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The main purpose of the research was to explain the differences between nominal and actual chemical compositions of silicate-phosphate glasses in the SiO2-P2O5-K2O-MgO-SO3 system. The actual compositions of the materials were determined with X-ray fluorescence (XRF) analyses. Changes in the chemical composition were explained by examining the melting processes for selected glass batches with differential scanning calorimetry-thermogravimetry-related gas analysis by mass spectrometry (DSC-TG-EGA (MS)) and high-temperature X-ray diffraction (HT-XRD). It was found that changes in the chemical composition of the sulfur-bearing glasses were associated with the release of gaseous products. The main gases released during thermal decomposition of the selected glass batch were water vapor, carbon dioxide, carbon monoxide, and ammonia. Since these glasses have potential for use as glassy fertilizers, there is no doubt that the present study is important from an environmental point of view. [ABSTRACT FROM AUTHOR]

The main physico‐chemical properties and the underlying influence of thermal treatment on the phase composition and structural characteristics of the natural phosphate Kef Esnoun region in Djebel Onk, Algeria, are discussed in this work. The primary goal is to increase the natural phosphate value as an alternative material in heterogeneous catalysis. The phase evolution during the heat treatment of the natural phosphate was carried out at different temperatures ranging from 600 to 1000 °C. Several complementary analytical methods were used for their characterization before and after thermal treatments. The obtained results by X‐Ray Diffraction supplemented by the Rietveld method and confirmed by molecular spectroscopy have shown that the raw natural phosphate consists primarily of a fluorapatite‐type structure (Ca5(PO4)3F). Furthermore, high‐temperature X‐ray diffraction and thermal analyses have shown that dolomite which is one of the natural phosphate constituents is fully decomposed into CaO and MgO phases after heating at 700 °C. At 900 °C, the phase composition is (Ca5 (PO4)3F; 98.23 %), (MgO; 1.1 %) and (CaO; 0.67 %) with a crystallite size value of approximately 300 nm. Cell parameters increase with calcination temperatures due to the substitution of carbonate with PO4−3 groups. [ABSTRACT FROM AUTHOR]

Coal mineral matter is the leading cause of inevitable ash problems (fouling and slagging) during the combustion of coal. Low-temperature ash (LTA) samples of feed coals and the density separated fractions were subjected to high-temperature X-ray diffraction (HT-XRD) to identify the mineral reactions occurred at elevated temperatures under oxidizing conditions. Excluded minerals were mainly contained in the sink fractions, while included minerals were mainly present in the float fractions. QEMSCAN results indicate that the mineral associations in carbominerites and included minerals in Feeds A, B and C and sinks B and C are responsible for the melt formation during HT-XRD experiments. HT-XRD results indicate the presence of mullite, anorthite, and amorphous aluminosilicate materials formed in the thermally treated LTA samples. The formation of these slagging crystalline and glassy phases could be attributed to either crystallization during the cooling of the molten solution, or via solid-state reactions at elevated temperatures. A comprehensive knowledge of the included and excluded minerals can be used to prepare a blended feedstock for combustion processes. The operational ash-related problems in the combustion and gasification processes could be minimized by implementing this comprehensive knowledge of the transformation of coal minerals at elevated temperatures. [ABSTRACT FROM AUTHOR]

Ag2CdSnS4 was synthesized by a two step mechanochemical synthesis route. From a detailed analysis of the observed reflections in the X-ray powder diffraction pattern, the crystal structure proposed in the literature (space group Cmc21 [E. Parthé, K. Yvon, R. H. Deitch, Acta Crystallogr.1969, B25, 1164–1174; O. V. Parasyuk, I. D. Olekseyuk, L. V. Piskach, S. V. Volkov, V. I. Pekhnyo, J. Alloys Compd.2005, 399, 173–177]) is questionable. Our structural investigations presented in this contribution point to the fact that Ag2CdSnS4 crystallizes in the monoclinic wurtzkesterite-type structure (space group Pn). At around T = 200°C, a phase transition to the orthorhombic wurtzstannite-type structure (space group Pmn21) is observed. [ABSTRACT FROM AUTHOR]

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The temperature-dependent structure and dielectric properties of Bi 0. 9 5 Ba 0. 0 5 Fe 0. 9 5 Ti 0. 0 5 O3 ceramic are studied systematically. At the temperature range of 25–800 ∘ C, the cell parameters are increasing, this indicates its distorted rhombohedral R 3 c structure. A structural phase transformation from rhombohedral R 3 c to cubic Pm3 m is observed at 850 ∘ C. The thermal expansion coefficients in the temperature range 25–700 ∘ C are calculated. Meanwhile, the temperature-dependent dielectric constant ( 𝜀 ′ ) and dielectric loss (tan δ ) at different frequencies are measured. This work attempts to show the thermodynamic stability and the effect of charge defects on the electric properties for doped BiFeO3 ceramics. [ABSTRACT FROM AUTHOR]

To evaluate the relationship between arrangement of oxide ion vacancies and oxide ion conduction in a mixed ionic-electronic conductor Ba2(Fe0.9In0.1)2O5+δ, we studied temperature dependences of electrical conductivity and the crystal structure including the oxide ion vacancies using high-temperature X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy, and electrical conductivity measurements with four-probe method. The sample's crystal structure was observed to be of a perovskite type with a partial ordering of oxide ion vacancies below 600°C. Increasing the temperature above 600°C led to associative O2 desorption and complete randomization of the arrangement of oxide ion vacancies to form a cubic phase. The electrical conductivity of the sample under N2 flow showed an Arrhenius-type behavior with two trends against temperature. Activation energies were estimated as 0.61 eV below 600°C and 0.27 eV above 600°C. The lower value of 0.27 eV showed fairly good agreement with that of activation energy for oxygen permeation fluxes in this material. It was concluded that the fully random distribution of oxide ion vacancies led to improved oxide ion migration in Ba2(Fe0.9In0.1)2O5+δ. [ABSTRACT FROM AUTHOR]

To evaluate the relationship between arrangement of oxide ion vacancies and oxide ion conduction in a mixed ionic-electronic conductor Ba2(Fe0.9In0.1)2O5+δ, we studied temperature dependences of electrical conductivity and the crystal structure including the oxide ion vacancies using high-temperature X-ray diffraction, thermogravimetry-differential thermal analysis-mass spectroscopy, and electrical conductivity measurements with four-probe method. The sample's crystal structure was observed to be of a perovskite type with a partial ordering of oxide ion vacancies below 600°C. Increasing the temperature above 600°C led to associative O2 desorption and complete randomization of the arrangement of oxide ion vacancies to form a cubic phase. The electrical conductivity of the sample under N2 flow showed an Arrhenius-type behavior with two trends against temperature. Activation energies were estimated as 0.61 eV below 600°C and 0.27 eV above 600°C. The lower value of 0.27 eV showed fairly good agreement with that of activation energy for oxygen permeation fluxes in this material. It was concluded that the fully random distribution of oxide ion vacancies led to improved oxide ion migration in Ba2(Fe0.9In0.1)2O5+δ. [ABSTRACT FROM AUTHOR]