ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 20, Number 5
JKCSEZ 20(5)
October 20, 1976 

The x or x0 + x' values of the nonstoichiometric chemical formula TiO2-x or Ti2-(x0 + x') have been measured by a specially made magnetic quartz microbalance in a temperature range from 600 to 1300℃ under oxygen pressures of 1×10-6 to 1 atm. The standard x or x0 value of the rutile is 0.00148. The x values under oxygen pressure of 1 atm decrease with temperatures and then the stoichiometric rutile (or x = 0) is formed at 1130℃. The x values varied between 0.00148 and 0.01719 at a temperature range from 600 to 1300℃ under 1×10-9 ∼ 1×10-2 atm oxygen pressures. The enthalpies of formation of the nonstoichiometric rutile, Hf, varied between 21.05 and 29.97 Kcal/mole under the above conditions. The 1/n values calculated from the plots of log X' vs. log PO2 are -1/2 ∼ -1/4 under low oxygen pressure range of 1×10-6 to 1×10-4 atm. Many physical properties of the titanium dioxide, such as the stability of the rutile, Electrical conductivity, catalytic activity and defects, can be explained through the x values and the thermodynamic data calculated from the temperature and oxygen pressure dependences of the x' values.