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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 31, Number 3
JKCSEZ 31(3)
June 20, 1987 

Polaron Conductivity of Rutile Doped with MgO

MgO 도프된 Rutile의 Polaron 전도도
Keu Hong Kim, Hyung Tack Kim, Jae Shi Choi

김규홍, 김향택, 최재시
0.35. 0.75 및 1.25mol% MgO-TiO2계의 전기전도도가 600 ~ 1100℃ 및 10-8 ~ 10-1 atm의 산소분압하에서 측정되었다. 일정한 산소분압하에서 log σ vs. 1/T은 두 온도구간에서 직선관계를 보였으며 직선의 기울기로 부터 계산된 활성화에너지는 본성 영역과 외성 영역에서 각각 1.94eV 및 0.48eV이다. 이 계의 결함구조는 외성 영역에서 Vo이며 본성 영역에서Ti3.로 제안되었다. 특히 외성 영역에서 polaron model이 σ의 T 및 p 의존성으로 부터 규명되었다.

The electrical conductivity measurements have been made on polycrystalline samples of various compositions in the MgO-TiO2 system from 600 to 1100℃ under PO2's of 10-8 to 10-1 atm. Plots of log σ vs. 1/T at constant PO2 are found to be linear with the inflections, and the activation energies are 1.94eV for the intrinsic range and 0.48eV for the extrinsic range, respectively. The log σ vs. log PO2 curves are found to be linear at constant temperature, and the conductivity dependences of PO2 are closely approximated by σ α PO2-1/6 for the extrinsic and σ α PO2-1/4 for the intrinsic range, respectively. The dominant defects in this system are believed to be oxygen vacancy for the extrinsic and Ti3+ interstitial for the intrinsic range. The conduction mechanisms in both the extrinsic and the intrinsic ranges are proposed by the results of the electrical conductivity dependence on the oxygen partial pressure. Polaron model was suggested in the extrinsic region by the conducativity dependences of temperature and PO2.

215 - 224
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