矿化剂浓度和反应时间对微波水热合成高纯BiFeO_3粉体的影响

Effect of Mineralizer Concentration and Reaction Time on High Purity BiFeO_3 Powders Synthesized by Microwave Hydrothermal Method

以Fe(NO3)3·9H2O和Bi(NO3)3·5H2O为反应原料,KOH为矿化剂,采用微波水热法制备高纯的单相BiFeO3粉体。研究了KOH浓度和微波水热反应时间对BiFeO3粉体纯度和相变的影响。研究表明,当KOH浓度高于6 mol/L时能合成出纯相BiFeO3粉体,随着水热矿化剂浓度的提高粉体形貌逐渐由准立方演变为截角立方,最后趋于类八面体结构的团聚体。当延长微波水热反应时间,BiFeO3粉体逐渐由三方相结构(R3m)向六方相结构(R3c)转变。当KOH浓度为10 mol/L,Bi3+/Fe3+摩尔比为1,微波水热时间为30 min,反应温度在200℃就可制备出高纯BiFeO3粉体,其饱和磁化强度约为0.075 emu/g。

The high purity BiFeO_3 powders were synthesized by microwave hydrothermal method, using Fe （NO_3）_3 · 9H_2O and Bi（NO_3）_3· 5H_2O as starting materials and KOH as the mineralizer. The effects of KOH concentration and reaction time on the purity and phase transition of BiFeO_3 powders were studied. The results show that the pure BiFeO_3 could be obtained when the concentration of KOH is above 6 mol/ L. The aggregates evolved from a quasi-cube into truncated cube and tended to oetahedral finally. The phase structure of BiFeO_3 changed from rhombohedral （R3m） to hexagonal （R3c） gradually as the reaction time increasing. When the mineralizer concentration is 10 mol/L, Bi^3＋/Fe^3＋ is 1, the high purity BiFeO3 powders which their saturation magnetization reached 0. 075 emu/g can be prepared by microwave hydrothermal method at 200 ℃ for 30 min.