MnO_2掺杂NiFe_2O_4的初期烧结动力学特征

Early-stage sintering kinetic characteristics of MnO_2-doped NiFe_2O_4 spinel

借助热膨胀仪,采用恒升温速率法研究了升温速率和添加剂MnO_2对镍铁尖晶石的初期烧结行为影响。结果表明,较低的升温速率可以使样品获得较大的线收缩,添加MnO_2,可以降低样品的开始形成烧结颈温度,加快镍铁尖晶石的致密化过程。添加MnO_2后各体系的初期烧结均由晶界扩散机制转变成了体积扩散机制,烧结过程的表观活化能均大幅下降,其中添加1.0%(质量分数)MnO_2的体系下降最为明显,从未添加时的813.9kJ/mol降到了441.9kJ/mol。

The influence of heating rates and MnO2 additives on early-stage sintering behavior to synthesizeNiFe2O4 has been investigated. The results show that lower heating rates can produce more obvious shrinkage.Introduction of MnO2 can shift the onset of sintering toward lower temperatures. The early-stage sintering ofNiO-Fe2O3 system is mainly controlled by grain boundary diffusion. For MnO2-doped samples, the early-stagesintering mechanisms are controlled by volume diffusion. The apparent activation energy of these doped samplesdecreased obviously, and for the 1.0wt% MnO2-doped sample, apparent activation energy decreased from 813.9to 441.9 kJ/mol.