采用变温X射线衍射技术对六方钛酸钡陶瓷材料的结构监控

Structural Monitoring of Hexagonal BaTiO_3 Ceramic Materials via Temperature-Dependent X-Ray Diffraction Technique

对于由冷压陶瓷技术所开发的纯六方Ba(Ti0.95Fe0.05)O3-δ陶瓷,采用变温XRD技术测量该陶瓷在不同温度下的XRD谱,鉴定晶体结构.澄清了六方钛酸钡(BaTiO3)介电陶瓷材料的晶体结构是否在BaTiO3的居里温度(TC=130℃)发生结构相变,并验证开发的变温X射线衍射(XRD)技术在无机粉体材料结构监控的可行性.结果表明:BaTiO3陶瓷在TC发生四方-立方的结构相变,以45°附近两个分立的(002)/(200)衍射峰演变为单一对称的(200)衍射峰为标志;而六方Ba(Ti0.95Fe0.05)O3-δ陶瓷直到300℃都不发生结构相变.对于六方Ba(Ti0.95Fe0.05)O3-δ陶瓷,升高温度并不能导致吸附环境氧来填充氧空位,Fe3+-Vo-Fe3+缺陷复合体所维持的晶格电中性仍占据统治地位,六方-立方结构相变不发生.该项研究为变温XRD技术在工业生产上对无机粉体材料的监控应用提供了技术依据.

For the hexagonal Ba（Ti0.95Fe0.05）O3-δ ceramic synthesized using the cold-pressing ceramic technique,its XRD spectra were measured by using the temperature-dependent XRD technique and its structure was identified. Whether the structural transition of the hexagonal BaTiO3 dielectric ceramic occurs at the Curie temperature of BaTiO3 （ Tc = 130℃ ） has been clarified, the temperature-dependent X-ray diffraction technique for monitoring the structure of inorganic powder materials is valid has been verified. The results indicates that structure of the BaTiO3 ceramic changes from tetragonal to cubic at Tc, which is marked by the evolution of the two separate （ 002 ） / （200） diffraction peaks into a symmetric （200） peak. The structure of the hexagonal Ba（Ti0.95Fe0.05）O3-δ（BTF）ceramic did not change up to 300℃. For BTF, increasing temperature could not lead to the occupation of oxygen vacancies absorbed by environmental oxygen. The lattice electro-neutrality maintained by Fe3＋Vo-Fe3＋ defect complexes predominated in BTF. The phase transition from hexagonal to cubic did not occur. This study provides technical reference for application of monitoring the structure of inorganic powder materials in industry production via the temperature-dependent X-ray diffraction technique.