Title of article :
Oxygen nonstoichiometry of undoped BaTiO3−δ
Author/Authors :
Lee، نويسنده , , Doh-Kwon and Yoo، نويسنده , , Han-Ill، نويسنده ,
Issue Information :
دوهفته نامه با شماره پیاپی سال 2001
Abstract :
Oxygen nonstoichiometry (δ) of “undoped”, polycrystalline BaTiO3−δ (but with two different nominal purity) has been measured as a function of oxygen partial pressure in the range of 10−15≤PO2/atm≤0.1 at elevated temperatures (1073≤T/K≤1273) by a solid-state coulometric titration technique. Each isotherm varies sine-hyperbolically against log(PO2) with an inflexion point therein (corresponding to the electronic stoichiometric composition or δ=0). The nonstoichiometry variation is attributed to oxygen vacancies compensated mostly by background and/or intrinsic acceptors in the higher PO2 region and by electrons in the lower PO2 region. The purity effect on nonstoichiometry is discussed. The intrinsic electronic excitation equilibrium constant is evaluated and compared exhaustively with the reported. The relative partial molar enthalpy and entropy of component oxygen are also evaluated as functions of the nonstoichiometry.
Keywords :
oxygen nonstoichiometry , BaTiO3?? , Relative partial molar enthalpy and entropy of oxygen , Coulometric titration
Journal title :
Solid State Ionics
Journal title :
Solid State Ionics