Mechanical processing of nanometric magnesium titanate precursors

摘要

The influence of mechanical treatment could be assessed on mixtures of two unary or coprecipitated binary xerogel precursors of magnesium titantates. The precursors in various stoichiometric rations were subjected to milling action, at room temperature, for periods ranging form 0 to 24h, followed by heating at 600 deg C for 3-4 h. After a short mechanical processing to ensure good mixing of unary xserogel precursors, smal yields were obtained of nanocrytalline geikielite, accompanied by pericalse and anatase. After prologned milling one of the latter two phases disappeared, however, the other one persisted and yields of magnesium titanates were far form being quantitative. The reason for this is failure of the mechanical treatment to totally comminute the single component agregates and produce intimate binary mixtures, that ould convert into titanates in a few hours at 600 deg C . Mechanical treatment of coprecipitated precursors yielded after ehating less well developed crystallites than those obtained from the same precursors without mechanical trematment. A possible reason for this behaavior is mechanochemical dehydration of hydroxlyl group pairs beonging to different metals and leading to a disordered polymeric stucture that crystallizes more slowly.