Sc_(2-x)Ga_xW_3O_(12)体系负热膨胀性能研究  

Negative thermal expansion of Sc_(2-x)Ga_xW_3O_(12)solid solution

作　　者：刘福生[1] 陈贤鹏[1] 谢华兴[1] 敖伟琴[1] 李均钦[1] 

机构地区：[1]深圳市特种功能材料重点实验室,深圳大学材料学院,深圳518060

出　　处：《物理学报》2010年第5期3350-3356,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50871070);深圳市基础研究计划项目(批准号:JC200903120081A;CXB200903090012A)资助的课题~~

摘　　要：通过固相反应法,在1100℃下成功制备出了系列Ga掺杂Sc2-xGaxW3O12(x=0,0.05,0.1,0.2,0.3,0.5,0.8)固溶体.X射线粉末衍射结构精修表明,Ga以替代Sc的形式成功进入Sc2-xGaxW3O12晶格,但不能获得端元组分Ga2W3O12化合物.晶胞参数的精修结果表明所有样品均具有负膨胀性能;随着Ga掺杂量的增加,固溶体Sc2-xGaxW3O12的晶胞参数a,c及晶胞体积随之收缩,而晶胞参数b则随之增大,固溶体Sc2-xGaxW3O12的平均体膨胀系数绝对值随之减小.在室温—300℃之间,随着温度的增加,体积膨胀系数绝对值急剧减小,而在300—800℃之间基本保持稳定,当温度大于800℃时,体积膨胀系数绝对值继续减小,逐渐向零膨胀靠近,并具有向正膨胀转化的趋势.Series of Ga-doped Sc2-xGaxW3O12 samples （ x = 0,0. 05,0. 1,0. 2,0. 3,0. 5,0. 8） were synthesized by solid state reaction at 1100 ℃. Rietveld refinement of the X-ray powder diffraction patterns show that Ga substituted Sc in Sc2 -x GaxW3O12 structure successfully. The client component Ga2W3O12 cannot be obtained in this work. The lattice parameters obtained by Rietveld refinement showed that all samples have negative thermal expansion between 25—1000 ℃. Lattice parameters a,c and cell volume of the Sc2-xGaxW3O12 decrease with the increases of Gallium content,but accompanied with the expansion of lattice parameter b. The average volume expansion coefficient also decreases with the increase of the Gallium content. As the temperature increases,the absolute value of the volume expansion coefficients decrease dramatically between room temperature and 300 ℃ ,but remain almost unchanged between 300 and 800 ℃ ,and decrease further at the temperature higher than 800 ℃ ,tending to zero and turning into positive expansion.

关 键 词：负热膨胀 热膨胀系数 RIETVELD结构精修 

分 类 号：O614.412[理学—无机化学]