Cation self diffusion in nanocrystalline monoclinic zirconia

吉田等人最近展示了这一点。(2004)，单斜氧化锆具类似超塑性的行为。然而，为了进一步了解控制超塑性行为的精确机制，有必要知道阳离子在这种特殊微观结构中的扩散系数。虽然已经有一些关于阳离子在其他晶型氧化锆中扩散的研究，但还没有关于单斜氧化锆阳离子扩散的报道，因为在单斜到四方相变温度(1443K)以上烧结不可能制备致密样品。本项目的目标是克服这些困难，并测量单斜氧化锆中的阳离子扩散。将粉末热等静压至单斜晶系向四方晶系转变温度以下，可得到近全致密的单斜晶系氧化锆粉。在最近的一项研究中(Swaroop等人2005年)，证明了Hf和Yb可以分别作为锆和Y的示踪剂。示踪源将用脉冲激光沉积的方法沉积在单斜氧化锆片上。扩散实验结束后，利用二次离子质谱仪获得示踪剂的深度分布，由此推算出晶格和晶界的阳离子扩散系数。

It has been shown recently by Yoshida et al. (2004) that monoclinic zirconia exhibits superplasticity-like behaviour. However, in order to further understand the precise mechanism that controls the superplastic behaviour, it is essential to know the diffusivities of the cations in this special microstructure. Although there are several studies on cation diffusion in other polymorphs of zirconia, there are no reports on the diffusion in monoclinic zirconia since it is not possible to prepare dense samples by sintering above the monoclinic to tetragonal transformation temperature (1443 K). The objective of this project is to overcome these difficulties and to measure cation diffusion in monoclinic zirconia. Nearly fully dense monoclinic zirconia will be prepared by hot isostatically pressing the powder below the monoclinic to tetragonal transition temperature. In a recent study (Swaroop et al. 2005), it was demonstrated that hafnium and ytterbium can act as tracers for zirconium and yttrium, respectively. The tracer source will be deposited on monoclinic zirconia by pulsed laser deposition. After the diffusion experiment, secondary ion mass spectrometry will be used to obtain the tracer depth profiles wherefrom lattice and grain boundary cation diffusivities will be deduced.