Metal oxides structures

Lithium-ion cells operate during charge and discharge by a mechanism that involves the electrochemical insertion of lithium into, and extraction from, positive and negative electrode host structures. For example, in the well known Li tC6 / Li, tCo02 system, which is assembled in the discharged state, lithium ions are extracted from the metal oxide structure and... 

C. N. R. Rao, B. Raveau, Transition Metal Oxides Structures, Properies, and Synthesis of Ceramic Oxides. Wiley, 1998. 

In recent years, the growing numbers of publications are concerned with ultra-fine metal oxide structures because of their useful applications as bactericides, adsorbents, energy storage media, magnetic data storage, and ferrofluids and specifically as catalysts [6, 7]. 

I shall take the simple view that most metal oxide structures are derivatives of a closest packed 02 lattice with the metal ions occupying tetrahedral or octahedral holes in a manner which is principally determined by size, charge (and hence stoichiometry) and d configuration (Jj). The presence of d electrons can lead to pronounced crystal field effects or metal-metal bonding. The latter can lead to clustering of metal atoms within the lattice with large distortions from idealized (ionic) geometries. 

M-M multiple bonding has long been known in metal oxide structures. The first Mo=Mo bond was seen in one crystalline form of Mo02 which has a distorted rutile structure wherein the Mo(4+) ions occupy adjacent octahedral holes throughout the lattice ( 4). The octahedra are distorted because of the short Mo-Mo distances 2.51 X. La. RejO has a fluorite type structure in which 02 is substituted for F and four of the five Ca2 sites are occupied by La3 ions. The remaining Ca2 site is occupied by an (Re=Re)8 unit with an Re-Re distance 2.259(1) A... 

Micro-Raman spectroscopy Crystal phase structure, crystal size, surface metal oxide structure and coverage Trained Free... 

Vapor deposition techniques have been extensively studied for the fabrication of metal and metal oxide structures. Indeed, the first reported tungsten oxide nanorods were essentially grown by this method. This groundbreaking synthesis of W02.72 leaves room for improvement, however, as it requires a reaction temperature of 1600°C in an argon atmosphere. Additionally, the researchers found the reaction product to be commingling WO2.72 nanorods and WO3 platelets rather than pure nanorods. Later,... 

Role of Electronic Structure in the Susceptibility of Metastable Transition-Metal Oxide Structures to Transformation... 

Some metal oxide structures are unstable when over-delithiated, and as a consequence, the crystal lattice collapses to form a new phase that is electrochemically inactive. Examples are the so-called Jahn—Teller effect for spinel cathodes and similar behavior for LiNi02 and LiCo02 materials as well. These irreversible processes are considered to be caused by the intrinsic properties of the crystalline materials instead of electrolytes and are, therefore, beyond the scope of the current review. See ref 46 for a detailed review. 

Sensor Cell Operating Mode. The simplest method of sensor operation is as a galvanic cell, whereby the sensor acts as a fuel cell and generates a current proportional to the gas concentration to be detected (1 ). However, when detecting certain species in air, it is difficult to obtain a counter-reference electrode in an acid system that will maintain the sensing electrode at a predetermined potential of approximately 1.0 V, to minimize interference. Counter-reference electrodes such as Pt/air (Op) or noble metal/ noble metal oxide structures have rest potentials in the 1.0 to... 

In the development of meta oxiae photocata-ysts with high and stable photocatalytic activity for water decomposition, the establishment of a correlation betweer photocatalytically active sites and metal oxide structures is desirable. In particular, it is important to see how the local structures of metal oxides are associated with the essential steps such as photoexcitation, the transfei of excited charges to the surface, and reduction/oxidation of adsorbec reactants. This chapter deals with photolysis of water by titanates with tunnel structures. The roles of tunnel-related local structures ir the photocatalysis and of Ru02 promoters loaded on the titanates are presented. 

As more Raman spectra of supported metal oxide catalysts appeared in the literature, many contradictory models for the dispersed metal oxide structure were proposed. It was observed in 1983-1984 by Wang and Hall (1983), Chan et al. (1984), and Stencel et al. (1984) that supported Re207, M0O3, and WO3-V2O5 were in hydrated states during ambient Raman measurements. However, the molecular structures of the various hydrated dispersed metal oxide species on oxide supports were not fully understood at that time. 

Rao, C., Raveau, B. (1998). Transition Metal Oxides Structure, Properties, and Synthesis of Ceramic Oxides (2nd ed.). New York Wiley-VCH. A book that covers a lot about solid-state chemistry of the transition metal oxides. 

I 3 The Use of Infrared Spectroscopic Methods Table 3.2 Typical oxygen atom vibrational modes for metal oxide structures. 

Table 2 Estimated metal-oxygen Raman stretching frequencies (cm ) for perfect tetrahedral and octahedral metal-oxide structures ...

A considerable number of materials called titanates are known, some of which are of technical importance. Nearly all of them have one of the three major mixed metal oxide structures (page 54), and indeed the names of two of the structures are those of the titanium compounds that were the first found to possess them, namely, FeTi03, Hmenite, and CaTi03, perovskite. Other titanites with the ilmenite structure are MgTiOa, MnTi03, CoTi03... 

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