Author
K.A. Thomas
Bio: K.A. Thomas is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Calorimeter & Schottky anomaly. The author has an hindex of 4, co-authored 8 publications receiving 67 citations.
Papers
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TL;DR: A wide variety of electropositive elements of the periodic table can be inserted into the vacant sites in the host framework structure of hexagonal NbTiP 3 O 12 (an analog of nasicon) to give rise to isostructural phases as discussed by the authors.
38 citations
TL;DR: In this paper, the specific heat of samples of Y1−xPrxBa2Cu3O7−y for x = 0.5 has been measured from 4.5 to 65 K using a quasi-adiabatic calorimeter.
17 citations
TL;DR: In this paper, the authors show that while La and Pr form complete solid solutions, Tb does not substitute for Y. They also show that PrBa 2 Cu 3 O 7 exhibits a semiconductor behavior.
Abstract: Studies on the title compounds show that while La and Pr form complete solid solutions, Tb does not substitute for Y. Superconducting transition temperature (T c ) decreased with increasing x from 91K but pronounced effect is noted for Ln=Pr. PrBa 2 Cu 3 O 7 exhibits a semiconductor behavior.
6 citations
4 citations
TL;DR: In this paper, superconductivity with a T{sub c,zero} at 75 plus minus 1 K has been observed in Tl-M-Ba-Cu-O (M = Ce, Th) system for a starting nominal composition of Tl{sub 2.2}M{sub 1}Ba{ sub 2}Cu{sub 3}O{sub y}.
2 citations
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TL;DR: A wide range of materials based on crystalline and glassy Nasicon compositions are considered in this paper, and their structure, compositional diversity, evolution, and applications are reviewed.
Abstract: Nasicons (sodium super ion conductors) are a class of solid electrolytes. Their structure, compositional diversity, evolution, and applications are reviewed. A wide range of materials is considered based on crystalline and glassy Nasicon compositions.
407 citations
TL;DR: The properties of the Y1−xPrxBa2Cu3O7 (YPrBCO) system are reviewed in this paper, including superconducting, normal state, structural, chemical, optical, magnetic, and thermal properties.
Abstract: The properties of the Y1−xPrxBa2Cu3O7 (YPrBCO) system are reviewed. These include superconducting, normal state, structural, chemical, optical, magnetic, and thermal properties. The destruction of superconductivity with Pr doping is discussed in view of possible models such as hole filling, localization, magnetic pair-breaking, and the role of hybridization. Applications to electronic devices using YBCO/PrBCO/YBCO multilayers are also reviewed.
327 citations
TL;DR: In this article, the crystal structure, superconductivity and magnetic properties of the title compounds have been investigated and the results revealed that with the concentration of Pr being constant, the transition temperatureTc of this system decreases with the increasing of La, or rather with an increasing of effective ionic radii of rare earth elements and disappears at aboutx=0.6.
Abstract: The crystal structure, superconductivity and magnetic properties of the title compounds have been investigated. The results revealed that with the concentration of Pr being constant, the transition temperatureTc of this system decreases with the increasing of La, or rather with the increasing of effective ionic radii of rare earth elements and the superconductivity disappears at aboutx=0.6. The coefficient of electron specific heat and the density statesN (0) which were infered from the magnetic measurements also decrease with the increasing of the effective radii. The relation between the radii of rare earth elements and hybridization is briefly discussed.
134 citations
TL;DR: The crystallographic changes that occur with increasing Pr concentration in the Y−xPrxBa2Cu3O7−δ system have been studied by neutron diffraction as discussed by the authors.
Abstract: The crystallographic changes that occur with increasing Pr concentration in the Y−xPrxBa2Cu3O7−δ system have been studied by neutron diffraction. As x is increased from 0 to 1, the orthorhombic a, b and c lattice parameters expand monotonically, while the orthorhombic distortion, espressed as b a , decreases, reflecting increased occupation of O(5) sites at the expense of O(4) chain site occupancy. The separation of the CuO2 planes in PrBa2Cu3O7−δ indicates that the Pr ions have an intermediate valence of ∼3.3 in this compound. Evidence is presented for increased interaction between the Pr ions and oxygen ions in adjacent CuO2 planes.
106 citations
TL;DR: In this paper, the authors deal with aspects of the modelling of the compositions and properties of inorganic compounds with tetrahedral anions on the basis of crystal-chemical information.
Abstract: The review deals with aspects of the modelling of the compositions and properties of inorganic compounds with tetrahedral anions on the basis of crystal-chemical information. One of the possible algorithms employing crystal-chemical data for the modelling of the compositions, structures, and properties of new compounds is proposed on the basis of the structures of six structural types (glaserite, β-K2SO4, bredigite, palmierite, NASICON, and whitlockite). The likely usefulness of such data for the solution of various problems in materials science is demonstrated. The bibliography includes 208 references.
90 citations