关键词: 形成机制, SrCeO3, Sr2CeO4, SrO-CeO2体系

Abstract: The solid state reaction process of the mixture of SrCO₃ and CeO₂ powders with different Sr/Ce ratios was studied by using XRD and TG/DTA methods. The results show that only Sr₂CeO₄ phase is formed for a firing temperature lower than 950℃ while Sr₂CeO₄ and SrCeO3 phases are simultaneously developed in the initial stages of the reaction for a firing temperature above 950℃. In the initial stages of the reaction above 950℃,the major product is Sr₂CeO₄ for close to 950℃ and it becomes SrCeO3 above 1000℃. There are two types of formation mechanism for SrCeO₃ and Sr₂CeO₄, respectively. When the firing temperature is above 1000℃, SrCeO₃ is formed directly by SrO and CeO₂ while Sr₂CeO₄ is created by SrCeO₃ and SrO. However, SrO and CeO₂ convert directly to Sr₂CeO₄ below 950℃ and SrCeO₃ is produced by the reaction of Sr₂CeO₄ and CeO₂ for close to 950℃. Based on these results, the reaction mechanism of SrO-CeO₂ system is derived and the wrong results in the XRD data of SrCeO₃ (JCPDS36-980) have been clarified. The fluorescence spectra of Sr₂CeO₄ show that the formation mechanism has effect on its excitation spectra.

Key words: formation mechanism, SrCeO3, Sr2CeO4, SrO-CeO2 system