personally just attended a conference on high-tech start-ups and the defense industry, it 's amusing to see a timely example of the increasing prominence of defense funding in high-tech start-ups. To read more about radiation detection with diamond - a specialty of our group - click here.

We are the change that we seek

2008-11-04T22:57:00.010Z

Sick of nanodiamonds and spin? Feel like your research is under-represented? Why not join our team and write for The Diamond Geyser! Send an email to us to be inaugurated, or if blogging doesn't take your fancy make your voice heard in the comments section below.

Crystal cleared! The pressure's off...

2008-11-03T18:49:00.017Z

Chen et al. from the Carnegie Institution of Washington have found you can take one 'H' out of HPHT annealing. High Pressure High Temperature (HPHT) annealing is used to enhance the optical properties of diamond however the high pressures required (5GPa) mean a specific, expensive kit is needed to do so. The Low Pressure High Temperature (LPHT) annealing developed by Chen et al. means that high-quality, fast-grown (150µm/h) single crystal diamond can be annealed straight after its growth in the same CVD reactor.

Chen et al. have achieved reductions in optical absorption of single crystal CVD diamond by up to 6 times by annealing them at pressures of only 25MPa; 200 times less than HPHT methods. Reductions in UV, visible and infrared light have been observed after LPHT annealing, whilst increases in specific absorption bands is providing insight into the purifying mechanism.

General reductions in spectral signatures have indicated that the LPHT goes to work by removing due to C-H bonding from the crystal lattice. Reductions in characteristic spectral absorption line of N-V-H (Nitrogen Vacancy Hydrogen) centres along with increases in the N-V centres' line also suggests that LPHT annealing could be used to control the concentration of N-V centres in single crystal CVD diamond.

That could be of interest to the quantum folk out there. What will this do for nanodiamonds?

Inkjet nanodiamond printing

2008-10-27T11:16:00.007Z

Making a diamond circuit is an expensive and multifaceted process. My current project (which is building a multiple electrode array out of conductive diamond) has involved seeding a substrate with nanodiamonds, growing a film from the nanodiamond seeds, doing RIE etching tests, making a photolithography mask, imprinting said-mask onto a photoresist and finally etching the diamond tracks. Chen et al. at the Alabama Micro/Nano Science and Technology Centre have been developing a new approach to patterning diamond films using a trusty inkjet printer that cuts this list down to manageable 2 items.

By infusing a specially made ink of ethylene glycol with a suspension of nanodiamonds, they have managed to print near-continuous films of nanodiamonds onto silicon substrates, with feature sizes of 12µm. Having patterned the nanodiamonds, the group has grown films of nanocrystalline diamond on top of the seeded patterns using the CVD process. Chen's technique not only saves money and time in thin film patterning, but it also reduces waste by avoiding seeding a whole substrate with nanodiamonds. Chen et al. optimised the ink's viscosity so that nanodiamonds were held in non-aggregated suspension, did not re-flow once printed and did not clog the inkjet nozzle. Whilst inkjet printing is not likely to replace conventional photolithgoraphy for patterning diamond, this interesting approach will allow 3D printing through sequential printing and growth.

The full paper entitled, 'Inkjet printing of nanodiamond suspensions in ethylene glycol for CVD growth of patterned diamond structures and practical applications' can be found in here.

Diamond Lasers

2008-10-21T11:57:00.007+01:00

Diamond is not a direct band gap material; to promote electrons into its conduction band it needs an interaction with a phonon to create a population inversion. This fact would stop most scientists in their tracks when choosing a material to build a laser, however Dr. Alan Kemp at the University of Strathclyde has been supported by a grant of more than £600,000 from the EPSRC to do just that. Although diamond is not suited to being a conventional lasing material, it shows great potential as being an excellent suitor for a Raman laser.

Raman lasers are a class of laser which circumvent the direct band gap problem. By using light to excite lattice phonons - rather than electrons - they can create a population inversion to fuel a laser system. As the excited phonons relax, they emit secondary light photons, which are then reflected back into the crystal and amplified into a coherent laser beam. The wavelength of the secondary light depends on the energy of phonon vibrations, hence Raman lasers allow the tuning of laser beams. As Dr. Kemp says, the ability to shift the wavelengths “gives access to the application-rich, but currently source-poor, yellow-orange region of the spectrum.”

Most commercial lasers operate in the near infrared region of the spectrum between 0.8 µm to 1.1 µm with a particular concentration around 1 µm (1.03 – 1.07 µm) where most of the high performance laser work is done. “Perhaps the most important challenge in modern solid-state laser engineering,” says Dr. Kemp, “is to find ways to generate new wavelengths but in doing so to retain as much as possible of the convenience and performance of current lasers.”

Diamond is lending itself well to tackling this important challenge; it's indirect band gap, high Raman gain coefficent and large Raman shift extend its application potential, however diamond is most importantly lending itself to the more conventional challenges encountered by laser engineers. “The least glamorous but most pervasive problem in laser engineering, particularly when you want high performance in a small package, is how to deal with heat,” says Dr. Kemp.

Diamond has a complementary repertoire of properties for lasing, those being; a very high thermal conductivity, a very small coefficient of thermal expansion and an ultra-low birefringence (when the speed of light in a medium varies if the polarisation of the light changes) which will allow it to handle much higher power loads than current solid state Raman lasers.

Detonation Nanodiamond Paper

2008-10-13T12:18:00.008+01:00

This is our work on Detonation Nanodiamond published on APL:
'Electrical properties of aggregated detonation nanodiamonds'

This is another interesting paper on the same subject:
'New prospects and frontiers of nanodiamond clusters'

Nanodiamond-Embedded Microfilms go to pre-clinical trials

2008-10-06T16:28:00.006+01:00

After surgery to remove a tumour, there is the risk of the tumour returning. This risk can be reduced with chemotherapeutic drugs, however the carpet-bombing method employed by chemotherapy brings about nasty side effects and unnecessary healthy tissue damage.

Targeting the tumour directly is a hot topic, and one that has driven many advances in biological and physical nanotechnology. Ho et al.s' approach is to use nanodiamond clusters embedded with DOX - Doxorubicin Hydrocholride, a chemotherapeutic agent - sandwiched between two biocompatible microfilms. Nanodiamond clusters have sequestrating abilities; ionic complexes are formed between the nanodiamond and DOX so that the effect of the drug is passivated until release.

This passivation combined with the slow release of the drug (further amplified by the sandwiching microfilm) results in an idyllic slow release of DOX, avoiding the damaging initial burst other therapies can give. The flexible film can be implanted simply at the end of surgery, and been shown to steadily release DOX for at least one month.

DOX is not the only drug that can be stored in the nanodiamond clusters. Anti-inflammatories, anti-viral and virtual any therapeutic molecule has been found to conjugate with the nanoclusters. The full paper and an interview with Ho can be found here.

Single Spin NMR Detection in Diamond

2008-10-03T15:46:00.005+01:00

Yesterday, Nature's most recent publication presented two new papers regarding single spin NMR detection in nitrogen-vacancy (N-V) defect centres of ultra-pure diamond. Maze et al. and Balasubramanian et al. reported complementary magnetic sensing techniques, that if used well in combination, could lead to the detection and imaging of individual nuclear spins to allow the determination of the structure of a single molecule. Most importantly, both experiments were carried out at room temperature; it will be these physiological conditions that will pave the way for biological applications such as the determination of protein structures or detailed imaging of the internal structure of a living cell.

An approachable summary of the two papers can be found here, or the rather daunting original papers, 'Nanoscale magnetic sensing with an individual electronic spin in diamond' and 'Nanoscale imaging magnetometry with diamond spins under ambient conditions' can be found in their respective links.

Turning alcohol into Diamond

2008-09-24T16:01:00.008+01:00

In June we saw Morales et al. turn tequila into diamond. Now Toyota et al. have transformed pure alcohol into diamond.

Far from being a gimmick, this new technique of diamond growth is proving to be very advantageous over conventional gas-phase plasma enhanced chemical vapour deposition (PECVD) techniques.

By creating an in-liquid plasma of methanol, Toyota et al. have utilised the high-density of the liquid to induce a high-speed chemical reaction at normal temperatures and pressures. Very high growth rates of diamond were found, reaching the breakneck speeds of 100µm/h. The growth parameters were tailored to optimise only growth rate and there is still much work needed to improve these values.

The simplicity of the growth-equipment and the approachable parameters presented by the Japanese Group show great promise for the better integration of diamond into non-diamond devices. Conventional growth temperatures and pressures prove inhospitable for most other electronic materials that are not diamond. The full paper entitled, 'Submerged synthesis of diamond in liquid alcohol plasma' can be found here.

Diamond AFMs from ADT

2008-09-10T12:29:00.003+01:00

“Remember phonograph needles? They had to be replaced every second or third time you listened to a record—very similar to today’s AFM probes. Then came diamond styli which ushered in the era of the LP (long playing record) which transformed the music industry. What diamond did for records it will do to micromachines such as sensors, resonators, switches, and AFM probes,” says Advanced Diamond Technologies's president Neil Kane.

ADT have just made available the world's first all-Diamond AFM tip; the NaDiaProbe. NaDiaProbes provide outstanding sharpness, dimensional stability and wear resistance. Compared with standard silicon or SiN probes, NaDiaProbes will last over 100 times longer when imaging hard surfaces whilst maintaining tip radii better than 25 nm. NaDiaProbes also exhibit the low adhesion and low surface energy properties of diamond which enhance performance when imaging soft, sticky materials.

The NaDaiProbes not only outperform conventional SiN probes, but they also possess a higher price perfomance ratio (x30) to their SiN counterparts. That is, until you break it.

"Thin, smooth, diamond films on wafers enable groundbreaking products - in this case, the world's first diamond microdevice," said Dr. John Carlisle, ADT's chief technical officer. "NaDiaProbes showcase our ability to make diamond products using semiconductor manufacturing techniques, and they pave the way for advanced MEMS (micro-electrical-mechanical systems) devices. When it comes to an engineering material, it doesn’t get any better than diamond.”

sp3 Diamond Technologies are a cut above the rest

2008-09-04T16:50:00.002+01:00

sp3 Diamond Technologies are the proud owners of a new Bettonville 5XS IR Nd: YAG (TEM 00) Laser in its Alberta facility. The new laser gives sp3 the ability to cut more complex shapes with highly vertical edges (<1º) allowing them to sell their CVD diamond to a broader range of cutting tool customers. The new tool has already attracted new customers to the business.

Diamonds see the light

2008-09-02T18:37:00.004+01:00

Hydrogen-terminating diamond surfaces can result in the rare phenomenon of a negative electron affinity. Electrons readily leave the surface of the diamond into the adjoining medium, leaving behind a shallow layer of electron holes. This gives H-terminated diamond surfaces p-type semiconductor conductivity.

B. Rezek et al. have exploited this effect to possibly mediate charge transfer between diamond and the visibly photo active molecule, polypyrrole (PPy). Whilst there is much work that needs to be done to uncover the possible transfer mechanism between the two substances, light and dark light conditions show clear differences in the surface potential of the diamond and PPy layer.

The results indicate potential for light-to-electrical interfaces on diamond, which will be encouraging to fluorescent microscopists everywhere.

Plenty of room for nanofactories

2008-08-13T17:02:00.008+01:00

Feynman first proposed the molecular lab in his famous 1959 lecture, There's Plenty of Room at the Bottom. "... I am not afraid to consider the final question as to whether, ultimately - in the great future - we can arrange the atoms the way we want; the very atoms, all the way down! What would happen if we could arrange the atoms one by one the way we want them?".

In the not-so distant future, the Nanoscience department of the University of Nottingham is also not afraid to consider this question, having just secured a five-year £1.53 million grant to create the first Diamond Nanofactory. Professor Philip Moriarty and his group will lead the nanofactory collaboration, entitled 'Digital Matter? Towards Mechanised Mechanosynthesis', to build nanoscale diamond devices, atom by atom, using scanning probe microspcopy techinques under high vacuum. Theoretical work has already suggested the possibility of a rechargable toolset that will be able to extract hydrogen, deposit carbon, and donate hydrogen to a diamond surface. The EPSRC grant will fund experiments to explore the possiblity of such diamond mechanosythesis (DMS).

DNA and Diamonds

2008-08-08T14:50:00.007+01:00

Yang et al. have used diamond wires to detect single strands of DNA (ssDNA) electronically. Electronic detection of DNA strands is a promising alternative to fluorescent detection as they will be much simpler to implement. Strands of ssDNA were attached to reactive ion etched diamond cones. Upon hybridisation with a complementary strand in solution, an electrical read-out was recorded that could detect DNA at the picomolar concentrations. Yang et al.'s work, originally published in Angewandte Chemie, has since been reported in Nature. The original paper can be found here.

2008-08-07T11:34:00.004+01:00

OK, guys, so I have arrived in blog land for the first time...watch this space

Smooth etching

2008-08-05T15:38:00.007+01:00

This paper is slightly old (Apr08 - ancient), however it is very relevant to my last post and my current work, so here it is...

Quantum Computing using Diamond is a promising technology. To realise such technology, efficient waveguides must be made in diamond to transport light around the device with minimal losses.

M. P. Hiscocks et al. have developed a process that produces the smoothest side walls of diamond (using RIE) etching to-date, as reported in the paper, 'Reactive ion etching of waveguide structures in diamond'. The NCD is etched using a combination of 02, Ar and a small amount of CHF3 (to remove diamond whiskers formed because of micro-masking during RIE etching).

A new spin on diamond quantum computers

2008-07-31T15:53:00.004+01:00

The Stuttgart Group, belonging to the EQUIND (Engineered Quantum Information in Nanostructured Diamond) project, have recently demonstrated 'Multipartite Entanglement Among Single Spins in Diamond'. P. Neumann et al. achieved nuclear spin correlations of nitrogen-vacancy defect centres, exhibiting quantum entanglements of up to 3 C13 nuclei for timescales of up to milliseconds. They have used hyperfine and dipolar coupling to control two nuclear spins on an individual basis, in turn demonstrating the entanglement of the C13 nuclei. Entanglement is an essential quantum effect in order to realise quantum computers. Diamond, unlike most materials, is advantageous because entanglement can be achieved at room temperature. This paper reports single nuclear spin entanglements for the first time.

For an more introductory article on the role of diamond in quantum computing, visit here.

Bubbles that produce diamonds

2008-07-28T17:24:00.011+01:00

Collapsing bubbles can form very high temperatures and pressures. The Pistol Shrimp uses its powerful claw to shoot collapsing bubbles at its prey, creating temperatures in excess of 5000K and stunning 8kPa shockwaves.

A. Kh. Khachatryan et al. have employed this effect to synthesise diamond from graphite under the surprising conditions of 120ºC and atmospheric pressure, by using ultrasound cavitation.

The formation of high and low pressure nodes in ultrasound acoustic waves result in the formation and quick collapse of cavitation bubbles. A liquid exposed to ultrasound experiences low nodal-pressures below its vapour pressure; this causes the liquid to change phase into a vapour, producing nascent bubbles. The following high pressure node of the ultrasound (combined with surface tension) collapses the bubbles to create the high temperatures and pressures necessary for graphite-to-diamond transformation.

Well-defined diamond particles of 5-10µm were formed at a 10% mass yield (from a hexagonal graphite suspension). The cavitation process required 600kJ of energy for every gram of diamond, whereas a CVD reactor requires 2000MJ per gram.

- The spherical collapse of bubbles is important to achieve maximum cavitation impulse, however, this author wonders how ultrasound cavitation would fare in repairing graphitised surfaces of diamond devices.

Rob

H. Tracy Hall passes away

2008-07-26T14:28:00.010+01:00

H. Tracy Hall - the first man to make synthetic diamond - passed away this Friday aged 88 years old.

In 1954, using temperatures of more than 2760ºC and 103420 bars of pressure, Hall became the first person to make synthetic diamond. In 1966, aware of the huge potential of the industrial diamond industry, Hall teamed up with two other BYU professors to found Megadiamond, a manufacturer of diamonds and high-pressure equipment.

"People had been trying to synthesize diamonds for hundreds of years," said Leo Merrill, an acquaintance and colleague since 1952.
"He should have gotten a Nobel Prize."

Hall, who battled Alzheimer's and diabetes, is survived by four brothers, seven children, 35 grandchildren, and 53 great-grandchildren.

Warning: Slippery when wet

2008-07-16T16:59:00.008+01:00

A.R. Konicek et al. have made headway into uncovering the origins of ultralow friction in diamond.

The paper, entitled "Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond", sheds light on the debate of whether the slippery nature of diamond comes from the rehybridisation of sp2 bonds (graphite) or from the passivation of dangling bonds by environmental passivating species (H2 and H2O).

For the first time, spectroscopic experiments investigating surface wear of UNCD (under wet-and-dry and high-and-low loadings) conclude that there is 'definitive evidence supporting the passivation hypothesis'.

This conclusion was formed, in part, from the observation of increased C-O and C=O bonding. In the presence H2O, the dangling bonds become either -OH or -H terminated. Dangling bonds of carbon increase friction and wear due to interfacial bonding; -H and -OH ions passivate these bonds reducing friction.

I want diamond coated ice skates.

Rob