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Bi2Te3 is a thermoelectric material with high thermoelectric conversion efficiency near room temperature. The control of its components is an effective method to improve the thermoelectric properties of Bi–Te based materials. In this paper, seven-layer Bi–Te thin films with Te content ranging from 36.29% to 77.29% were deposited on non-rotating glass substrates by co-sputtering and the samples were rapidly thermally annealed in a nitrogen atmosphere. The films were characterized by x-ray diffraction, scanning electron microscopy, and Hall effect measurement methods, and the effects of the components on the film morphology and thermoelectric properties were investigated. The results showed that the films were composed of mainly Bi2Te3 after annealing. As the Te element content increased, the grain size in the film surface first increased and then decreased, the layers between the interfaces became less obvious, and the number of voids decreased. Subsequently, thin films with Te content between 60% and 75% were deposited on a rotating substrate; the thermoelectric properties were relatively high and stable after annealing. A film with Te content of 69.29% had a good crystallization quality and large grain size with a maximum power factor of 8.17 µW/(K2 cm) after annealing at 350 °C for 17 min. [ABSTRACT FROM AUTHOR]

A modified model is proposed to describe the dielectric nonlinear behavior in bismuth-based cubic pyrochlores by introducing non-tunable factor into Tagantsev's model. To validate the model, Bi1.5MgNb1.5-x Ti x O7 (BMNT) films were fabricated via chemical solution deposition. Bias field dependence of the permittivity predicted by the modified model agrees well with experimental results. A method for calculating barrier heights for hopping ions is presented based on the modified model. The maximum barrier heights for hopping dipoles in BMNT films derived from the model decrease from 0.206eV to 0.172eV with increasing Ti content from x=0 to x=0.15. [ABSTRACT FROM AUTHOR]

Abstract: Cubic pyrochlore Bi3/2ZnNb3/2O7, Bi3/2Zn1/2Mg1/2Nb3/2O7 and Bi3/2Zn1/3Mg1/3Ni1/3Nb3/2O7 thin films were fabricated on Au/Ti/SiO2/Si (100) substrates using a chemical solution spin coating process. Tunability of Bi3/2ZnNb3/2O7 thin films was improved from 22% to 35% by substituting Mg2+ and Ni2+ for Zn2+ at a bias field of ∼1MV/cm. Dielectric loss of thin films remained below 0.004 at 1MHz and was almost independent of Mg2+ and Ni2+ doping and bias field. Effects of Mg2+ and Ni2+ substitution on the tunability were discussed based on Raman spectral analyses. The F 2g(1) mode correlated with the vibration of A–O bond significantly influenced the tunability of thin films. [Copyright &y& Elsevier]

The investigation of the electrical transport properties of ZrS 2 is conducted up to 30.7 GPa using first-principles calculation and electrical experimental methods. The electrical parameters of ZrS 2 are investigated under high pressure conditions using the thin film integrated microcircuit technology on a diamond anvil cell. The structural phase transitions occur at approximately 2.0 GPa and 6.0 GPa, as evidenced by changes in the energy band structure and discontinuities in electrical parameters. At around 12.3 GPa, the pressure-induced metallization is observed by temperature-induced resistivity and the closing of the band gap. The sudden decrease in resistivity can be attributed to the combined contribution of an increase in carrier concentration and mobility. Similarly, the abrupt decrease in Hall coefficient is attributed to the increase in carrier concentration. [Display omitted] • ZrS 2 undergoes two phase transitions by theoretical calculation. • The reversible structural phase transitions causes changes in electronic properties. • Metallization occurs at around 12.3 GPa via temperature-induced resistivity. • The measured electrical parameters confirm the generation of phase transitions. [ABSTRACT FROM AUTHOR]

Abstract: The Bi1.5MgNb1.5O7 (BMN) thin films were prepared on Au-coated Si substrates by rf magnetron sputtering. We systematically investigated the structure, dielectric properties and voltage tunable property of the films with different annealing temperatures. The relationships of leakage current and breakdown bias field with annealing temperature were firstly studied and a possible explanation was proposed. The deposited BMN thin films had a cubic pyrochlore phase when annealed at 550°C or higher. With the increasing of annealing temperature, the dielectric constant and tunability also went up. BMN thin films annealed at 750°C exhibited moderate dielectric constant of 106 and low dielectric loss of 0.003–0.007 between 10kHz and 10MHz. The maximum tunability of 50% was achieved at a bias field of 2MV/cm. However, thin films annealed at 750°C had lower breakdown bias field and higher leakage current density than films annealed below 750°C. The excellent physical and electrical properties make BMN thin films promising for potential tunable capacitor applications. [Copyright &y& Elsevier]