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Dissociation des dislocations sur les plans (110) dans les cristaux ioniques du type NaCl
ii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
represented by the following equations: nit
= =
24. 670 x l0~6+ 1. 742 x 10’8t -5. 141 x 10”2t2 -3. 660 x 10’~ 7. 112 x 10’% -3. 339 x 10”~t2 -
where t is in °C. (Received 24 August 1967) -
5.
EFFET DES CORRELATIONS ENTRE
ELECTRONS SUR LES~PROPRIETES DES ALLIAGES DILUES: UN TRAITEMENT VARIATIONNEL B. Coqblin et G. Toulouse(Physique des Solides, Faculté des Sciences, 91, Orsay) On étudie l’effet des correlations entre electrons sur les propriétês des alliages dilués a partir de l’Hamiltonien d’Anderson, sans et avec degenérescence orbitale. On utilise une méthode variationnelle. Les conditions de decouplage magnétique sont étudiées; il apparait en particulier que la fonction d’onde d’essai pour l’état de base n’est jamais magnétique, en l’absence de dégénérescence orbitale. The effect of electronic correlations on the properties of dilute alloys is studied within the Anderson Hamiltonian, without and with orbital degeneracy; a variational method is used, The magnetic decoupling conditions are studied; it appears, in particular, that the trial ground state wave function is never magnetic, in the absence of orbital degeneracy. (Received 28 July 1967) 6.
STUDIES ON THE DEFECT STRUCTURE OF STRONTIUM OXIDE W. D. Copeland and R. A. Swalin (School of Mineral and Metallurgical Engineering, University of Minnesota, Minneapolis, Minnesota)
An investigation has been conducted in order to gain information on the defect structure of SrO in the temperature range 600°C~ T 1400°C and oxygen pressure range 10..12 atm. P0 2 I atm. The problems of investigating this system in the high oxygen pressure regions have been discussed. Measurements have been reported including phase equilibria, lattice parameter, electrical conductivity, thermo-electric power and thermogravimetric analysis of the SrO system. No new oxide phases of strontium
Vol.5, No. 11
were discovered in the temperature and pressure ranges investigated. The lattice parameter of SrO was found to be constant at 5.1600 ±0. 0005 ~ within the given temperature and pressure ranges, although larger lattice parameter values were observed in the strontium excess region. A tentative defect model has been proposed which postulates that Frenkel disorder on the anion sublattice predominates. The enthalpy of formation of negatively charged oxygen interstitials and holes as given by the reaction 1/2 02 (g) = O’~+ h’ + (H 0 + H1) is found to be (H0 + H1) = 2. 0 eV. The enthalpy of formation of negatively charged oxygen interstitials and holes as given by the reaction ~ = O~+ V0’ + Hp7 is HF’ = 3.0eV. The oxygen interstitials were found to be2 /sec highly at 1300°C an enthalpy of motion of Hm mobile withand diffusivity of 2.4 x 10’~cm 0.6 eV. (Received 2 June 1967) (Revised 26 September 1967) 7.
ELECTRONIC PROCESSES IN THE PHOTO-CRYSTALLIZATION OF VITREOUS SELENIUM J. Dresner and G. B. Stringfellow (RCA Laboratories, Princeton, New Jersey)
The effect of highly absorbed light in increasing the growth rate of surface crystallites in vitreous (amorphous, polymeric) selenium films has been studied in detail. It is demonstrated that the action of the light results from the production of hole-electron pairs in the vitreous phase, and that the growth rate is controlled by the flux of holes towards the crystal boundary. The response time of the photo- crystallization effect is determined by hole trapping below the surface of the film. Examination of the topography of the energy bands shows that the crystallites act as a sink for holes. A qualitative model, based on the diffusion of holes towards the crystal boundary followed by a molecular reorientation, is described. The breaking of an Se-Se bond upon formation of a free hole may also be effective. (Received 14 June 1967)
8.
DISSOCIATION DES DISLOCATIONS SUR
LES PLANS (110) DANS LES CRISTAUX IOMQUES DU TYPE Na Cl G. Fontaine (Laboratoire de Physique des Solides, Faculté des Sciences d’Orsay 91, Orsay, France)
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
represented by the following equations: nit
= =
24. 670 x l0~6+ 1. 742 x 10’8t -5. 141 x 10”2t2 -3. 660 x 10’~ 7. 112 x 10’% -3. 339 x 10”~t2 -
where t is in °C. (Received 24 August 1967) -
5.
EFFET DES CORRELATIONS ENTRE
ELECTRONS SUR LES~PROPRIETES DES ALLIAGES DILUES: UN TRAITEMENT VARIATIONNEL B. Coqblin et G. Toulouse(Physique des Solides, Faculté des Sciences, 91, Orsay) On étudie l’effet des correlations entre electrons sur les propriétês des alliages dilués a partir de l’Hamiltonien d’Anderson, sans et avec degenérescence orbitale. On utilise une méthode variationnelle. Les conditions de decouplage magnétique sont étudiées; il apparait en particulier que la fonction d’onde d’essai pour l’état de base n’est jamais magnétique, en l’absence de dégénérescence orbitale. The effect of electronic correlations on the properties of dilute alloys is studied within the Anderson Hamiltonian, without and with orbital degeneracy; a variational method is used, The magnetic decoupling conditions are studied; it appears, in particular, that the trial ground state wave function is never magnetic, in the absence of orbital degeneracy. (Received 28 July 1967) 6.
STUDIES ON THE DEFECT STRUCTURE OF STRONTIUM OXIDE W. D. Copeland and R. A. Swalin (School of Mineral and Metallurgical Engineering, University of Minnesota, Minneapolis, Minnesota)
An investigation has been conducted in order to gain information on the defect structure of SrO in the temperature range 600°C~ T 1400°C and oxygen pressure range 10..12 atm. P0 2 I atm. The problems of investigating this system in the high oxygen pressure regions have been discussed. Measurements have been reported including phase equilibria, lattice parameter, electrical conductivity, thermo-electric power and thermogravimetric analysis of the SrO system. No new oxide phases of strontium
Vol.5, No. 11
were discovered in the temperature and pressure ranges investigated. The lattice parameter of SrO was found to be constant at 5.1600 ±0. 0005 ~ within the given temperature and pressure ranges, although larger lattice parameter values were observed in the strontium excess region. A tentative defect model has been proposed which postulates that Frenkel disorder on the anion sublattice predominates. The enthalpy of formation of negatively charged oxygen interstitials and holes as given by the reaction 1/2 02 (g) = O’~+ h’ + (H 0 + H1) is found to be (H0 + H1) = 2. 0 eV. The enthalpy of formation of negatively charged oxygen interstitials and holes as given by the reaction ~ = O~+ V0’ + Hp7 is HF’ = 3.0eV. The oxygen interstitials were found to be2 /sec highly at 1300°C an enthalpy of motion of Hm mobile withand diffusivity of 2.4 x 10’~cm 0.6 eV. (Received 2 June 1967) (Revised 26 September 1967) 7.
ELECTRONIC PROCESSES IN THE PHOTO-CRYSTALLIZATION OF VITREOUS SELENIUM J. Dresner and G. B. Stringfellow (RCA Laboratories, Princeton, New Jersey)
The effect of highly absorbed light in increasing the growth rate of surface crystallites in vitreous (amorphous, polymeric) selenium films has been studied in detail. It is demonstrated that the action of the light results from the production of hole-electron pairs in the vitreous phase, and that the growth rate is controlled by the flux of holes towards the crystal boundary. The response time of the photo- crystallization effect is determined by hole trapping below the surface of the film. Examination of the topography of the energy bands shows that the crystallites act as a sink for holes. A qualitative model, based on the diffusion of holes towards the crystal boundary followed by a molecular reorientation, is described. The breaking of an Se-Se bond upon formation of a free hole may also be effective. (Received 14 June 1967)
8.
DISSOCIATION DES DISLOCATIONS SUR
LES PLANS (110) DANS LES CRISTAUX IOMQUES DU TYPE Na Cl G. Fontaine (Laboratoire de Physique des Solides, Faculté des Sciences d’Orsay 91, Orsay, France)