抄録
Isothermal shrinkage and electrical resistance of powder compacts of highly pure yttria (purity: 6 nine) were simultaneously measured over the temperature interval 800°to 950°C in an atmosphere of nitrogen, air and oxygen during sintesing. By X-ray diffraction analysis, no new phase of yttria was detected in the range of temperature and oxygen partial pressure investigated. It was found that the oxygen partial pressure has an effect on both the shrinkage and electrical resistance of powder compacts of yttria. The isothermal shrinkage increased and the electrical resistance decreased with increasing oxygen partial pressure. The result of thermoelectric power measurement indicated p-type character in all experimental conditions studied.
From these results, it may be concluded qualitatively that predominant defect in high purity yttria is excess oxygen defects resulting from the deviation of stoichiometry more or less associated with electron holes.
