THE PECULIARITIES OF THE LOCAL THERMAL-DIFFUSIVITY OF LARGE SYNTHETIC DIAMONDS

A series of large diamond single crystals was prepared using Fe-Ni solvent-catalyst by the temperature gradient method. Local thermal diffusivity was measured by an original experimental technique and the results obtained were: 2.2 to 8.0 cm(2)/s for nitrogen-containing samples and similar to 11 cm(2)/s for nitrogen-free samples (grown with Ti getter). To explain the observed peculiarities of the distribution of the local thermal diffusivity, visible-IR absorption spectra, photo- and cathodoluminescence in the visible range and X-ray projection topographs were studied. The body of the results obtained enabled us to suggest that, in synthetic diamonds of the type studied, the main contribution to the thermal resistance is made by phonon scattering on defects including Ni ions in their structure.