Studies on porous lead free piezoelectric ceramics

Abstract

Porous lead-free piezoelectric materials have gained popularity for their non-toxicity, high sensitivity and high figures of merit. Their potential applications are in various fields like energy storage, sensing technologies etc. Low density, low relative permittivity and low specific heat are features of porous ceramics due to the presence of pores. The addition of porosity also provides exceptional thermal and sound insulation capabilities. Porous piezoelectric ceramics typically have low cost, great controllability, and substantial signal and energy output. They have the potential for a vast performance development space and have a variety of uses as transducers, sensors etc. In this thesis, potassium sodium niobate (KNN) and lithium sodium niobate (LNN) were taken as the lead free materials. This thesis has focused on the preparation, morphology, and analysis of porous ferroelectric materials for their electrical and piezoelectric properties and also focuses on the mechanism that affects porous piezoelectric materials performance. This research work has been worked out in four parts. In the first part porous lead-free 0.92 (K0.5Na0.5) NbO3. 0.08 Bi0.5K0.5TiO3 (KNN BKT) piezoelectric samples were prepared by solid state method. Porosity was induced by sacrificial method using various percentage of ammonium oxalate monohydrate (AOM) as the pore former (10-40 vol %). The samples elementary analysis and their piezoelectric, dielectric properties were studied. From the analysis it was revealed that porous sample with 30-40vol% showed improved piezoelectric properties at high temperature. So, for rest of the work the pore forming agent content was chosen as 30-40 vol%. newline