Microstructural and physical properties of samarium orthoferrite thin films by the sol–gel method
Hussein Baqiah, Mohd Mustafa Awang Kechik, Naif Mohammed Al‐Hada, Jian Liu, Shicai Xu, Na Zhang, Qiang Li, Zhenxing Wang, Rashad Al-Gaashani, Jihua Wang
Abstract
Samarium orthoferrite, SmFeO3 (SFO), is a multifunctional material with promised applications. In this paper, SFO thin films were prepared by sol–gel method onto a quartz substrate at different annealing temperatures (T = 700, 750, 800 and 850 °C) and onto LaNiO3 (LNO) buffered quartz substrate using T = 800 °C. The phase formation, microstructure, electronic, optical, magnetic and ferroelectric properties of the films were investigated and compared. Minimal annealing temperature (T) from thermogravimetric analysis was about 720 °C. From X-ray diffraction analysis, film T = 700 °C showed mixed phases of SFO and a trace amount of Sm2O3 while single phase of SFO was observed for films T = 750 – 850 °C. The lattice parameter c and microstrain reduced for films T = 700 – 800 °C and then increased for film T = 850 °C. From Atomic force microscopy analysis, the porosity, root mean square roughness and particle size of the films increased with the rise of T. All films exhibited high optical transmittance (∼79 – 95 %) in 800 – 550 nm wavelength range and showed two main optical absorptions peaks at about 285 and 385 nm. At lower energy transition, the band gap (Eg) reduced from ∼ 2.79 to 2.72 eV for films T = 700 – 800 °C and then increased to ∼ 2.79 eV for film T = 850 °C. The film’s magnetisation (Ms) tended to increase with T increment. The SFO/LNO film showed higher Ms and Eg than film T = 800 °C.