Spinels from cumulus and non-cumulus members of the 0thris ophiolite display a considerable variation in composition. Cumulus pierites and gabbros contain either a primary chromite and/or a reaction spinel formed by reaction with co-existing sili?ate,-" (Cr--A1 varia tion) or intercumulus liquid (Cr--Fe variation). Non-cumulus peridotites contain spinels which vary along a Cr--A1 trend. Harzbur...

Many compounds with the spinel structure type have been analyzed for their thermoelectric properties. Published data was used to augment experimental results presented here to select promising thermoelectric spinels. Compounds studied here include C~~,~Al~.5Cr2Se4, Cu05Coo.5Cr2Se4, C~o,~Ino,~Cr2Se~ and CuIr2Se4. Many exhibit low lattice thermal conductivity of about 20 mW/cmK, independent of te...

In this work, nanostructured LiMn₂O₄ (LMO) and LiMn₂O3.99S0.01 (LMOS1) spinel cathode materials were comprehensively investigated in terms of electrochemical properties. For this purpose, electrochemical impedance spectroscopy (EIS) measurements as a function of state of charge (SOC) were conducted on a representative charge and discharge cycle. The changes in the electrochemical performance of...

The Mössbauer spectra of nanoferrite materials such as Ni0.25Mn0.75Fe2O4, Co0.5Mn0.5Fe2O4 and Ni0.4Co0.6Fe2O4 have been reported and the above materials were prepared by sol-gel combustion method using metal nitrates as source material and Polyvinyl alcohol(PVA) as...

We report the particle size dependent magnetic behaviour in the antiferro-magnetic spinel CoRh 2 O 4. The nanoparticles were obtained by mechanical milling of bulk material, prepared under sintering method. The XRD spectra show that the samples are retaining the spinel structure. The particle size decreases from 70 nm to 16 nm as the milling time increases from 12 hours upto 60 hours. The magne...

The elasticity of high-pressure mantle phases may be characterized by crystal chemically similar compounds. Analogue compounds available as single crystals yield the most reliable elastic constant data. The single-crystal elastic constants of pleonaste and hercynite spinel, rutile-structure germanium dioxide, and spessartite-almandine garnet are studied, in most cases as a function of pressure ...

Low-temperature structures of the lithium manganese spinels were determined using TOF neutron Rietveld analysis. The spinels LiMn2O4 with different values, (0.016, 0.040, and 0.132) showed the cubic-orthorhombic phase transitions, and the lattice distortion decreased with decreasing . Although no anomaly corresponding to the cubic-orthorhombic phase transition was observed in the DSC curve for ...

The theory of structural phase transition in CuTi2S4 is proposed. The symmetry of order parameters, thermodynamics and the mechanism of the atomic structure formation of the rhombohedral Cu-Ti-thiospinel have been studied. The critical order parameter inducing the phase transition has been found. Within the Landau theory of phase transitions, it is shown that the phase state may change from the...

OBJECTIVES Aim of the study was to analyze the mold filling capacity and the dimensional accuracy of a spinel-based investment for titanium castings. METHODS Expansion of the investment in dependence of the preheating temperature was measured in a dilatometer. The degree of transformation of MgO and Al2O3 to spinel (MgAl2O4) was evaluated by means of X-ray powder diffraction. Mold filling cap...