Electropositive Nanodiamond-Coated Quartz Microfiber Membranes for Virus and Dye Filtration.

Electropositive membranes demonstrating high flux at low pressure differentials show great promise as universal separation platforms for viruses and other charged entities when centralized systems of water and power are scarce. However, the fabrication of a suitably stable membrane with optimal electrostatic characteristics remains a challenge. Here, hydrogenated detonation nanodiamond was loaded onto a quartz microfiber support membrane and coupled to the membrane surface under a high vacuum annealing process. The fabricated membranes display a zeta potential of +45 mV at pH 7 and an isoelectric point around pH 11. We show that the nanodiamond coating is robust to prolonged periods of pressurized water flow by performing extensive zeta potential measurements over time, and water filtration tests demonstrated excellent membrane retention for the electronegative dye molecule acid black 2, and at least a 6.2 log10 reduction in MS2 bacteriophage from feed waters (>99.9999%).

Author Correction: Superconducting Diamond on Silicon Nitride for Device Applications.

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Superconducting boron doped nanocrystalline diamond on boron nitride ceramics.

In this work we have demonstrated the growth of nanocrystalline diamond on boron nitride ceramic. We measured the zeta potential of the ceramics to select the diamond seeds. Diamond was then grown on the seeded ceramics using a microwave chemical vapour deposition system. A clear difference was found between the samples which were seeded with nanodiamond and the ones not seeded before growth. Raman spectroscopy confirmed the excellent quality of the diamond film. Dielectric measurements showed an increase in the dielectric constant of the material after diamond growth. The diamond was also doped with boron to make it superconducting. The film had a transition temperature close to 3.4 K. Similar strategies can be applied for the growth of diamond on other types of ceramics.

Superconducting Diamond on Silicon Nitride for Device Applications.

Chemical vapour deposition (CVD) grown nanocrystalline diamond is an attractive material for the fabrication of devices. For some device architectures, optimisation of its growth on silicon nitride is essential. Here, the effects of three pre-growth surface treatments, often employed as cleaning methods, were investigated. Such treatments provide control over the surface charge of the silicon nitride substrate through modification of the surface functionality, allowing for the optimisation of electrostatic diamond seeding densities. Zeta potential measurements and X-ray photoelectron spectroscopy (XPS) were used to analyse the silicon nitride surface following each treatment. Exposing silicon nitride to an oxygen plasma offered optimal surface conditions for the electrostatic self-assembly of a hydrogen-terminated diamond nanoparticle monolayer. The subsequent growth of boron-doped nanocrystalline diamond thin films on modified silicon nitride, under CVD conditions, produced coalesced films for oxygen plasma and solvent treatments, whilst pin-holing of the diamond film was observed following RCA-1 treatment. The sharpest superconducting transition was observed for diamond grown on oxygen plasma treated silicon nitride, demonstrating it to be of the least structural disorder. Modifications to the substrate surface optimise the seeding and growth processes for the fabrication of diamond on silicon nitride devices.