A very low temperature green processing for developing high dielectric Al2O3, SrTiO3 ceramic composites

Title : A very low temperature green processing for developing high dielectric Al2O3, SrTiO3 ceramic composites

Abstract:

Processing of ceramics and its composites either by conventional or advanced processing techniques necessitates very high sintering temperature (>1000oC) and moderate to long duration of time. On the other hand, the Cold Sintering Process (CSP) is a low temperature green technology proven a significant lowering in sintering temperature and time for a wide range of oxide ceramics. This energy-efficient method facilitates enhanced integration with different materials and even with polymers as well. The present work demonstrates the advantage of CSP in the processing of monolith ceramics (Al2O3, SrTiO3) at extremely low temperature of 300oC. Also Al2O3-(20-30 wt.%) HDPE composites are successfully processed at extremely low temperature of 120oC. High dielectric constant (ε’) of 11.73 and low dielectric loss (tanδ) of ~ 0.0076 observed for CSPed- Al2O3-20HDPE and a little low ε’ of 9.13 and low tanδ of 0.0066 was evident for Al2O3-30HDPE at 1MHz. Such dielectric behavior of Al2O3 composites are related to crystallite size, dangling bond density and decrease in microstrain. It was also observed that the dielectric constant of monolithic Al2O3 is around 90 at 20MHz. In case of SrTiO3, it was observed that the dielectric constant and loss decreased (up to 8MHz) from 275 and 0.75 to 118 and 0.05, respectively. This work reveals the advantage of cold sintering in densifying and enhancing dielectric properties of ceramics.

Biography:

Dr. Brahma Raju Golla is currently working as Associate Professor at Department of Metallurgical and Materials Engineering, National Institute of Technology (NIT) Warangal, India. He has more than 15 years of research and teaching experience. Before joining NIT Warangal, Golla worked as Assistant Professor for a semester at Malaviya National Institute of Technology (MNIT) Jaipur, India and as an Invited Scientist in Engineering Ceramics Research Group at Korea Institute of Materials Science (KIMS) South Korea for more than 2 years. Golla pursued his postdoctoral research for 2 years on drying characterization of ceramic films in Nonmetallic-Inorganic Materials Group, Technical University (TU) Darmstadt, Germany soon after completion of PhD. Dr. Golla earned his doctorate in Materials and Metallurgical Engineering under the supervision of Prof. Bikramjit Basu from IIT Kanpur, India in 2009. His research focuses on processing-structure-property correlation of Ultra High Temperature Ceramics, Advanced Materials Processing, and Tribology of Materials. He has supervised 4 PhDs, 20 Masters (M. Tech) and 38 Undergraduate (B. Tech) Students. So far Dr. Golla contributed 3 book chapters in Ceramic Handbooks, edited 1 Conference Proceedings and is author/coauthor of more than 55 archival research papers in peer reviewed international journals.