用正电子湮没谱学研究氯化稀土在NaY沸石上的分散

Dispersion of Rare-earth Chloride in NaY Zeolite Studied by Positron Annihilation Spectroscopy

用正电子湮没谱学研究氯化富铈稀土与NaY沸石机械混合形成的稀土NaY沸石 (RE NaY)中 ,氯化稀土在NaY中的分散 .分别测量不同质量比的RE NaY ( 1%～ 2 0 %)经 5 0 0℃烘烤 1h ,RE NaY ( 5 %)经过不同温度烘烤 1h ,以及RE NaY( 5 %)经 5 0 0℃烘烤不同时间后的正电子寿命谱 .所有寿命谱都出现了 5个寿命分量 ,其中第 3 ,4,5寿命分别与 β笼、超笼及沸石微粒界面空洞的大小和数量相关 .

A series of samples of rare-earth NaY zeolite (RE-NaY), prepared from mechanical mixtures of rare-earth chloride with NaY zeolite, were studied by positron annihilation spectroscopy. We measured the positron lifetime spectra as a function of the rare-earth chloride content in the RE-NaY heated at 500 degreesC for 1 h, as a function of the heating temperature with heating time of 1 h, and as a function of the heating time at 500 degreesC for RE-NaY (5%) respectively. All lifetime spectra were resolved into five components, in which the third, the fourth and the fifth components are related to the ortho-positronium annihilation in sodalite cage, supercage and interface void, respectively. The experimental results showed that positron annihilation spectroscopy was sensitive to the change of the dispersion of rare earth in NaY zeolite.