Vibrational and Reflectional Spectra of cBN

Spectra of synthesized cBN crystal (black, yellow, brown in color and 50 m) were measured by using IR, Raman and UV. The results are described in the following sections: (1) According to the infrared absorption spectrum, the sharp 1 818 cm-1 and 1 548 cm-1 absorption spectrum bands is intrinsic vibration of cBN, while the defect absorption appears at 800 cm-1, 1 560 cm-1~1 740 cm-1 and 2 400 cm-1. (2) The Raman scattering spectrum shows that two lines appeared at 1 052 cm-1 and 1 034 cm-1 are in agreement with the fact the cBN possesses cubic symmetry without inversion center. The lines in the spectrum correspond to the Stokes components of first modes Raman scattering with the emission of transverse and longitudinal optical phonons in the center of the Brillouin zone. The presence of line 144 cm-1 can be accounted for by the emergence of local oscillation modes connected with the presence of impurity-defect complexes in the lattice. (3) The result of cBN reflection at spectrum indicates that three types of cBN crystals possess greater values of band gap which are Eg=6.12 eV (black), Eg=5.73 eV (yellow), Eg=5.71 eV (brown), respectively.