Domain and Grain Boundary Structural Effects on the Resistivity Behavior in Donor Doped, PTCR Barium Titanate

Polycrystalline barium titanate (BaTiO$\sb3$) can be made n-type conducting and reveal a positive temperature coefficient of resistivity (PTCR) near the ferroelectric phase transition (T$\sb{\rm c}$). This is accomplished by development of a grain boundary potential barrier, the height of which is low at temperatures below T$\sb{\rm c}$ and high at temperatures above. The properties of the grain boundary region, its structure, chemical composition and related defect structure are not well understood. The purpose of this investigation is to address these deficiencies in the literature. This was achieved by characterizing the structure using TEM, SEM, HREM, EDS, and TEM as a function of temperature and relating the observed structure to the resistivity-temperature characteristics. Y$\sb2$O$\sb3$ and La$\sb2$O$\sb3$ doped BaTiO$\sb3$, PTCR systems were studied and compared.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ceramics Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Roseman, Rodney Dean

Contributors dc:contributor

• Buchanan, Relva C.

• Engineering, Materials Science

Identifier

(UMI)AAI9411768

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/72172