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At room temperature, monoclinic In 2 W 3 O 12 ceramics exhibits positive thermal expansion. However, it transforms into an orthorhombic phase above 253 ℃, and then stably exhibits negative thermal expansion (NTE). In this work, to improve the NTE performance and extend the NTE temperature range of In 2 W 3 O 12 , the K x Mn x In 2-x W 3 O 12 (0≤x≤0.5) ceramics were synthesized via the solid-state reaction method. The effects of (KMn)3+ double cation co-doping on the composition, microstructure, and thermal expansion behaviors of In 2 W 3 O 12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. The results show that (KMn)3+ cations can replace In3+ in In 2 W 3 O 12 ceramics. As the (KMn)3+ doping amount increases, monoclinic In 2 W 3 O 12 gradually changed into monoclinic K x Mn x In 2-x W 3 O 12. Meanwhile, the grains grow up and the density of K x Mn x In 2-x W 3 O 12 ceramics was increased. Pure monoclinic K x Mn x In 2-x W 3 O 12 ceramics were prepared when x rises to 0.25 and 0.4. Among them, the thermal expansion coefficient of K 0.4 Mn 0.4 In 1.6 W 3 O 12 ceramics in 100–700 ℃ is as high as -17.83×10-6 ℃-1, which was significantly improved compared to In 2 W 3 O 12 ceramics. In addition, the structural phase transition of In 2 W 3 O 12 ceramics around 253 ℃ was gradually eliminated and the NTE temperature range was widened. Double cation (KMn)3+ co-doping effectively improves the NTE performance of In 2 W 3 O 12. • (KMn)3+ co-doped In 2 W 3 O 12 ceramics were prepared by solid-state method. • (KMn)3+ co-doping induces a phase transition in In 2 W 3 O 12 ceramics. • Monoclinic K x Mn x In 2-x W 3 O 12 ceramics show stronger NTE as x increases. [ABSTRACT FROM AUTHOR]

High-entropy alloy CoCrFeNiMn was produced by short high energy ball milling (90 min) and spark plasma sintering (10 min at 1073 K). Co-existence of two fcc-phases with lattice parameters 0.360 nm and 0.356 nm was demonstrated via HRTEM, XRD and other methods. The matrix fcc-phase with larger parameter transforms into the more compact phase during annealing up to 1273 K. Similar transformation partially occurs after SPS. Some elements, mostly Cr and Mn, released from the matrix phase and formed precipitates. Up to three types of precipitates, with characteristic size from 10-30 nm to 200–300 nm, have been detected and studied. Electric and thermal properties of the material, measured at room and elevated temperature, shown that lattice thermal conductivity plays an important role, along with free electron thermal conductivity. Image 1 • CoCrFeNiMn produced by 90 min of high energy ball milling and consolidated by SPS. • Two fcc-phases present in the alloy with lattice parameters 0.360 and 0.356 nm. • The loose fcc-phase transforms into more compact phase when annealing up to 1273 K. • Cr and Mn release from the fcc-matrix phase forming precipitates 10-30 and 200–300 nm. • Electric and thermal conductivities are measured at room and elevated temperature. [ABSTRACT FROM AUTHOR]

Monoclinic Cu 4 O(SeO3) 3 has been prepared hydrothermally with subsequent heating in evacuated silica tubes. It has been characterized in measurements of dc and ac magnetic susceptibility χ and specific heat C p. The title compound orders magnetically at T 1 = 13.2 K and evidences a pre-transitional anomaly at T 2 = 17.2 K. In the range T 1 < T < T 2 , the application of external magnetic field rapidly suppresses excessive magnetization of this intermediate phase, but the hump in specific heat appears. The magnetic system of the title compound is constituted by the layered network of isolated Cu atoms and O 2 Cu 6 units composed by edge-sharing anion-centered OCu 4 tetrahedra. First principles calculations provided values of both ferromagnetic and antiferromagnetic exchange interactions within O 2 Cu 6 units J 1 – J 11 and J 12 – J 22 , and antiferromagnetic intralayer J 23 – J 30 and interlayer J 31 – J 32 exchange interactions. Basing on signs and values of these interactions a magnetic model of monoclinic Cu 4 O(SeO3) 3 is suggested. • O 2 Cu 6 units of edge-sharing OCu 4 tetrahedra are the building blocks of Cu 4 O(SeO3) 3. • It orders magnetically at T 1 = 13.2 K and shows a pre-transitional anomaly at T 2 = 16.5 K. • Basing on signs and values of exchange interactions a magnetic model is suggested. [ABSTRACT FROM AUTHOR]

Abstract B 4 C/TiB 2 ceramic composites were fabricated by reinforcing carbon and silicon (10 wt.% total mass) with the help of pressureless sintering at 2150 °C. The influence of C and Si additives on the phase composition, microstructures and mechanical properties of B 4 C/TiB 2 ceramic composites were investigated through the characterizations of XRD, SEM, BSEM and EDS. Compared to B 4 C/TiB 2 ceramic composites without C-Si additives, coarsely plate-like SiC grains were formed in composites at a C: Si mass ratio ∼0:10. By increasing the C:Si mass ratio, the size of the plate-like SiC grains decreases, while the amount of plate-like SiC grains increases. When the C:Si mass ratio was 7:3, multilamellar graphite appeared on the B 4 C grain boundary. Moreover a large number of lamellar graphite grains appeared at a mass ratio of C:Si ∼10:0. Graphite reacted with B 2 O 3 on the B 4 C grain boundary, and the sintered body shrank quickly. Due to the presence of lamellar graphite, the relative density of the sintered body significantly increased from 89.2% to 98.9%. The mechanical properties such as flexural strength ∼336 MPa (∼26.79% increment) and fracture toughness ∼ 5.11 MPam1/2 (∼21.19% increment) were significantly improved compared with the B 4 C/TiB 2 ceramic composite. Graphical abstract Image 1 Highlights • High-performance B 4 C/TiB 2 composites were prepared by pressureless sintering. • The size of plate-like SiC grains decreases with mass ratio of C:Si increasing. • Fracture toughness of sample C10S0 improve owing to crack deflection and bridging. [ABSTRACT FROM AUTHOR]

In this study, copper/few-layered graphene (Cu/FLG) composite powder is prepared using two different approaches, chemical synthesis and mechanical milling, and the effect of the processing routes on the mechanical and thermal behaviors of hot-pressed pallets is examined. With both processing routes, the strength of the matrix is increased ∼3.90 and ∼2.82 times by grain refinement, and is further increased 1.14 times by incorporating 0.5 vol.% FLG. In addition, for both processing routes, the coefficient of thermal expansion is reduced from ∼17.07 to ∼15.15 (ppm/K) by incorporating 0.5 vol.% of FLG in both composites. Considering its cost-effectiveness, simplicity, and potential for mass-production, the mechanical process demonstrates the ability to produce Cu/FLG composites with a high mechanical and thermal performance that is comparable to solution-based chemical synthesis routes. [ABSTRACT FROM AUTHOR]

The double perovskite praseodymium cobaltites PrBaCo 2− x Ni x O 6− δ , where 0.1 ≤ x ≤ 0.3, were obtained by combustion of organo-metallic precursors and shown to have a tetragonal structure with the crystalline lattice parameters a ≈ 3.91 and c ≈ 7.63 Å consistent with electron compensation 2Co 3+ = Ni 2+ + Co 4+ of Ni 2+ impurity centers. The oxygen content (6 – δ ) vs. log ( p O 2 ) dependencies were measured by a coulometric titration technique for x = 0.2 at 650–950 °C and oxygen pressure variations within 10 −10 – 0.6 atm. The reductive decomposition of the cobaltite is found to take place at δ = 1.13. The experimental data were utilized in order to derive partial thermodynamic functions of oxygen that govern defect equilibration. The oxygen partial enthalpy Δ H ¯ O and entropy Δ S ¯ O are found to exhibit strong changes near (6 – δ ) = 5. The observed behavior is explained in frameworks of the defect formation model, which involves reactions of charge disproportionation of Co 3+ cations, oxygen exchange with the gas phase and oxygen disordering over O2 and O3 structural positions. [ABSTRACT FROM AUTHOR]

In high-temperature applications such as hot sections of gas turbines, the sintering rate of the porous microstructure of a ceramic coating, and their mechanical and thermomechanical properties are important parameters for thermal barrier coating systems. In the present research, hardness, elastic modulus, thermal expansion, thermal stress and sintering rate of the porous microstructure of yttria-stabilized zirconia (YSZ) and ceria-stabilized zirconia (CSZ) were investigated and compared using the thermal spray technique on IN738LC base metal in thermal cycling to 1100 °C. To determine the structural and phase characteristics of the coatings, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were employed. The experimental results showed that the CSZ coatings exhibit a considerably better sintering rate of the porous microstructure resulting in better mechanical, and thermomechanical properties when compared to the YSZ coatings. Moreover, the study of microstructures of coatings showed that the CSZ coating is formed with a laminar and porous structure, with pores being smaller and more uniform than those of the YSZ coating. [ABSTRACT FROM AUTHOR]

The effect of substitution of Er at the Yb sites in YbMnO 3 on its magnetic and magnetocaloric is reported. All Yb 1−x Er x MnO 3 (x = 0.1, 0.2, 0.3, 0.5, 0.7 and 1.0) samples show hexagonal structure with P 6 3 cm space group as confirmed by powder X-ray Diffraction. The antiferromagnetic ordering temperature (Néel temperature, T N ) is observed to decrease from 86 K for x = 0.1–76 K for x = 1.0. All compounds show ferromagnetic (FM) ordering due to alignment of the Yb/Er moments below 4 K. A field induced transition is also observed in the isothermal magnetization measurements. The magnetic entropy change increased from 3.0 ± 0.3 to 4.5 ± 0.7 J/mole-K in a magnetic field of 100 kOe, whereas the Relative Cooling Power (RCP) changed from 52 ± 7 to 140 ± 3 J/mol under an applied magnetic field of 100 kOe, when x increased from 0.1 to 1.0. [ABSTRACT FROM AUTHOR]

We present a detailed study of post-deposition annealing effects on contact resistance of Au, Ti, Hf and Ni electrodes on Mg 2 Si thin films. Thin-film Mg 2 Si and metal contacts were deposited using magnetron sputtering. Various post-annealing temperatures were studied to determine the thermal stability of each contact metal. The specific contact resistivity (SCR) was determined using the Cross Bridge Kelvin Resistor (CBKR) method. Ni contacts exhibit the best thermal stability, maintaining stability up to 400 °C, with a SCR of approximately 10 −2 Ω-cm 2 after annealing. The increased SCR after high temperature annealing is correlated with the formation of a Mg-Si-Ni mixture identified by cross-sectional scanning transmission electron microscopy (STEM) characterization, X-ray diffraction characterization (XRD) and other elemental analyses. The formation of this Mg-Si-Ni mixture is attributed to Ni diffusion and its reaction with the Mg 2 Si film. [ABSTRACT FROM AUTHOR]

The effects of magnesium addition on the microstructure, hardness, chemical composition and thermal expansion coefficient of NiAlCr alloys in as-cast and heat-treated states were studied. NiAlCr alloys containing 1, 2.5 and 3.8 at.% Mg were prepared via atmosphere-controlled induction melting following vacuum arc melting. According to the XRD results, as-cast alloys were mainly composed of martensite, β-NiAl and γ′-Ni 3 Al. High amounts of Mg in alloys resulted in a slight increase in CTE. Increasing Mg also changed the morphology of the interdendritic Ni 3 Al phase from continuous network to discontinuous structure, resulting in Ni 2 Mg precipitates with hardness of 1280 HV 0.002 . In the furnace cooling procedure following the annealing procedure at 1050 °C for 96 h, martensite completely transformed into β-NiAl with α-Cr precipitates. The single phase Ni 3 Al transformed into Al 0.9 Ni 4.22 -Ni 3 Al lamellar structure and Ni 2 Mg phase disappeared. The presence of Mg in solid solution did not influence CTE of the alloys. [ABSTRACT FROM AUTHOR]

A new method is proposed to predict the formation of high-entropy single-phase oxide with a pyrochlore structure synthesis from non-equivalent principal elements. Based on this concepte, the La 2 B 2 O 7 (B = Zn2+, Mg2+/Ni2+, Ce4+/Zr4+/Hf4+/Sn4+/Ti4+, W6+, Mo6+) were designed, in which high-entropy La 2 (ZnMgZrWMo) 2 O 7 , La 2 (ZnMgHfWMo) 2 O 7 and La 2 (ZnMgSnWMo) 2 O 7 pyrochlore ceramics were successfully prepared by solid-phase sintering. The microstructure of the entropy-stabilized phase was demonstrated using X-ray diffraction and elemental mapping, and the thermal properties including the thermal expansion coefficient and thermal conductivity were analyzed. The results show that La 2 (ZnMgZrWMo) 2 O 7 has a higher thermal expansion coefficient (13.9 × 10–6 K–1) and lower thermal conductivity (0.8 W/m·K) than its corresponding single-components compound. In addition, La 2 B 2 O 7 (B = Zn2+, Mg2+, Zr4+/Hf4+/Sn4+, W6+, Mo6+) pyrochlore high-entropy ceramics exhibit good calcium – magnesium – aluminosilicate (CMAS) resistance, the apatite protective layer generated after the reaction of La with CMAS effectively prevents further corrosion. This study suggests a novel method for predicting the formation of high-entropy single-phase oxides of pyrochlore structures and provides a new design concept for anti-CMAS corrosion materials. • A novel prediction criterion is proposed to synthesis high-entropy single-phase oxide with a pyrochlore structure. • High-entropy ceramic synthesized by non-equivalent state principal element has better thermophysical properties. • La3+ in the pyrochlore structure can react with CMAS faster to form a resistant layer preventing further corrosion. [ABSTRACT FROM AUTHOR]

It is attempt to enhance the thermal conductivity of Al 2 O 3 /glass by introducing one-dimensional materials into the Al 2 O 3 /glass composite which are fired at 850 °C. The influences of AlN whiskers, carbon fibers and copper fibers on the thermal conductivity of Al 2 O 3 /30 vol% glass composites were studied by the laser thermal conductance instrument, XRD and SEM. The results show that the adding of one-dimensional materials with excellent thermal conductivity remarkably enhances the thermal property of the composites. The oxidation of AlN or copper was not detected when the composites were sintered at 850 °C with 25 MPa for 45 min in a nitrogen atmosphere. Fibers are more effective to enhance the densification of the composites than the whiskers. The highest value of the thermal conductivity of Al 2 O 3 /glass/copper fiber achieves 38.9 W (mK) −1 , an increase of about 500%. The clear enhancement of the thermal conductivity is due to the bridging network formed by the one-dimensional materials. [ABSTRACT FROM AUTHOR]

In this paper, solvothermally synthesized tungsten oxide (WO 3 ) nanocrystals were modified by changing the reaction temperature. The effect of reaction temperature on the morphology and NO 2 sensing properties of WO 3 nanocrystals was investigated. Numerous analytical techniques, such as field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), have been employed to characterize their feature. The NO 2 -sensing properties of the sensors based on the WO 3 nanocrystals with various morphologies to NO 2 with the concentration ranging from 100 ppb to 3 ppm were examined at different temperatures ranging from room temperature (RT) to 250 °C. It is found that the solvothermal reaction temperature played a critical role on determining the morphology of the WO 3 nanocrystals, and all the sensors exhibited a high response, rapid response characteristics and excellent selectivity toward NO 2 at low operating temperature. Especially, the 170 and 180 °C solvothermally synthesized sensors showed an anomalous p-type conductive behavior at approximate below 38 and 55 °C, respectively. [ABSTRACT FROM AUTHOR]

We determined the crystalline characteristics of the hexagonal α-alumina phase by X-ray diffraction at high temperatures between 293 and 2308 K under dynamic vacuum then under constant flow of nitrogen. The experimental values obtained under dynamic vacuum allow to deduce, an anisotropy of the ‘c’ direction compared to the ‘a’ direction of approximately 12% in the range of 293 K–1760 K. On the other side, no anisotropy remains above 1765 K. This anisotropy reflects the fact that aluminum atoms occupy 2/3 of the octahedral sites in the compact hexagonal sublattice formed by the oxygen atoms. We have also reacted alumina when heated under a constant flow of nitrogen. Nitriding alumina occurs around 1765 K and then forms aluminum mononitride, AlN, ZnS-Wurtzite type hexagonal structure. The thermal expansion of this mononitride cell is linear and is characterized by an anisotropy of the direction 'a' in comparison to the direction 'c' of about 17%. [ABSTRACT FROM AUTHOR]

• 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]

Zn 2 SnO 4 nanowires are successfully synthesized by a carbon assisted thermal evaporation process with the help of a gold catalyst under ambient pressure. The as-synthesized nanowires are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) equipped with an energy dispersive X-ray spectroscopy (EDS). The XRD patterns and elemental mapping via TEM–EDS clearly indicate that the nanowires are Zn 2 SnO 4 with face centered spinel structure. HRTEM image confirms that Zn 2 SnO 4 nanowires are single crystalline with an interplanar spacing of 0.26 nm, which is ascribed to the d-spacing of (3 1 1) planes of Zn 2 SnO 4 . The optimum processing condition and a possible formation mechanism of these Zn 2 SnO 4 nanowires are discussed. Additionally, sensor performance of Zn 2 SnO 4 nanowires based sensor is studied for various test gases such as ethanol, methane and hydrogen. The results reveal that Zn 2 SnO 4 nanowires exhibit excellent sensitivity and selectivity toward ethanol with quick response and recovery times. The response of the Zn 2 SnO 4 nanowires based sensors to 50 ppm ethanol at an optimum operating temperature of 500 °C is about 21.6 with response and recovery times of about 116 s and 182 s, respectively. [ABSTRACT FROM AUTHOR]

We report detailed electrical, magnetic and thermoelectric studies on Bi-doped L 0.7− x Bi x Sr 0.3 MnO 3 (0 ⩽ x ⩽ 0.25) manganites. The XRD patterns and Rietveld analysis show that the studied materials are single phased. All the compounds, exhibit the expected metal–insulator transition and a decrease in the characteristic metal–insulator transition temperature ( T MI ) is observed to decrease with increase in Bi-content. Low temperature resistivity data indicates that grain boundaries and electron–electron scattering processes contribute vital role in the conduction process. Magnetic studies also show that the Curie temperature T C is found to decrease with Bi-content. It is observed that M ZFC and M FC curves become more manifested as Bi-content is increased which indicates an increase in magnetic frustration arising due to bending of Mn–O–Mn bond. High temperature analysis on the electrical resistivity and thermoelectric power data indicates that small polaron hopping (SPH) model is valid for all the samples. [ABSTRACT FROM AUTHOR]

New Sb 2 O 3 -based multicomponent heavy metal oxide glasses in the Sb 2 O 3 –Na 2 O–WO 3 –PbO system were prepared using a conventional melt-quenching technique. Glass formation behavior of these glasses and their thermal, physical and structural properties were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), differential scanning calorimetry (DSC), UV–Vis–NIR spectroscopy and Fourier transform infrared (FTIR) spectroscopy analyses according to the increasing PbO concentration by keeping the Sb 2 O 3 /WO 3 ratio constant. Thermal analysis of the glasses were realized in terms of glass transition temperature ( T g ), crystallization temperature ( T c / T p ), glass stability against crystallization (Δ T ), activation energy of the glass transition reaction ( E g ) and fragility parameter ( m ). Density ( ρ ), molar volume ( V M ), oxygen molar volume ( V O ), oxygen packing density (OPD), refractive index, band gap energy ( E g ), average cross-link density ( n c ‾ ) , number of bonds per unit volume ( n b ) and Poisson’s ratio ( μ cal ) values were calculated for the interpretation of physical and structural properties of the glasses. FTIR spectra of the glasses were evaluated in terms of structural transformations on the glass network. [ABSTRACT FROM AUTHOR]

A molybdenum trioxide micropowder (МоО 3 MP) with an average crystallite size of 821 nm was obtained by the thermal treatment of an initial molybdenum nanopowder (Mo NP) with an average crystallite size of 150 nm. The structure of these powders and their resistance to carbon monoxide action at an increased temperature were studied by X-ray diffraction, X-ray fluorescence, and IR spectroscopy. The Mo NP sample contained 88.25% molybdenum and 11.51% oxygen and, as a whole, showed resistance to CO action at 200 °C. However, its crystallites were observed to grow under the specified conditions, and their final average size exceeded 1000 nm. The obtained MoO 3 MP sample contained 67.50% molybdenum and 32.34% oxygen. Мо 2 С, Мо and Мо 4 О 11 were identified in addition to МоО 3 after a treatment with CO at 200 °C. It is concluded that the МоО 3 MP is unstable under the action of carbon monoxide at the indicated temperature. It is suggested that a dissociative sorption of CO involving МоО 3 occurs. [ABSTRACT FROM AUTHOR]

Abstract: The equiatomic multicomponent AlCoCrCuFeNi hexanery high entropy alloy (HEA) was synthesized by mechanical alloying. The effect of the addition of W and Zr was studied by making equiatomic AlCoCrCuFeNiW septenary and AlCoCrCuFeNiWZr octonary high entropy alloys. The effect of alloying addition with milling time was studied using XRD, DSC/TGA, SEM, TEM and Mossbauer spectroscopy. Supersaturated solid solution structure was achieved after 60h milling for hexanery alloy and after 40h milling for both septenary and octonary high entropy alloys. The variation of Mossbauer parameters for AlCoCrCuFeNi system with the addition of W and Zr makes its magnetic environment more complex which is indicated by the conversion of magnetic AlCoCrCuFeNi HEA (60h milling) to partially paramagnetic AlCoCrCuFeNiW (40h milling) to completely paramagnetic AlCoCrCuFeNiWZr high entropy alloy. [Copyright &y& Elsevier]

Abstract: Structural investigations of CdI2 doped silver phosphate glass-nanocomposites in the system xCdI2–(1− x)(yAg2O–(1− y)P2O5) are presented in this paper. Although, X-ray diffraction patterns show amorphous nature of the compositions, electron microscopic studies show several nanocrystalline phases such as CdI2, β-AgI, AgPO3 and Ag4P2O7 dispersed within the glass matrix. The presence of CdI2 nanoparticles in cluster form is dominant for the compositions in the limit of the glass forming domain. The particle size in polyphosphate compositions is higher than that of metaphosphate or ultraphosphate compositions. FTIR spectra of these compositions have been investigated. It has been observed that the presence of different nanocrystalline phases does not affect the basic glass network. Differential scanning calorimetric results show that the incorporation of CdI2 within the glassy matrix increases the glass transition temperature. It is observed that the structural characteristics of the CdI2 doped silver phosphate glasses are quite different from that of other divalent metal iodide doped glasses. [Copyright &y& Elsevier]

Abstract: Ball milling (BM) was used to produce reactive Al–Ni powder mixtures that exhibit self-propagating exothermic reactions (SPER) for nano–micro heater applications. Powders with an Al–Ni molar ratio of 1:3 were milled, cold pressed into pellets and ignited using a heat source. The structural and thermal properties of the pellets were characterized before and after ignition using X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The reaction characteristics of the pellets were evaluated using an infrared camera during ignition experiments. Pellet microstructures show that the BM technique created nanoscale lamellar structures, with dimensions diminishing with increasing milling time. Pellets milled longer than 16h exhibited SPER. Flame velocity increased with pellet density. [ABSTRACT FROM AUTHOR]

Abstract: Gd6UO12(s) was synthesized by citrate–nitrate combustion method. Thermal expansion measurements of this compound were carried out in the temperature range of 298–1273K by high temperature X-ray powder diffractometry and compared with other rare earth compounds of similar stoichiometry reported in literature. Heat capacity of Gd6UO12(s) was also measured by differential scanning calorimetry in the temperature range of 330–720K. Enthalpy, entropy and free energy functions for Gd6UO12(s) were computed. [Copyright &y& Elsevier]

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: In situ X-ray diffraction and magnetic susceptibility measurements were performed to determine the structure, thermal and magnetic properties of the ternary alloys CuMPd6 (M=Ti, V, Mn and Fe). The X-ray diffraction experiments of the polycrystalline specimens annealed at 1273K have shown that a single phase (A1-type face-centered cubic (fcc) structure) is formed at this stoichiometric composition up to a temperature of 1178K. The integrated intensity data obtained from the diffraction experiments were utilized to determine the lattice parameters, Debye temperatures (Θ D), the mean linear thermal expansion (MLTE) and the coefficients of thermal expansion (α(T)). The lattice parameters showed a positive deviation from the Vegard''s law, whereas the Debye temperatures were found to be of the same order as for CuPd3 alloy. The contribution of the static displacements to the temperature factors was found to be nearly zero for the four alloys. The linear thermal expansion follows the classical Grüneisen relationship in these alloys. The trend of magnetic properties in these alloys was observed to be similar to that for CuMPt6 alloys (see text) i.e. paramagnetic – spin glass – ferromagnetic with the increasing atomic number of the metal M. The results have been discussed by comparing with those given in literature. [Copyright &y& Elsevier]

Abstract: Using cold graphite mold casting method, Al-based chill-zone alloys cylinders of millimeter scale thickness [Y. Li, K. Georgarakis, S.J. Pang, A. LeMoulec, T. Zhang, A.R. Yavari, unpublished research.] were prepared. Using high-resolution scanning electron microscopy (HRSEM), it was found that hard submicron crystalline surface layers of thickness about 200μm form when the melt can be undercooled. The structure and the thermal properties of the chill-zone alloy were examined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). A metastable phase Al19Ni5Y3 nucleated during cooling then transformed to equilibrium intermetallics after annealing. The chill-zone alloy shows high mechanical strength in excess of 1GPa at high ambient temperatures and good plasticity. The combination of high strength and good plasticity will be discussed in relation to the special structure of the chill-zone alloy. [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: The thermal expansion and stability of predominantly single-phase Ti2SC powders in argon and air was investigated by Rietveld analysis of synchrotron X–ray diffraction spectra. When the sample was heated in an Ar atmosphere, it started to dissociate into TiS2 (see footnote 1) at ≈400°C. At 8.5 (5)×10−6 °C−1 and 8.8 (2)×10−6 °C−1 the thermal expansion coefficients along the a and c-directions, respectively, are quite similar. The volumetric thermal expansion is 25.2 (5)×10−6 °C−1. When Ti2SC was heated in air, it started to oxidize, at 400°C, first to anatase, which converts, at higher temperatures, to rutile. The sulfur and carbon atoms presumably diffuse outward and escape as gases. [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: Mg–9%Li–1%Zn alloy was successfully cast into a 37mm thick ingot, and then rolled to a thickness of 2mm in this study. Effects of thermal and mechanical treatments on the microstructures and strengthening mechanisms were investigated. The experimental results indicated that the as-cast microstructure of the Mg–9%Li–1%Zn alloy had a dual phase structure with dispersed fine particles of ZnO and MgO oxides. After annealing heat treatment of the as-rolled specimen, α phase was elongated and aligned in the rolling direction, and β phase showed a recrystallized grain structure. The variation in hardness during isothermal heat treatment was believed to correspond to an unstable phase or spinodal decomposition causing age hardening effect. Cold working presented moderate hardening effect, and the hardness of the cold-rolled specimen was almost proportional to the extent of cold working. [Copyright &y& Elsevier]

Abstract: The subsolidus phase relationships of the system ZnO–Li2O–WO3 have been investigated by X-ray diffraction (XRD) analyses. There are one ternary compound, five binary compounds and eight 3-phase regions in this system. The new ternary compound Li2Zn2W2O9 was found by the powder diffraction pattern. The corresponding crystal structure of this compound was refined by Rietveld profile fitting method. It belongs to a trigonal system with space group and lattice constants are a =5.1438(2)Å, c =14.1052(3)Å, and its thermal property was studied. [Copyright &y& Elsevier]

Abstract: Three new series of Ho2−x Er x Mo4O15 (x =0.0–2.0), Ho2−x Sm x Mo4O15 (x =0.0–0.6) and Ho2−x Ce x Mo4O15 (x =0.0–0.25) solid solutions have been prepared successfully by solid-state reaction and studied by powder X-ray diffraction. All the XRD patterns of these molybdates can be indexed in monoclinic space group P21/c. Lattice parameters a, b and c of Ho2−x Ln x Mo4O15 decrease linearly with increasing erbium content and increase with increasing samarium or cerium content. Thermal expansion behaviors of Ho2−x Ln x Mo4O15 have been investigated in the 25–500°C temperature range with high-temperature X-ray diffraction. The temperature dependence of Mo(2)–O14 interaction looks like to be responsible for their thermal expansion behaviors. [Copyright &y& Elsevier]

Abstract: The aim of the work is to analyse thermal properties and microstructure of solders, which should be suitable for application in electronics. The solders must have low enough working temperature to avoid thermal damage of the assembly and uniform microstructure in whole bulk. For solders presented in this work the required temperatures are less than 150°C. They represent alternative, for example, to the conductive adhesives, which are in use. Five types of solders have been studied. They were created from the metals: Sn, In, Bi, Cd. The solder on the basis of Bi/Sn, has the composition of 58wt.% Bi and 42wt.% Sn of eutectic point of the alloy and the melting point of 141°C. The second solder of the composition of 53wt.% Bi, 26wt.% Sn and 21wt.% Cd proved the melting temperature of 103°C. The next both solders are on Sn/In basis. The solder with composition of 70wt.% In and 30wt.% Sn has the melting point temperature of 126°C. The second solder of nearly eutectic composition, 50wt.% Sn and 50wt.% In has lower melting temperatures about 117°C. The last one is ternary solder with composition of 53wt.% Sn, 37wt.% Bi and 10wt.% In with the melting point between 100 and 123°C. Differential scanning calorimetry (DSC) was used to determine the thermal properties of these solders. For the study of microstructure light microscopy and X-ray diffraction analysis were used. The analysis of solders microstructure show that almost all solders have homogenous distribution of two or three phases in the microstructure. [Copyright &y& Elsevier]

Abstract: In situ X-ray diffraction experiments were performed on six samples of the ternary Au–Ag–Pd alloys (with A1 structure) having different compositions using a Cu-target. The integrated intensity data obtained in the temperature range of 373–1200K was utilized to determine the lattice parameters and the thermal parameters like Einstein''s temperatures (Θ E), the mean-square amplitudes () and the coefficients of thermal expansion with a high accuracy. The lattice parameter showed a small negative deviation from the Vegard''s rule. It is also found that the mean-square amplitudes are independent of the static displacements. The mean-square amplitudes of vibration and the linear thermal expansion follow the classical Grüneisen relationship in these alloys. [Copyright &y& Elsevier]

• The effect of Mn additions on the structural and magnetic properties of AlCoCrFeNi was studied. • The arc-melted alloys consisted of a mixture of B2 and bcc phases, the relative amount of which was dependent on Mn content. • Gas atomised powders were single phase with the B2 structure. • Mn additions increased saturation magnetisation but lowered the magnetic transition temperature and the thermal stability. ga1 Alloys of AlCoCrFeMn x Ni (x = 0.0, 0.04, 0.08, 0.12 and 0.16) have been synthesized through arc–melting and gas atomisation (x = 0.0 and 0.16) to investigate the effect of Mn additions to AlCoCrFeNi. Here, the structure, magnetic properties and the thermal stability of the alloys is presented. Electron microscopy confirmed the elemental composition and revealed the microstructure to consist of two spinodally decomposed phases. Rietveld analysis of standard powder X-ray diffraction showed the arc-melted samples consisted of two phases, a B2 phase and a bcc phase while the gas atomised powders consisted of a single-phased B2 structure. Magnetic measurements revealed an increase in the saturation magnetisation at room temperature by 68% for AlCoCrFeMnNi compared to AlCoCrFeNi. The thermal stability of the alloys was investigated using magnetometry, differential scanning calorimetry and in–situ X-ray diffraction, which showed that an increase in Mn content adversely effected the thermal stability of the alloy. [ABSTRACT FROM AUTHOR]

In this manuscript the crystal structure of Li 3 UF 7 from powder X-ray and neutron diffraction studies is reported. The existence of Li 3 UF 7 has been debated for a long time, as it is often missed in a number of phase diagram studies. This study adopted a judicious composition of LiF and UF 4 , and an optimum cooling rate to prepare Li 3 UF 7. The Li 3 UF 7 phase could be obtained by cooling the molten LiF-UF 4 with large excess of LiF at a rate of 5 K/min while slower cooling tends to form LiUF 5. The crystal structures of Li 3 UF 7 and LiUF 5 in the temperature range of 300–10 K have been obtained from the powder neutron diffraction studies. At 300 K, Li 3 UF 7 has an orthorhombic lattice with unit cell parameters: a = 8.698(2) Å, b = 8.692(2) Å, c = 12.803(1) Å, V = 968.0(4) Å3; Z = 8 (Space group: C cca), and is isostructural to orthorhombic Li 3 ThF 7. On cooling, the orthorhombic distortion of Li 3 UF 7 increases but does not reveal any structural transition down to 10 K. The crystal structure of Li 3 UF 7 is built from the defective (Li-deficient) layers of edge shared octahedral LiF 6 and layers corner connected UF 9 polyhedra. Analogous studies on LiUF 5 have also been carried out, which has a tetragonal (Space Group: I 4 1 /a) lattice with unit cell parameters: a = 14.8882(8) Å, c = 6.5438(7) Å, V = 1450.5(2) Å3; Z = 16. The structure of LiUF 5 is built from the three-dimensional sub -lattice formed by U 4 F 30 units and the empty tunnels of the sublattice are occupied by Li 4 F 16 clusters formed by four edge shared LiF 6 octahedra. Also, the details of crystal chemistry of the compounds in LiF-UF 4 systems and their thermal stabilities are discussed. The complexity in the crystal chemistry in LiF-UF 4 system is manifested in multiple close by thermal events in the DTA runs which has also been discussed in the manuscript. ga1 • Synthesis and crystal structure of metastable Li 3 UF 7 in LiF-UF 4 are reported. • Conditions for formation of different phases in LiF-UF 4 system are delineated. • Crystal structures of Li 3 UF 7 and LiUF 5 down to 5 K are studied by LT-PND. • Anisotropic thermal expansion in Li 3 UF 7 is observed in between 5 and 300 K. • LiF-UF 4 phase diagram and comparative crystal chemistry phases in it are discussed. [ABSTRACT FROM AUTHOR]

NaCl:XCe3+ crystals (with X = 0.0 (pure NaCl), 0.001, 0.003, 0.005, 0.006, 0.008 and 0.01) have been grown in large size by using the resistance heating Czochralski method and characterized structurally, mechanically, thermally and optically by carrying out X-ray diffraction (XRD), micro-hardness, thermal stress, optical absorption, photoluminescence (PL) emission, photoluminescence excitation (PLE), thermo-luminescence (TL) and decay time measurements. XRD analysis indicates compression of the NaCl host lattice due to incorporation of Ce3+ ions. Hardness analysis has confirmed that Ce3+ doping improves the hardness of NaCl crystal in proportion with the Ce3+ concentration. Thermal stress analysis indicates that the grown crystals are of high quality. Optical absorption spectra obtained for the Ce3+ doped crystals have illustrated the presence of four peaks at 203, 215, 223, 303 and 414 nm. The Ce3+ doping has been found to influence the excitation and emission peaks due to Ce3+ (4f↔5d) transitions. The TL glow curves obtained show one sharp peak located at about 145 °C; the peak at 120 °C becomes prominent on bleaching with F-light after irradiation. The luminescence decay time has been found to gradually decrease with the increase in Ce3+ concentration. The PL and TL performances have been found to be maximum for the NaCl:0.008Ce3+ crystal. The present study indicates that the NaCl:Ce3+ crystals grown can be considered as promising materials for their use in dosimetry and scintillation applications. • Large-size NaCl:Ce3+ crystals with different Ce concentration were grown by the Czochralski method. • Hardness of NaCl:Ce3+ crystals is better than that of NaCl crystal and increases with increase in Ce concentration. • Thermoluminescence (TL) intensity of NaCl:Ce3+ crystals is much higher than that of NaCl crystal. • NaCl:Ce3+ crystals have short luminescence decay time varying from 46.6 to 29.5 ns. [ABSTRACT FROM AUTHOR]

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]

Abstract: In0.82Ga0.18As epilayers were grown by LP-MOCVD on InP (100) substrates with two-step growth method. It was analyzed that growth temperature of buffer layer exerted an influence on its crystalline quality and optical property, which were characterized by X-ray diffraction, scanning electron microscopy, and photoluminescence. The experiments showed that the crystalline quality and the optical property of the In0.82Ga0.18As epilayers had close relation to the growth temperature of buffer layer and the optimum buffer''s growth temperature was about 450°C. [Copyright &y& Elsevier]

The standard enthalpies of formation of the Ag 30 Li 70 and Ag 20 Li 80 gamma phases (cubic, sg. I-43 m) were measured using the solution calorimetry method; the standard enthalpy of formation of the Ag 10 Li 90 alloy, corresponding to a hypothetical γ phase, was determined using the same method. All the measured and literature values of the standard enthalpies of formation of the Ag–Li intermetallic phases were compared with the data calculated using ab initio for stable and unstable phases and Miedema's model. The XRD pattern for a sample with Ag 30 Li 70 was obtained and it was verified that it contained the γ phase, as expected. Moreover, the structure of the γ-phase for the Ag 4 Li 9 disordered phase was minimized and the vibrational heat capacity at constant volume and the thermal coefficient of linear expansion were calculated using ab initio methods. The simulated XRD pattern of the latter phase was compared with the experimental pattern. It was determined that only one gamma phase, with a homogeneity range not wider than 0.69 ≤ x(Li) ≤ 0.73, is stable for T ≥ 298 K. Furthermore, besides AgLi-β with a homogeneity range of 0.50 ≤ x(Li) ≤ 0.60 at 298 K, a cubic Ag 15 Li 49 -β is stable for x(Li) = 0.77. The entropy term stabilizes the cubic structure of the AgLi-β which can be tetragonal at 298 K. The enthalpies and Gibbs energies of formation were calculated at 298, 320, 425, and 600 K. A new "map" of the phases in equilibrium at different temperatures is proposed. • Characterization of the Ag–Li system for energy storage and high temperature solders. • Ag–Li phase diagram completely redrawn at room temperature. • Cubic β phases stabilised by the entropy term as temperature increases. • Only one γ phase found instead of three. • A new phase, β 2 , found to be stable above room temperature. [ABSTRACT FROM AUTHOR]

In the present work, Ni–Si eutectic alloys with nominal compositions of Ni 80 Si 20 , Ni 70 Si 30 , Ni 55 Si 45 and Ni 45 Si 55 (Ni and Si with the purity of 99.99%) were prepared by arc melting method under vacuum/argon atmosphere. The effects of Si/Ni ratio on the microstructural properties, thermal transformation behavior, micro-hardness and magnetic properties of the Ni–Si eutectic alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), differential thermal analysis (DTA), Vickers microhardness measurement and Vibrating Sample Magnetometer (VSM). The phases expected according to Ni–Si phase diagram for conventional solidified eutectic Ni–Si alloys are considerably consistent with phase detected by XRD in this study. The quantitative results confirm that the chemical composition of the alloys very close to eutectic compositions and the microstructures are in typical lamellar eutectic morphology. The maximum microhardness value of 1126 HV obtained for Ni 70 Si 30 alloy which has highest melting temperature amongst Ni–Si eutectics. The microhardness values decreases with increase of Si/Ni ratio. Ni 80 Si 20 and Ni 55 Si 45 alloys are soft ferromagnetic, Ni 70 Si 30 and Ni 45 Si 55 alloys are paramagnetic with no magnetic saturation. [ABSTRACT FROM AUTHOR]