Pb(Mg_<1/3>Nb_<2/3>)O_3セラミックスのペロブスカイト相の生成と微構造に及ぼすコロンバイトMgNb_2O_6の影響

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The influence of the calcination conditions of MgNb_2O_6 on the perovskite formation and microstructure of Pb(Mg_<1/3>Nb_<2/3>)O_3 prepared by the columbite process was investigated. The purity of MgNb_2O_6 was found to significantly affect the formation process of perovskite phase. Lower purity of MgNb_2O_6 led to retard the formation of perovskite phase. Calcination at temperatures above 800℃ resulted in the complete formation of MgNb_2O_6. Pure MgNb_2O_6 efficiently reacted with PbO, and accelerated the formation of perovskite phase. On the condition of without adding excess MgO or PbO, heating 1000℃-calcined MgNb_2O_6 with PbO at 800℃ for 2h resulted in monophasic Pb(Mg_<1/3>Nb_<2/3>)O_3 having submicron size. On the other hand, when MgNb_2O_6 was prepared by 1200℃-calcination, the unfavorable grain-growth of MgNb_2O_6 caused the decrease in the reactivity between MgNb_2O_6 and PbO. The over-calcination of MgNb_2O_6 also led the grain size of Pb(Mg_<1/3>Nb_<2/3>)O_3 to greatly increase to be around 2.5 μm. Consequently, the calcination conditions of MgNb_2O_6 markedly affected the reaction kinetics and grain size of Pb(Mg_<1/3>Nb_<2/3>)O_3.
社団法人日本セラミックス協会の論文
1995-11-01