ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 28, Number 4
JKCSEZ 28(4)
August 20, 1984 

The x-values in the nonstoichiometric chemical formulas YO1.5+x and HoO1.5+x, have been measured in the temperature range from 700℃ to 1000℃ under oxygen pressures from 2×l0-1 to 1×10-6 atm by gravimetric method. The observed x-values increase with increasing temperature and oxygen pressure. The ethalpies of formation of excess oxygen in yttrium oxide and holmium oxide decrease with decreasing oxygen pressure and are all positive values representing an endothermic process. The 1/n values calculated from the slopes of the plots of log x vs. log PO2 increase with temperature and are positive values which means the higher oxygen pressure dependence at higher temperature. We have examined the nonstoichiometric defect and conduction mechanism from x-values and thermodynamic data.