从四方到单斜 ZrO2 的气相相关相变的定量微观观察,Journal of the American Ceramic Society

当前位置： X-MOL 学术 › J. Am. Ceram. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

从四方到单斜 ZrO2 的气相相关相变的定量微观观察
Journal of the American Ceramic Society ( IF 3.5 ) Pub Date : 2024-02-23 , DOI: 10.1111/jace.19749
Maged F. Bekheet ₁ , Lukas Schlicker ₁ , Radian Popescu ₂ , Wiebke Riedel ₃ , Matthias Grünbacher ₄ , Simon Penner ₄ , Aleksander Gurlo ₁

Affiliation

ZrO ₂是一种具有多种应用的多功能材料，包括结构陶瓷、传感器和催化剂。 ZrO ₂的性能很大程度上取决于其晶体结构，而晶体结构取决于温度和气氛。因此，这项工作的重点是定量分析从室温到 1273 K 的加热-冷却循环过程中，四方 t-ZrO ₂到单斜 m-ZrO ₂的温度和气体环境依赖性相变。在不同还原强度的气体气氛（即 5 vol% H ₂ /Ar、He、CO ₂和空气）中进行的射线衍射 (XRD) 研究揭示了惰性和还原环境的稳定作用，直接在反应中产生不同的温度起始点。冷却期间的相变（即，对于5vol%H ₂ /Ar、He、CO ₂和空气分别为435、510、710和793K ）。 Rietveld 精修显示大气对产品复合基体中两种多晶型物的晶粒尺寸、晶胞和重量分数有直接影响。在仅加热至约 850 K 的样品中，四方相到单斜相 (t–m) 的相变受到抑制，与气体气氛无关。非原位XRD、透射电子显微镜、电子顺磁共振和氧滴定实验的结果证实，相变伴随着微晶/颗粒尺寸和晶格缺陷（即氧空位）数量的变化。由于不同的起始温度，相变的动力学限制和晶粒烧结之间复杂的相互作用产生不同的相变途径，并最终导致t-ZrO ₂和m-ZrO ₂的最终微晶尺寸非常不同。

"点击查看英文标题和摘要"

A quantitative microscopic view on the gas-phase-dependent phase transformation from tetragonal to monoclinic ZrO2

ZrO₂ is a versatile material with diverse applications, including structural ceramics, sensors, and catalysts. The properties of ZrO₂ are largely determined by its crystal structure, which is temperature- and atmosphere dependent. Thus, this work focuses on a quantitative analysis of the temperature- and gas atmosphere-dependent phase transformation of tetragonal t-ZrO₂ into monoclinic m-ZrO₂ during heating–cooling cycles from room temperature to 1273 K. Synchrotron-based in situ X-ray diffraction (XRD) studies in gas atmospheres of different reduction strengths, namely, 5 vol% H₂/Ar, He, CO_2, and air, revealed a stabilizing effect of inert and reductive environments, directly yielding different temperature onsets in the phase transformation during cooling (i.e., 435, 510, 710, and 793 K for 5 vol% H₂/Ar, He, CO₂, and air, respectively). Rietveld refinement shows a direct influence of the atmosphere on grain size, unit cell, and weight fraction of both polymorphs in the product composite matrix. The tetragonal-to-monoclinic (t–m) phase transformation is suppressed in the sample heated only up to ∼850 K, independent of the gas atmosphere. The results of ex situ XRD, transmission electron microscopic, electron paramagnetic resonance, and oxygen titration experiments confirmed that the phase transformation is accompanied by a change in the crystallite/particle size and the amount of lattice defects (i.e., oxygen vacancy). Due to the different onset temperatures, a complex interplay between kinetic limitations of phase transformation and grain sintering yields different pathways of the phase transformation and, eventually, very different final crystallite sizes of both t-ZrO₂ and m-ZrO₂.

更新日期：2024-02-23

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文本刊介绍/投稿指南