We report here the top-seeded solution growth of KTiOPO_(4)crystals from the K_(2)O-P_(2)O_(5)-TiO_(2)-WO_(3) system.KTiOPO_(4) crystallizes as the single stable phase over the ternperature range 930-700℃.Growth rate...We report here the top-seeded solution growth of KTiOPO_(4)crystals from the K_(2)O-P_(2)O_(5)-TiO_(2)-WO_(3) system.KTiOPO_(4) crystallizes as the single stable phase over the ternperature range 930-700℃.Growth rates up to 0.9mm/d could be used to grow optical quality crystals.展开更多
Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation a...Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation are 7.0 and 4 h respectively, the maxium separation factor of W and Mo is 9.29. And the experimental resules show that isothermal absorbing tungsten and molybdenum belongs to Langmuir model and Freundlich model respectively, and the absorbing kinetics for tungsten is controlled by intra-particle diffusion. With a solution containing 70 g/L WO3 and 28.97 g/L Mo, the effluent with a mass ratio of Mo to WO3 of 76 and the eluate with a mass ratio of WO3 to Mo of 53.33 are obtained after column test.展开更多
Pyrochlore-type tungsten oxide (PTO), WO3·0.5H2O, is an emerging material with very wide potential applications. The influences of iron valences and the additive amount of ferrous ion on tungsten crystallization ...Pyrochlore-type tungsten oxide (PTO), WO3·0.5H2O, is an emerging material with very wide potential applications. The influences of iron valences and the additive amount of ferrous ion on tungsten crystallization ratio and the acceleration mechanism of ferrous ion were investigated when PTO was hydrothermally prepared in aqueous ammonium tungstate solution containing ammonium carbonate. The results show that ferrous ion can remarkably accelerate tungsten crystallization while both elemental iron and ferric ion have little influence on the crystallization. Moreover, the tungsten crystallization ratio increases with increasing the amount of ferrous ions added and reaches the maximum of about 60% with ferrous ion concentration of 16 g/L. FTIR analysis of the spent solution after PTO crystallization shows that ferrous ion can accelerate the conversion of WO4 tetrahedral to WO6 octahedron. Combined with XPS and XRD analyses of the hydrothermal product, the acceleration effect of ferrous ion on tungsten crystallization could basically be attributed to the increase in the interplanar spacing of PTO lattice caused by the incorporation of ferrous ion into PTO crystal lattice. The results presented is conducive to the efficient preparation of PTO powder and cleaner tungsten metallurgy.展开更多
文摘We report here the top-seeded solution growth of KTiOPO_(4)crystals from the K_(2)O-P_(2)O_(5)-TiO_(2)-WO_(3) system.KTiOPO_(4) crystallizes as the single stable phase over the ternperature range 930-700℃.Growth rates up to 0.9mm/d could be used to grow optical quality crystals.
基金Project(51174232)supported by the National Natural Science Foundation of China
文摘Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation are 7.0 and 4 h respectively, the maxium separation factor of W and Mo is 9.29. And the experimental resules show that isothermal absorbing tungsten and molybdenum belongs to Langmuir model and Freundlich model respectively, and the absorbing kinetics for tungsten is controlled by intra-particle diffusion. With a solution containing 70 g/L WO3 and 28.97 g/L Mo, the effluent with a mass ratio of Mo to WO3 of 76 and the eluate with a mass ratio of WO3 to Mo of 53.33 are obtained after column test.
基金Project(51274243) supported by the National Natural Science Foundation of China
文摘Pyrochlore-type tungsten oxide (PTO), WO3·0.5H2O, is an emerging material with very wide potential applications. The influences of iron valences and the additive amount of ferrous ion on tungsten crystallization ratio and the acceleration mechanism of ferrous ion were investigated when PTO was hydrothermally prepared in aqueous ammonium tungstate solution containing ammonium carbonate. The results show that ferrous ion can remarkably accelerate tungsten crystallization while both elemental iron and ferric ion have little influence on the crystallization. Moreover, the tungsten crystallization ratio increases with increasing the amount of ferrous ions added and reaches the maximum of about 60% with ferrous ion concentration of 16 g/L. FTIR analysis of the spent solution after PTO crystallization shows that ferrous ion can accelerate the conversion of WO4 tetrahedral to WO6 octahedron. Combined with XPS and XRD analyses of the hydrothermal product, the acceleration effect of ferrous ion on tungsten crystallization could basically be attributed to the increase in the interplanar spacing of PTO lattice caused by the incorporation of ferrous ion into PTO crystal lattice. The results presented is conducive to the efficient preparation of PTO powder and cleaner tungsten metallurgy.
