Thermodynamic stability of intergranular amorphous films in bismuth-doped zinc oxide

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1998.tb02299.x· OSTI ID:616211

Wang, H; Chiang, Y M ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering

It is shown that the solid-state equilibrium configuration of Bi-doped ZnO grain boundaries is a nanometer-thick amorphous film. Polycrystalline Bi-doped ZnO was investigated using high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM). The equilibrium state below the eutectic temperature and at 1 atm total pressure was approached from three different routes: samples were cooled from above the eutectic temperature (T{sub eutectic} = 740 C), processed entirely below the eutectic temperature, and desegregated by high applied pressure (1 GPa) followed by annealing at ambient pressure to restore segregation. In all instances, the final state is an amorphous intergranular film 1.0--1.5 nm in thickness. The results show that a thin intergranular film in this system has lower free energy than the crystal-crystal grain boundary. The implications of these results for creation of electrically active grain boundaries in zinc oxide varistors are discussed.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-87ER45307
• OSTI ID: 616211
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 1 Vol. 81; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
BISMUTH OXIDES
DOPED MATERIALS
GRAIN BOUNDARIES
SEGREGATION
THERMODYNAMIC PROPERTIES
ZINC OXIDES