High Temperature Microbalance Technique for the Determination of the Metal Oxides Nonstoichiometry under Controlled Atmosphere

Various properties of the metal oxides are strongly affected by the nonstoichiometry. Therefore, nonstoichiometry is very important for understanding the basic character of the metal oxides. Nonstoichiometry of the metal oxides is often measured by the gravimetric measurements at high temperature under controlled atmospheres. As the vapor pressure of the metal is negligibly small compared to the oxygen, the nonstoichiometry behavior of the metal oxides is often measured as a function of the oxygen partial pressure. In this article, a brief review is made for the experimental technique of nonstoichiometry measurements by means of high temperature gravimetry under controlled gas-atmospheres: The oxygen nonstoichiometry is measured as the weight change at different oxygen partial pressures. The principle of the measurement is very simple. However, as the measurement is carried out at the equilibrium conditions at the high temperature under controlled oxygen partial pressures, and moreover, as the measurements often extend over a long period of time, the precision and long-time stability of the measuring system are important. Other important reminders will also be shown for the measurements procedure of the gas controlled high temperature microbalance.