Transport properties of Al or Cr-doped nickel oxide relevant to the thermal oxidation of dilute Ni-Al and Ni-Cr alloys

Influence of CaO on the thermodynamic and transport properties of cobaltous oxide

“…Platinum wires were used as electrical junctions. The oxygen partial pressure was measured near the sample by a yttria-stabilized zirconia gauge [10,11].…”

“…where e is the charge of the electron, p the hole concentration per cm 3 ,  their mobility regarded as a thermally activated hopping process ( =o exp-H/RT), H the enthalpy of conductivity defined by the relation H= H+HV/(1+) HV the enthalpy of formation of the defects, H 3 the hole enthalpy of mobility, and  the mean charge of the defects that can be determined from the slopes of the experimental diagrams, with [7][8][9][10][11],:…”

“…The chemical diffusion coefficient was determined for single crystals, initially in thermodynamical equilibrium with the surrounding atmosphere (argon/ P O2 =10 -3 atm), by following the electrical conductivity values after a sudden change of P O2 (air / P O2 =0.21atm) [7][8][9][10][11][12]. A concentration gradient of cationic vacancies (dCV/dz) sets up immediately near the surfaces of the single crystal, leading to a flux of cationic vacancies coupled to an opposite flux of cations near the surfaces.…”

“…Co1-xO is a member of an important series of transition metal oxides having a rocksalt structure and displaying p-type semiconduction at high temperature, as NiO for instance [1][2][3][4][5][6][7][8][9][10][11]. The prevailing point defects are  times negatively ionized cationic vacancies and electron holes, whose concentrations are determined by the thermodynamic equilibrium with the surrounding atmosphere, but also by the presence of diluted aliovalent cations.…”

Estimating the Internal Oxidation of Ni-Al Alloys

“…Many authors were interested in thermal oxidation of nickel which is considered as a model material. In high-purity nickel and in dilute alloys (b5% in weight), it was found that the rate controlling the transport process is the outward diffusion of cations through the Ni 1 −xO scale [7].…”