Rare earth (RE - Ce, Gd) modified Nd<inf>1-x</inf>RE<inf>x</inf>FeAsO<inf>0.7</inf>F<inf>0.3</inf> superconductor with enhanced magneto-transport properties

The influence of rare earth (RE – Ce, Gd) doping at the Nd site in the NdFeAsO0.7F0.3 superconductor wherein Ce and Gd have ionic radii in the order Ce &gt; Nd &gt; Gd is investigated.The authors P. M. Aswathy J. B. Anooja and Neson Varghese acknowledge the Council of Scientific and Industrial Research (CSIR) for providing fellowship. The authors acknowledge CSIR 12th Five Year Plan Project, “Sustainable technologies for the Utilization of Rareearths (SURE),” (No. CSC0132) and Department of Science & Technology (DST) for financial support.This is the accepted manuscript. The final version is available at http://pubs.rsc.org/en/Content/ArticleLanding/2015/RA/c5ra02499d#!divAbstract

Effect of deuteration on the electrical conductivity, dielectric constant and phase transitions in LiNH4SO4

Measurements of dc conductivity and dielectric constant show that deuteration causes an upward shift of the high temperature phase transition point from 186.5 to 191°C and a downward shift of the low temperature transition point from 10 to -1.5°C in LiNH4SO4. Mechanisms of phase transitions and of electrical transport in the crystal are discussed.University of Cochi

Electrical conductivity and thermally stimulated current in the paraelectric phase of (NH4)2SO4

Anomalous variations of d.c. electrical conductivity with temperature are observed in ammonium sulphate single crystals, suggesting a possible phase transition at 150°C. Measurements of thermally stimulated current also support these results. The mechanism of electrical conduction is explained on the basis of studies made on doped and quenched crystals.Cochin Universit

DC electrical conductivity and phase transitions in (NH4)3H(SO4)2

Four distinct peaks are observed at 140, -26, -132 and -140°C in the sigma x* against T-1 plot between 200 and - 196°C for (NH4)3H(SO4)2, corresponding to four different phase transitions of which the one at -26°C is reported here for the first time. Data on doped samples reveal the charge transport mechanism in the crystal.Cochin Universit

High‐temperature phase transitions in pure and deuterated ammonium dihydrogen phosphate: Conductivity and dielectric measurements

Results of axiswise measurements of the electrical conductivity (dc and ac) and dielectric constant of NH4H2PO4 confirm the occurrence of the recently suggested high‐temperature phase transition in this crystal (at 133 °C). The corresponding transition in ND4D2PO4 observed here for the first time takes place at 141.5 °C. The mechanism involved in these transitions and those associated with the electrical conduction and dielectric anomalies are explained on the basis of the motional effects of the ammonium ions in these crystals. Conductivity values for deuterated crystals give direct evidence for the predominance of protonic conduction throughout the entire range of temperatures studied (30–260 °C).University of Cochi