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Effects of Mn6+ substitution on dielectric and optical characteristics of SrLaLiTeO6 double perovskite

Citation

Halizan, Muhammad Zharfan; Mohamed, Zakiah; Yahya, Ahmad Kamal (2020), Effects of Mn6+ substitution on dielectric and optical characteristics of SrLaLiTeO6 double perovskite, Dryad, Dataset, https://doi.org/10.5061/dryad.70rxwdbvk

Abstract

In this paper, SrLaLiTe1-xMnxO6 (x = 0.02, 0.04, 0.06, 0.08, 0.10) double perovskites compounds have been prepared using solid state method. Studies on structural by applying X-ray diffraction (XRD) characterization found that all compounds formed in monoclinic, P21/n symmetry. As dopant concentration increased, field emission scanning electron microscope (FESEM) characterization used to found that larger grains were formed from x = 0.04 to x = 0.08 and affected dielectric properties studied by electrochemical impedance spectroscopy (EIS) characterization which showed enhancement of real dielectric permittivity, ε.  Dielectric property also showed nonDebye trend of DC conductivity, σDC. AC conductivity, σAC  revealed frequency dependent plot that obey the universal power law at all temperatures applied and the σAC behaviour in SrLaLiTe1-xMnxO6 is due to the tunnelling of polarons.

Methods

Polycrystalline powders of SrLaLiTe1-xMnxO6 (x = 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized using a solid-state reaction method. High-purity (≥99.99%) of strontium carbonate (SrCO3), lithium carbonate (Li2CO3), lanthanum oxide (La2O3), manganese (III) oxide (Mn2O3) and tellurium dioxide (TeO2) powders are used as raw materials. The chemical powders have been mixed at stoichiometric ratios with total mass of 5 g. The samples then grinded in agate mortar by pestle for 1 h to achieve good homogeneity. After grinding process, the mixed powder sample then pressed into pellet at pressure of 45 KPa using hydraulic press.  The pellet was then placed on an alumina crucible and calcinated in a box furnace at 850 oC for 10 h with heating rate of 15 oC/min and cooling rate of 1 oC/min. The sintering process followed with 900 oC for 10 h with heating rate of 15 oC/min and cooling rate of 1 oC/min. This action was expected to maintain the obtained stoichiometry close to the desired oxygen stoichiometry. The phase(s) of the final products were analysed by using XRD patterns collected by X-ray powder diffractometer PANanalytical model Xpert PRO MPD diffractometer equipped with a Cu Kα source from 10° to 90°. General Structure Analysis System (GSAS) and Graphical User Interface (i.e. EXPGUI) software were used for Rietveld refinement prior visualized in Visualisation for Electronic Structural Analysis (VESTA) program. Peak shape was modelled by pseudo-Voight function refined together with cell parameter, scale factor, zero factor and background function. For Fourier transform infra-red (FTIR) study, samples prepared by mixing thoroughly with potassium bromide (KBr) and the FTIR reflectance spectra were recorded in FTIR–Raman Drift Nicolet 6700 equipment ranging from 400 to 1500 cm-1. The surface morphology of the sintered pellets was obtained using FESEM characterization using SU 8000, Hitachi, Japan equipment. The dielectric and impedance with frequency range of 50 Hz to 1 MHz studies were collected using a HIOKI 3532–50 LCR Hi Tester connected to a computer while keeping the electrode pellets in sandwich geometry. Optical study performed by using Lambda 750, Perkin Elmer, Waltham, USA equipment for 2 to 5 hv range.

 

Funding

Ministry of Education Malaysia (MOE) and Universiti Teknologi MARA (UiTM), Award: 600-IRMI/FRGS5/3 (356/2019)

Ministry of Education Malaysia (MOE) and Universiti Teknologi MARA (UiTM), Award: 600-IRMI/FRGS5/3 (356/2019)