Evolution of structure and electrical properties during crystallization of radidly solidified Bi sub 4 Ti sub 3 O sub 12

Technical Report · Thu Jun 01 04:00:00 EDT 1989

DOI:https://doi.org/10.2172/5178234· OSTI ID:5178234

Drozdyk, L

Amorphous Bi{sub 4}Ti{sub 3}O{sub 12} was prepared by rapid solidification from the melt. Crystallization and microstructure development during heat treatment were investigated. Dielectric and ferroelectric properties were related to microstructure. The method of materials preparation led to interesting and desirable properties for amorphous and crystallized fine-grain electrical ceramics. Crystallization behavior during heat treatment was investigated by DSC, XRD, and TEM. Direct transformation to the expected crystalline phase occurred without any major intermediary steps. Transformation kinetics were determined by a variety of techniques, and the kinetic parameters were dependent on the method used. Fully crystallized material had structure and electrical properties which were dependent on the heat treatment conditions. For materials heat treated at 600{degree}C and above, the microstructures were dense, and with a uniform fine-grain size of < 1 {mu}m. The structures had residual strain. For decreasing heat treatment temperature, a decrease in grain size was observed, with an increase in strain, and a decrease in occurrence of domains. In addition to the observations for microstrain and domains, features of the dielectric anomaly at the Curie temperature implied increasing internal stress for materials heat treated at lower temperature. Ferroelectric hysteresis was observed for fully crystallized material. However, saturation was not possible for materials which were heat treated at 600{degree}C and below. Coercive fields for fine-grain material were higher than for single crystal material, and materials with smaller grain sizes had higher coercive fields.

• Research Organization: Illinois Univ., Urbana, IL (USA). Dept. of Ceramic Engineering
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC02-76ER01198
• OSTI ID: 5178234
• Report Number(s): DOE/ER/01198-T41; ON: DE90005221
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
AMORPHOUS STATE
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTALLIZATION
DIELECTRIC PROPERTIES
DIFFRACTION
ELECTRICAL PROPERTIES
HEAT TREATMENTS
KINETICS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SCATTERING
SOLIDIFICATION
THERMAL ANALYSIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION