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XRD measurements revealed that the investigated NaLiMnP2O7 compound consists of two phases: Na2Mn3(P2O7)2 and LiMnPO4. We found by XRD measurements that at 313 K Na2Mn3(P2O7)2 shows the triclinic symmetry of the compound (space group P-1), while LiMnPO4 phase showed the orthorhombic crystal symmetry (space group Pnma). The phase change between 773 K and 813 K was proved by thermal XRD, impedance spectroscopy and DTA analysis. No evident changes of peak intensities in thermal XRD were observed for LiMnPO4 phase. The impedance of NaLiMnP2O7 ceramics was measured at different temperatures and the total ionic conductivity of the compound was found to be of 5.3 × 10−9 S/m at 400 K on heating stage and only slightly higher on cooling stage. However, the conductivity value at 800 K was much higher – about 1.45 S/m on both stages. The step-like phase transition resulted in the conductivity increase of about 3 orders of magnitude in a narrow range of temperature. The ionic transference number was found to be 0.91 at room temperature. The XRD spectra and conductivity analysis of synthesised two separate phases showed that the phase transition takes place only in Na2Mn3(P2O7)2 ceramics. [ABSTRACT FROM AUTHOR]

Materials LaAlO3and A2+TiO3, where A is Ba, Ca, Pb and Sr, have been investigated in order to determine the “effective” temperature dependent ionic radii of 12-fold coordinated Ba2+, Ca2+, Pb2+, Sr2+and La3+, and, 6-fold coordinated Al3+, Ti4+and O2−within the “simple” “ideal” cubic Perovskite structure. The recently developed planar and volume constrained Perovskite model, which incorporates thermal expansion, has been utilized to determine ionic radii values. As compared with Goldschmidt based models, the newly determined radii provide significant improvements for more precise modeling of the lattice parameter of Perovskites at room temperature as well as over extended temperature ranges. [ABSTRACT FROM AUTHOR]

Ca properties in the sintering behavior of gadolinia-doped ceria were investigated. Their structures and conductivities were characterized by X-ray diffraction, scanning electron microscopy, and AC impedance spectroscopy. All the electrolytes were found to be of single phase with a cubic fluorite structure. AC impedance measurements showed that the conductivities for Ce0.85Gd0.10Ca0.05O2-δsample increased by increasing the sintering temperature. At 1500°C the Ce0.85Gd0.10Ca0.05O2-δhad low resistivity values, high conductivity, and low activation energy. [ABSTRACT FROM AUTHOR]

Ammonium acetate complexed polyvinyl alchohol (PVA) samples are prepared following the solution cast technique. Pure PVA shows semicrystalline nature. The amorphous nature of the PVA increases with the increase in ammonium acetate salt concentration in it. The bands due to pure PVA in FTIR spectra shift towards higher frequency region with increase in concentration indicate salt dissolution. The 20 mole% ammonium acetate complexed PVA exhibits highest conductivity at 25°C amongst all samples under study. [ABSTRACT FROM AUTHOR]

The current state-of-the-art in using electrolyte, yttria stabilized zirconia (YSZ) in solid oxide fuel cell suffers from a variety of challenges for commercialization due to the unavailability of sealant materials and corrosion at high temperature (∼800°C). Recently, development of CeO2-carbonate based low temperature solid oxide fuel cells capable of operating at 300-600°C attracted the attention of many researchers. Three compositions have been prepared for this study: 1) GdCeO2-(LiNa)CO3, 2) GdCeO2-Li2CO3 and 3) GdCeO2-Na2CO3. Phase formation, microstructural evolution and ionic conductivity have been investigated. XRD results indicated the formation of GdCeO2-(LiNa)2CO3 phase. However, the peaks corresponding to carbonate phase was absent in the case of GdCeO2-Li2CO3 and GdCeO2-Na2CO3. SEM microstructure analysis revealed enhanced crystal growth in the case of GdCeO2-Na2CO3. The sample Gd-CeO2 that contains 25wt.% (LiNa)CO3 sintered at 600°C showed the highest ionic conductivity of 0.1600 Scm-1 at 550°C and low activation energy of 0.0912 eV. The ionic conductivities of GdCeO2-Li2CO3 and GdCeO2-Na2CO3 were 0.0050 and 0.0549 Scm-1 respectively at 550°C. The highest ionic conductivity of GdCeO2-(LiNa)2CO3 is attributed to higher defect density formed by the eutectic composition of Li2CO3 and Na2CO3 ∼497°C. [ABSTRACT FROM AUTHOR]

The dielectric properties of Cu6PS5I crystals were investigated in broad frequency (20 Hz-1 GHz) and temperature (25 K-300 K) range. At high temperatures and low frequencies dielectric spectra are highly influenced by very high ionic conductivity. The temperature dependence of the static dielectric permittivity reveals just one phase transition at Tc1 = 156 K. The frequency spectra of conductivity, at low frequencies (20 Hz-1 MHz) obeys the Almond-West power law. The activation energy of conductivity changes at 194 K, which indicates the second phase transition of Cu6PS5I. [ABSTRACT FROM AUTHOR]

The dielectric properties of newly synthesized AgInP2S6 crystals were investigated in broad frequency (20 Hz-1 MHz) and temperature range (110 K-350 K). No anomaly in temperature dependence of complex dielectric permittivity indicating the polar phase transition can be detected down to the lowest temperatures. The dielectric properties of presented crystals are mainly caused by high conductivity. The frequency spectra of conductivity obey the Almond-West power law. The activation energy of conductivity was found to be EA/k = 7734 K. A suggestion is given that the electric conductivity in these crystals can be interpreted by ionic mechanism. [ABSTRACT FROM AUTHOR]