The quaternary semiconductor compounds Cu2ZnSnSe4, Cu2ZnSiSe4, and Cu2ZnSn1 – xSixSe4 solid solutions on their basis have been synthesized from the elementary components Cu, Zn, Sn, Si, and Se by the single-temperature method. The room- temperature unit-cell parameters of the obtained compounds and solid solutions are determined by the X-ray method. It is established that two series of solid solutions are formed in the Cu2ZnSn1 – xSixSe4 system: one is based on the Cu2ZnSnSe4 compound with a tetragonal structure at x ≤ 0.5 and the other is based on the Cu2ZnSiSe4 compound with a orthorhombic structure at x ≥ 0.7.

The high-temperature orthorhombic phase of Cu 2 CdGeSe 4 quaternary compound, tetragonal phase of Cu 2 CdSnSe 4 compound, and Cu 2 CdGe x Sn 1 – x Se 4 solid solutions have been grown from elementary components Cu, Cd, Ge, Sn, and Se by one-temperature synthesis. The unit-cell parameters of the grown compounds and solid solutions have been determined by X-ray diffraction analysis at room temperature. It is shown that a continuous series of solid solutions, based on Cu 2 CdSnSe 4 compound, is formed in the Cu 2 CdGe x Sn 1 – x Se 4 system in the range of 0 ≤ х ≤ 0.8, and the Cu 2 CdGe x Sn 1 – x Se 4 system at x ≥ 0.9 is an orthorhombic crystalline phase.

The effect of various doses of electron irradiation on the dielectric constant and electrical conductivity of triple nonlinear AgGaSe2 crystals at different measuring field frequencies in the temperature range of 100-300 K has been investigated. It has been found that single-crystal irradiation leads to a dielectric constant decrease and an electrical conductivity significant increase. It is shown that the dielectric constant and electrical conductivity increase with an temperature increase. It has been established that AgGaSe2 crystals are characterized by the presence of several conductivity types. A significant frequency dispersion of the dielectric properties of the investigated crystals was found.

The quaternary compounds Cu2ZnGeSe4, Cu2ZnSiSe4 and their solid solutions are synthesized from the elementary components Cu, Zn, Ge, Si, and Se by the single-temperature synthesis method. The unit-cell parameters of the synthesized compounds and Cu2ZnGe1 –xSixSe4 solid solutions are determined at room temperature by X-ray diffraction (XRD). It is shown that the unit-cell parameters a, b, and c decrease as x increases. It is found that two series of solid solutions are formed in the Cu2ZnGe1– xSixSe4 system: one is based on the Cu2ZnGeSe4 compound and the other is based on Cu2ZnSiSe4.

The high-temperature orthorhombic phase of Cu2CdGeSe4 quaternary compound, tetragonal phase of Cu2CdSnSe4 compound, and Cu2CdGexSn1 – xSe4 solid solutions have been grown from elementary components Cu, Cd, Ge, Sn, and Se by one-temperature synthesis. The unit-cell parameters of the grown compounds and solid solutions have been determined by X-ray diffraction analysis at room temperature. It is shown that a continuous series of solid solutions, based on Cu2CdSnSe4 compound, is formed in the Cu2CdGexSn1 – xSe4 system in the range of 0 ≤ х ≤ 0.8, and the Cu2CdGexSn1 – xSe4 system at x ≥ 0.9 is an orthorhombic crystalline phase.

The influence of various doses of electron irradiation on the dielectric permeability and specific conductance of ternary nonlinear optical crystals of AgGaSe 2 at various frequencies of the measuring field in a range of temperatures of 100–300 K is studied. It is found that the irradiation of single crystals leads to a decrease in the values of dielectric permeability and a significant increase in conductance. It is shown that dielectric permeability and conductance increase with the growth in temperature. It is found that the presence of several types of conductance is characteristic for the crystals of AgGaSe 2 . Substantial frequency dispersion of the dielectric properties of the studied crystals is found.

Quaternary compounds (Cu 2 ZnGeSe 4 and Cu 2 ZnSnSe 4 ) and solid solutions on their basis are prepared via single-temperature synthesis from Cu, Zn, Ge, Sn, and Se. The crystallographic characteristics of the synthesized compounds and Cu 2 ZnGe x Sn 1 – x Se 4 solid solutions are determined using the X-ray diffraction method at room temperature. It is found that parameters a and c reduce with increasing Ge concentration.

The quaternary semiconductors Cu2CdSnS4, Cu2CdSnSe4 and Cu2CdSn(SxSe1–x)4 solid solutions were synthesized by the one-temperature method from the elementary components. The X-ray diffraction method showed that the obtained polycrystalline samples are single-phased. The unit cell parameters of the synthesized compounds and Cu2CdSn(SxSe1–x)4 solid solutions were determined from diffraction spectra by the full-profile analysis using the Rietveld method with the Fullprof software package. It has been established that with an increase in sulfur concentration, the unit cell parameters decrease smoothly linearly in accordance with the Vegard rule, which indicates the formation of a continuous series of solid solutions in the Cu2CdSn(SxSe1–x)4 system within the range 0 ≤ x ≤ 1. The parameter of crystal lattice tetragonal distortions h of the investigated compounds is calculated. The h values are close to 1 for all the compositions studied, which indicates a small crystal lattice distortion of the obtained samples.

The effect of electron irradiation on conductivity and dielectric permeability of Cu2ZnSnS4 and Cu2ZnSnSe4 single crystals and solid solutions based on them is studied. It is shown that values of dielectric permeability decrease with an increase in the irradiation dose while those of specific electric conductivity sharply increase.

Изучено влияние электронного облучения на проводимость и диэлектрические характеристики монокристаллов Cu2ZnSnS4, Cu2ZnSnSe4 и твердых растворов на их основе. Показано, что с увеличением дозы облучения значения диэлектрической проницаемости уменьшаются, а удельной электропроводности резко возрастают. DOI: 10.21883/FTT.2017.02.44040.263

Проведены исследования влияния состава и температуры на электропроводность и диэлектрическую проницаемость системы Tl(GaS2)1-x(InSe2)x. Установлено, что с ростом температуры диэлектрическая проницаемость и удельная проводимость увеличиваются, а с ростом концентрации InSe2 изменяются по линейному закону, при этом проводимость уменьшается, а диэлектрическая проницаемость растет. Подтверждено наличие в исследованной системе двух рядов твердых растворов. Показано, что с ростом концентрации InSe2 температуры фазовых переходов соразмерная-несоразмерная фаза смещаются в область более низких температур. Работа выполнена при поддержке Белорусского фонда фундаментальных исследований (договор N Ф15-016 от 04 мая 2015 г.). DOI: 10.21883/FTT.2017.08.44745.22

The effect of composition and temperature on the electrical conductivity and the permittivity of the Tl(GaS2)1 – x (InSe2) x has been studied. It is found that the permittivity and the conductivity increase with temperature and vary linearly as the InSe2 concentration increases: in this case, the conductivity decreases and the permittivity increases. It is confirmed that the system under study contains two series of solid solutions. It is shown that the commensurate–incommensurate phase transition temperatures shift to lower values as the InSe2 concentration increases.

The unit-cell parameters of crystals obtained in the Tl(GaS 2 ) 1– x (InSe 2 ) x system are measured by X-ray diffraction. The relationship between these parameters and composition is determined. It is shown that, with growing x , the a , b , and c parameters increase and the β angle decreases. Two types of solid solutions are found in the Tl(GaS 2 ) 1– x (InSe 2 ) x system: one is based on compound TlGaS 2 with monoclinic structure and the other is based on TlInSe 2 with tetragonal structure.

Quaternary compounds Cu2ZnSnS4 and Cu2ZnSnSe4 and solid solutions on their basis have been fabricated by one-temperature synthesis from elementary components: Cu, Zn, Sn, S, and Se. Single crystals of these compounds have been grown by the method of chemical gas-transport reactions from polycrystalline samples. The compositional dependence of the unit-cell parameters of Cu2ZnSn(S x Se1–x )4 has been investigated by X-ray diffraction. It is found that parameters a and c linearly decrease with an increase in sulfur concentration in accordance with Vegard’s law. The temperature dependences of parameters a and thermalexpansion coefficients α a of Cu2ZnSnS4 and Cu2ZnSnSe4 single crystals in the range of 100–300 K are determined.