Interactions and Chemistry of Defects at the Grain Boundaries of Ceramics

• Published in: Journal of the American Ceramic Society Vol. 84; no. 3; pp. 539 - 550
• Main Authors: Han, Joo-Hwan, Kim, Doh-Yeon
• Format: Journal Article
• Language: English
• Published: Westerville, Ohio American Ceramics Society 01.03.2001; Blackwell; Wiley Subscription Services, Inc
• Subjects: Condensed matter: structure, mechanical and thermal properties; defects; Defects and impurities in crystals; microstructure; Exact sciences and technology; Grain and twin boundaries; grain boundaries; Interaction between different crystal defects; gettering effect; interfaces; Physics; Structure of solids and liquids; crystallography; Theories and models of crystal defects; Grain boundaries; Temperature dependence; Inorganic compounds; Ionic compound; Segregation; Doping; Theoretical study; Ceramics; Electric charges; Crystal defect interaction; Thermodynamic analysis; Defect structure; Electrostatic potential
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.2001.tb00695.x

A thermodynamic approach is used to derive a defect chemistry formulation at the grain boundary of an ionic solid. Considering the elastic and/or electrostatic interactions between charged defects, the equilibrium electrostatic potential and the concentration of charged defects at the grain boundaries can be quantitatively predicted. The obtained result has general applicability at all levels of defect concentrations. Defect concentration at the boundary has been determined to critically depend on the interactions between defects, electrostatic potential, and segregation. These interactions, either acting individually or coupling with each other, lead to a nonuniform defect distribution near the grain boundary. Calculations also show that the grain‐boundary segregation of an aliovalent solute is greatly affected by doping through the electrostatic or elastic interactions. The variation of the grain‐boundary characteristics with the processing parameters, such as dopant concentration and temperature, is discussed in relation with the proposed model.