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Electrical conductivity in lithium ferrite and lead zirconate--titanate ceramics

Technical Report ·
OSTI ID:7349481
Electrical conduction in polycrystalline lead zirconate-titanate and lithium ferrite ceramics was investigated. The effects of temperature, impurities, defect structure, nonstoichiometry, and microstructure on the electrical conductivity were determined and compared with the existing theoretical models. It is shown that electrical conduction in lead zirconate-titanate follows typical semiconductor behavior. Holes contributed by lead vacancies are the major charge carriers. Impurity ions which serve as acceptors or donors significantly affect the conduction process. The activation energy is 3.6 eV for intrinsic conduction, 1.41 eV for extrinsic conduction due to Nb/sub 2/O/sub 5/ doping, and 1.01 eV due to Sc/sub 2/O/sub 3/ doping. Data are presented to show the influence of stoichiometry which affects the concentration of charge carrier, and temperature which affects the mobility of charge carrier, on the dc resistivity of lithium ferrite. The exponential temperature dependence of the mobility is in agreement with the proposed electron-hopping model. Charge transport occurs by thermally activated electron hopping between the octahedral Fe/sup 2 +/ and Fe/sup 3 +/ ions. The hopping activation energy is 0.06 eV. Experimental evidence indicates that there is no influence of microstructure on the electrical conduction behavior. The effect of controlled amounts of NiO and NiFe/sub 2/O/sub 4/ dopants on the dc resistivity of lithium ferrite is also presented. 44 fig, 47 references. (auth)
Research Organization:
California Univ., Berkeley (USA). Lawrence Berkeley Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
7349481
Report Number(s):
LBL-4930
Country of Publication:
United States
Language:
English