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Ta-doped Ti1-xTaxCoSb (0≤x≤0.08) half-Heusler compounds were synthesized by melting and annealing process. Their thermoelectric properties were studied in the temperature range of 300–900 K. The Ti1-xTaxCoSb compounds exhibit negative Seebeck coefficients with considerably large absolute values. With increasing Ta substitution, the electrical conductivity was greatly increased, but the thermal conductivity was reduced. Because of the combined effects of increased electrical conductivity and reduced thermal conductivity, the thermoelectric performance of Ti1-xTaxCoSb alloys was apparently improved by doping Ta. The dimensionless figure of merit of 0.3 was obtained for Ti0.92Ta0.08CoSb compound at 900 K. This value is about ten times larger than that of the undoped TiCoSb compound. [ABSTRACT FROM AUTHOR]

Single phases of SrBi2-χNdχNb2O9 (χ=0, 0.1, 0.2, and 0.4) ceramics were prepared by the solid-state reaction method and studied by dielectric and Raman spectroscopy. The substitution of Nd3+ for Bi3+ induced a dielectric relaxation behavior for SrBi2-χNdχNb2O9 (χ=0.1, 0.2, and 0.4). When χ=0.4, the dielectric response of SrBi1.6Nd0.4Nb2O9 is characteristic of typical relaxor ferroelectrics, which could be attributed to the disorder induced by the Nd3+ substituting for Bi3+ in Bi2O2 layers. The dielectric relaxation of SrBi1.6Nd0.4Nb2O9 was fitted using the Vögel-Fulcher relationship, which indicates that SrBi1.6Nd0.4Nb2O9 is analogous to a spin glass with thermally activated polarization fluctuations above a static freezing temperature. Raman spectra of SrBi2-χNdχNb2O9 ceramics could indicate that the structural distortion of NbO6 octahedron decreases with the increase in Nd content, which results in the decrease in Tm for SrBi2-χNdχNb2O9 ceramics. [ABSTRACT FROM AUTHOR]

The complex dielectric permittivity of the morphotropic phase boundary [001]-oriented PMN–x%PT single crystal with x=33%, grown by the modified Bridgman technique, has been investigated as a function of both temperature and dc poling field. Structural phase transformation sequence is discussed in the light of polarization rotation process. A remarkable shift in the rhombohedral-tetragonal phase transition temperature is observed with changing of the poling field. It is found that high temperature poled state remained stable even after removal of the field. [ABSTRACT FROM AUTHOR]

Studies the control of the B-site order of lead Pb(Mg[sub 1/3]Nb[sub 2/3)O[sub 3] by the partial substitution at the A site by both donor La[sup 3+]/Bi[sup 3+] and acceptor K[sup +1]. Origins of Raman bands; B-site order induced by A-site substitution.