Point Defects and Diffusion in Paratellurite

J. Wegener, O. Kanert, R. Küchler, A. Watterich

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

125Te nuclear spin relaxation (NSR) and electrical conductivity measurements were performed on ultrapure single-crystalline paratellurite (α-TeO2) between about 50 K and the melting point (1007 K) at various oxygen partial pressures (1 bar 10-4 bar). At elevated temperatures the NSR rate 1/T1 and conductivity σ are caused by the diffusive motion of point defects. From the observed pO2-dependence of 1/T1 and σ a defect model is developed which is shown to be consistent with the experimental data. The model involves ionic oxygen interstitials (O‘), doubly charged oxygen vacancies (Vö) and charge-compensating electron holes (h*). The observed pressure dependence suggests that the NSR rate is induced by the motion of while the conductivity is due to the mobility of h•. Evaluation of the data leads to 3.3 eV for the incorporation enthalpy of oxygen on interstitial sites and to 4.5 eV for the formation enthalpy of oxygen Frenkel pairs (Oi″). Further, the chemical diffusion coefficient Dcis found to be caused by the ambipolar diffusion of O″i and h•. At 950 K we obtained from both the NSR and conductivity experiments Dc = (1 ± 0.3) •10-5 cm2/s.

Original languageEnglish
Pages (from-to)1151-1158
Number of pages8
JournalZeitschrift fur Naturforschung - Section A Journal of Physical Sciences
Volume49
Issue number12
DOIs
Publication statusPublished - Dec 1 1994

Keywords

  • Conductivity
  • Diffusion
  • NMR
  • Oxides
  • Point defects

ASJC Scopus subject areas

  • Mathematical Physics
  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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