空气中退火对钨酸铅纳米晶的影响

Influence of annealing in air on PbWO_4 nanocrystals

以钨酸钠和醋酸铅为原料,加表面活性剂聚乙二醇200,合成钨酸铅纳米晶。合成的样品呈淡黄色,这是由于样品中存在铅空缺和氧空缺导致的。对样品进行X射线和红外分析及透射电子显微镜分析,结果表明:样品结晶良好,粒径在10～20nm之间。将样品在不同温度下退火2h,研究空气中退火对性能的影响。结果表明:在600℃和700℃退火2h后,样品X射线和红外图谱中出现非特征峰;随着退火温度的升高,样品颗粒度变大。样品的光致发光谱中出现蓝色、绿色和红色发光带,随着退火温度的升高,强度增加。在700℃退火2h后,样品颜色变为白色,绿色发光带消失。

Lead tungstate nanocrystals were prepared by heating a lead tungstate muddy solution at 100 ℃,which was made with natrium tungstate and lead acetate as starting materials, and adding polyglycol 200 as surfactant. The color of the products is straw yellow, because of the existence of defects of V_Pb and V_o. Results of X-ray diffraction（XRD）, IR analysis and observation of transmission electron microscopy indicate that crystallitzation of lead tungstate nanocrystals with diameter in the range of 10-20 nm are excellent.The products were heat-treated 2 h at different temperatures to study the influence of annealing on their properties. When the products are annealed at 600 ℃ and 700 ℃ for 2 h, nonstandard diffraction peaks are observed in their XRD and IR patterns. The size and the intensities of luminescent emissions in blue, green and red range of products increase with increasing temperatures.The luminescent emission in green range disappears for the sample annealed at 700 ℃ for 2 h, and with its color becoming white.