Study of Structural and Dielectrical Properties of Lead Free Polycrystalline Electro Ceramics Ba<SUB>5</SUB>CaTi<SUB>2</SUB>Nb<SUB>8</SUB>O<SUB>30</SUB> (BCTN) for Microwave Tunable Device Applications

Abstract

Tungsten bronze structure ceramics have found vital potential in many applications such as actuators, transducer, electro-optic, ferroelectric random access memory and microwave devices. These type ceramics are extensively used in many industrial applications due to their spontaneous polarization and wellknown for its high dielectric constant, low dielectric loss, low leakage current density, good thermal stability and high piezoelectric coefficient. In present work, Ba 5 CaTi 2 Nb 8 O 30 (BCTN) has been synthesized first time through solid state reaction method. The microstructures, dielectric, ferroelectric, ferromagnetic and Raman spectra have been investigated by means of X-ray diffraction, Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), LCR meter, P-E loop tracer, VSM and Raman spectrometer respectively. X-ray diffraction study revealed the formation of single phase tetragonal structure with space group P4bm. The crystallite size was observed to be in the range 14.4 nm. Detailed dielectric properties of BCTN compound as function of temperature at different frequencies show that sample exhibits diffuse type transition at curie temperature 316˚C. The P-E and M-H studies confirmed the coexistent ferroelectricity and magnetism at room temperature.