A series of Mn1.56(Co1−xAlx)0.96Ni0.48O4 (x = 0.1, 0.2, 0.3, and 0.4) films were prepared by the chemical solution deposition method and then post-heated at 150°C for 300 h. Scanning electron microscopy and x-ray diffraction revealed remarkable improvements in relative density and crystallinity in post-heated Mn1.56(Co1−xAlx)0.96Ni0.48O4 (x = 0.1, 0.2, 0.3, and 0.4) films. From x-ray photoelectron and Raman spectroscopy, it was found that the Mn3+/Mn4+ ratio decreases after post-heating, which leads to a decrease in Raman mode intensity. Furthermore, spectroscopic ellipsometry results show that both the refractive indexes and extinction coefficients of post-heated films are higher than those of annealed films in the visible range. However, the band gaps of all the films decreased significantly after the heating process. These investigations suggest that the post-heating treatment may be preferable for fabricating Mn1.56Co0.96Ni0.48O4 thin films for optical detection.
This work was supported by the National Key Research and Development Program of China (Grant No. 2017YFB0406405), the National Natural Science Foundation of China (Grant No. 61804178) and the Xinjiang Uygur Autonomous Region of China (No. 2017D01B51).
1.CAS Key Laboratory of Functional Materials and Devices for Special Environments, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and ChemistryCASUrumqiChina
2.School of Physics Science and TechnologyXinjiang UniversityUrumqiChina