Change of Oxygen Concentration with Temperature of the Nickel and Cobalt Oxide Solid Solution Solutions

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概要

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• The oxide solid solution MeO (= n MiO + m CoO) having a rock salt type structure is obtained; its lattice parameter varies with cation composition according to Vegard's law. The deviation from stoichiometry in MeO thus produced was found to be less than 10^<-2>% (in excess of oxygen). Taking this well defined divalent oxide. MeO as a reference, change of oxygen concentration was studied as functions of both temperature and cation composition, with special reference to the correlation between the nature of the defects in oxides introduced by reaction with oxygen in air and the various physical and chemical properties which they exhibit. It turned out that the whole reaction process is divided into five distinct stages when the temperature is raised from room to higher temperatures. At the first and the second stages, surface and subsurface reactions predominate. The third stage is characterized by incorporation of gaseous oxygen into the lattice. The first step of incorporation takes place without change of crystal structure, resulting in formation of the oxide phase characterized by (1) having smaller unit cell dimension, (2) having random distribution of trivalent as well as divalent cations among the lattice sites and (3) having low activation energy for current carriers (〜0.02eV). The second step is the spinel formation, resulted from the more ordered re-arrangement of these cations. As the result, the activation energy increases to 〜0.1eV. The fourth stage corresponds to transitional region in which the decomposition of the spinel into the rock salt type divalent oxide MeO occurs. The hysteresis is here appreciable in the reaction: oxide with spinel type structure 〓 MeO. The reaction products at the fifth stage correspond to oxides with equilibrium intrinsic defects determined by the temperature and oxygen partial pressure of the atmosphere. Products of each reaction stage, without exception, proved to be p-type semiconductors.

• 社団法人日本物理学会の論文
• 1958-07-05

著者

• Sakata Kimiko

  Institute Of Science And Technology University Of Tokyo

• Sakata Tamio

  Research Laboratory Ohkura Electric Company

関連論文

• On the Resistivity and Crystal Structure of Binary Oxide of Nickel and Cobalt
• Change of Oxygen Concentration with Temperature of the Nickel and Cobalt Oxide Solid Solution Solutions

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