MANIFESTATION OF DISTORTIONS OF CRYSTAL LATTICE IN THE IR REFLECTION SPECTRA OF ABRASION TREATED ZnSe CERAMICS

Abstract

The FTIR reflection spectra of ZnSe ceramics prepared by hot pressing (HP), physical vapor deposition (PVD), and PVD combined with isostatic hot pressing (HIP) are presented. The optical constants of polished and dry-ground specimens were taken for comparison. The grinding treatment simulated the erosion of faces of optical elements made of zinc selenide under hard dust particles and weathering. In polished spectra, the residual stresses manifested themselves in the IR reflection spectra of the ZnSe^PVD and ZnSe^HIP ceramics characterized by the pronounced orientation of grains but were lacking in the spectra of the ZnSe^HIP ceramics due to a cancellation effect in randomly oriented grains of the latter material. The stresses detected by shifts of the absorption bands calculated by the Kramers-Kronig method increased significantly after the abrasive treatment of the specimens. In addition, the absorption bands caused by anharmonicity of the distorted lattice increased several times. The latter effect was dependent on the processing pre-history of the ceramics.