| abstract |
A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 125 µm; and one or both of the following characteristics measured. at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and. having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ¤0.2cm-1 at 10.6 µm; and. a dielectric loss coefficient at 145 GHz, or tan δ ¤2 x 10-4. A microwave reactor and process for synthesising the CVD diamond wafer are also disclosed. |