Phase transformation, morphology, DC electrical resistivity and dielectric properties investigations of properties of manganese doped barium titanate nanoparticles

Abstract

In this work, manganese (Mn) doped barium titanate BaTi1-xMnxO3 nanoparticles with varying composition of Mn (x = 0.0, 0.10 and 0.20) were prepared by using sol–gel self-ignition wet chemical route. The influence of Mn doping on crystal structure, infra-red, morphology, DC electrical resistivity and frequency dependent dielectric studies was systematically investigated. To know the crystalline nature and purity of the prepared samples, a non-destructive X-ray diffraction (XRD) tool was used. The analysis of XRD results revealed that pure BaTiO3 and BaTi1-xMnxO3 with x = 0.1, samples show tetragonal structure and for higher Mn content (x = 0.20) shows the hexagonal structure. The values of interplanar spacing, Miller indices, etc. were used to determine the unit cell parameters, X-ray density and unit cell volume. The highest intensity peak (110) observed in XRD pattern was considered to determine the crystalline size and which is found to be in the range of 3 to 8 nm. Scanning electron microscopy (SEM) technique was employed to study the surface morphology. SEM analysis confirm the dense nature of the grains with hexagonal shape for x = 0.2. EDX results confirm the presence of Ba, Ti, Mn and O elements as per the stoichiometric proportion. The functional groups and chemical bonds of Mn doped BaTiO3 were obtained by Fourier transform infrared spectroscopy (FTIR). The temperature dependant DC electrical resistivity studies were performed by standard two probe technique. The conductivity plot exhibits negative temperature coefficient (NTC). The activation energy and resistivity both decreased with Mn doping. The dielectric properties such as dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tan δ) were studied by means of LCR-Q meter. The variation of these parameters as a function of frequency shows the exponential decrease. The dielectric constant and dielectric loss reduces, whereas dielectric loss tangent increase on Mn doping. The ac conductivity increases with frequency.