The distribution of vacancies in lanthana-doped lead titanate

The incorporation of lanthanum sesquioxide in lead titanate has been investigated at constant temperature and at constant partial pressures of oxygen and of lead monoxide in respect of lanthanum contents in the range 0.5 ≦ y ≦ 50 mol%. The gravimetric method has been used to determine the amount of lead monoxide liberated by the incorporation of the lanthana and volatilized at high temperatures. In all probability the lanthanum ions occupy the lead sites in lead titanate. In the case of lanthanum contents y ≧ 5 mol% vacancies occur exclusively at lead sites, while in the case of lanthanum contents y < 5 mol% vacancies are formed also at titanium sites.