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Formation of point defects in strontium titanatf
lxxii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
6. 0 kcal/mole. (RecEived 22 June 1966) (Revised 11 August 1966) 12.
FORMATION OF POINT DEFECTS IN STRONTIUM TITANATF L. C. Walters and R. E. Grace (School of Materials Science and Metallurgical Engineering, Purdue University, Lafayette, Indiana)
The electrical conductivity and thermoelectric power of single crystal strontium titanate were determined as a function of the ~H2 0 /~H2ratio over crystals at various temperatures. Electrical conductivity measurements were made in the temperature range from 900°to 1300°C; thermoelectric data were 0/~H taken from ratios600°to from 2 1300°C. x 10 toA 3range x 10 of was ~H2 inves~igated. Typical values of the electrical conductivity at a temperature of 1000°Cand Pjj~O/~H ratio of I x 103 and 1 x 10 were 1.2 ohn~’~m ~ and 0. 53 ohm 1cm respectively; under the same conditions the thermoelectric power was found to be -0. 600 mv/°Kand -0. 662 mv/°K. The thermoelectric measurements showed the crystals to ben-type. ‘
Vol. 4, No. 10
atmospheric concentrations concurrently with the conductivity of zinc oxide photocells and calculating the degree of correlation between the variables. A highly significant correlation was found between zinc oxide conductivity and atmospheric ion concentration. A similar correlation was found between photoconductivity and humidity. However, the humidity varied over a narrow range and its effect, therefore, was relatively small. It is suggested that the variations in conductivity arise primarily from the reversible adsorption of negative ions which promotes a field efffct on the mobility of the carriers in zinc oxide. (Received 14 February 1966) (Revised 11 August 1966) 14.
2
-2
EXPERIMENTS ONHALL THE MAGNETO RESISTIVITY AND EFFECTS IN Ni and Ni ALLOYS A. C. Ehrlich, R. Huguenin and D. Rivier (Institut de Physique Exp~rimentalede l’Universit~de Lausanne
1,
An oxygen vacancy defect model was found applicable to non-stoichiometric strontium titanate at elevated temperatures. In damp hydrogen the enthalpy of formation of an oxygen vacancy and two electrons in the conduction band was 86, 500 ± 3, 000 cal/mole. (Received 22 June 1966) (Revised 11 August 1966) 13.
THE EFFECT OF VARIATIONS IN THE CONCENTRATION OF ATMOSPHERIC CONSTITUENTS ON THE ELECTRICAL CONDUCT1VITY OF ZINC OXIDE J. McK Nobbs (Australian Defence Scientific Service, Defence Standards Laboratories, Department of Supply, Adelaide, Australia )
The electrical conductivity of zinc oxide powders exjiibtts diurnal variations of up to two orders of magnitude when exposed to the atmosphere. Fifteen atmospheric variables were investigated as possible causes of these variations. However, only water vapour, ozone and atmospheric ions induced either dark or photoconductivlty changes in zinc oxide. The effects of these constituents were determined by recording their
The low temperature transverse magnetoresistivity and Hall resistivity in three high purity polycrystaline Ni samples and three very dilute Ni based alloys (Ni-Fe, Nt-Co and Ni-Cu) were measured. The results are reported on Kohler diagrams. The transverse magnetoconductivities and the Hall conductivities were calculated and are also reported on Kohier diagrams. It is found that : (1) for the purest samples the magnetoresistivity and the Hall conductivity show large and systematic deviations from Kohler’s rule while the Hall resistivity and the rnagnetoconductivity obey it very well; (2) for the alloys the Hall resistivities and magnetoconductivities fall respectively on different Kohler curves than the pure samples, but among themselves are in agreement with Kohier’s rule. These results are discussed. (Received 25 May 1966) (RevIsed 15 August 1966) 15.
INTERFACE STATES AND INTERFACE DISORDER IN THE St-St0 2 SYSTEM Akos G. Revesz, Karl H. Zaininger and Russell J. Evans (RCA laboratories, David Sarnoff Research Center, Princeton, New Jersey, U. S. A.)
The density of surface states in the Si-Sb2 system depends on the oxidation conditions and post oxidation treatment. It increases with oxidation rate, decreases with oxidation
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
6. 0 kcal/mole. (RecEived 22 June 1966) (Revised 11 August 1966) 12.
FORMATION OF POINT DEFECTS IN STRONTIUM TITANATF L. C. Walters and R. E. Grace (School of Materials Science and Metallurgical Engineering, Purdue University, Lafayette, Indiana)
The electrical conductivity and thermoelectric power of single crystal strontium titanate were determined as a function of the ~H2 0 /~H2ratio over crystals at various temperatures. Electrical conductivity measurements were made in the temperature range from 900°to 1300°C; thermoelectric data were 0/~H taken from ratios600°to from 2 1300°C. x 10 toA 3range x 10 of was ~H2 inves~igated. Typical values of the electrical conductivity at a temperature of 1000°Cand Pjj~O/~H ratio of I x 103 and 1 x 10 were 1.2 ohn~’~m ~ and 0. 53 ohm 1cm respectively; under the same conditions the thermoelectric power was found to be -0. 600 mv/°Kand -0. 662 mv/°K. The thermoelectric measurements showed the crystals to ben-type. ‘
Vol. 4, No. 10
atmospheric concentrations concurrently with the conductivity of zinc oxide photocells and calculating the degree of correlation between the variables. A highly significant correlation was found between zinc oxide conductivity and atmospheric ion concentration. A similar correlation was found between photoconductivity and humidity. However, the humidity varied over a narrow range and its effect, therefore, was relatively small. It is suggested that the variations in conductivity arise primarily from the reversible adsorption of negative ions which promotes a field efffct on the mobility of the carriers in zinc oxide. (Received 14 February 1966) (Revised 11 August 1966) 14.
2
-2
EXPERIMENTS ONHALL THE MAGNETO RESISTIVITY AND EFFECTS IN Ni and Ni ALLOYS A. C. Ehrlich, R. Huguenin and D. Rivier (Institut de Physique Exp~rimentalede l’Universit~de Lausanne
1,
An oxygen vacancy defect model was found applicable to non-stoichiometric strontium titanate at elevated temperatures. In damp hydrogen the enthalpy of formation of an oxygen vacancy and two electrons in the conduction band was 86, 500 ± 3, 000 cal/mole. (Received 22 June 1966) (Revised 11 August 1966) 13.
THE EFFECT OF VARIATIONS IN THE CONCENTRATION OF ATMOSPHERIC CONSTITUENTS ON THE ELECTRICAL CONDUCT1VITY OF ZINC OXIDE J. McK Nobbs (Australian Defence Scientific Service, Defence Standards Laboratories, Department of Supply, Adelaide, Australia )
The electrical conductivity of zinc oxide powders exjiibtts diurnal variations of up to two orders of magnitude when exposed to the atmosphere. Fifteen atmospheric variables were investigated as possible causes of these variations. However, only water vapour, ozone and atmospheric ions induced either dark or photoconductivlty changes in zinc oxide. The effects of these constituents were determined by recording their
The low temperature transverse magnetoresistivity and Hall resistivity in three high purity polycrystaline Ni samples and three very dilute Ni based alloys (Ni-Fe, Nt-Co and Ni-Cu) were measured. The results are reported on Kohler diagrams. The transverse magnetoconductivities and the Hall conductivities were calculated and are also reported on Kohier diagrams. It is found that : (1) for the purest samples the magnetoresistivity and the Hall conductivity show large and systematic deviations from Kohler’s rule while the Hall resistivity and the rnagnetoconductivity obey it very well; (2) for the alloys the Hall resistivities and magnetoconductivities fall respectively on different Kohler curves than the pure samples, but among themselves are in agreement with Kohier’s rule. These results are discussed. (Received 25 May 1966) (RevIsed 15 August 1966) 15.
INTERFACE STATES AND INTERFACE DISORDER IN THE St-St0 2 SYSTEM Akos G. Revesz, Karl H. Zaininger and Russell J. Evans (RCA laboratories, David Sarnoff Research Center, Princeton, New Jersey, U. S. A.)
The density of surface states in the Si-Sb2 system depends on the oxidation conditions and post oxidation treatment. It increases with oxidation rate, decreases with oxidation