The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction （XRD） and in situ high-temperature XRD quantitative analysis,in addition to scanning electron microscopy measurement,the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem,the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area,the approximate composition areas of two two-phase regions and one three-phase region,（L2＋Cr）,（L2＋M）,and （L1＋L2＋Tr）,were determined. Moreover,the precise composition areas of both of the three-phase regions （L2＋Cr＋M） and （L2＋M＋A） were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.
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.
