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Abstract: Bulk polycrystalline Sn0.95Fe0.05O2−σ and Sn0.93Fe0.05M0.02O2−σ (M=Sb/Mg) samples were fabricated. Detailed X-ray diffraction and transmission electron microscopy analyses revealed that the dopants most probably replaced the Sn in SnO2 structure, instead of forming impurity phase or nanocluster. By varying the dopant M (Sb/Mg), the electron- (Sb) and hole- (Mg) doping effect on the magnetic properties of Sn0.93Fe0.05M0.02O2−σ was investigated. Compared with Sn0.95Fe0.05O2−σ , the saturation magnetization decreased after doping with Sb and increased after doping with Mg. The changes of Fe oxidation state and carrier type, discovered from X-ray photoelectron spectroscopy, are believed to be responsible for the co-doping tuned ferromagnetism in Sn0.93Fe0.05M0.02O2−σ . [Copyright &y& Elsevier]

Abstract: In the present work, the impedance spectroscopy and conductivity mechanism of multiferroic CoFe2O4–Pb(Zr0.53Ti0.47)O3 composite thick films have been investigated. Temperature dependent impedance spectroscopy analysis was conducted in the temperature range of 25–275°C with the frequency ranging from 100Hz to 1MHz. Two impedance relaxation peaks were observed at high frequency with low temperature, and low frequency with high temperature. These peaks were attributed to grain and grain boundary effect, respectively. Electric modulus spectra clearly presented the contributions from both effects in terms of remarkably semicircle arcs. Two different grain boundary effects were reflected in the electric modulus spectra: one caused by homogeneous PZT grain boundary and the other due to the heterogeneous CFO and PZT grain boundary. The activation energy calculated from modulus spectra was consistent with the estimated value from impedance spectra. Investigation on dielectric spectra revealed a dc conductivity region and two nearly constant loss regions, corresponding to the grain effect and two different grain boundary effects, which were also demonstrated in ac conductivity spectra. Furthermore, ion hopping and transport mechanism were unveiled through the analysis on ac conductivity spectra. [ABSTRACT FROM AUTHOR]

Soft-magnetic multilayers with or without SiO 2 interlayer were fabricated on Si (111) substrates using magnetron sputtering. The static magnetic and high frequency electromagnetic properties of FeCoB(60 nm)/SiO 2 (6 nm)/FeCoSiB(t nm) or FeCoB(60 nm)/FeCoSiB(t nm)were systematically investigated. The experimental results showed that all multilayers had an in-plane uniaxial magnetic anisotropy and the interlayer of SiO 2 could decouple the different magnetic phases leading to steps in hysteresis loops. Two resonance peaks of complex permeability spectra were observed for FeCoB(60 nm)/SiO 2 (6 nm)/FeCoSiB(t nm) films. The method to adjust the resonance frequency and FWHM is simple and robust, which may be potential for industrial application. [ABSTRACT FROM AUTHOR]

Abstract: The p-type Bi0.4Sb1.6Te3 system compounds with fine microstructure were prepared by mechanical alloying (MA) and equal channel angular extrusion (ECAE) in the present work. A preferentially orientated microstructure that the (110) plane preferentially orientated along the perpendicular direction to extrusion and the basal planes (00 l) preferentially orientated along the extrusion direction was formed in the ECAE process, and the orientation factors F of the basal planes (00 l) of the extruded alloys was about 0.36. The electrical and thermal transmission performances were strongly affected by the preferential orientation and the thermoelectric properties in the extrusion direction were obviously improved by the ECAE process. The maximum dimensionless figure of merit of the 4wt.% Te-doped Bi0.4Sb1.6Te3 alloys was obtained in the extrusion direction at testing temperature 343K, ZT=0.979. [Copyright &y& Elsevier]

Abstract: Starting from elemental bismuth, tellurium and selenium powders, n-type Bi2Te2.85Se0.15 solid solution with fine microstructure was prepared by mechanical alloying (MA) and plasma activated sintering (PAS) in the present work. The effect of PAS process on microstructure and thermoelectric properties of the sintered samples was investigated. The sintering temperature of PAS process (683K) was 80–100K lower than that of conventional hot pressing and the whole PAS process was also greatly shortened to about 30min. A preferentially orientated microstructure with the basal planes (00 l) perpendicular to pressing direction was formed in the PASed sample and the maximum figure of merit (Z) at room temperature was 1.80×10−3 K−1. [Copyright &y& Elsevier]

Pyrochlore-free nano-sized (1−x)PMN–xPT (x=0, 0.10, 0.35) (PMN–PT) powders were synthesized from a mixture of the commercial oxides PbO, MgO, TiO2 and Nb2O5 by a high-energy ball milling process. The grain size estimated from XRD patterns for the three samples was about 10–30 nm. The high sinterability of the synthesized PMN and PMN–PT powders was evidenced by the fact that almost fully dense ceramics for the three systems could be readily achieved at temperatures as low as 950°C. The relationship between microstructure, electrical properties of the PMN and PMN–PT ceramics and sintering temperature was investigated. The dielectric properties of 0.90PMN–0.10PT are comparable to those of the traditional ceramic samples, while 0.65PMN–0.35PT has a better higher dielectric constant than those of traditional ceramics after sintering at 1100°C for 1 h. [Copyright &y& Elsevier]

Solid solutions of (Zr1−xTix)O2 (x=0.44, 0.48, 0.52 and 0.60) with a srilankite structure were produced directly from ZrO2 and TiO2 oxide powders via a high-energy ball milling process in air at room temperature. (Zr1−xTix)O2 phase was formed as the samples were milled for 8 h. After milling for 20 h, a single phase of (Zr1−xTix)O2 could be obtained. The effects of annealing on the phase formation and stability of the solid solution (Zr1−xTix)O2 were investigated in the oxide mixtures milled for different time durations. [Copyright &y& Elsevier]

In this paper, the microstructure and thermophysical properties of two CoNiCrAl bond coat alloys with differing Al contents were investigated. Two CoNiCrAl alloys with compositions of Co-31.7%Ni-20.8Cr-10Al and Co-31.7%Ni-20.8Cr-12Al (all in wt%) were prepared by vacuum induction melting and casting. The microstructure of the as-cast CoNiCrAl alloys was characterised by scanning electron microscopy (SEM), X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD). The phase changes of the CoNiCrAl alloys as a function of temperature were studied by differential scanning calorimetry (DSC). Thermophysical properties such as thermal conductivity, thermal diffusivity and thermal expansion were evaluated. The as-cast CoNiCrAl alloys exhibited a two-phase structure, consisting of the Al-rich BCC β phase and Co and Ni-rich FCC γ phase. It was found that the β-phase fraction increased with the overall Al content in the alloy. A two-stage thermal expansion was noted for both CoNiCrAl alloys. In addition, it was shown that the CoNiCrAl alloy with the higher Al content exhibited a lower thermal expansion coefficient at high temperatures. This is because more β phase was formed in the CoNiCrAl-12 alloy, resulting in a reduced thermal expansion coefficient. • Two CoNiCrAl bond coat alloys were prepared at different Al contents. • The volume fraction of the β phase increased with Al content. • No significant difference was found in the thermal conductivity. • A two-stage thermal expansion behaviour was noticed. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic properties of Gd2(fum)3(H2O)4·3H2O were investigated by static and alternating susceptibility, specific heat and adiabatic magnetization. The material is characterized by weak antiferromagnetic interactions, arising predominantly from dipolar couplings that leads to magnetic ordering at T N =0.19K. A pronounced change in the magnetic entropy was found near the critical temperature. The magnetocaloric behavior estimated from specific heat data is confirmed by adiabatic magnetization above 0.2K. In addition, adiabatic magnetization and demagnetization near the critical temperature revealed only a small hysteresis. Finally, the magnetothermal response and resulting refrigeration capacity of Gd2(fum)3(H2O)4·3H2O is compared with other magnetic refrigerants proposed for low-temperature applications. [Copyright &y& Elsevier]

Abstract: For optimizing the magnetostriction in Fe–Ga alloys, a novel tensile-stress heat-treatment method has been used for textured polycrystalline rods. Utilizing the consistency between the intrinsic magnetocrystalline anisotropy and the shape anisotropy in the textured structure, a large magnetostriction up to 200ppm has been obtained in an alloy with composition Fe83Ga17 without application of pre-stress. Such samples also exhibit large pre-stress adjustable magnitude, about 90% for total magnetostriction. Due to the complete alignment of the magnetic moments, a magnetostriction contribution of the bcc (A2) phase can be ruled out and the magnetostrictive behavior of the Fe3Ga (DO3) phase has been investigated in detail. [Copyright &y& Elsevier]

Abstract: Bismuth telluride based n-type thermoelectric materials were prepared via the route of mechanical alloying (MA) and subsequent hot pressing (HP) process. Influence of hot press process parameters on the thermoelectric properties was investigated. Increasing hot pressing temperature from 340 to 400°C, the figure of merit of the hot pressed sample increases rapidly, and then it grows slowly and no improvement is obtained when further increasing from 460 to 500°C. Prolonging hot pressing time appropriately is helpful to improve thermoelectric properties, a maximum figure of merit of 1.7×10−3 K−1 has been obtained for the 4h HP-ed sample. [Copyright &y& Elsevier]