Preparation of Semiconducting Titanates by Chemical Methods

Semiconducting barium titanate has been prepared both by coprecipitating the lanthanum in the preparation of barium titanyl oxalate and by precipitation of lanthanum hydroxide in a slurry of the titanate. Partial substitution of strontium or lead for barium and zirconium for titanium has also been achieved using this oxalate process. The electrical conductivity of these materials was measured and is discussed. The effect of excess titanium on the electrical properties was also determined and an excess of 1 to 2 mole % was found to raise the positive temperature coefficient under the firing conditions employed.