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In today’s battle for the environment, renewable energy sources, including solar energy, plays a significant role. Therefore, it is necessary to develop new materials for solar cells. Ag2ZnSnS4 (AZTS) is a material that makes it possible to increase the efficiency of photovoltaic modules, compared to cells based on Cu2ZnSnS4. AZTS was obtained by several methods, but in these research it was synthesized by Chemical Vapor Transport method (CVT), using zinc chloride as transporting agent, for the first time. X-ray powder diffraction was used in the structural tests, which showed that through the CVT method it is possible to obtain a pure Ag2ZnSnS4 phase with a stannite crystal structure. Raman measurements were conducted to determine the crystal quality of samples and to check their phase homogeneity. Raman spectra were calculated from DFT analysis applying the LDA and GGA approximations. The measured Raman peaks were assigned to calculated ones for AZTS structure.

A growing interest in devices based on spintronics demands a development of magnetic semiconductors. A promising material for such applications is kesterite doped with ferromagnetic elements. We present a method of obtaining Cu2MSnS4 (M = Zn, Fe, Mn, Ni) single crystals, using metals, elemental sulfur and minor amounts of iodine. The syntheses were carried out in quartz ampoules closed under vacuum and heated in a tube furnace at 650 °C for 7 to 90 days. A method of synthesis of comparatively good tetragonal single crystals of Cu2FeSnS4 and Cu2MnSnS4 was achieved. Raman spectra of purely Mn- and Ni-substituted kesterites have been measured for the first time.

Powder diffraction data for fine AlN and GaN powders were collected at a Bragg–Brentano diffractometer equipped with a Johansson monochromator and a semiconductor strip detector. Rietveld-refinements were performed in order to determine the structural parameters of these wurtzite-type (space group, P 6 3 mc ) materials. The following crystallographic data were obtained: a = 3.11197(2) A, c = 4.98089(4) A, c / a =1.60056(2), u = 0.3869(5) for aluminium nitride and a = 3.28940(1) A, c = 5.18614(2) A, c / a = 1.62606(1), u = 0.3789(5) for gallium nitride. These structural data are discussed in the light of earlier experimental and theoretical results.

Silicon nitride powders were obtained in a reaction of SiO 2 powders with NH 3 . The influence of the following parameters on the quality of Si 3 N 4 was determined: silica particle size, temperature and furnace heating programme, sample heating time, ammonia flow rate and application of the selected mineralising agents. The powders of silica were characterised by: optical microscopy, SEM, X-ray phase analysis and thermal analysis. The products of the syntheses were tested by: optical microscopy, SEM, X-ray phase analysis, IR spectroscopy and classic quantitative analysis. The investigations resulted in elaboration of a method of preparation of crystalline silicon nitride powders containing more than 96% Si 3 N 4 . The discussion on the influence of magnesium nitride additive on the Si 3 N 4 synthesis process has also been carried out.

Lattice parameter and thermal-expansion coefficient for magnesium nitride, Mg 3 N 2 , were determined using X-ray powder diffraction at the B2 beamline in Hasylab (DESY) in the temperature range from 11 K up to 304.5 K. The relative change of lattice parameter on raising the temperature in the studied range is about 0.14%. At 300 K, its value is 9.9644(1) A and the linear thermal expansion coefficient derived from a polynomial approximation is a =1.1×10 −5 K −1 .