IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613 All rights reserved by www.ijsrd.com 155 Study of Structural and Dielectric properties of BaTiO 3 Doped with Mg- Cu-Zn Ferrites S.Abdul Khader 1 T.Sankarappa 2 1,2 Department of Physics 1,2 Gulbarga University, Gulbarga-585106, Karnataka, India Abstract— The magnetoelectric (ME) composites having the general formula, (x) Mg 0.25 Cu 0.25 Zn 0.5 Fe 2 O 4 + (1-x) BaTiO 3 (x=15%, 30%, 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO 3 and highly magnetostrictive magnetic component Mg0.25Cu0.25Zn0.5Fe 2 O 4 . The presence of constituent phases of ferrite, ferroelectric and their composites were confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM), which revealed uniform mixing of two phases. The variations in dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz were measured in a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric parameters has been analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model. Key words: Dielectric, Ferroelectric, Magneto Electric (ME), Composites I. INTRODUCTION Piezomagnetic-piezoelectric composites exhibit unique magneto-electric phenomena which are facilitated by mechanical deformations [1–3]. Upon application of a magnetic field to ME composites, the ferromagnetic component produces a deformation due to magneto-striction that is transferred to the ferroelectric component via interfacial bonding, in turn this induces an electric charge across the piezoelectric phase due to piezoelectricity. ME materials evolve from single phase compounds to particulate composites, to laminated composites. The difficulties associated with uniting electric and magnetic orderings in a single phase material have been circumvented by forming multi-phase ME composites consisting of ferromagnetic and ferroelectric components that can be electromagnetically coupled by stress mediation [4]. ME effect in composites is a product tensor property and that first proposed by van Suchtelen [5]. The ME composites have applications field as sensors, waveguides, switches, phase invertors, etc. [7]. Mg 0.25 Cu 0.25 Zn 0.5 Fe 2 O 4 (MCZF) are considered to be the important soft magnetic materials because of their high initial magnetic permeability, saturation magnetization, high electrical resistivity and low core losses [3,4]. The selection of a suitable combination of magnetic and electric materials to achieve better ME effect is a difficult task. For the present work, MCZF as piezomagnetic material and BaTiO 3 (BT) as a piezoelectric material were choosen and the composites were prepared and studied the effect of composition and frequency on the dielectric properties. The study offered a valuable information on the behavior of localized electric charge carriers which is useful in understanding magneto electric effect [10, 11]. II. EXPERIMENTAL The nano ferrite Mg 0.25 Cu 0.25 Zn 0.5 Fe 2 O 4 (MCZF) in the powder form has been prepared by solution combustion method using stoichiometric compositions of corresponding metallic nitrates as oxidizers and citric acid as fuel. Barium titanate (BT) powder of size 100 nm procured from Sigma Aldrich. The ME composites were prepared by thoroughly mixing MCZF and BT powders in required molar proportions and sintered at 1000 0 C for 4 hrs and were cooled slowly to room temperature. These sintered powders were pressed into pellets of 10 mm diameter and 1-2 mm thickness. The pellets were again sintered at 1000 0 C for 2 hrs and cooled to room temperature. The synthesized ME composites, (MCZF) x (BT) 1-x with x = 15%, 30% & 45% have been labeled as MBT1, MBT2 and MBT3 respectively. The composites were prepared in ferroelectric-rich regions [8, 13]. The presence of constituent phases in the composites and the crystal structure of constituent phases and their composites were determined by XRD studies using Bruker AXS D8 Advance X-ray diffractometer (λ=1.5406 A 0 ). Surface morphology has been investigated using Field Emission Scanning Electron Microscope (FESEM, JEOL JSM 6700). The Capacitance and dissipation factor, tanį as a function of frequency in the range 100 Hz-1MHz was studied using a precision LCR meter (Hioki make LCR Hi- Tester 3250). The dielectric constants (İ') and dielectric loss factor (İ'') were determined using the formulae [14,18] İ' = Ct/İ 0 A (1) İ''=İ'tanį (2) Where, t is the thickness and A the area of the pellet. The ac conductivity, ı ac was determined from the dielectric properties using a relation, ı ac = ω İ 0 İ'' (3) Where, İ 0 is the vacuum permittivity and ω =2Πf with f being frequency. III. RESULTS AND DISCUSSION A. Phase The XRD patterns of pure MCZF, BT and composites MBT1, MBT2 and MBT3 are shown in Fig.1. The diffraction patterns of composites showed the presence of both ferrite and ferroelectric phases. The ferrite phase showed a cubic spinel structure with a=8.4 A 0 and the average crystallite size of 60.15 nm. Ferroelectric phase exhibited perovskite tetragonal structure with a=4.022 A 0 , c=4.025 A 0 (c/a=1.0007). The lattice parameters of the constituent phases are found to be same for MBT1, MBT2