Preparation and thermal decomposition of new pyrochlore Pb2FeWO6.5
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A new compound Pb2FeWO6.5 having a pyrochlore structure has been synthesized by soaking the powder prepared from coprecipitation at 650 °C for 30 d. Using a conventional solid-state reaction, single-phase Pb2FeWO6.5, however, cannot easily be obtained. The coprecipitation technique not only contributes to the completion of reactions, but also lowers the formation temperatures. Enhanced homogeneity and reactivity in coprecipitated powder are considered to accelerate the progress of the reactions. Pb2FeWO6.5 is determined to be characteristic of a cubic pyrochlore structure having a lattice parameterao = 1.0432 nm. This compound exists stably below 700 °C, above which it decomposes to PbFe2/3W1/3O3 and PbWO4. A drastic change in microstructure is induced after complete decomposition at 860 °C.
KeywordsPolymer Microstructure Thermal Decomposition Drastic Change Formation Temperature
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