The mechanical properties (fracture strength, fracture toughness, and Vickers microhardness) of MgAl2O4 and x wt% ZrO2–MgAl2O4 (1 # x # 30) hot-pressed materials were measured at room temperature. Two kinds of materials, which were prepared from either ball-milled or attrited powders, were investigated. Compared with an unreinforced spinel, a twofold (or greater) increase in both strengthening ...

Reduction of polycrystalline and crystalline magnesium orthovanadate Mg V O by hydrogen was investigated in the temperature 3 2 8 range of 560–9208C. A single crystal of orthorhombic Mg V O with a cation-deficient-spinel structure (25% of the magnesium atoms on 3 2 8 octahedral sites are vacant) was transformed into cubic Mg V O which has a cation-stuffed-spinel structure (8a and 16c sites were...

This book chapter is organized into four major parts. Firstly, it will cover an introduction of using spinel ferrite nanoparticles in biomedical applications, including the antibacterial properties. The second part will provide an overview of the structure and magnetism of spinel ferrites. The third part will focus on the preparation of cobalt ferrite and transition metal substituted cobalt fer...

Simple algebraic equations show that the bulk compressibility in spinel-type compounds can be expressed by means of cation oxide polyhedral compressibilities and a term that accounts for the pressure effect on the internal oxygen position in the unit cell. The equations explain ~i! the difference of compressibilities at octahedral and tetrahedral sites, ~ii! why the macroscopic bulk modulus can...

The performance of Cell-Batt Li-ion cells and Sony 18650 cells using non-stoichiometric spinel and LiCoO2, respectively, as positive electrode material has been studied under several modes of charging. During cycling, the cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. Capacity fade of spine...

Introduction: Grain size separate CG from the Murray CM2 carbonaceous chondrite contains mostly spinel grains of average diameter 0.5 μm [1]. Zinner et al. [2] found that approximately 1% of these spinel grains are of presolar origin as determined by their large O isotopic anomalies. These O isotopic measurements were made with the NanoSIMS on individual grains that were well separated from one...

The mechanical properties (fracture strength, fracture toughness, and Vickers microhardness) of MgAl2O4 and x wt% ZrO2–MgAl2O4 (1 # x # 30) hot-pressed materials were measured at room temperature. Two kinds of materials, which were prepared from either ball-milled or attrited powders, were investigated. Compared with an unreinforced spinel, a twofold (or greater) increase in both strengthening ...

The A2BO4 spinel oxides are distinguished by having either a normal (N) or an inverse (I) distribution of the A, B cations on their sublattices. A point-ion electrostatic model parametrized by the oxygen displacement parameter u and by the relative cation valencies Z{A} vs Z{B} provides a simple rule for the structural preference for N or I: if Z{A}>Z{B} the structure is normal for u>0.2592 and...

Quaternary compounds AB 2 X 3 Y (A = Cu, Ag ; B = In ; X = S, Se, Te ; Y = Cl, Br, I) could be synthesized at high pressures and temperatures. The crystal structures found are defect-zincblende (AgIn2Se3l, AgIn2Te3l, CuIn2Se3Br, CuIn2Se3I, CuIn2Te3Cl, CuIn2Te3Br, CuInTesI), spinel (AgIn2S3Cl, AgIn2S3Br, AgIn2Se3Cl, AgIn2Se3Br, AgIn2Se3l) and defectrocksalt (AgIn2Te3Cl, AgIn2Te3Br). A second for...

The influence of prolonged ball milling on structural changes of hexagonal and spinel type complex iron oxides has been studied by x-ray diffraction and high resolution electron microscopy. The XRD and HREM results for ball milled SrFel2Olg ferrite show fast decomposition and formation of Fe203 and SrO simple oxides. Microstructural developments for a powder mixture of Co(OH)2 and Fe203 show th...