Process for treatment of a sapphire part with a beam of a mixture of mono- and multicharged ions of a gas which are produced by an electron cyclotron resonance (ECR) source, where: the voltage for acceleration of the ions is between 10 kV and 100 kV; the implanted dose, expressed in ions/cm.sup.2, is between (510.sup.16)(M/14).sup.1/2 and 10.sup.17(M/14).sup.1/2, where M is the atomic mass of the ion; the rate of displacement V.sub.D, expressed in cm/s, is between 0.025(P/D) and 0.1(P/D), where P is the power of the beam, expressed in W (watts), and D is the diameter of the beam, expressed in cm (centimetres). A part made of sapphire having a high transmittance and which is resistant to scratching is thus advantageously obtained.

An electrochemical cell includes a working electrode in contact with an aqueous electrolyte solution, a counter electrode in contact with the aqueous electrolyte solution, and a reference electrode in contact with the aqueous electrolyte solution. The working electrode comprises a plasma modified epitaxial synthesized graphene surface fabricated on SiC.

An electrochemical cell includes a working electrode in contact with an aqueous electrolyte solution, a counter electrode in contact with the aqueous electrolyte solution, and a reference electrode in contact with the aqueous electrolyte solution. The working electrode comprises a plasma modified epitaxial synthesized graphene surface fabricated on SiC.

The luminance of a transmission mode X-ray scintillator diamond plate is dominated by induced defect centers having an excited state lifetime less than 10 msec, and in embodiments less than 1 msec, 100 usec, 10 used, 1 used, 100 nsec, or even 50 nsec, thereby providing enhanced X-ray luminance response and an X-ray flux dynamic range that is linear with X-ray flux on a log-log scale over at least three orders of magnitude. The diamond plate can be a single crystal having a dislocation density of less than 10.sup.4 per square centimeter, and having surfaces that are ion milled instead of mechanically polished. The defect centers can be SiV centers induced by silicon doping during CVD diamond formation, and/or NV0 centers formed by nitrogen doping followed by applying electron beam irradiation of the diamond plate and annealing.

The luminance of a transmission mode X-ray scintillator diamond plate is dominated by induced defect centers having an excited state lifetime less than 10 msec, and in embodiments less than 1 msec, 100 usec, 10 used, 1 used, 100 nsec, or even 50 nsec, thereby providing enhanced X-ray luminance response and an X-ray flux dynamic range that is linear with X-ray flux on a log-log scale over at least three orders of magnitude. The diamond plate can be a single crystal having a dislocation density of less than 10.sup.4 per square centimeter, and having surfaces that are ion milled instead of mechanically polished. The defect centers can be SiV centers induced by silicon doping during CVD diamond formation, and/or NV0 centers formed by nitrogen doping followed by applying electron beam irradiation of the diamond plate and annealing.

There is described a single crystal CVD diamond material comprising three orthogonal dimensions of at least 2 mm; one or more regions of low optical birefringence, indicative of low strain, such that in a sample of the single crystal CVD diamond material having a thickness in a range 0.5 mm to 1.0 mm and an area of greater than 1.3 mm1.3 mm and measured using a pixel size of area in a range 11 m.sup.2 to 2020 m.sup.2, a maximum value of n.sub.[average] does not exceed 1.510.sup.4 for the one or more regions of low optical birefringence, where n.sub.[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness; one or more regions of high optical birefringence, indicative of high strain, such that in said sample of the single crystal CVD diamond material and measured using said pixel size, n.sub.[average] is greater than 1.510.sup.4 and less than 310.sup.3; and is wherein every 1.3 mm1.3 mm area of the sample of the single crystal CVD diamond material comprises at least one of said regions of high optical birefringence. There is also described a method of making the CVD diamond material.

There is described a single crystal CVD diamond material comprising three orthogonal dimensions of at least 2 mm; one or more regions of low optical birefringence, indicative of low strain, such that in a sample of the single crystal CVD diamond material having a thickness in a range 0.5 mm to 1.0 mm and an area of greater than 1.3 mm1.3 mm and measured using a pixel size of area in a range 11 m.sup.2 to 2020 m.sup.2, a maximum value of n.sub.[average] does not exceed 1.510.sup.4 for the one or more regions of low optical birefringence, where n.sub.[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness; one or more regions of high optical birefringence, indicative of high strain, such that in said sample of the single crystal CVD diamond material and measured using said pixel size, n.sub.[average] is greater than 1.510.sup.4 and less than 310.sup.3; and is wherein every 1.3 mm1.3 mm area of the sample of the single crystal CVD diamond material comprises at least one of said regions of high optical birefringence. There is also described a method of making the CVD diamond material.

A method for the production of a graphene layer structure having from 1 to 100 graphene layers, the method comprising providing a substrate having a thermal resistance equal to or greater than that of sapphire, on a heated susceptor in a reaction chamber, the chamber having a plurality of cooled inlets arranged so that, in use, the inlets are distributed across the substrate and have a constant separation from the substrate, supplying a flow comprising a precursor compound through the inlets and into the reaction chamber to thereby decompose the precursor compound and form graphene on the substrate, wherein the inlets are cooled to less than 100 C., preferably 50 to 60 C., and the susceptor is heated to a temperature of at least 50 C. in excess of a decomposition temperature of the precursor, using a laser to selectively ablate graphene from the substrate, wherein the laser has a wavelength in excess of 600 nm and a power of less than 50 Watts.

A method for the production of a graphene layer structure having from 1 to 100 graphene layers, the method comprising providing a substrate having a thermal resistance equal to or greater than that of sapphire, on a heated susceptor in a reaction chamber, the chamber having a plurality of cooled inlets arranged so that, in use, the inlets are distributed across the substrate and have a constant separation from the substrate, supplying a flow comprising a precursor compound through the inlets and into the reaction chamber to thereby decompose the precursor compound and form graphene on the substrate, wherein the inlets are cooled to less than 100 C., preferably 50 to 60 C., and the susceptor is heated to a temperature of at least 50 C. in excess of a decomposition temperature of the precursor, using a laser to selectively ablate graphene from the substrate, wherein the laser has a wavelength in excess of 600 nm and a power of less than 50 Watts.

A synthetic single crystal diamond contains nitrogen atoms at a concentration of more than 600 ppm and 1500 ppm or less, and the nitrogen atoms do not include any isolated substitutional nitrogen atom.