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Abstract: The crystal structure of the semiconductor compound CuFe2InSe4 was analyzed using X-ray powder diffraction data. The powder pattern refined by the Rietveld method was composed of 86.6% of the principal phase CuFe2InSe4 and 13.4% of the binary phase FeSe. CuFe2InSe4 crystallizes in the tetragonal space group (no. 121), Z =2, with unit cell parameters a =5.7694(3)Å, c =11.495(1)Å, V =382.62(4)Å3. FeSe crystallizes in the tetragonal space group P4/nmm (no. 129), Z =2, and a =3.784(1)Å, c =5.502(2)Å, V =78.78(4)Å3. The refinement of 28 instrumental and structural parameters led to R p =8.2%, R wp =10.7%, R exp =6.7% and S =1.7; R B =9.9% (CuFe2InSe4), R B =8.8% (FeSe) for 76 and 36 independent reflections, respectively. [Copyright &y& Elsevier]

The semiconducting compound Cu2SnSe3 has been investigated by means of X-ray powder diffraction and its structure has been refined by the Rietveld method. The compound crystallizes in the monoclinic space group Cc (Cs4, No. 9), Z=4, with unit cell parameters a=6.9670(3) A˚, b=12.0493(7) A˚, c=6.9453(3) A˚, β=109.19(1)°, and V=550.6(5) A˚3. The refinement of 36 instrumental and structural parameters converged to Rp=6.1%, Rwp=8.6%, Rexp=5.7%, RB=6.4%, S=1.5, for 4501 step intensities and 280 independent reflections. The structure of Cu2SnSe3 can be described as an adamantane compound derivative of the sphalerite structure. [Copyright &y& Elsevier]

Abstract: Single crystals of MnIn2−2 x Ga2 x Se4 with , were grown by the chemical vapor transport (CVT) technique using iodine as transport agent. Crystals with dimensions up to 12–15mm wide were obtained and characterized by powder X-ray diffraction, optical absorption and magnetic susceptibility. Two crystallographic phases were found from X-ray diffraction experiments, the former tetragonal for and rhombohedral for . The characterization of the crystals was done by optical absorption and magnetic susceptibility. The system behaves as a paramagnetic semiconductor with a direct energy gap. [Copyright &y& Elsevier]

Abstract: The magnetic properties of CoCr2S4 have been studied by DC and AC magnetization experiments in the temperature range 1.8–350K. The temperature dependence of the DC magnetization, together with a calculated saturation magnetization per molecule of 2.73μ B at 1.8K, suggests that CoCr2S4 presents a ferrimagnetic behavior with a critical temperature of 223K. Both the real and the imaginary parts of the AC magnetic susceptibility exhibit a sudden increase at 225K. Between 250 and 200K the real part of the susceptibility(χ′) is typical of a material at the phase transition from a paramagnetic to a long-range-ordered state with T c=223±2K. The imaginary part (χ″) presents a cusp at 120K. An interesting behavior appears below ≅8K, where χ′ is strongly reduced and simultaneously χ″ is increasing showing a maximum at 4.3K. This particular evolution of χ″ with the temperature suggests a richer magnetic behavior for CoCr2S4 at low temperatures. [Copyright &y& Elsevier]

Abstract: In an attempt to resolve the crystal structure and the corresponding space group of the magnetic semiconductor Cu2FeSnS4, samples of this compound were studied by X-ray diffraction, differential thermal analysis, Raman scattering and magnetic susceptibility. It was found that at room temperature this compound prepared by a careful crystal growth process, including annealing to equilibrium at a suitable temperature followed by slow cooling of the samples to 300 K, crystallizes in a tetragonal structure with space group . [Copyright &y& Elsevier]

Abstract: X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu2Cd1−z Mn z SnSe4 and Cu2Cd1−z Fe z SnSe4 alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. For Cu2Cd0.8Fe0.2SnSe4 as well as for Cu2Cd0.2Fe0.8SnSe4 the crystal structures were refined using the Rietveld method. It was found that the internal distortion parameter σ decreases as Cd is replaced by either Mn and/or Fe. For the Cu2Cd1−z Mn z SnSe4 and Cu2Cd1−z Fe z SnSe4 alloy systems, only two single solid phase fields, the tetragonal stannite α and the wurtz–stannite δ (Pmn21) structures were found to occur in the diagram. In addition to the tetragonal stannite α phase extra X-ray diffraction lines due to MnSe and/or FeSe2 were observed for as grown samples in the range 0.7< z <1.0. However, it was found that the amount of the extra phase decreased for the compressed samples. [Copyright &y& Elsevier]

Abstract: Measurements of magnetic susceptibility χ, in the temperature range from 2 to 300K, and of magnetization M vs. applied magnetic field B, up to 5T, at various temperatures were made on polycrystalline samples of the Mn2GeTe4 compound. It was found that Mn2GeTe4 has a Néel temperature T N of about 135K, shows mainly antiferromagnetic behavior with a very weak superimposed ferromagnetic component that is attributed to spin canting. Also, the magnetic results suggest that a possible spin-glass transition takes place at T f≈45K. The spin-glass order parameter q(T), determined from the susceptibility data, was found to be in agreement with the prediction of conventional spin-glass theory. The M vs. B results indicated that bound magnetic polarons (BMPs) occur in the compound, and that the effects from BMPs disappear at approximately 80K. The M vs. B curves were well fitted by a Langevin type of equation, and the variation of the fitting parameters determined as a function of temperature. Using a simple spherical model, the radius of the BMP in the material was found to be about 27Å; this value is similar to the effective Bohr radius for an acceptor in the II–IV–V2 and I–III–VI2 ternary semiconductor compounds. [Copyright &y& Elsevier]

Abstract: X-ray powder diffraction and differential thermal analysis (DTA) measurements were made on polycrystalline samples of the Cu2Zn1−z Fe z GeSe4 alloy system. The diffraction patterns were used to show the equilibrium conditions and to estimate crystalline parameter values. It was found that, at room temperature, a single phase solid solution with the tetragonal stannite α structure occurs across the whole composition range. The DTA thermograms were used to construct the phase diagram of the Cu2Zn1−z Fe z GeSe4 alloy system. It was confirmed that the Cu2ZnGeSe4 compound melts incongruently. It was observed that undercooling effects occur for samples with z >0.9. [Copyright &y& Elsevier]

Abstract: A combined study of X-ray diffraction data and micro-Raman scattering of Cu2GeSe3 is presented. From the analysis of the X-ray data it is confirmed that this compound crystallizes in an orthorhombic cell, space group . From Raman spectra, optical modes are identified and their possible symmetry assignments are suggested. Peaks at 212, 266 and 300 cm−1, tentatively assigned to B2 modes, agree well with those reported from infrared reflectivity. The most strong peak at 189 cm−1 which is only Raman active is assigned to one of the two A2 modes. Lines at 135, 235 and 254 cm−1 are attributed to A1 or B1 modes. The highest phonon frequency band, observed at 385 cm−1, probably comprises the remaining A2 mode and an overtone from the strong line at 189 cm−1. [Copyright &y& Elsevier]

Abstract: The low-temperature magnetic properties of MnIn2S4 have been studied using AC magnetic susceptibility and magnetization experiments. High-temperature susceptibility fits indicate the presence of antiferromagnetic interactions. Low-field magnetization data show a peak at 5.6±0.1K, below which strong irreversibility is observed between zero-field-cooled (ZFC) and field-cooled (FC) cycles suggesting that the observed peak corresponds to a spin-glass-like transition instead of the antiferromagnetic one previously reported. Further evidence of this magnetic state comes from AC susceptibility data at different frequencies. The in-phase component χ′(T) exhibits the behavior expected of spin glasses, i.e. a shift of the cusp to higher temperatures for higher frequencies. [Copyright &y& Elsevier]

Abstract: X-ray powder diffraction measurements and differential thermal analysis (DTA) were made on polycrystalline samples of the Cu2Cd1−z Mn z GeSe4 and Cu2Cd1−z Fe z GeSe4 alloy systems. The diffraction patterns were used to show the equilibrium conditions and to derive lattice parameter values. The effect of the annealing temperature and cooling rate to room temperature are discussed. For the Cu2Cd1−z Fe z GeSe4 system, only two single solid phase fields, the tetragonal stannite α and the wurtz-stannite δ structures were found to occur in the diagram. For the Cu2Cd1−z Mn z GeSe4 system, in addition to the tetragonal stannite α and the wurtz-stannite δ phases, MnSe was found to exist in the diagram. The DTA experiments showed that the cooling curves for both systems exhibited effects of undercooling. [Copyright &y& Elsevier]