Synthesis and characterization of high dielectric constant material based on Er-doped BaTiO3 for capacitor applications

Abstract

High dielectric constant material becomes an important parameter to be used as capacitor for storage in most electronic devices due to miniaturization trend of smart devices and electronic gadgets. BaTiO3 was used in this study as it was reported to have a high dielectric constant (εr= 4000-10000) at Curie temperature (TC) around 110˚C. Furthermore, it was reported that by doping Erbium (Er) into BaTiO3, it can improve the dielectric properties of BaTiO3. BaTiO3 and Er-doped BaTiO3 with composition of Ba1-xErxTiO3 in the range of (0 ≤ x ≤ 0.01) have been synthesized via conventional solid state reaction method. The characterizations of these compositions were made using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) analysis and Impedance Analyzer analysis. XRD analysis shows that BaTiO3 and Er-doped BaTiO3 has phase pure after heating at 1400˚C. Both BaTiO3 and Er-doped BaTiO3 exhibit tetragonal structure with space group of P4mm. Solid solution limit of Er-doped BaTiO3 composition is beyond x=0.01. For structural analysis, Rietveld refinement analysis were done on BaTiO3 for 5 models (A, B, C, D and E) to find the suitable atomic position with low 2 value to be used as standard model to refine other Er-doped BaTiO3 samples. Model C is the best model with low 2 value of 3.808. With Rietveld refinement analysis, study on incorporation of Er into the A-site and B-site of perovskite ABO3 structure was done. The result indicates that Er can be at both side either A or B site because of the 2 value that is very similar. For microstructural analysis, SEM was used to study the grain size effect by doping Er into BaTiO3. The smallest grain size for Ba1-xErxTiO3 was 3.76 m at x=0.0075. For electrical properties, the composition of Ba1-xErxTiO3 at x=0.0075 has the highest dielectric constant value, εr= ~ 6500 as compared to pure BaTiO3 with dielectric constant value, εr= ~ 5200. Instead of that, the sample at x=0.0075 has low dielectric loss with value less than 0.1. The highest capacitance value for x=0.0075 at the highest dielectric constant value is C= ~4 x 10-9 Fcm-1 with total conductivity, ζ= 4 x 10-7Scm-1. The Capacitance-Voltage (C-V) characteristic were measured from 0 to 30 V and all the samples show a high capacitance by increasing the voltage up to 30 V with no signal of breakdown region. The sample with the highest dielectric constant, low loss and good C-V characteristic is the sample with x= 0.0075.