Abstract—

The Bi₁₂TiO₂₀, Bi₄Ti₃O₁₂, and Bi₂Ti₄O₁₁ bismuth titanates have been prepared by solid-state reactions, via multistep firing of stoichiometric mixtures of their constituent oxides in air at temperatures from 1003 to 1273 K (Bi₁₂TiO₂₀, to 1123 K). The heat capacity of polycrystalline samples of the synthesized compounds has been determined by differential scanning calorimetry in the temperature range 330–1050 K. The C_p(T) curves of Bi₄Ti₃O₁₂ and Bi₂Ti₄O₁₁ show peaks at temperatures of 943 and 509 K, respectively, due to ferroelectric phase transitions. The experimental data have been used to evaluate the enthalpy increment, entropy change, and reduced Gibbs energy change of the bismuth titanates.

中文翻译：

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Bi 2 O 3 -TiO 2系统中化合物的热容

摘要-

Bi ₁₂ TiO ₂₀，Bi ₄ Ti ₃ O ₁₂和Bi ₂ Ti ₄ O ₁₁钛酸铋已通过固相反应制备，方法是在空气中1003至1273 K的温度下多组分焙烧其组成氧化物的化学计量混合物（Bi ₁₂ TiO ₂₀，至1123 K）。已通过差示扫描量热法在330–1050 K的温度范围内确定了合成化合物的多晶样品的热容。Bi ₄ Ti ₃ O ₁₂的C _p（T）曲线由于铁电相变，Bi ₂ Ti ₄ O ₁₁和Bi ₂ Ti ₄ O ₁₁在943和509 K的温度下分别显示出峰。实验数据已用于评估钛酸铋的焓增，熵变和降低的吉布斯能量变化。