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Article
Increase of Magnetic Transition Temperatures by Reduction of Local Disorder for Perovskite Manganites
We report the synthesis of Sr1-xCaxMnO3 and La0.5Ba0.5MnO3 perovskites over extended cation and oxygen composition ranges and describe the dependence of their phase stability on the tolerance factor t = t(x,T,δ) ...
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Reference Work Entry At a glance
Energy-dispersive techniques
In the first part of this chapter the principles of the white-beam, energy-dispersive method for X-ray diffraction are described with special emphasis on the use of synchrotron radiation. Expressions are given...
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Article
Specific Heat of Mg11B2, a Two-Gap Superconductor
We report measurements of the specific heat of Mg11B2, from 1 to 50 K and in magnetic fields to 9 T, and give the values of parameters relevant to the superconductivity. The superconducting-state electron contrib...
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Chapter
Decrease of Ferromagnetic Transition Temperature in Nonstoichiometric SrRu1−v O3 Perovskites
We have discovered that synthesis at high-pressure oxygen of 600 atm at 1100°C produces nonstoichiometric SrRu1−v O3 perovskites with randomly distributed vacancies on the Ru-sites. The incre...
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Chapter and Conference Paper
Defects and Disorder in Magnetoresistive Double Perovskite A2FeMoO6 (A = Sr,Ba)
A2FeMoO6 (A = Sr, Ba) is a double perovskite having an ordered ferrimagnetic structure of Fe and Mo magnetic superlattices. The Fe and Mo atoms are ordered on alternating, corner-shared octahedral sites, however,...
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Article
Pressure Dependence of Cr3+ Fluorescence in θ-Alumina
The ruby fluorescence has, for many years, been used as a convenient tool for the determination of pressure in diamond-anvil cells. Subsequently, its use was extended to measure stresses in fibers and composit...
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Article
The complex nature of superconductivity in MgB2 as revealed by the reduced total isotope effect
Magnesium diboride, MgB2, was recently observed to become superconducting1 at 39 K, which is the highest known transition temperature for a non-copper-oxide bulk material. Isotope-effect measurements, in which at...
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Chapter
Universal Phase Diagrams and “Ideal” High Temperature Superconductors: HgBa2CuO4+δ
The structural and superconducting properties of HgBa2CuO4−δ have been investigated over an extended range of do** (0<δ<0.25). Two series of samples were measured in which oxygen content was varied using differ...
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Chapter
Spectacular Magneto-Related Properties of Complex Oxides
Perovskite manganites display unusual correlations between magnetic, electronic, and structural properties that are caused by strong electron-electron and electron-phonon interactions. In this paper we discuss...
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Chapter
Structure- Properties Relationships For Manganese Perovskites
By combining the results of dc magnetization, ac susceptibility, magnetoresistivity, magnetostriction, and x-ray and neutron powder diffraction data for stoichiometric La1- xSrxMnO3 we have constructed a phase di...
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Chapter and Conference Paper
Improved Y-123 Materials by Chemical Substitutions
By using the knowledge accumulated during last decade about the relationship between the structural features and the superconducting properties we have attempted to design an improved Y123 material that would ...
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Article
Scaling of transition temperature and CuO2 plane buckling in a high-temperature superconductor
A characteristic feature of the high-temperature superconductors is the existence of a chemical composition that gives a maximum transition temperature, Tc, separating the so-called under-doped and over-doped re...
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Article
Oxygen Transport in the Sr2Fe3−x, CoxOy System
The mixed-conducting Sr-Fe-Co oxide has potential use as a gas separation membrane. Its superior oxygen transport reveals the feasibility of using oxide membranes in large-scale oxygen separation. Sr2Fe3-xCoxOy (...
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Article
Phase Stability of The Mixed-Conducting Sr-Fe-Co-O System
Mixed-conducting ceramic oxides have potential uses in high-temperature electrochemical applications such as solid oxide fuel cells, batteries, sensors, and oxygen-permeable membranes. The Sr-Fe-Co-O system co...
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Article
Crystal Structures of Mixed-Conducting Oxides Present in The Sr-Fe-Co-O System
The potential applications of mixed-conducting ceramic oxides include solid-oxide fuel cells, rechargeable batteries, gas sensors and oxygen-permeable membranes. Several perovskite-derived mixed Srs-Fes-Co oxi...
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Article
Chemical do** and improved flux pinning in Hg-based superconductors
Chemical do** of a small amount (0.02∼0.3) of rhenium (Re) ion into HgBa2Can−1CunOy(n=1∼4) has been studied. The flux pinning strength in these Hg-based superconductors is significantly enhanced compared to the...
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Article
Layered CMR Manganites: Structure, Properties, and Unconventional Magnetism
Neutron powder diffraction studies of the layered compounds R1.2Sr1.8Mn2O7, (R = La, Pr, Nd), RSr2Mn2O7 (R = Pr, Nd), and La1.4Sr1.6Mn2O7 show that the degree of distortion of the MnO6 octahcdra do not correlate ...
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Article
Dependence of superconducting transition temperature on do** and structural distortion of the CuO2 planes in La2−xMxCuO4 (M=Nd, Ca, Sr)
We have separated the structural and do** effects on the superconducting transition temperature in La2−xMxCuO4 (M=Nd, Ca, Sr). At a fixed do** level, the highest Tc is found for flat and square CuO2 planes in...
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Article
Phase development of Bi-2212 superconductor: A time-resolved neutron powder diffraction investigation
Time-resolved in situ neutron powder diffraction and Rietveld refinement have been used to study the synthesis of Bi-2212 from hydroxide precursors in a 2% O2 atmosphere. Bi-2212 was found to form within the temp...
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Chapter and Conference Paper
Chemical Stabilization and Flux Pinning in Hg-Based Superconductors
Effect of chemical stabilization by substitution of a small amount (0.1~0.25) of rhenium (Re) ion on the Hg-site in HgM2Can-1Cun0y (M=Ba or Sr, n=l~4) has been studied. The flux pinning behavior in these Hg-based...
