稀土钇、镧掺杂TiO_2薄膜的拉曼谱分析

Raman spectral analysis of TiO_2 thin films doped with rare-earth yttrium and lanthanum

采用溶胶-凝胶法在石英玻璃衬底上用旋涂法制备了未掺杂、掺杂钇和掺杂镧的TiO2薄膜样品,对样品在700—1100℃范围内进行退火处理,并对样品的拉曼光谱进行了分析.分析表明:随着退火温度的升高,未掺杂TiO2薄膜发生了从锐钛矿相经混相最终向金红石相的转换,掺杂钇和掺杂镧对TiO2薄膜的晶相转换起阻碍作用,掺杂镧的阻碍作用更强;稀土掺杂能使TiO2薄膜晶粒细化,并使晶粒内部应力增大从而阻碍晶格振动,掺杂镧比掺杂钇的效果更明显;样品表现出明显的声子局域效应,即随晶粒尺寸减小,特征拉曼峰位蓝移、半高全宽增大和峰形非对称展宽.

TiO2 thin films doped with rare-earth yttrium and lanthanum were prepared on quartz plate by sol-gel /spin-coating technique. The samples were annealed at 700 to 1100 ℃ and the Raman spectra of the samples were obtained. Analysis of Raman spectra shows that with increasing annealing temperature,the anatase form of undoped TiO2 thin film transforms eventually into the rutile phase with mixed anatase / rutil phase as an intermediate. Yttrium doping and lanthanum doping of TiO2 thin films can inhibit the phase transformation,and the latter effect is stronger. Rare-earth doping refines grain size of TiO2 thin films and increases the internal stress,thereby preventing lattice vibration. The effect of La doping is stronger than yttrium doping. The samples show significant phonon confinement effect. That is to say,the characteristic Raman peaks blue shift and the full widths at half height increase and the peak shap easymmetricaly stretches with decrease of grain size.