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用变温XRD,变温IR以及TG-DTA等方法,系统地研究了具有Dawson结构的Y_m H_n P_2 M_(18)O_(62)·qH_2OOY=K~+,NH_4~+,Cu~(2+);M=Mo,W)的热解性质,获得了它们较为精确的热分解温度,对其热分解的判断方法提出了一些新的见解.结果表明.以钼为配位原子的Dawson结构钾盐,铵盐.铜盐分别在250℃,210℃,240℃发生了热重排,生成了具有Keggin结构的化合物.以钨为配位原子的钾盐在410℃也有相似的行为,但铵盐和铜盐却没有观察到类似的热重排现象,分别在400℃,450℃直接热分解为WO_3.这些结果显示,热重排现象的发生可能与相应的Keggin结构化合物的热稳定性有关.
The Dawson structure of Y_m H_n P_2 M_ (18) O_ (62) · qH_2OOY = K ~ +, NH_4 ~ +, Cu ~ (2+) was systematically investigated by means of the variable temperature XRD, temperature-programmed IR and TG- M = Mo, W), the more accurate thermal decomposition temperatures are obtained, and some new opinions on the methods of thermal decomposition are proposed.The results show that Dawson structure potassium salt with molybdenum as the coordination atom, Ammonium salt.Copper salts were thermally rearranged at 250 ℃, 210 ℃ and 240 ℃, respectively, to form a compound with Keggin structure.The potassium salt with tungsten as a coordination atom also had similar behavior at 410 ℃, but ammonium salt and No similar thermal rearrangement was observed for copper salts, which were directly thermally decomposed to WO_3 at 400 ℃ and 450 ℃, respectively.These results show that the thermal rearrangement may be related to the thermal stability of the corresponding Keggin structure.