Magnetic Driven Electrical Conductivity and Band Gap Energy of SrTi1-X CrxO3
Markus Diantoro (a,b*), Ishmah Luthfiyah (a), Ulwiyatus Sa-adah (a), Siti Wihdatul Himmah (a), Hari Wisodo (a,b), Zainul Arifin Imam Supardi (c), Arif Hidayat (a,b)
a) Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jl. Semarang 5 Malang 65145, Indonesia
b) Centre of Advanced Materials for Renewable Energy, Universitas Negeri Malang, Jl. Semarang 5, Malang 65145, Indonesia
c) Department of Physics, Universitas Negeri Surabaya, 60254 Surabaya, Indonesia
*markus.diantoro.fmipa[at]um.ac.id
Abstract
SrTiO3 perovskite possesses high dielectric properties and potentially applied as a high-temperature thermoelectric material. Theoretically, physical properties of SrTiO3 can be improved by doping process. Modification of local structure will influence its electrical conductivity, thus a crystal field changes or geometric distortion occurs. Currently, SrTiO3 has been widely studied with various dopants. However, so far there is no comprehensive study about structural modification using multivalent magnetic ion of Chromium (Cr) and external magnetic fields to the electrical conductivity. Cr ions have various valences of 2+, 3+, 4+, 5+, 6+ and the symmetry of Cr is 4h with 6 coordination numbers which can change the local structure of SrTiO3. Besides, Ti ions in SrTiO3 have 67 pm and Cr has symmetry of 4h for the valence of 3+. Under these conditions, Cr will reduce the lattice parameters and a slight shift of apical oxygen to the basal plane will be observed. Since Cr interact with electromagnetic wave in the range of visible light, it might be expected that this compound would show a shift of band gap energy. As the valence also changes to a possible mixed state, the physical properties may exist in complex states. SrTi1-xCrxO3 samples were prepared via solid-state reaction in the various molar ratio of Cr doping. The phase and structure were analyzed using X-ray Diffraction. XRD confirmed that SrTi1-xCrxO3 compounds phase were formed and a slight change in lattice parameters was observed. The local octahedral sixfold symmetry structure of SrTi1-xCrxO3 compounds also changed to be tetragonal with the presence of Cr. Based on the EDX data, the composition of SrTi1-xCrxO3 compounds corresponded to the composition designed. Furthermore, the magnetic field induced I-V conductivity measurement showed that higher Cr fraction enhanced its electrical conductivity. The optical band gap analysis from UV-Vis spectroscopy showed that the band gap reduce accordingly.
Keywords: Magnetic driven, SrTiO3, Cr, conductivity, band gap
Topic: Magnetic Methods