Spectral diagnostics of oscillation centers in crystals with hydrogen bonds

Abstract

Practical application of crystals in optoelectronics and laser engineering requires the directions of optical axes and the types of oscillation centers be known, and this is an important and necessary condition. We have studied the infrared transmittance and absorption spectra of hexagonal lithium iodate α-LiIО3 crystals grown by open evaporation method in H2O and D2O solutions and natural lamellar monoclinic crystals of phlogopite and muscovite. The band gap of the test crystals has been determined from the transmittance spectra. The absorption spectra have provided information on the activation energy and wavelength of the activation centers related to the oscillations of protons, hydroxonium ions Н3О+, protium Н+, ОН- groups and HDO molecules. There has been a good correlation between the parameters of infrared spectra, thermally stimulated depolarization current spectra and nuclear magnetic resonance spectra. We have analyzed the possibility of oscillation center diagnostics based on infrared spectra which also allow determining the directions of optical axes. The experimental results confirm the possibility of using IR spectra for determining the type of oscillation centers and the presence of lattice anisotropy in test crystals.