Grain boundary oxidation in PTCR barium titanate thermistors. [positive temperature coefficient of resistivity]

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

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb03798.x· OSTI ID:6238672

Alles, A B; Burdick, V L ^[1]

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1. New York State College of Ceramics at Alfred University, Alfred, NY (United States)

The phenomenon of grain boundary oxidation in PTCR BaTiO[sub 3] thermistors is discussed. In particular, the energy spectra of the surface states were calculated for different samples, and these were related to the nominal composition, the impurity content of the base BaTiO[sub 3] powder used, and the prevalent atmospheric conditions during cooling and/or annealing. It is proposed that the interaction of manganese with oxygen creates deep-lying traps, and, in general, some proof is offered that the majority of the surface states are due to different oxidizing chemisorbed gases. It is believed that the ability of a particular sample to adsorb such gases in adequate amounts, and thus exhibit an appreciable PTCR effect, is related to the presence of acceptor-type dopants preferentially segregated onto the grain surfaces. Notably, the role of 3d transition metal cations in this process is discussed in some detail.

• OSTI ID: 6238672
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:2; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALKALINE EARTH METAL COMPOUNDS
ANNEALING
BARIUM COMPOUNDS
CATIONS
CERAMICS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISORPTION
COOLING
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY SPECTRA
GRAIN BOUNDARIES
HEAT TREATMENTS
IONS
MANGANESE
MATERIALS
METALS
MICROSTRUCTURE
N-TYPE CONDUCTORS
OXIDATION
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POWDERS
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SEMICONDUCTOR MATERIALS
SEPARATION PROCESSES
SORPTION
SPECTRA
THERMISTORS
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS