Optical Properties of the (CuInSe2) x ·(2ZnSe)1−x and (CuInTe2) x (·2ZnTe)1−x Solid Solutions

Crystals of the compounds CuInSe₂, CuInTe₂, ZnSe, and ZnTe, and the solid solutions (CuInSe₂) _x ·(2ZnSe)_1–x and (CuInTe₂) _x ·(2ZnTe)_1–x were grown by the Bridgman and chemical transport reactions methods. Their transmission and reflection spectra in the region of the main absorption line edge were studied. The forbidden band gap of the indicated materials was determined and its concentration dependences were built for the solid solutions. It is established that the forbidden band gap changes linearly with the x composition and is satisfactorily described by the square-law dependence.     

双层钙钛矿锰氧化物Nd_(2-2x)Ca_(1+2x)Mn_2O_7(x=0.4,0.5)的磁相变特性

利用固相反应法制备了Nd2-2x Ca1+2x Mn2O7(x=0.0-0.9)多晶样品,通过FULLPROF程序对样品X射线衍射图谱进行了精修,样品的空间群为14/mmm.测量了样品x=0.4,0.5的磁性(5K相似文献   

Surface structure of TiO2(011)-(2x1)

A combined experimental and first principles study of the (2x1)-reconstructed rutile TiO2(011) surface is presented. Our results provide evidence that the surface structure is described by a model that includes onefold coordinated (titanyl) oxygen atoms giving rise to double bonded Ti=O species. These species should play a special role in the enhanced photocatalytic activity of the TiO2(011) surface.     

Phase Manipulation between c(4 x 2) and p(2 x 2) on the Si(100) surface at 4.2 K

Phase manipulation between c(4x2) and p(2x2) on the Si(100) surface has been demonstrated at 4.2 K for the first time using a low-temperature scanning tunneling microscope. We have discovered that it is possible to change the c(4x2) surface into the p(2x2) surface, artificially, through a flip-flop motion of the buckling dimers by using a sample bias voltage control. Also, scanning at a negative bias voltage or applying a pulse voltage can restore the c(4x2) surface. The STM images as a function of bias voltage and tunneling current reveal the interesting dynamics of the buckling dimers on the long debated surface. Our results will show that energetic tunneling electrons are most likely responsible for the observed phase transition from c(4x2) to p(2x2).     

Electrophysical and photoelectric properties of (CdSe)1−x(CuInSe2)x solid solutions

The results are given of measurements of the electrophysical properties in the interval of temperatures 300–900°K and of the photoelectric properties at 300°K of (CdSe)_1–x–(CuInSe₂)_x solid solutions. It is shown that the electrophysical and photoelectric properties of the solid solutions depend on the composition and temperature. The forbidden-band widths calculated from the temperature dependence of the conductivity and from the photoconductivity spectrum, respectively, vary from 1.68 and 1.77 eV for initial compound CdSe to 1.25 and 1.18 eV for the solid solution Cu_0.1Cd_0.9In_0.1Se_1.1.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 41–43, January, 1992.     

The Growth of P-type TlGaSe2(1−x) S2x Single Crystals

TlGaSe_2(1–x) S_2x single crystals were grown by the modified Bridgman-Stockbarger method in our crystal growth laboratory. A^IIIB^III C₂ ^VI compounds are formed of elements from vertical groups of the periodic table (group III: Tl, Ga, In; group VI: Se, S, Te) and are classified into two types. The first type has a layer structure: TlGaSe₂, TlGaS₂ and TlInS₂. The second type has a chained structure: TlInSe₂, TlInTe₂ and TlGaTe₂. None of the grown crystals had cracks and voids on the surface. The freshly cleaved crystals had a mirror-like surface and there was no need for mechanical or chemical polishing treatments. By the hot probe technique, we have found that the crystals were of p-type. The ingots produced were single crystalline and the useful region of single crystal was 90% with steps of 10 K if changes were small, and with steps of 3 and 5 K if changes were large in the direct and indirect band gaps energies. The direct and indirect band gaps for TlGaSe_2(1–x)S_2x samples were calculated as a function of temperature.     

Dielectric characteristics and phase transitions in Tl(InS2) 1 − x (FeSe2) x solid solutions

This paper reports on a study of the electrical conductivity and permittivity of Tl(InS_{2) 1−x} (FeSe_{2) x} crystals as functions of composition and temperature. It has been found that the permittivity decreases in magnitude, while the electrical conductivity increases with increasing x. Crystals Tl(InS_{2) 1−x} (FeSe_{2) x} have been observed to undergo a sequence of phase transitions characteristic of TlInS₂, which manifests itself in formation of anomalies in the σ = f(T) and ɛ = f(T) temperature dependences. It has been shown that as x increases, the phase transition temperatures decrease, while the temperature region within which the incommensurate phase persists broadens slightly.