Dependence of yttrium and lanthanum vanadate composition on pH of Na3VO4 initial solution

Chemical and phase compositions of yttrium and lanthanum vanadates formed when mixing solutions of yttrium (lanthanum) nitrate and sodium vanadate, pH of which is changed from 13 to 5, with subsequent separation of precipitates from mother solutions are studied. It is established that dependences Msub(V)=f(pH), where Msub(V) - is the number of V2O5 moles per one Me2O3 mole in precipitates have a stepped character. Individual compounds are formed at certain pH values of the medium. Phase composition depends on duration of contact with mother medium and content of preceding conjugate form of vanadate-ions