A study of the crystal structural variations related to alkaline earth orthosilicate (Sr1-xBax)2SiO4 solid solutions

• Main Authors: Wen-YuChien, 簡文昱
• Other Authors: Jennifer Kung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/77691620220092850657

碩士 === 國立成功大學 === 地球科學系 === 103 === The crystal structural variations in Strontium-Barium orthosilicate (Sr1-xBax)2SiO4 solid solution series as a function of the chemical composition were studied by using X-ray powder diffraction and analyzed using the Rietveld method, which enables us to obtain the information of crystal structure including cell parameters, cation distribution and structure parameters. The Rietveld method results indicate the cation distribution has the preference of Ba2+ ions occupied to the ten-coordinated site M(1) and Sr2+ ions occupied to the nine-coordinated site M(2) in the solid solutions. Due to the two lattice sites have different site environment, the lattice constants increase nonlinearly with increasing Ba-content should be attributed to the variations of the specific bond lengths in the specific direction of the lattice. In this study, the satellite diffraction peaks of the incommensurate structure are observed from the X-ray powder diffraction data. The results indicate the crystal structure in the range below values of around 25 mol% Ba2SiO4 (X≦0.25) should be an incommensurate structure.