DOI: 10.5061/dryad.70rxwdbvk
title: Effects of Mn6+ substitution on dielectric and optical characteristics of SrLaLiTeO6 double perovskite

description: 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 non–Debye 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.
description: Polycrystalline powders of SrLaLiTe<sub>1-<i>x</i></sub>Mn<i><sub>x</sub></i>O<sub>6</sub> (<i>x </i>= 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 (SrCO<sub>3</sub>), lithium carbonate (Li<sub>2</sub>CO<sub>3</sub>)<sub>, </sub>lanthanum oxide (La<sub>2</sub>O<sub>3</sub>), manganese (III) oxide (Mn<sub>2</sub>O<sub>3</sub>) and tellurium dioxide (TeO<sub>2</sub>) 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 4–5 KPa using hydraulic press.  The pellet was then placed on an alumina crucible and calcinated in a box furnace at 850 <sup>o</sup>C for 10 h with heating rate of 15 <sup>o</sup>C/min and cooling rate of 1 <sup>o</sup>C/min. The sintering process followed with 900 <sup>o</sup>C for 10 h with heating rate of 15 <sup>o</sup>C/min and cooling rate of 1 <sup>o</sup>C/min. This action was expected to maintain the obtained stoichiometry close to the desired oxygen stoichiometry.<i> </i>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<sup>-1</sup>. 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 h<i>v</i> range.