Complex oxides magnetic properties

Structure factor for small single crystals of C-type rare earth oxides of Y2O3, DyaOs, and H02O3 was investigated from the synchrotron X-radiation point of view [30]. Approximate symmetry in the deformation electron density (Ap) around a rare earth atom with pseudo-octahedral oxygen coordination is similar to the cation geometry. Interactions appeared between heavy rare earth atoms show a pronounced effect on the Ap map. The electron-density symmetry around second rare earth atom is also influenced appreciably by cation-anion interactions and the oxides magnetic properties also reflect this complexity. 

The magnetic properties of ferrites are intricately related to composition, microstmcture, and processing much more so than in the case of metals primarily because of the complex chemistry of the oxides and because of the ceramic processing requited to produce the finished parts. 

Evidently, the most interesting materials are those in a fractional oxidation state, with general formula (cation)[M(dmit)2] (n > 1), since they can exhibit both electrical and magnetic properties. Only eight such complexes have been reported so far. All of them but (BDTA)[Ni(dmit)2]2 [89] have been obtained as powders. They have in general been poorly characterized, and their stoichiometries have been determined from elemental analysis. Among these powdered compounds, the... 

The electronic and magnetic properties of bridged dimetallic complexes such as 104 and 105 have been explored. Oxidation of the CoII-Co11 phenylene-bridged species 104 affords the mixed valence Con-Com complex and the diamagnetic CoIII-Co111 dication.128 Magnetic, IR, and electrochemical evidence on neutral 104 indicates weak Co-Co interaction. 

The Mn- Mn separations in both planar and butterfly complexes are very similar and range between 2.80 A and 3.45 A. The magnetic properties of these complexes have been studied extensively, and showed antiferromagnetic interactions between the manganese(III) centers. Electrochemical behavior of the butterfly conmlexes is summarized in Table 9 and both oxidative and reductive processes are observed. 

The first indications of covalency in complexes of two metal oxides appear if one of the metals belongs to the platinum group. The oxide complexes in this group are not well known only very recently a few complexes have been prepared and their magnetic properties measured. The compound Na2Ir03, that is formed when a mixture of the metal and Na2GOs is heated in oxygen... 

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