No abstract

Polycrystalline thiospinels CuCr 2-x Sn x S 4 (x = 0.4, 0.8, 1.0 and 1.4) were synthesized via conventional solid-state reaction. The samples were characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray analysis (SEM-EDS) and Raman spectroscopy. All the samples were indexed in the space group. The Raman spectra confirmed the structure of normal spinel type with five characteristic signals for the active modes in Raman. Magnetic measurements, performed for the phases with x = 0.8 and 1.0, showed irreversible antiferromagnetism with dominant ferromagnetism and spin glass behavior.

A new series of (Cu) tet [Cr 2−x Sn x ] oct S 4−y Se y compounds was prepared by solid-state reaction at high temperature. Determination of the crystal structures by single-crystal X-ray diffraction revealed that CuCr 1.

No abstract

No abstract

Herein, we report the synthesis, characterization, and electrical properties of lead-free AgSnm[Bi1−xSbx]Se2+m (m = 1, 2) selenides. Powder X-ray diffraction patterns and Rietveld refinement data revealed that these selenides consisted of phases related to NaCl-type crystal structure. The microstructures and morphologies of the selenides were investigated by backscattered scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The studied AgSnm[Bi1−xSbx]Se2+m systems exhibited typical p-type semiconductor behavior with a carrier concentration of approximately ~+1020 cm−3. The electrical conductivity of AgSnm[Bi1−xSbx]Se2+m decreased from ~3.0 to ~10−3 S·cm−1 at room temperature (RT) with an increase in m from 1 to 2, and the Seebeck coefficient increased almost linearly with increasing temperature. Furthermore, the Seebeck coefficient of AgSn[Bi1−xSbx]Se3 increased from ~+36 to +50 μV·K−1 with increasing Sb content (x) at RT, while its average value determined for AgSn2[Bi1−xSbx]Se4 was approximately ~+4.5 μV·K−1.

No abstract

Herein, we report the structural characterization and vibrational and physical properties of Cu2ZnSn1−xSixSe4 solid solutions synthesized using the ceramic method. X-ray diffraction analysis and Rietveld analysis of the samples indicated that by increasing the x value from 0 to 0.8, the volume of the unit cell decreased because the ionic radius of silicon is smaller than that of tin. Simultaneously, a phase transition between stannite and wurtz-stannite was observed. The Raman peaks were analyzed by fitting the spectra to identify the vibrational modes by comparison with the experimental data from Cu2ZnSnSe4 and Cu2ZnSiSe4. The spectra of Cu2Zn(Sn1−xSix)Se4 (x = 0.2 and 0.3) show two dominant peaks at approximately 172 and 195 cm−1, which are assigned to the A1 mode of the stannite structure. The optical band gaps for Cu2Zn(Sn0.8Si0.2)Se4 and Cu2Zn(Sn0.2Si0.8)Se4 were 1.30 and 1.74 eV, respectively. These values were intermediate to those of the end members. Electrical properties of Cu2Zn(Sn0.8Si0.2)Se4 revealed p-type conductivity behavior with a carrier concentration of approximately ~+3.50 × 10−19 cm−3 and electrical mobility of 2.64 cm2/V·s.