SYNTHESIS OF COMPLEX METAL-OXIDES USING HYDROXIDE, CYANIDE, AND NITRATE SOLID-SOLUTION PRECURSORS

Precursor solid solutions provide convenient routes for preparing complex metal oxides. Hydroxide solid solutions of the general formula Ln//1// minus //xM//x(OH)//3 (where Ln equals La or Nd and M equals Al, Cr, Fe, Co, or Ni) and La//1// minus //x// minus //yM prime //xM double prime //y(OH)//3 (where M prime equals Ni and M double prime equals Co or Cu) crystallize in the rare earth trihydroxide structure and can be decomposed at relatively low temperatures to yield complex metal oxides. Several oxides of the type LaNiO//3, NdNiO//3, LaNi//1// minus //xCo//xO//3, and LaNi//1// minus //xCu//xO//3 have been prepared by the hydroxide precursor route. Thermal decomposition of cyanide precursors of the type Ln left bracket M//1 // minus //xM prime //x(CN)//6 right bracket multiplied by (times) 5H//2O and Ln//1// minus //xLn prime //x left bracket M(CN)//6 right bracket multiplied by (times) 5H//2O yields the quaternary oxides which are not readily made by ceramic methods.