Thermal Properties of BaTiO3/Ag Composites Undergoing Phase Transformation Due to Temperature Changes
Conference Paper
Overview
Identity
Additional Document Info
View All
Overview
abstract
Ferroelectric ceramics, such as Barium Titanate (BaTiO3), have been widely used in many multilayer capacitors (MLCs) and piezoelectric devices. However, the applicability of BaTiO3 is restricted by its brittleness. Ductile/softer materials like silver or polymers can be blended with piezoelectric ceramics to create active composites with high electro-mechanical coupling properties and less brittle. The objective of this study is to characterize the physical and thermal properties of barium titanate/silver (BaTiO3/Ag) composites and investigate the influence of the microstructural characteristics on the overall thermal properties of the BaTiO3/Ag composites. Composites with 0%, 5%, 10% and 15% volume fraction of silver were manufactured by powder metallurgy technique. First, x-ray diffraction (XRD) was used to check if BaTiO3 is chemical inert to Ag. The coefficient of thermal expansion (CTE) was then determined using thermo-mechanical analyzer (TMA) within the temperature range of -50 to 250 C. Finally, the heat capacity as a function of temperature was determined from differential scanning calorimetry (DSC). It is noted that BaTiO3 is a polycrystalline material. The shape of each crystallite of the BaTiO 3 sample depends on the ambient temperatures and the overall properties of BaTiO3 samples are influenced by the crystallite structures. It was found that the cubic phase has the highest values of CTE, while the orthorhombic phase has the lowest values of CTE. We also found that the influence of volume content of silver on the phase transition temperatures is negligible. These investigations provide useful information for numerical modeling and reliability verification of BaTiO3 based devices.
