Oxygen electron doped

YBa2Cu307 5 is around 97°, the exact value dependent on 8, and in the orthorhombic form of La, Sr Cu04 the octahedra are tilted with respect to each other. In the electron-doped systems the planes are unusual in that there are no axial oxygen atoms at all. There does not seem to be any correlation of with the Cu-O-Cu angle and thus superconductivity is found in both flat and distorted sheets. 

Syntheses at high pressures have been essential for obtaining superconductivity in the t-SrCuOz perovskite which contains infinite sheets of copper oxygen squares. Electron doping by a R substitution leads to n-type superconductivity. 

In terms of formal charges on the ions, p-type (or hole-doped) YBCO may be written as Y +(Ba +)2(Cu +)2Cu (0 )7 5. YBCO becomes superconductive at < 0.4, with its most pronounced superconductivity at 8 = 0.05. It should be noted that there are other examples of p-type superconductors that involve metal doping rather than varying oxygen content, such as La2 xStxCu04 (Tc = 34 K at X = 0.15). Similarly, electron-doped (n-type) superconductors may be synthesized such as Nd2 xCcxCu04 (Tc = 20 K), written formally as Nd2 x -"Ce, (e )xCu2+04. 

Strontium titanate [12060-59-2] SrTiO, becomes an n-ty e semiconductor when additional electrons are created on the Ti lattice sites by donor doping or when oxygen is removed from the material through heat treatment in a reducing atmosphere. The mobiUty of the electrons in the conduction band is about 6 crc] j(V-s). On the other hand, when ZnO is reduced, 2inc interstitials are formed and these act as donors, each yielding a free electron. 

Another application is in tire oxidation of vapour mixtures in a chemical vapour transport reaction, the attempt being to coat materials with a tlrin layer of solid electrolyte. For example, a gas phase mixture consisting of the iodides of zirconium and yttrium is oxidized to form a thin layer of ytnia-stabilized zirconia on the surface of an electrode such as one of the lanthanum-snontium doped transition metal perovskites Lai j.Srj.M03 7, which can transmit oxygen as ions and electrons from an isolated volume of oxygen gas. 

References to a number of other kinetic studies of the decomposition of Ni(HC02)2 have been given [375]. Erofe evet al. [1026] observed that doping altered the rate of reaction of this solid and, from conductivity data, concluded that the initial step involves electron transfer (HCOO- - HCOO +e-). Fox et al. [118], using particles of homogeneous size, showed that both the reaction rate and the shape of a time curves were sensitive to the mean particle diameter. However, since the reported measurements refer to reactions at different temperatures, it is at least possible that some part of the effects described could be temperature effects. Decomposition of nickel formate in oxygen [60] yielded NiO and C02 only the shapes of the a—time curves were comparable in some respects with those for reaction in vacuum and E = 160 15 kJ mole-1. Criado et al. [1031] used the Prout—Tompkins equation [eqn. (9)] in a non-isothermal kinetic analysis of nickel formate decomposition and obtained E = 100 4 kJ mole-1. 

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