Thermal conductivity of Tb2(MoO4)3 crystals at low temperatures

Thermal conductivity of the improper ferroic Tb₂(MoO₄)₃ was measured in the range 0.3 K–100 K by the method of the stationary heat flow. An additional maximum in thermal conductivity observed at 0.45 K is due to the anomaly of specific heat corresponding to the antiferromagnetic phase transition. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of water content on electrical conductivity of fish skin collagen

The increased interest in fish skin collagen results from the risk of BSE disease and the production of native collagen by the acidic hydration method. As a material, FSC derived by the novel acidic hydration method was used. The bovine Achilles tendon (BAT) collagen type I was applied as a control material. Measurements were carried out at the temperature range 2980 K-510 K. Each sample was heated twice. During the first heating run for FSC, to 380 K, the maximum was localized at 343 K, at electrical conductivity of 7 · 10⁻⁶ S/m. In the second heating run to 510 K, the maximum was observed at 443 K for FSC, and at 487 K for BAT collagen. The peaks revealed in the temperature range 320-350 K were related to the free water and bound water release, alike for FSC and BAT collagen. The process of water removal for both types of collagen takes place in similar temperature ranges.     

Structure and electrochemical properties of carbon aerogels synthesized at ambient temperatures as supercapacitors

In this paper, the carbon aerogels derived from organic sol-gel process were prepared by means of ambient drying technique. Morphology and physical properties of the carbon aerogels were characterized by scanning electron microscopy (SEM) and N₂ sorption isotherm. It was found that the carbon aerogels were porous materials with pearly network structure, the particle size of carbon aerogels increased with the increase of R/C ratio (molar ratio of resorcinol to catalyst). The BET surface areas of obtained carbon aerogels were in the range 600-1000 m²/g. Electrochemical performances of the carbon aerogels electrodes were studied by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance measurement. The results indicated that carbon aerogels electrodes had good electrochemical performance, high reversibility and high specific capacitance. Moreover, the utilization efficiency of carbon aerogels was promoted due to excellent electronic conductivity and extensive mesoporous network of carbon aerogels. The specific capacitance of the electrode is 183.6 F/g with R/C ratio 1500. In addition, the carbon aerogel electrode for the application of supercapacitor had low resistance, small leakage current and good electrical conductivity.     

Structural, thermal and electrical properties of PVA-LiCF3SO3 polymer electrolyte

The development of polymeric systems with high ionic conductivity is one of the main objectives in Li rechargeable battery. In the present study, the different composition of PVA-LiCF₃SO₃ polymer electrolyte has been prepared by solution cast technique using DMSO as solvent. The FTIR study confirms the polymer-salt complex formation. The amorphous nature of the polymer has been confirmed by XRD analysis. DSC measurements show decrease in T_g with increasing salt concentration. The temperature dependent conductivity obeys Arrhenius relationship. The maximum conductivity has been observed in the order of 7 × 10^− 4 S cm^− 1 for 25 mol% of LiCF₃SO₃. The activation energy has been found to be 0.16 eV. The two peaks have been observed in the dielectric loss spectrum which shows two types of relaxation α and β.     

Electrical conductivity and photoreflectance of nanocrystalline copper nitride thin films deposited at low temperature

Nanocrystalline thin films of copper nitride were grown on Si (1 0 0) wafers at a low substrate temperature by reactive magnetron sputtering of Cu target with the mixture of nitrogen and argon. The influence of nitrogen deficiency upon the structural, optical and electrical properties of as-deposited films was investigated. X-ray diffraction confirms the presence of cubic Cu₃N and Cu biphases irrespective of carefully optimized processing parameters. With a Cu content approaching the stoichiometry for Cu₃N, the films assume a smooth morphology with densely-packed nanocrystallites of about 40–60 nm in size. Those deposits containing more than 79% Cu are metallic conductors with excellent electrical conductivity via a percolation mechanism, whereas the slightly substoichiometric Cu₃N films show a typical behavior of deficit semiconductor, with an optical gap of about 1.85 eV as revealed by photoreflectance measurement. All the observations are discussed in terms of nitrogen reemission from the growing film.