Yb_2O_3对TiO_2/(O′+β′)-Sialon复相陶瓷中TiO_2相变的影响

Effect of Yb_2O_3 Additive on Transformation Behavior of Anatase for TiO_2/(O′+β′)-Sialon Multi-Phase Ceramics

以纳米锐钛矿型TiO2粉和(O′+β′)-Sialon粉为原料制备出了TiO2/(O′+β′)-Sialon复相陶瓷,研究了Yb2O3添加剂对材料中锐钛矿型TiO2相变的影响,对其影响机制进行了探讨。采用XRD对材料进行物相组成和晶格参数表征。结果表明,Yb2O3对锐钛矿相变开始温度无明显影响,但对相变有显著的促进作用,随添加量的增加,其作用逐渐减弱。添加的Yb2O3同时以两种形式存在:一部分进入TiO2晶格,一部分堆积在TiO2晶粒表面。Ybn+进入TiO2晶格置换Ti4+和Yb3+与TiO2发生氧化还原反应促进相变,而存在于TiO2表面的Yb3+与TiO2相互作用形成Ti-O-Yb键而抑制相变。Yb2O3对锐钛矿相变的影响是这两方面机制共同作用的结果。

TiO2/（O＇＋β＇）-Sialon muhiphase ceramics were prepared with nano TiO2 （anatase） powder and （O＇＋β＇）-Sialon powder as raw materials. Effect of Yb2O3 additive on transformation behavior of anatase for TiO2/（O＇＋β＇）-Sialon muhi-phase ceramics was investigated and its influence mechanism was discussed. XRD was employed for the analysis of phase composition and lattice parameters. The results show that even though Yb2O3 has no obvious influence on starting temperature of phase transformation, it significantly accelerates the transformation process, which displays a weakened effect with more Yb2O3 addition.There exist two forms of the added Yb2O3 ： some enters into TiO2 lattice and the other deposits on the surface of TiO2. The function of Yb2O3 on phase transformation of anatase can be attributed to the coaction of the active and negative influence mechanisms as following. Some Yb^n＋ enters into TiO2 lattice and replaces Ti^4＋ , as well as the redox reaction between Yb^3 ＋ and TiO2, which promotes the transformation, whereas the other Yb2O3 deposits on the surface of TiO2, and Ti - O- Yb bond is formed by the interaction of Yb^3＋ and TiO2, which inhibits the process.