Grain boundary phenomena at barium titanate doped by vapour phase diffusion.

• Grant number: 01/02560-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2001
• End date: January 31, 2002
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: José Arana Varela
• Grantee: Suman Chatterjee
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

In a variety of ceramic processes, doping in trace amounts is required e.g., to achieve semiconduction, to control grain size, to control the grain boundary potential barrier, etc. Besides, a preferential distribution of dopants in grains and grain boundaries is also very important in various device fabrications. Hence, this grain boundary engineering is a very important topic of concern now a day in the electroceramic industry. The grain boundary plays a vital role in various electroceramic components like - PTC thermistors, Varistors, Barrier layer capacitors, etc. The composition, structure and phases in the grain boundary are controlled by the variation of sintering temperature, cooling rate, addition of second phase in the grain boundary, addition of dopants and various other mechanisms. The main objective of this project is to develop a simple, cost-effective and useful method for grain boundary engineering by doping through vapour phase. After realization, the method can make use of highly developed technology of semiconductor doping with a higher degree of accuracy compared to solid state doping conventionally used in ceramic industry. (AU)