Preparation and infrared emissivities of alkali metal doped ZnO powders
来源期刊：中南大学学报(英文版)2014年第9期
论文作者：LI Hui-hui(李会会) HUANG Yun-xia(黄云霞) LI Zhi-min(李智敏) YAO Yin-hua(姚银华) ZHANG Shu-yuan(张淑媛)
文章页码：3449 - 3455
Key words：infrared emissivity; alkali metal; crystalline quality; optical band-gap; ZnO powders
Abstract: Alkali metal (Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value (0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.
LI Hui-hui(李会会), HUANG Yun-xia(黄云霞), LI Zhi-min(李智敏), YAO Yin-hua(姚银华), ZHANG Shu-yuan(张淑媛)
(School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China)
Abstract:Alkali metal (Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value (0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.
Key words:infrared emissivity; alkali metal; crystalline quality; optical band-gap; ZnO powders
