The influence of thermal treatment on phase development in ZrO2–Fe2O3 and HfO2–Fe2O3 systems
The influence of thermal treatment on phase development in ZrO2–Fe2O3 and HfO2–Fe2O3 systems
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DOI：
10.1016/s0925-8388(01)01401-3
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发表时间：
2001-08
影响因子：
6.2
通讯作者：
G. Štefanić;B. Gržeta;K. Nomura;R. Trojko;S. Musić
中科院分区：
文献类型：
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作者：
G. Štefanić;B. Gržeta;K. Nomura;R. Trojko;S. Musić
采用x射线粉末衍射（XRD）和激光拉曼光谱（laser Raman spectroscopy）研究了室温（500、600、800和1100℃）热处理对zro2 - fe2o3和hfo2 - fe2o3体系非晶态前驱体的影响。Fe3+离子的掺入在一定程度上稳定了氧化锆（ZrO2）和半氧化铪（HfO2）的高温晶型。在fe2o3含量≥10 mol%的固溶体中，zro2和hfo2的立方晶型发生稳定化。超过固溶极限的Fe3+离子的存在导致zro2和hfo2的亚稳态晶型向单斜晶型转变。在RT下，fe2o3在ZrO2中的最终固溶极限在600℃煅烧后为~ 33 mol%，在800℃煅烧后为~ 9 mol%，在1100℃煅烧后为~ 2 mol%。经过相同热处理后，fe2o3在hfo2中的末端固溶极限非常相似，只是稍微小一些。粉末模式拟合法测定的zro2和HfO2立方晶型的单位胞体积随铁含量的增加而线性减小，但zro2晶型的减小幅度更大。用差热分析和热重分析跟踪了非晶态前驱体的热行为。两种体系的结晶温度均随fe2o3含量的增加而升高，zro2 - fe2o3体系的结晶温度从405℃升高到730℃，hfo2 - fe2o3体系的结晶温度从520℃升高到720℃。结果表明，fe2o3含量大于30 mol%的非晶态前驱体为单共凝胶。利用57fe Mössbauer光谱分析了Fe3+离子在zro2型晶格中的状态及其向α- fe2o3相偏析的过程。与α- fe2o3相比，超细磁场值明显降低，表明α- fe2o3晶格中掺入了Zr4+离子，其数量随着处理温度的升高而减少。
The effects of thermal treatment (500, 600, 800 and 1100°C) of the amorphous precursors of ZrO2–Fe2O3and HfO2–Fe2O3systems, coprecipitated from aqueous solutions of the corresponding salts, were studied at room temperature (RT) by X-ray powder diffraction (XRD) and, in some cases, by laser Raman spectroscopy. The incorporation of Fe3+ions partially stabilized the high temperature polymorphs of zirconia (ZrO2) and hafnia (HfO2). The stabilization of the cubic polymorphs of ZrO2and HfO2occurred in the solid solutions with an Fe2O3content of ≥10 mol%. The presence of Fe3+ions above their solid solubility limit caused the transition of metastable polymorphs of ZrO2and HfO2to monoclinic polymorphs. The terminal solid solubility limit of Fe2O3in ZrO2, as estimated at RT, was ∼33 mol% after calcination at 600°C, ∼9 mol% after calcination at 800°C and ∼2 mol% after calcination at 1100°C. After the same thermal treatment, the terminal solid solubility limits of Fe2O3in HfO2proved to be very similar only a little smaller. The unit-cell volume of the cubic polymorphs of ZrO2and HfO2, determined by powder-pattern-fitting methods, decreased linearly with the increase in iron content, but the rate of decrease was greater in the ZrO2polymorph. The thermal behavior of the amorphous precursors was also followed by differential thermal analysis and thermogravimetric analysis. The crystallization temperature of both systems increased with an increase in the Fe2O3content, from 405 to 730°C in the ZrO2–Fe2O3system, and from 520 to 720°C in the HfO2–Fe2O3system. The results indicated that the amorphous precursors with more than 30 mol% of Fe2O3were single co-gels. The status of the Fe3+ions in the ZrO2-type lattice and the process of their segregation into the α-Fe2O3-phase were examined by57Fe Mössbauer spectroscopy. Significantly lower values of the hyperfine magnetic fields compared to that of α-Fe2O3indicated the incorporation of Zr4+ions into the α-Fe2O3lattice, the amount of which decreased with the increasing temperature of treatment.