Thermischer Zerfall von AlPO4−SiO2-Mischkristallen

摘要

AlPO4-10 mole SiO2solid solutions, representing the stacking-disordered cristobalite-tridymite structure, in contrast to pure AlPO4show a remarkable reduction of rate of thermal decomposition. This is brought into connection with the formation of molten surface layers of SiO2−P2O5. Simple mixtures of AlPO4with SiO2in the form of quartz powder or amorphous silica gel show this effect only scarcely. Additions of GeO2, SnO2or TiO2do not show this effect at all. In contrast to melts of the composition SiP2O7, melts of GeP2O7, SnP2O7and TiP2O7decompose quickly at 1400°C. AlAsO4even with the addition of SiO2decomposes very rapidly above 1000