钴掺杂摩尔分数对二氧化钛粉体热致变色变发射率性能的研究

Thermochromic and variable emissivity properties of Co-doped TiO_2 powders with different mole fraction of Co

采用固相合成法制备不同摩尔分数Co的TiO_2粉体,用X射线电子显微镜、扫描电子显微镜、紫外可见吸收光谱、IR-2双波段发射率测量仪对粉末进行结构表征和变色变发射率性能测试。结果表明:掺杂CoO的摩尔分数不超过5%时,Co能完全进入TiO_2晶格,超过5%时会形成第二相CoTiO_3;随掺杂CoO摩尔分数的增加,Co/TiO_2粉末的晶粒尺寸逐渐增加,颜色由宝绿色向鲜绿色转变,从浅绿逐渐变深;在测试温度从25℃逐渐升高到800℃时,粉体都是从绿色变到黄色,降至室温时,又会恢复至原来的绿色;从室温升到800℃时,发射率变化量随掺杂摩尔分数的增加逐渐变大,从0.139增大到0.376。

Co-doped TiO2 powders with different mole fraction of Co were successfully prepared through solid-state reaction.The structure,morphologies,thermochromic and variable emissivity properties were characterized and analyzed by X-ray electron microscopy,scanning electron microscopy,UV-visible absorption spectra,IR-2 dual band emissometer.The results show that Co can completely enter TiO2 crystal lattice when the mole fraction of Co doped oxide does not exceed 5%.The second impurity CoTiO3 phase is formed with different doping when the mole fraction of Co is more than 5%.With the increase of the mole fraction of Co oxide,the grain size of Co/TiO2 powders increases gradually.The color of the powders changes from bao green to bright green,from light green to dark green.When the testing temperature gradually increases from 25 ℃ to 800 ℃,all the prepared powders change from green to yellow,which can return back to the original color when cooled to room temperature.Simultaneously,the variation of infrared emissivity of the Co-doped TiO2 powders increases from 0.139 to 0.376 with testing temperature changing from room temperature to 800 ℃.