Fe_xO—TiO_2体系的固相反应机理

Solid state reaction mechanism of the Fe_xO—TiO_2 system

采用扩散偶法研究了1323~1473 K下FexO-Ti O2体系的固相反应,反应过程中氧分压由一定比例的CO-CO2混合气体控制.扩散偶截面的微观形貌用电子探针进行观察,并对Fe2＋、Ti4＋和O2-离子的扩散浓度轮廓进行定量分析.结合Fe O-Ti O2体系相图确定了固相反应中有钛铁晶石、钛铁矿和假铁板钛矿相生成,且它们的生长受扩散控制.依据扩散组元的摩尔分数变化绘制了铁离子的扩散路径图,并在此基础上描述了该体系的固相反应机理.

The diffusion couple was used to study solid state reaction in the FexO- Ti O2 system at a temperature range of 1323 to1473 K,during which the oxygen partial pressure was controlled by CO- CO2 gas mixture. The cross-sections of the diffusion couple were observed by electron probe microanalysis（ EPMA）,and the diffusion concentration profiles of Fe2 ＋,Ti4 ＋,and O2-ions were also determined. In combination with the phase diagram of the Fe O-Ti O2 system,it was found that ulvospinel,ilmenite,pseudobrookite phases formed during the reaction and their growth was diffusion-controlled. According to the concentration changes of diffusion ions,the diffusion path of Fe ions was plotted,based on which the solid state reaction mechanism of this system was reasonably proposed.