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• A comparative analysis of Zn 1.88–2 x Mn 2 x Mg 0.12 SiO 4 and Zn 2–2 x Mn 2x SiO 4 was performed. • Lattice parameters of both solid solutions change nonmonotonically. • Melting points of solid solutions decrease with increasing manganese concentration. • The introduction of 6 at% magnesium reduces decay time by almost a factor of two. [Display omitted] The effect of magnesium introduction on the structural, thermal, and luminescent characteristics of Zn 2 SiO 4 :Mn at the fixed magnesium concentration of 6 at% has been studied. Zn 1.88–2 x Mn 2 x Mg 0.12 SiO 4 phosphors were synthesized by the solid phase method. The structural properties were studied using X-ray diffraction. The luminescent properties were characterized by the PLE and PL spectra. The charge state of manganese ions was determined by the XPS method. It was found that the Zn 1.88–2 x Mn 2 x Mg 0.12 SiO 4 samples at x ≤ 0.14 were single-phase. The unit cell parameters of the solid solutions changed nonmonotonically with increasing x. The change in the linear trend of the parameters occurred at x = 0.06, and was caused by the oxidation of a part of the Mn2+ ions to Mn3+. The introduction of 6 at% magnesium into the Zn 2–2x Mn 2x SiO 4 structure caused an inversion of the crystallographic positions in which manganese was predominantly oxidized. It was shown that the melting temperatures of the Zn 2–2x Mn 2x SiO 4 and Zn 1.88–2 x Mn 2 x Mg 0.12 SiO 4 solid solutions decreased with increasing manganese concentration, but were practically independent of the presence of magnesium. The structural phase transition α→β was recorded in the premelting region for all Zn 2–2 x Mn 2 x SiO 4 compositions. For the Zn 1.88–2 x Mn 2 x Mg 0.12 SiO 4 solid solutions, the α→β transition was registered only for x ˂0.06. The optimal photoluminescence intensity of Zn 2–2 x Mn 2 x SiO 4 shifted to the region of lower values of x with the introduction of magnesium and turned out to be maximum for Zn 1.76 Mn 0.12 Mg 0.12 SiO 4. The introduction of 6 at% magnesium reduced the decay time by almost a factor of two; for the sample with x = 0.06 the decay time was 0.654 ms. [ABSTRACT FROM AUTHOR]

Abstract: The melt-spinning processes of binary Sn–10wt.% Sb and ternary Sn–10wt.% Sb–In were analyzed using X-ray diffractometer and differential thermal analysis (DTA). The results showed that supersaturated solid solution and new intermetallic compound In3Sn were produced during melt-spinning technique not found under equilibrium conditions. It is also found that a small amount of In addition significantly lowers the melting point of the Sn–10wt.% Sb alloy and reduce the crystal size to ≈60nm. Also, tin–antimony solder doped with In exhibits good mechanical properties, Vickers hardness and mechanical strength due to refined microstructure. This work was performed to study the influence of rapid solidification and indium addition on structure and properties of tin–antimony based alloys. [Copyright &y& Elsevier]

Abstract: The thermal behaviour of individual and mixed solids, with different molar ratios, of basic copper carbonate and ammonium metavanadate was reported. The pure and mixed solids were thermally treated at 300, 500, 750 and 1000°C. The thermal products at various calcination temperatures were characterized by means of thermal analyses (TG–DTG–DTA), X-ray diffraction (XRD) and electron spin resonance (ESR) techniques. The catalytic activity of all solids was measured using hydrogen peroxide decomposition at 30, 40 and 50°C. The results revealed that pure basic copper carbonate decomposed to CuO at 300°C and to Cu2O at temperature above 950°C, where as pure ammonium vanadate decomposed to (NH4)2V6O16 and NH4V4O10 as an intermediate compound at 250 and 350°C before the formation of V2O5 at 450°C. CuO enhanced the formation of V2O5 at 300°C. A series of copper vanadate phases were detected, Cu5V2O10, Cu2V2O7 and Cu3V5O4, for the mixtures 3Cu:1V, 1Cu:1V and 1Cu:3V preheated at 750°C, respectively. These phases were formed as a result of solid–solid interactions between copper and vanadium oxides. The calcination temperature and the composition of the Cu–V mixtures affect the degree of crystallinity and pattern intensities of different phases detected at treatment temperatures ranged between 300 and 1000°C. The catalytic activity of mixed CuO–V2O5 was found to be greater than that of single oxides obtained at the same calcination temperatures. This might be attributed to increase in the concentration of active sites by creation of new ion pairs. No measurable catalytic activity was observed for all solids calcined at 750 and 1000°C. This might be attributed to restriction of catalytically active constituents. [Copyright &y& Elsevier]

Abstract: Several stoichiometric ternary Ti–Al–Si and quaternary Ti–Al–Si–C alloys have been prepared by mechanical alloying of elemental powder blends. The structural and morphological evolutions in these powders are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results have shown that the elemental powders Ti–Al–Si are progressively transformed into a nanocrystalline solid solution and amorphous phase during mechanical alloying. The results for the powder mixture of quaternary 58Ti–30Al–6Si–6C have shown that supersaturated solid solutions of Ti in nano- and submicro-scales are formed, while Ti5Si3 and TiC compounds are produced in the powder mixture of 50Ti–15Al–20Si–15C. These compositions may be used as distinct precursors for preparing in situ titanium aluminide composites. Investigations on thermal stability of 40h-milled quaternary powders have indicated that Ti5Si3 is first formed at a lower temperature followed by Al2Ti4C2 and TiC at an intermediate temperature (820°C). In the case of ternary system a stable Ti5Si3 phase is formed through a series of transitions when heated to 1200°C. All the above phases are stable at elevated temperatures. [Copyright &y& Elsevier]

Abstract: Polycrystalline Bi1− x Sb x (x =0.10, 0.12 and 0.15) semiconducting alloys were synthesized by mechanical alloying in order to achieve homogeneous thermoelectric materials with improved mechanical strength. The homogeneity of the powder samples were repeatedly checked by X-ray diffraction and scanning electron microscopy to standardize the milling conditions. The best possible homogenized material was developed with the milling conditions of BPR 30:1, ball diameter 30mm, 400rpm and milling time of 15h. The electrical resistivity, thermoelectric power and thermal conductivity were measured in the temperature range 300–500K. It was found through these experiments that the composition with x =0.12 behaved in a normal semiconducting way, whereas the other two compositions (x =0.10 and 0.15) showed degenerate semiconductor behaviour. These features have been qualitatively explained from the band structure and interband scattering mechanisms. [Copyright &y& Elsevier]

Abstract: Thermally induced intermartensitic transformation in polycrystalline Ni52.5Mn23.7Ga23.8 has been investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It is found that after annealing at 500°C for 4h an intermartensitic transformation, seven-layered orthorhombic martensite (7M) → five-layered tetragonal martensite (5M), appears in polycrystalline Ni52.5Mn23.7Ga23.8 alloy quenched from 800°C, where the sequence of phase transformations is austenite phase (A) → 7M→5M during cooling and 5M→7M→A during heating. The intermartensitic transformation is an independent phase transformation, but the critical transition temperatures and the transformation temperature ranges of 7M→5M are strongly affected by the martensitic transformation. [Copyright &y& Elsevier]