The influence of light on the low-frequency dielectric properties of the TlInS 2 layered crystal is investigated for the first time. It is established that the illumination of the crystal during measurements leads to a substantial change in the behavior of the temperature dependence of the permittivity ɛ of the TlInS 2 compound doped with the lanthanum impurity in the range of the existence of the incommensurate phase. The temperature dependences of the permittivity ε of the TlInS 2 compound doped with the lanthanum impurity after preliminary cooling of the crystal in constant electric fields with different strengths are studied for the first time. The inference is made that the experimentally observed photodielectric effect is associated with the localization of charge carriers at defect levels in the band gap of the crystal with the formation of local polarized states.

The effect of external fields (dc electric field, light illumination) on the memory effect of the incommensurate phase in the ferroelectric-semiconductor TlGaSe2 is studied using the measured dielectric constant. The results obtained are discussed. It is shown for the first time that the effect of external fields on the anomaly related to the memory effect in TlGaSe2 can be reduced to the following universal empirical rule: when a sample is held for many hours at a constant temperature T0 in the temperature range of the incommensurate phase in a dc electric field, the deflection amplitude in the low-temperature part of the anomaly in the temperature dependence of the relative change in the dielectric constant Δɛ/ɛ increases (the deflection in the high-temperature part of the Δɛ/ɛ anomaly disappears) as compared to this segment in the dependence obtained during isothermal annealing of this sample at the same temperature without an electric field. The crystal remembers its thermal history at a temperature that is several kelvins higher than T0. Light illumination increases the deflection amplitude in the high-temperature part of the Δɛ/ɛ(T) anomaly and shifts the temperature at which the crystal remembers its thermal history toward lower temperatures with respect to T0.

The temperature dependences of the dielectric constants of the ferroelectric semiconductors TlInS2 and TlGaSe2 have been studied following their annealing within the incommensurate phase. Unusual memory effects accompanied by both a remarkable inflection of the temperature dependence curves in the incommensurate phase and various shifts of the incommensurate (Ti) and commensurate (Tc) phase transition temperatures have been revealed in both crystals. The observed effects are explained on the basis of a defect density wave model taking into account the interaction of modulation waves with charge carriers localized at impurity states. The thermally activated population of these states during the heating or cooling processes is responsible for the changes of the phase transition temperatures.

The temperature dependences of the dielectric constants of the ferroelectric semiconductors TlInS2 and TlGaSe2 have been studied following their annealing within the incommensurate phase. Unusual memory effects accompanied by both a remarkable inflection of the temperature dependence curves in the incommensurate phase and various shifts of the incommensurate (T-i) and commensurate (T-c) phase transition temperatures have been revealed in both crystals. The observed effects are explained on the basis of a defect density wave model taking into account the interaction of modulation waves with charge carriers localized at impurity states. The thermally activated population of these states during the heating or cooling processes is responsible for the changes of the phase transition temperatures.

Contactless methods for measurement of (using various physical phenomena) linear and angular displacements are examined. The outlook for photoelectric transducers is indicated. A three-position sensor (TPS) is described that implements the "data bias" method to eliminate reading uncertainty. Various uses of the TPS and possibilities for its wide application are shown.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

physica status solidi (b)Volume 176, Issue 1 p. K39-K40 Short Note Far-Infrared Absorption Spectra of ε-InSe A. Ismailov, A. Ismailov Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorS. Babaev, S. Babaev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorM. Tagyev, M. Tagyev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorK. Allakhverdiev, K. Allakhverdiev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this author A. Ismailov, A. Ismailov Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorS. Babaev, S. Babaev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorM. Tagyev, M. Tagyev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this authorK. Allakhverdiev, K. Allakhverdiev Institute of Physics, Azerbaijan Academy of Sciences, Baku Search for more papers by this author First published: 1 March 1993 https://doi.org/10.1002/pssb.2221760137Citations: 2 Azizbekov av. 33, 370143 Baku, Azerbaijan. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume176, Issue11 March 1993Pages K39-K40 RelatedInformation

Experimental results of Raman scattering spectra of ϵ-InSe crystals are presented at 300 K and pressures up to 10.2 kbar. Values of the mode-Grüneisen parameters were calculated using frequency-pressure dependences for five observed phonons. Changes of the shear force constants under pressure were analysed using linear-chain model both for ϵ-InSe and ϵ-GaSe crystals. The decrease of the shear force constants between metallic planes with increasing pressure are explained qualitatively by charge transfer from intralayer to interlayer space.

An investigation is made of the polarized far IR and Raman scattering spectra of layered single crystals of ternary compound TlInS2 in the 6 to 300 K temperature range including the series of the phase transition. New unknown low-frequency Raman and IR active phonons are observed. It is shown that the interpretation of the vibrational properties of TlInS2 crystal are in good agreement with the C space group. A low-frequency Raman active soft mode is observed and analysed in the ferroelectric phase of this crystal. The pecularities in changing of the spectra of optical phonons, connected with a transition of the crystal from the para to ferroelectric state, from modulating structure, and quadrupling along C-axis are observed and analysed. [Russian Text Ignored].

AbstractThe influence of high pressure up to 13 GPa on the optical transmission spectra of layered AIIIBIIIC crystals was investigated. The value of the pressure coefficient of the transmission spectra at 30% transmission is reported. Results indicate that these materials undergo a series of phase transitions in the region investigated.

Raman scattering spectra of ϵ-GaSe and β-Gas crystals were examined at temperature 8° and 295°K with a resolution of 0.7 cm−1. At low temperature the Davydov splitting of modes in ϵ-GaSe could be accurately measured. The largest splitting of the Raman bands in ϵ-GaSe was found to be about 3 cm−1 and correlates well with that predicted from a model based on the molecular nature of this compound.

physica status solidi (b)Volume 126, Issue 2 p. K139-K143 Short Note The Influence of Hydrostatic Pressure on the Fundamental Absorption Edge of Crystals with TlSe-Type Structure K. R. Allakhverdiev, K. R. Allakhverdiev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorS. S. Babaev, S. S. Babaev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorN. A. Bakhyshov, N. A. Bakhyshov Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorT. G. Mamedov, T. G. Mamedov Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorE. Yu. Salaev, E. Yu. Salaev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorI. K. Efendieva, I. K. Efendieva Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this author K. R. Allakhverdiev, K. R. Allakhverdiev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorS. S. Babaev, S. S. Babaev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorN. A. Bakhyshov, N. A. Bakhyshov Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorT. G. Mamedov, T. G. Mamedov Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorE. Yu. Salaev, E. Yu. Salaev Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this authorI. K. Efendieva, I. K. Efendieva Institute of Physics, Academy of Sciences of the Azerbaidzhan SSR, Baku Search for more papers by this author First published: 1 December 1984 https://doi.org/10.1002/pssb.2221260244Citations: 13 prospekt Narimanova 33, 370143 Baku, USSR. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume126, Issue21 December 1984Pages K139-K143 RelatedInformation