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Chaléur specifique et supraconductivité dans des alliages de structure A 15 À base de chrome
Solid State Communications,
Vol. 8, pp. i—v, 1970.
Pergainon Press.
Printed in Great Britain.
Abstracts of Articlesto be Published in The Journal of Physics and Chemistry of Solids J Phys. Chem. Solids (to be published)’ should be cited in references to material quoted from this section prior to the publication of the relevant article.
1.
MOSSBAUER MEASUREMENTS OF BiFeO3 AND BiFeO3 -PbZrO3 SYSTEMS
Received 28 Augusi 1969 Revised,8 May 1970
A. Biran, Elscint Laboratories, P.O.B. 5258, Haifa, Israel and P.A. Montano and U. Shimony, Faculty of Physics, Technion, Haifa, Israel
2.
The Mössbauer effect was used in a study of BiFeO3 with an excess of Bi2 03, and of stoichiometric BiFeO3-PbZrO3 solid solutions. M6ssbauer spectra of BiFeO3 were taken over the temperature range of 78—770°K. The internal field was found to follow a Brillouin curve of S = 5/2 with Néel temperature = 640±50K and H,, (O°K)= 555±10kG. The quadrupole splitting shows irregular changes at 400°Kand 5000 K, corresponding to crystallographic phase transitions; these results are supported by center shift measurements. Discrepancies with regard to quadrupole splitting above the Neel temperature are attributable to the presence of phases other than BiFeO3. Measurements on (BiFeO3)~.(PbZr03)~~ systems over a range of compositions (x = 0.2, 0.3, 0.4, 0.5) showed no magnetic ordering at room temperature down to 78°K,although it was reported for similar compositions of BiFeO3—PbTiO3 this can be explained by changes in the conditions for exchange interaction in the Fe—O—Fe line. An increase of the QS of BiFeO3—PbZrO3 with the mole percentage of BIFeO3 was observed and interpreted in terms of the electric field gradient3 due induced dipole moments at site;toathe correlation also exists between Fe’ volume and the QS increase with the the cell mole percentage. By contrast, the center shift does not change significantly with the composition,
CHALEUR SPECIFIQUE ET SUPRACONDUCTIVITE DANS DES ALLIAGES DE STRUCTURE A 15 A BASE DE CHROME R. Flükiger, F. Heiniger, A. Junod, Spitzli et J.L. Staudenmann, Institut de Physique de la Matiêre Condensée Universit~de Genêve, CH—1211 Gen~ve4
J. Muller, P.
The low temperature specific heat has been measured in AlS4ype binary alloys of chromium with Ru, Rh, Os, Ir, Pt, Si, Ga and Ge. We found that the electronic density of states is higher in Cr-alloys with a lower degree of atomic order. Received 13 April 1970
3.
FLUORINE SELF DIFFUSION IN LiF AND NaF H.J. Matzke, European Institute for Transuranium Elements 75 Karlsriihe, Postfach 2~66,Germany
The self diffusion of F-18 in single crystals of LiF and NaF has been measured between 580 to 830°C(for LiP’) and 630 to 940°C(for NaF). It is suggested that vacancy pairs contribute to fluorine diffusion at temperatures near to the melting point yielding high values for both the activation enthalpy, ~H, (3.0 ±eV for LiF and i
Vol. 8, pp. i—v, 1970.
Pergainon Press.
Printed in Great Britain.
Abstracts of Articlesto be Published in The Journal of Physics and Chemistry of Solids J Phys. Chem. Solids (to be published)’ should be cited in references to material quoted from this section prior to the publication of the relevant article.
1.
MOSSBAUER MEASUREMENTS OF BiFeO3 AND BiFeO3 -PbZrO3 SYSTEMS
Received 28 Augusi 1969 Revised,8 May 1970
A. Biran, Elscint Laboratories, P.O.B. 5258, Haifa, Israel and P.A. Montano and U. Shimony, Faculty of Physics, Technion, Haifa, Israel
2.
The Mössbauer effect was used in a study of BiFeO3 with an excess of Bi2 03, and of stoichiometric BiFeO3-PbZrO3 solid solutions. M6ssbauer spectra of BiFeO3 were taken over the temperature range of 78—770°K. The internal field was found to follow a Brillouin curve of S = 5/2 with Néel temperature = 640±50K and H,, (O°K)= 555±10kG. The quadrupole splitting shows irregular changes at 400°Kand 5000 K, corresponding to crystallographic phase transitions; these results are supported by center shift measurements. Discrepancies with regard to quadrupole splitting above the Neel temperature are attributable to the presence of phases other than BiFeO3. Measurements on (BiFeO3)~.(PbZr03)~~ systems over a range of compositions (x = 0.2, 0.3, 0.4, 0.5) showed no magnetic ordering at room temperature down to 78°K,although it was reported for similar compositions of BiFeO3—PbTiO3 this can be explained by changes in the conditions for exchange interaction in the Fe—O—Fe line. An increase of the QS of BiFeO3—PbZrO3 with the mole percentage of BIFeO3 was observed and interpreted in terms of the electric field gradient3 due induced dipole moments at site;toathe correlation also exists between Fe’ volume and the QS increase with the the cell mole percentage. By contrast, the center shift does not change significantly with the composition,
CHALEUR SPECIFIQUE ET SUPRACONDUCTIVITE DANS DES ALLIAGES DE STRUCTURE A 15 A BASE DE CHROME R. Flükiger, F. Heiniger, A. Junod, Spitzli et J.L. Staudenmann, Institut de Physique de la Matiêre Condensée Universit~de Genêve, CH—1211 Gen~ve4
J. Muller, P.
The low temperature specific heat has been measured in AlS4ype binary alloys of chromium with Ru, Rh, Os, Ir, Pt, Si, Ga and Ge. We found that the electronic density of states is higher in Cr-alloys with a lower degree of atomic order. Received 13 April 1970
3.
FLUORINE SELF DIFFUSION IN LiF AND NaF H.J. Matzke, European Institute for Transuranium Elements 75 Karlsriihe, Postfach 2~66,Germany
The self diffusion of F-18 in single crystals of LiF and NaF has been measured between 580 to 830°C(for LiP’) and 630 to 940°C(for NaF). It is suggested that vacancy pairs contribute to fluorine diffusion at temperatures near to the melting point yielding high values for both the activation enthalpy, ~H, (3.0 ±eV for LiF and i