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Papers by J. Gopalakrishnan

Research paper thumbnail of An investigation of structural, magnetic and dielectric properties of R2NiMnO6 (R=rare earth, Y)

Materials Research Bulletin, 2009

We have investigated the structure, magnetic and dielectric properties of the double perovskite o... more We have investigated the structure, magnetic and dielectric properties of the double perovskite oxides, R2NiMnO6 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho and Y). We could refine powder X-ray diffraction patterns of all the phases on the basis of monoclinic (P21/n) double perovskite structure where Ni and Mn atoms are ordered at 2c and 2d sites, respectively. All the phases

Research paper thumbnail of ChemInform Abstract: Ln2MoTiO7-x (Ln: Rare Earth or Y): A New Series of Oxide Pyrochlores Prepared by Topochemical Reduction of A2MoTiO8 Scheelites

Research paper thumbnail of Soft-chemical routes to synthesis of solid oxide materials

Research paper thumbnail of Flux creep and critcal-current anisotropy in Bi2Sr2CaCu2O8+δ

Physical Review B, 1989

... VOLUME 39, NUMBER 10 Flux creep and critical-current anisotropy in Bi2Sr2CaCu20g + 8 BDBiggs,... more ... VOLUME 39, NUMBER 10 Flux creep and critical-current anisotropy in Bi2Sr2CaCu20g + 8 BDBiggs, MN Kunchur, JJ Lin,* and SJ Poon Department of ... the volume magnetization M. For the H ± case, J, is isotropic in the plane normal to the field, as are the sam-ple dimensions ...

Research paper thumbnail of Properties and structures of R 2− x A x CuO 4 phases: R= La, Pr and Nd; A= Sr, Pb and Cd

Research paper thumbnail of X-ray spectroscopic study of chromium, nickel, and molybdenum compounds

The Journal of Physical Chemistry, 1980

ABSTRACT

Research paper thumbnail of Studies on some Ln2MoO5 oxides

Journal of the Less Common Metals, 1979

Research paper thumbnail of Preparation and thermal decomposition of some oxomolybdenum(VI) oxalates

Journal of Inorganic and Nuclear Chemistry, 1970

Research paper thumbnail of Superconducting and magnetic behavior in La/sub 2-x/Na/sub x/CuOâ

New phases of the type La/sub 2-x/A/sub x//sup 1 +/CuO/sub 4-y/ have been prepared where A/sup 1 ... more New phases of the type La/sub 2-x/A/sub x//sup 1 +/CuO/sub 4-y/ have been prepared where A/sup 1 +/ is sodium or potassium. The sodium phases are superconducting for x values from 0.2 to 0.5 at temperatures up to about 40 K. In addition, there are unusual magnetic properties below about 10 K that may be indicative of spin glass behavior. Phases of the type La/sub 2-x/K/sub x/CuO/sub 4-y/ could only be prepared with x values up to about 0.1, and these phases are not superconducting above 4.2 K. 10 references, 2 figures, 2 tables.

Research paper thumbnail of Thermodynamic evidence for phase transition in MoO2−δ

The Journal of Chemical Thermodynamics, 2007

Research paper thumbnail of Some ABO3 oxides with defect pyrochlore structure

Solid State Communications, 1975

... For x = 0.15 (ie, BiVO315) E = 0.26 eV, while for the composition x = 0.5 (BiVO3 ), E = 0.33 ... more ... For x = 0.15 (ie, BiVO315) E = 0.26 eV, while for the composition x = 0.5 (BiVO3 ), E = 0.33 eV. The Vol. 17, No.4 ABO3 OXIDES WITH DEFECT PYROCHLORE STRUCTURE 547 FIG. 1. Electrical conductivity and Seebeck coefficient of BiVO315. ...

Research paper thumbnail of Bulk Superconductivity up to 122 K in the Tl-Pb-Sr-Ca-Cu-O System

Science, 1988

New high-temperature superconductors based on oxides of thallium and copper, but not containing b... more New high-temperature superconductors based on oxides of thallium and copper, but not containing barium, have been prepared. A transition temperature (T(c)) of about 85 K is found for (Tl(0.5)Pb(0.5)) Sr(2)CaCu(2)O(7) whereas (Tl(0.5)Pb(0.5))Sr(2)Ca(2)Cu(3)O(9) has a T(c) of about 120 K. Both materials possess tetragonal symmetry with a = 3.80 A, c = 12.05 A for (Tl(0.5)Pb(0.5))Sr(2)CaCu(2)O(7), and a = 3.81 A, c = 15.23 A for (Tl(0.5)Pb(0.5))Sr(2)Ca(2)Cu(3)O(9). A structure refinement of the latter phase has been carried out with single-crystal x-ray diffraction data.

Research paper thumbnail of Superconducting Tl2.0Ba2.0CuO6+δ: A high resolution neutron powder and single crystal x-ray diffraction investigation

Physica C: Superconductivity, 1989

ABSTRACT

Research paper thumbnail of Superconducting properties of single-crystal Nb sphere formed by large-undercooling solidification process

Physica C: Superconductivity, 2003

Research paper thumbnail of Static magnetic order in electron-superconductor related compounds

Physica C: Superconductivity, 1989

Research paper thumbnail of New oxide superconductors

Physica C: Superconductivity, 1988

Crystals of the new high temperature superconductor Bi2Sr3-xCaxCu2O8+y have been grown and studie... more Crystals of the new high temperature superconductor Bi2Sr3-xCaxCu2O8+y have been grown and studied. Single crystal x-ray diffraction data were used to determine a pseudo tetragonal structure based on an A-centered orthorhombic cell with a = 5.399 Å, b = 5.414 Å, and c = 30.904 Å. The structure contains the copper-oxygen sheets as in La2CuO4 and YBa2Cu3O7, but the copper-oxygen

Research paper thumbnail of Oxygen nonstoichiometry in copper-oxide based superconductors and related systems: Structure of nonsuperconducting Bi2Sr3−xYxCu2O8+y (x≈0.6–1.0)

Physica C: Superconductivity, 1989

Structural refinements of the new compounds Bi 2 Sr 3−x Y x Cu 2 O 8+y in the range of x that giv... more Structural refinements of the new compounds Bi 2 Sr 3−x Y x Cu 2 O 8+y in the range of x that gives insulating rather than superconducting behaviour (x≈0.6 and 1.0) have been obtained from single crystal X-ray and neutron powder diffraction data. Results indicate oxygen ...

Research paper thumbnail of Crystal structure of the high-temperature superconductor TI2Ba2CaCu2O8

Nature, 1988

Nature is the international weekly journal of science: a magazine style journal that publishes fu... more Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and ...

Research paper thumbnail of Absence of magnetic order in (Ba, K)BiO3

Research paper thumbnail of Studies of static magnetic order in electron-superconductors and their parent compounds

Research paper thumbnail of An investigation of structural, magnetic and dielectric properties of R2NiMnO6 (R=rare earth, Y)

Materials Research Bulletin, 2009

We have investigated the structure, magnetic and dielectric properties of the double perovskite o... more We have investigated the structure, magnetic and dielectric properties of the double perovskite oxides, R2NiMnO6 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho and Y). We could refine powder X-ray diffraction patterns of all the phases on the basis of monoclinic (P21/n) double perovskite structure where Ni and Mn atoms are ordered at 2c and 2d sites, respectively. All the phases

Research paper thumbnail of ChemInform Abstract: Ln2MoTiO7-x (Ln: Rare Earth or Y): A New Series of Oxide Pyrochlores Prepared by Topochemical Reduction of A2MoTiO8 Scheelites

Research paper thumbnail of Soft-chemical routes to synthesis of solid oxide materials

Research paper thumbnail of Flux creep and critcal-current anisotropy in Bi2Sr2CaCu2O8+δ

Physical Review B, 1989

... VOLUME 39, NUMBER 10 Flux creep and critical-current anisotropy in Bi2Sr2CaCu20g + 8 BDBiggs,... more ... VOLUME 39, NUMBER 10 Flux creep and critical-current anisotropy in Bi2Sr2CaCu20g + 8 BDBiggs, MN Kunchur, JJ Lin,* and SJ Poon Department of ... the volume magnetization M. For the H ± case, J, is isotropic in the plane normal to the field, as are the sam-ple dimensions ...

Research paper thumbnail of Properties and structures of R 2− x A x CuO 4 phases: R= La, Pr and Nd; A= Sr, Pb and Cd

Research paper thumbnail of X-ray spectroscopic study of chromium, nickel, and molybdenum compounds

The Journal of Physical Chemistry, 1980

ABSTRACT

Research paper thumbnail of Studies on some Ln2MoO5 oxides

Journal of the Less Common Metals, 1979

Research paper thumbnail of Preparation and thermal decomposition of some oxomolybdenum(VI) oxalates

Journal of Inorganic and Nuclear Chemistry, 1970

Research paper thumbnail of Superconducting and magnetic behavior in La/sub 2-x/Na/sub x/CuOâ

New phases of the type La/sub 2-x/A/sub x//sup 1 +/CuO/sub 4-y/ have been prepared where A/sup 1 ... more New phases of the type La/sub 2-x/A/sub x//sup 1 +/CuO/sub 4-y/ have been prepared where A/sup 1 +/ is sodium or potassium. The sodium phases are superconducting for x values from 0.2 to 0.5 at temperatures up to about 40 K. In addition, there are unusual magnetic properties below about 10 K that may be indicative of spin glass behavior. Phases of the type La/sub 2-x/K/sub x/CuO/sub 4-y/ could only be prepared with x values up to about 0.1, and these phases are not superconducting above 4.2 K. 10 references, 2 figures, 2 tables.

Research paper thumbnail of Thermodynamic evidence for phase transition in MoO2−δ

The Journal of Chemical Thermodynamics, 2007

Research paper thumbnail of Some ABO3 oxides with defect pyrochlore structure

Solid State Communications, 1975

... For x = 0.15 (ie, BiVO315) E = 0.26 eV, while for the composition x = 0.5 (BiVO3 ), E = 0.33 ... more ... For x = 0.15 (ie, BiVO315) E = 0.26 eV, while for the composition x = 0.5 (BiVO3 ), E = 0.33 eV. The Vol. 17, No.4 ABO3 OXIDES WITH DEFECT PYROCHLORE STRUCTURE 547 FIG. 1. Electrical conductivity and Seebeck coefficient of BiVO315. ...

Research paper thumbnail of Bulk Superconductivity up to 122 K in the Tl-Pb-Sr-Ca-Cu-O System

Science, 1988

New high-temperature superconductors based on oxides of thallium and copper, but not containing b... more New high-temperature superconductors based on oxides of thallium and copper, but not containing barium, have been prepared. A transition temperature (T(c)) of about 85 K is found for (Tl(0.5)Pb(0.5)) Sr(2)CaCu(2)O(7) whereas (Tl(0.5)Pb(0.5))Sr(2)Ca(2)Cu(3)O(9) has a T(c) of about 120 K. Both materials possess tetragonal symmetry with a = 3.80 A, c = 12.05 A for (Tl(0.5)Pb(0.5))Sr(2)CaCu(2)O(7), and a = 3.81 A, c = 15.23 A for (Tl(0.5)Pb(0.5))Sr(2)Ca(2)Cu(3)O(9). A structure refinement of the latter phase has been carried out with single-crystal x-ray diffraction data.

Research paper thumbnail of Superconducting Tl2.0Ba2.0CuO6+δ: A high resolution neutron powder and single crystal x-ray diffraction investigation

Physica C: Superconductivity, 1989

ABSTRACT

Research paper thumbnail of Superconducting properties of single-crystal Nb sphere formed by large-undercooling solidification process

Physica C: Superconductivity, 2003

Research paper thumbnail of Static magnetic order in electron-superconductor related compounds

Physica C: Superconductivity, 1989

Research paper thumbnail of New oxide superconductors

Physica C: Superconductivity, 1988

Crystals of the new high temperature superconductor Bi2Sr3-xCaxCu2O8+y have been grown and studie... more Crystals of the new high temperature superconductor Bi2Sr3-xCaxCu2O8+y have been grown and studied. Single crystal x-ray diffraction data were used to determine a pseudo tetragonal structure based on an A-centered orthorhombic cell with a = 5.399 Å, b = 5.414 Å, and c = 30.904 Å. The structure contains the copper-oxygen sheets as in La2CuO4 and YBa2Cu3O7, but the copper-oxygen

Research paper thumbnail of Oxygen nonstoichiometry in copper-oxide based superconductors and related systems: Structure of nonsuperconducting Bi2Sr3−xYxCu2O8+y (x≈0.6–1.0)

Physica C: Superconductivity, 1989

Structural refinements of the new compounds Bi 2 Sr 3−x Y x Cu 2 O 8+y in the range of x that giv... more Structural refinements of the new compounds Bi 2 Sr 3−x Y x Cu 2 O 8+y in the range of x that gives insulating rather than superconducting behaviour (x≈0.6 and 1.0) have been obtained from single crystal X-ray and neutron powder diffraction data. Results indicate oxygen ...

Research paper thumbnail of Crystal structure of the high-temperature superconductor TI2Ba2CaCu2O8

Nature, 1988

Nature is the international weekly journal of science: a magazine style journal that publishes fu... more Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and ...

Research paper thumbnail of Absence of magnetic order in (Ba, K)BiO3

Research paper thumbnail of Studies of static magnetic order in electron-superconductors and their parent compounds