Properties of rare-earth orthoferrites perovskite driven by steric hindrance

REFeO3 (RE = La, Pr, Nd, Sm) perovskites present interesting properties and are studied for their potential applications as smart devices and the requirement of miniaturization and low power consumption in such electronic components has led to the development of thin films. The understanding of crystallization mechanisms and the characterization of such perovskites are thus important to understand their properties. In this study, we purpose a systematic comparison of structural, optical and electrical properties of REFeO3 thin films, and we investigate the direct link between properties and crystallographic distortion. The as-deposited films are annealed in air under XRD measurements in order to investigate their complete crystallization kinetic, using Johnson Mehl Avrami Kolmogorov model. TEM observations of films are in agreement with this model. Then, optical and electrical characterization of films were performed by using UV-visible spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), and 4-probes measurements. We found that the activation energy of crystallization, the infrared vibration mode position and the activation energy of conduction mechanism are driven by distortion of the perovskite, which can be described by the Goldschmidt tolerance factor. All the studied properties are shifted due to decrease of RE ionic radius and the direct relationship between structural distortion and physical properties shifting is discussed. (C) 2015 Elsevier B.V. All rights reserved.