不同方法制备CaMoO4∶0.05Eu3+红色荧光粉的对比研究

分别以高温固相法、溶胶-凝胶法、水热法和共沉淀法合成Eu3+掺杂的CaMoO4红色荧光粉,通过X-射线衍射(XRD)、场发射扫描电镜(FESEM)、傅立叶变换红外光谱(FTIR)、光致荧光光谱(PL)进行表征,考察荧光粉晶相、形貌及发光性能对制备方法的依赖性。实验表明,由于Ca2+的半径(0.099 nm)与Eu3+半径(0.094 7 nm)大小相差不大,Eu3+容易取代Ca2+的位置进入晶格,Eu3+掺杂的CaMoO4在晶体结构上保持白钨矿结构。FESEM结果表明:未经后处理的水热法所得样品为片状、多孔结构;高温固相法所得样品尺寸大、团聚严重;溶胶-凝胶法所得样品分散度好、呈条形结构;共沉淀法所得样品形貌、尺寸比较均一。荧光光谱显示,四种样品发光强度差异很大,共沉淀法制得样品的发光强度为未经后处理的水热法制得样品的6-7倍,该现象主要是由样品形貌及表面缺陷的差异引起的。

Comparison of CaMoO4:Eu3+ Red Phosphors Prepared by Different Synthesis Methods

CaMoO4:Eu3+ red emitting phosphors were prepared by solid-state reaction,sol-gel,hydrothermal and co-precipitation methods.The obtained powders were characterized by X-ray diffraction(XRD),Field Emission Scanning Electronic Microscope(FESEM),Fourier Transform infrared spectrometry(FTIR) and Photoluminescence(PL) spectra.The results of XRD show that all the samples prepared by different methods keep the structure of CaMoO4 because of the radii of Eu3+ and Ca2+ are very close.FESEM micrographs illustrate that the morphology of the four samples shows a big difference.The emission intensity of the sample derived by hydrothermal method is the lowest,which is only 1/6 of that of the sample obtained by co-precipitation method.The difference in emission intensity is mainly caused by the different morphology and the defects on the surfaces of the samples derived by various synthesis methods.