ZrW2O7(OH,Cl)2·2H2O and its isomorphs were prepared by Acidic Steam Hydrothermal (ASH) method and the pure cubic ZrW2O8 was synthesized by dehydration of ZrW2O7(OH,Cl)2·2H2O. The control factors of ASH method, such as the type, concentration and volume of the acidic steam source, temperature and time of the reac- tion, were studied in detail. The results showed that HCl was a better volatile acidic steam source and the con- centration of HCl determined the product. At lower concentration of HCl, the main product was Na2W2O7·H2O rather than ZrW2O7(OH,Cl)2·2H2O. When the concentration was higher than 6 mol·L-1, the products in turn be- came sodium tungstates with the structure types of pyrochlore, hexagonal tungsten bronze and finally were trans- formed to ZrW2O7(OH,Cl)·22H2O precursors.
