钙钛锆石的自蔓延高温合成与热力学分析

基于自蔓延高温合成法，采用Fe₂O₃、CrO₃和Ca(NO₃)₂为氧化剂，Ti为还原剂制备了钙钛锆石。共设计了4个体系，计算了各体系的绝热温度，测量了各体系的实际燃烧温度，并探索了Ca(NO₃)₂为氧化剂时，TiO₂与Ti摩尔比（TiO₂∶Ti）对燃烧温度的影响。结果显示，所有体系均能自持发生，但以Fe₂O₃和CrO₃为氧化剂时，产物的主要物相为烧绿石(Ca₂Ti₂O₆)、Zr₅Ti₇O₂₄、钙钛矿(CaTiO₃)及少量TiO₂，以Ca(NO₃)₂为氧化剂时，各体系的主要物相均为钙钛锆石(CaZrTi₂O₇)、CaTiO₃及少量TiO₂。同时，以Ca(NO₃)₂为氧化剂时，随TiO₂∶Ti的降低，燃烧温度和绝热温度均逐渐升高。

SHS of Zirconolite and Its Thermodynamic Analysis

Zirconolite (CaZrTi2 O7 ) was prepared by self‐propagating high‐temperature synthesis (SHS) using Fe2 O3 ,CrO3 and Ca(NO3 )2 as the oxidants and Ti as the reduc‐tant .The adiabatic temperature was calculated ,and the combustion temperature was measured in this paper . The different molar ratios of TiO2 to Ti (TiO2 ∶ Ti) in the Ca(NO3 )2 reaction system were explored to investigate the combustion temperature of the designed SHS reactions .The results show that the SHS process can be sustained for all the designed reactions .However ,pyrochlore (Ca2Ti2O6 ) ,perovskite (CaTiO3 ) , Zr5 Ti7 O24 and trace of rutile (TiO2 ) were prepared using Fe2 O3 and CrO3 as the oxi‐dants .Zirconolite is successfully synthesized as the main phase with CaTiO3 and TiO2 as the minor phases when Ca(NO3 )2 is employed as the oxidant .The combustion tempera‐tures are much lower than the thermodynamically calculated adiabatic temperatures . Meanwhile ,the decrement of TiO2 ∶Ti is beneficial for the high adiabatic temperatures and combustion temperatures when using Ca(NO3 )2 as the oxidant .