A Study on Er3+ Substitution in Sol-gel BaTiO3 Thin Films Using X-ray Line Profile Analysis

Perovskite erbium doped barium titanate (Ba1-xErxTiO3) thin films, at different x values, have been fabricated on SiO2/Si substrate and characterized using X-ray diffraction (XRD) in the range of 20 degrees to 60 degrees to study the phase structure and geometric parameters for the films. XRD patterns show a broadening and shifting for the perovksite peaks toward higher angle due to Er3+ doping. The effect of Er3+ substitution into BaTiO3 lattice has been deeply investigated using X-ray line profine analysis through Scherrer equation, Williamson-Hall and size-strain plot (SSP) approaches. For all approaches used, it has been found that the crystallite size for the films decreases as the value of x increases, which is attributed to the relatively small Er3+ ionic size compared to Ba2+. In Williamson-Hall and SSP analysis, it is found that the microstrain created due to Er3+ doping causes distortion for the lattice and broadening for perovskite peaks as a result. Among all approaches used in this work, SSP shows to be the most suitable for this type of materials by giving the best fitted plots and goodness of fit R-2 close to 1.