Preparation of nanosized sodium–aluminum tungstate, NaAl(WO4)2

Investigations are carried out for preparing nanosized pure phase of NaAl(WO4)2 by means of solid state synthesis with mechanical activation, applying the sol–gel method (Pechini) and by co-precipitation. It is shown that it is not possible to obtain pure phase when the initial substances are in stoichiometric amounts due to the simultaneous formation of a number of accompanying tungstate phases. The reasons for their origin are discussed. A method is demonstrated for obtaining a pure phase of NaAl(WO4)2 by co-precipitation of aqueous Na2WO4 and Al(NO3)3 solutions with considerable excess of Na2WO4. It is proved that NaAl(WO4)2 with particle size 40–80 nm is obtained with final synthesis of the powders at temperature 600–650 °C and duration of thermal treatment of 1–2 h.

► Nanosized NaAl(WO4)2 obtained for a first time. ► Material for transparent ceramics. ► Three methods for preparation. ► X-ray, DTA, TEM investigations. ► Co-precipitation method gives 40–80 nm particles.