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.
Highlights
An important task of modern science is to provide nondestructive quality control methods for laser and optical crystals during crystal growth and study of new crystalline materials
It was assumed that the absorption band near 3400 nm confirms the probability that hydrogen ions are present [9, p. 275]. This wavelength corresponds to an oscillation center energy of 0.365 eV and this band iwas present in the IR spectra of the silicates and lithium iodate grown in H2O with iodic
The conclusions made from IR spectroscopic studies are in a good agreement with thermally stimulated depolarization current spectra (TSDC) and nuclear magnetic resonance (NMR) spectra
Summary
An important task of modern science is to provide nondestructive quality control methods for laser and optical crystals during crystal growth and study of new crystalline materials. The diagnostics of these materials can be considered as a nanotechnological problem since studying the types of oscillation centers implies monitoring the translation diffusion of nanoparticles in crystal nanostructures. Earlier the types of oscillation centers were determined from thermally stimulated depolarization current spectra (TSDC) [1]. This method requires low-temperature measurements at 77–350 K which complicates the diagnostics and requires much time. The mechanism of proton-ion conductivity and dielectric relaxation was studied [3,4,5,6,7] and the study showed the possibility of transportation and translation diffusion of protons in crystal lattice with hydrogen bonds in a wide range of temperatures with the formation of various oscillation centers
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