Facile preparation of uniform barium titanate (BaTiO 3 ) multipods with high permittivity: impedance and temperature dependent dielectric behavior Suryakanta Nayak, a Banalata Sahoo, b Tapan Kumar Chaki a and Dipak Khastgir * a Perovskite barium titanate (BaTiO 3 ) multipods were prepared via high temperature solid state reaction. The crystal structure and morphology of BaTiO 3 particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and scanning probe microscopy (SPM). The XRD analysis of the crystal structure revealed that a single-phase compound was formed having tetragonal crystal structure. Calorimetric study (DSC) over room to high temperature was used to find the energy involved in different steps of synthesis especially during the initiation and the termination process for the formation of BaTiO 3 . These multipods have high average aspect ratio (10, where average diameter 300 nm and average length 3 mm) as seen from FESEM. UV-Vis spectroscopy reveals that the prepared material is UV active. The bulk and surface chemical composition of these BaTiO 3 particles as investigated by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra reveals that in the prepared BaTiO 3 , the titanium ions exist in two different oxidation states, namely Ti 3+ and Ti 4+ . The BaTiO 3 multipod exhibits high permittivity with relatively low dielectric loss. From impedance analysis of the material, the dual resistivity characteristics, one for grain and the other for grain-boundary can be distinguished. An equivalent circuit has been proposed through analysis of the complex impedance plot (Nyquist plot) for BaTiO 3 multipods. This material has perfect capacitative nature as seen from the Bode plot, and can be used for charge storage devices and other electronic applications. From temperature dependent dielectric analysis, the Curie temperature of BaTiO 3 multipods is found to be 85  C. 1. Introduction Barium titanate is an important electroactive ceramic material. Over the past few decades, the preparation of barium titanate (BaTiO 3 ) in different nano forms such as nanoparticles, nano- cubes, nanorods, nanowires, and nanotubes has attracted great attention from many researchers particularly because of their unique ferroelectric and piezoelectric properties. These prop- erties are important and essential for the development of different nanoscale devices for transducers, piezoelectric sensors and actuators, energy-harvesting devices, memory devices including ferroelectric random access memories (FRAM), and also for optoelectronic applications. 1–8 Piezoelec- tric oxides are of interest because of their potential applications in different elds ranging from sensors to radio frequency devices. 9 Barium titanate is one of the most widely used ceramics in the electronics industry, especially for making multilayer ceramic capacitors (MLCCs). 10,11 Literatures reveal that BaTiO 3 can exist in different crystal structures depending on environmental temperatures, cubic (above Curie tempera- ture), tetragonal (5  C to Curie temperature), orthorhombic (90  C to 5  C), and rhombohedral (<90  C) (Fig. 1). 12–15 In the cubic form, all the Ba 2+ ions occupy eight corners of an elementary cubic cell, whereas single Ti 4+ ion is in the centre of the cube and the O 2 ions in the centre of each surface of that cube. However, below the Curie temperature BaTiO 3 exists in the distorted tetragonal structure with a mutual displacement of the centers of positive and negative charges within the sub- lattice. Consequently, a dipole moment arises parallel to one of the cubic areas of the original phase. Such a generated spon- taneous polarization in the tetragonal structure is the origin of its ferroelectric and piezoelectric behavior. 16–18 Zhu et al. have prepared barium titanate nanoparticles through hydrothermal technique using titanium hydroxide, titanium dioxide, and barium hydroxide as starting materials where different solvents have used during the product preparation and the purication process. 19 Peng et al. had taken H 2 TiO 3 and Ba(NO 3 ) 2 as the a Rubber Technology Centre, Indian Institute of Technology Kharagpur, W.B. 721302, India. E-mail: khasdi@rtc.iitkgp.ernet.in; Fax: +91-3222282292; Tel: +91-3222283192 b Department of Chemistry, Indian Institute of Technology Kharagpur, W.B. 721302, India Cite this: RSC Adv. , 2014, 4, 1212 Received 1st September 2013 Accepted 14th November 2013 DOI: 10.1039/c3ra44815k www.rsc.org/advances 1212 | RSC Adv. , 2014, 4, 1212–1224 This journal is © The Royal Society of Chemistry 2014 RSC Advances PAPER Published on 15 November 2013. Downloaded by Indian Institute of Science on 02/12/2013 03:12:41. View Article Online View Journal | View Issue