Abstract
In practical application of crystals in optoelectronics and laser technology it is necessary to know the direction of optical axes and types of oscillatory centers, which is a relevant and necessary condition. In this paper, the infrared spectra of transmission and absorption of hexagonal crystals of lithium iodate α-LiIO3, grown by open evaporation in H2O and D2O solutions, as well as natural lamellar crystals of phlogopite and muscovite monoclinic crystal are investigated. The band gap width of the investigated crystals is determined by transmission spectra. In the absorption spectra there were determined activation energy and wavelength of the oscillatory centers that are associated with the vibrations of protons, hydronium ions Н3О+, protium H+, OH groups and molecules HDO. The good correlation of the parameters of infrared spectra with the spectra of thermally stimulated depolarization currents and NMR spectra has shown. The possibility of diagnostics of types of oscillatory centers by means of infrared spectra is considered, which also allows to find out the direction of optical axes. The obtained results allow to use IR spectra to determine not only the types of vibrational centers, but also the presence of anisotropy of the crystal lattice of the studied crystals.
Highlights
In practical application of crystals in optoelectronics and laser technology it is necessary to know the direction of optical axes and types of oscillatory centers, which is a relevant and necessary condition
In the absorption spectra there were determined activation energy and wavelength of the oscillatory centers that are associated with the vibrations of protons, hydronium ions Н3О+, protium H+, OH groups and molecules HDO
The possibility of diagnostics of types of oscillatory centers by means of infrared spectra is considered, which allows to find out the direction of optical axes
Summary
С целью повышения точности, экспрессности и достоверности спектральной диагностики типов колебательных центров и оптических осей в кристаллах с водородными связями тщательно отполированные образцы помещают в ИК−спектрометр. Далее снимают ИК−спектры пропускания и поглощения, по которым определяют ширину запрещенной зоны для каждого кристалла. Это значение соответствует энергии колебательного центра 0,365 эВ, действительно, присутствует как в силикатах, так и на ИК−спектре иодата лития, выращенного в Н2О с примесью йодноватой кислоты HIO3 (в нейтральных кристаллах эта полоса отсутствует), вдоль оси шестого порядка С6. IR absorption spectrum of α−LiIО3 crystals, grown in H2O along the X−axis, with increased fragment of the spectrum ном в H2О, присутствуют полосы с энергией 0,27 эВ (гидроксоний Н3О+), 0,365 эВ (протий Н+) и ионов ОН−, а в кристалле, выращенном в D2О На ИК−спектрах, снятых лития, выращенных в D2O, эта полоса соответствует колебаниям связанных молекул полутяжелой воды HDO, что позволяет использовать данный метод для определения присутствия тяжелой воды в исвдоль оси X − полоса 1595 cм−1, соответствующая энергии 0,20 эВ (деформационное колебание δ); absorption spectrum of α−LiIO3 crystals]
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