二氧化钛纳米晶的缺陷性质和光电性能  

Defects distribution and photoelectric performance of titanium dioxide nanocrystals

作　　者：王立群 WANG Liqun(College of Physics and Materials Science,Tianjin Normal University,Tianjin 30038)

机构地区：[1]天津师范大学物理与材料科学学院,天津300387

出　　处：《天津师范大学学报（自然科学版）》2018年第4期17-22,共6页Journal of Tianjin Normal University：Natural Science Edition

基　　金：天津师范大学开发基金资助项目(043135202-XK1702)

摘　　要：为研究二氧化钛纳米晶的缺陷性质对其光电性能的影响,采用溶胶-凝胶法制备了二氧化钛纳米晶,利用X线衍射和正电子湮没寿命谱对样品的晶相、平均粒径和缺陷性质等进行表征,并以所得二氧化钛纳米晶为基础制备二氧化钛纳米晶薄膜,进一步分析其光电性能.结果表明:在450℃的热处理温度下,可以合成锐钛矿相占主要成分的二氧化钛纳米晶.随着热处理时间从30 min延长至90 min,二氧化钛纳米晶的平均粒径从12.8 nm增大到47.9 nm.随着平均粒径的增大,二氧化钛纳米晶表面缺陷的尺寸变小且浓度降低,同时晶界间的自由体积发生复合.在表面缺陷和平均粒径的双重影响下,二氧化钛纳米晶薄膜的瞬态光电流密度随平均粒径的增大表现出先增大后减小的变化趋势,其中,基于26.5 nm粒径二氧化钛纳米晶制备所得薄膜的瞬态光电流密度最大,其值为0.072 m A/cm2.Titanium dioxide nanocrystals were fabricated by the sol-gel process and made into a film to study their photo-electric performance in relation with the defect distribution on these nanocrystals. The crystal structure,mean grain sizes,and defects distribution of the materials were investigated through X-ray diffraction and positron annihilation lifetime spec-troscopy,respectively. The results show that the titanium dioxide nanocrystals obtained after the heat treatment at 450 ℃were mainly anatase phase. The mean grain sizes increased from 12. 8 nm to 47. 9 nm with the treatment time in creased from 30 min to 90 min. Meanwhile,the surface defects size and concentration on Ti O2 nanocrystals decreased,and the inter-granular free volume combined. As the mean grain size increased,the transient photocurrent density of the tit anium dioxide nanocrystal films initially enhanced and then decreased,which was resulted from the combined influence of the surface defects distribution and the mean grain sizes. The highest transient photocurrent density was 0.072 m A/cm2,achieved from the film based on titanium dioxide nanocrystals with the average grain sizes of 25.4 nm.

关 键 词：二氧化钛 纳米晶 正电子湮没 缺陷性质 光电性能 

分 类 号：Q469[生物学—生理学]