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The Effect of Electric Field on Sintering and Electrical Conductivity of Titania
Author(s) -
Jha Shikhar K.,
Raj Rishi
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12682
Subject(s) - sintering , materials science , activation energy , electric field , arrhenius equation , electrical resistivity and conductivity , conductivity , grain size , composite material , metallurgy , mineralogy , chemistry , electrical engineering , physics , quantum mechanics , engineering , organic chemistry
The effect of DC electric field on sintering, and on the electrical conductivity of undoped rutile, TiO 2 (99.99%), has been investigated at fields ranging from 0 V to 1000 V/cm. The experiments were carried out at a constant heating rate of 10°C/min with the furnace temperatures reaching up to 1150°C. The sintering behavior falls into two regimes: at lower fields, up to 150 V/cm, sintering is enhanced, but densification occurs gradually with time (Type A or FAST sintering). At higher fields sintering occurs abruptly, and is accompanied by a highly nonlinear increase in conductivity, which has been called flash sintering (Type B or FLASH sintering). Arrhenius plots of conductivity yield an activation energy of 1.6 eV in Type A and 0.6 eV in Type B behavior; the first is explained as ionic and the second as electronic conductivity. The evolution of grain size under both types of sintering behavior are reported. These results highlight that the dominant mechanism of field‐assisted sintering can change with the field strength and temperature. We are in the very early stages of identifying these mechanisms and mapping them in the field, frequency, and temperature space.