Thermal stability and phase transformation of barium orthotitanate (Ba2TiO4)
Thermal stability and phase transformation of barium orthotitanate (Ba2TiO4)
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DOI：
10.1080/01411594.2012.677448
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发表时间：
2013-04
影响因子：
1.6
通讯作者：
Bo Chen;F. Liao;H. Jiao;X. Jing
中科院分区：
文献类型：
--
作者：
Bo Chen;F. Liao;H. Jiao;X. Jing
采用1250℃加热2 h的方法制备了钛酸钡(Ba2TiO4)，用X射线衍射仪研究了Ba2TiO4的热稳定性以及低温单斜晶型(β-Ba2TiO4)和高温正交晶型(α‘-Ba2TiO4)之间的相变。β-Ba2TiO4向α‘-Ba2TiO4的马氏体相变开始于∼10 0℃，在∼2 2 0℃结束。相变磁滞回线为∼200°C，掺杂少量异价离子Nd3+(1.5%)或较大量等价离子Sr2+(10%)可使α‘-Ba2TiO4稳定到室温。掺杂样品经低温(如1100℃以下)处理后，掺杂样品中的α‘-Ba2TiO4部分转变为β-Ba2TiO4，而掺锶样品稳定地保持为α’-Ba2TiO4。
Barium orthotitanate (Ba2TiO4) was prepared by heating at 1250°C for 2 h. The thermal stability of Ba2TiO4 and the phase transformation between the low-temperature monoclinic polymorph (β-Ba2TiO4) and the high-temperature orthorhombic polymorph (α′-Ba2TiO4) were examined by X-ray diffraction. Ba2TiO4 can be corroded by CO2 below 700°C forming BaCO3 and BaTiO3, which is reversible above 750°C. A martensitic transformation from β-Ba2TiO4 to α′-Ba2TiO4 starts at ∼100°C and ends at ∼220°C in heating process. The transformation hysteresis loop is ∼200°C. α′-Ba2TiO4 can be stabilized to room temperature by doping small amount of aliovalent ion Nd3+ (1.5 mole%) or relatively large amount of isovalent ion Sr2+ (10 mole%). After annealing the doped samples at low temperatures (e.g., below 1100°C), for the Nd-doped sample, α′-Ba2TiO4 can be partially transformed to β-Ba2TiO4, whereas the Sr-doped sample is stably kept as α′-Ba2TiO4.