Novel niobium-doped titania varistor with added barium and bismuth

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb03700.x· OSTI ID:6468806

Yang, Seng Lu; Wu, Jenn Ming ^[1]

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1. National Tsing Hua Univ., Taiwan (China). Dept. of Materials Science and Engineering

Characteristics of the sintered compacts and the microstructures and electrical properties of Nb-doped TiO[sub 2] varistors with added Ba and Bi were studied at various sintering temperatures ranging from 1,250 to 1,400C. Adding both Ba and Bi to Nb-doped TiO[sub 2] ceramics resulted in a maximum intergranular phase and a minimum weight loss at 1,350C. In contrast, adding either Ba or Bi alone produced no such maxima and minima. The intergranular phases included mainly a Bi[sub 2]Ti[sub 2]O[sub 7] crystal phase, apt to occur at a triple junction, and a Ba-rich amorphous phase that surrounded the grains, but discontinuously. The intergranular phases varied consistently with variation in electrical properties. The optimum conditions for the most efficient boundary barrier layer, with the lowest weight loss and the highest resistivity at low frequencies, were 1350C with both Ba and Bi addition. The highest values for [alpha] ([approx]9.5), V[sub gb10] ([approx]0.8 V), and E[sub B] ([approx]0.42 eV) support that finding. The effective relative dielectric constant, K[sub eff][approx]20,000, also was obtained under optimum conditions. The single addition of either Ba or Bi, however, produced nearly the opposite results, as discussed in this paper.

• OSTI ID: 6468806
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:1; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
360606 -- Other Materials-- Physical Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
AMORPHOUS STATE
BARIUM COMPOUNDS
BARIUM OXIDES
BISMUTH COMPOUNDS
BISMUTH OXIDES
CAPACITORS
CHALCOGENIDES
COMPACTS
CRYSTAL-PHASE TRANSFORMATIONS
DATA
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
EQUIPMENT
EXPERIMENTAL DATA
FABRICATION
GRAIN BOUNDARIES
INFORMATION
MATERIALS
MICROSCOPY
MICROSTRUCTURE
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
RESISTORS
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR DEVICES
SEMICONDUCTOR RESISTORS
SINTERING
SPECTROSCOPY
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
TITANATES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
X-RAY SPECTROSCOPY