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Etude par effet Mossbauer de la briartite (Cu2FeGeS4)
Solid State Communications, Vol. 12, pp. vil—ix, 1973.
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to 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.
PRESSURE DEPENDENCE OF c-AXIS ELASTIC PARAMETERS OF ORIENTED GRAPHITE J. F. Green, P. Bolsaith and I. L. Spain, Laboratory for High Pressure Studies, Dept. of Chemical Engineering, University of Mary. land, College Park, Maryland 20742, U.S.A.
3.
The elastic c-axis moduli C33 and C~of cornpression-annealed pyrolytic graphite and their deny, atives with hydrostatic pressure have been measured at room temperature 2) overusing a pressure range from 1 to an ultrasonic pulse-echo 7000 bar (700 technique. TheMNm experiments were also made With material irradiated with fast neutrons. The pressure dependence of the c-axis compressibility of these materials was calculated from the experimental data, enabling pressure derivatives of the c-axis moduli to be also expressed as c-axis strain derivatives,
An injection type electro-luminescence in ZnSe crystal has been studied by using ZnSe—Sn02 heterojunction at 20°K.In the emission peak observed around side 2.70eV, clear- energy shift toward higher energy withaincreasing injection currentthe density has been found at low temperatures, which could be associated with the D--A pair (donor—acceptor pair) recombination process. The energy sum of the donor and acceptor activation is estimated to be larger than 137meV. In the higher temperature region, this emission line turns out due to the ‘free-to-bound’ recombination, and the related acceptor ionization energy is considered to be 120meV. By taking into consideration the energies of bound exciton emission, the exciton localization energies and the related donor and acceptor ionization energies are evaluated.
Received 6 November 1972
2.
OBSERVATION OF A DONOR—ACCEPTOR PAIR RECOMBINATION IN THE EDGE EMISSION OF ZnSe CRYSTAL B’ ELECTROLUMINESCENCE Kenji Ikeda, Ken Uchida and Yoshihiro Hamakawa, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
ABSENCE OF FIRST ORDER ELECTRONIC TRANSITIONS IN LIQUID METALS R. Grover and B. J. Alder, Lawrence Radiation Laboratory, University of California, Livermore, California 94550, U.S.A.
Received l0Febnsaiy 1972 Revised 29 January 1973
High pressure shock wave data on a wide variety of metals indicates that electronic transitions are
4.
continuously distributed in the liquid phase and accompanied by melting maxima. A qualitative explanation for this behavior is suggested.
ETUDE PAR EFFET MOSSBAUER DE LA BRIARTITE (Cu 2 FeGeS4) P. Imbert, F. Varret et M. Wintenberger, Service de Physique du Solide et de Résonance Magnétique, Centre d’Etudes Nucléaires de ~ac1ay,BP. n°2,91 Gif-sur-Yvette, France. —
Received 3 July 1972 Revised 30 January 1973 vii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS Mossbauer experiments on Cu2 FeGeS4 have shown 2~ions is that=the ground orbital level of the Fe 0>, which corresponds to the existence of an easy plane of magnetization perpendicular to the tetragonal axis Oz; in the antiferromagnetic phase the magnetic moments actually lie inside this plane. The tetragonal splitting of the ground orbital doublet F 3 is found to be about 1430 cm’, and the Ned temperature is 12.3 ±0.3K. A self-consistent calculation of molecular field is used to explain the order of magnitude of the hyperfine field observed at low temperature (Hhf = 167 ±2 koe at 4.2 K).
The lattice RbC1, RbBr, RbI, CsCl,parameter CsBr and of CsINaC1, fromKC1, roomKBr, temperature to near melting temperature, and of LiF, NaF and KI from room temperature to near 750°K,are measured using high temperature X-ray diffractometry. An orthogonal polynomial of second order with least square error approximation is fitted to the lattice parameter vs. temperature data to obtain the thermal expansion coefficient. The Gruneisen’s parameter is calculated using the available data, and in five salts it is found to increase gradually with temperature. Received 7 September 1972 Revised 2 February 1973
Received 13 December 1972 5.
ORDERING BEHAVIORS OF Cd—Mg AND Cd—Zn ALLOYS WITH THE H. C. P.-TYPE STRUCTURE K. Katada and M. Kogachi, Department of Physics, University of Osaka Prefecture Sakai, Osaka, Japan, and Y. Matsuo, Department of Physics, Faculty of Science, Nara Women’s University, Nara, Japan.
7.
-
The structure dependent energy and the ordering nergy for an h. c. p.-type binary alloy composed of simple metals are derived from a basis of the method of pseudopotentials. The expressions of the energies are characterized by the long-range and short-range order parameters. is calculated for alloysThe in long-range the Cd—Mgordering system. energy The numerical results reproduce well the fact that the Cd—Mg system has the BI 9-type ordered phase around the stoichiometnic composition of MgCd and the D0 19-type ones around Mg3 Cd and MgCd3. The calculated local ordering energies explain successfully the existence of a short. range order in the Cd—Mg system and also the insolubility between Cd and Zn.
Vol. 12, No. 12
ThERMOELECTRIC POWER OF ANTIFERROMAGNETIC SEMICONDUCTORS NEAR THE NEEL TEMPERATURE Ko Sugihara, Wireless Research Laboratory, Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka, Japan.
Thermoelectric power in antiferromagnetic semiconductors is calculated in the vicinity of the Néel temperature by assuming the presence of the welldefined propagating modes (magnon) and a temperature-dependent magnon velocity. Carriers are specified by the mobile carriers in a broad band with an isotropic effective mass. Magnons and carriers are coupled via the sd-interaction. Anomaly near TN does not result from the diffusion term Sdjff and it isWhich 5drag ascribed to the magnon-drag contribution is obtained from Sdrag
=
~R(q)c~ g
(q)/3e,
where R(q) is the momentum transfer ratio between the magnon system and carriers. cm(q) denotes the specific heat of the magnon q. The assumed temperature dependence of the magnon velocity makes Sdrag divergent at TN with TN T+ +0 and it might be removed in consideration of the magnon frequency spreading. Apart from this divergence the calculation provides a qualitative explanation for the anomalous —
Received 31 July 1972 Revised 5 January 1973
feature in MnTe. 6.
THERMAL EXPANSION OF ALKALI HAUDES ABOVE 300°K. K. K. Srivastava and H. D. Merchant, Department of Metallurgical Engineering, Indian Institute of Technology, Kanpur, India.
Received 6November 1972
8.
GENERALIZED FUNN OPERATORS WITH APPUCATIONS TO MULTI-COMPONENT ALLOYS
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to 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.
PRESSURE DEPENDENCE OF c-AXIS ELASTIC PARAMETERS OF ORIENTED GRAPHITE J. F. Green, P. Bolsaith and I. L. Spain, Laboratory for High Pressure Studies, Dept. of Chemical Engineering, University of Mary. land, College Park, Maryland 20742, U.S.A.
3.
The elastic c-axis moduli C33 and C~of cornpression-annealed pyrolytic graphite and their deny, atives with hydrostatic pressure have been measured at room temperature 2) overusing a pressure range from 1 to an ultrasonic pulse-echo 7000 bar (700 technique. TheMNm experiments were also made With material irradiated with fast neutrons. The pressure dependence of the c-axis compressibility of these materials was calculated from the experimental data, enabling pressure derivatives of the c-axis moduli to be also expressed as c-axis strain derivatives,
An injection type electro-luminescence in ZnSe crystal has been studied by using ZnSe—Sn02 heterojunction at 20°K.In the emission peak observed around side 2.70eV, clear- energy shift toward higher energy withaincreasing injection currentthe density has been found at low temperatures, which could be associated with the D--A pair (donor—acceptor pair) recombination process. The energy sum of the donor and acceptor activation is estimated to be larger than 137meV. In the higher temperature region, this emission line turns out due to the ‘free-to-bound’ recombination, and the related acceptor ionization energy is considered to be 120meV. By taking into consideration the energies of bound exciton emission, the exciton localization energies and the related donor and acceptor ionization energies are evaluated.
Received 6 November 1972
2.
OBSERVATION OF A DONOR—ACCEPTOR PAIR RECOMBINATION IN THE EDGE EMISSION OF ZnSe CRYSTAL B’ ELECTROLUMINESCENCE Kenji Ikeda, Ken Uchida and Yoshihiro Hamakawa, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
ABSENCE OF FIRST ORDER ELECTRONIC TRANSITIONS IN LIQUID METALS R. Grover and B. J. Alder, Lawrence Radiation Laboratory, University of California, Livermore, California 94550, U.S.A.
Received l0Febnsaiy 1972 Revised 29 January 1973
High pressure shock wave data on a wide variety of metals indicates that electronic transitions are
4.
continuously distributed in the liquid phase and accompanied by melting maxima. A qualitative explanation for this behavior is suggested.
ETUDE PAR EFFET MOSSBAUER DE LA BRIARTITE (Cu 2 FeGeS4) P. Imbert, F. Varret et M. Wintenberger, Service de Physique du Solide et de Résonance Magnétique, Centre d’Etudes Nucléaires de ~ac1ay,BP. n°2,91 Gif-sur-Yvette, France. —
Received 3 July 1972 Revised 30 January 1973 vii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS Mossbauer experiments on Cu2 FeGeS4 have shown 2~ions is that=the ground orbital level of the Fe 0>, which corresponds to the existence of an easy plane of magnetization perpendicular to the tetragonal axis Oz; in the antiferromagnetic phase the magnetic moments actually lie inside this plane. The tetragonal splitting of the ground orbital doublet F 3 is found to be about 1430 cm’, and the Ned temperature is 12.3 ±0.3K. A self-consistent calculation of molecular field is used to explain the order of magnitude of the hyperfine field observed at low temperature (Hhf = 167 ±2 koe at 4.2 K).
The lattice RbC1, RbBr, RbI, CsCl,parameter CsBr and of CsINaC1, fromKC1, roomKBr, temperature to near melting temperature, and of LiF, NaF and KI from room temperature to near 750°K,are measured using high temperature X-ray diffractometry. An orthogonal polynomial of second order with least square error approximation is fitted to the lattice parameter vs. temperature data to obtain the thermal expansion coefficient. The Gruneisen’s parameter is calculated using the available data, and in five salts it is found to increase gradually with temperature. Received 7 September 1972 Revised 2 February 1973
Received 13 December 1972 5.
ORDERING BEHAVIORS OF Cd—Mg AND Cd—Zn ALLOYS WITH THE H. C. P.-TYPE STRUCTURE K. Katada and M. Kogachi, Department of Physics, University of Osaka Prefecture Sakai, Osaka, Japan, and Y. Matsuo, Department of Physics, Faculty of Science, Nara Women’s University, Nara, Japan.
7.
-
The structure dependent energy and the ordering nergy for an h. c. p.-type binary alloy composed of simple metals are derived from a basis of the method of pseudopotentials. The expressions of the energies are characterized by the long-range and short-range order parameters. is calculated for alloysThe in long-range the Cd—Mgordering system. energy The numerical results reproduce well the fact that the Cd—Mg system has the BI 9-type ordered phase around the stoichiometnic composition of MgCd and the D0 19-type ones around Mg3 Cd and MgCd3. The calculated local ordering energies explain successfully the existence of a short. range order in the Cd—Mg system and also the insolubility between Cd and Zn.
Vol. 12, No. 12
ThERMOELECTRIC POWER OF ANTIFERROMAGNETIC SEMICONDUCTORS NEAR THE NEEL TEMPERATURE Ko Sugihara, Wireless Research Laboratory, Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka, Japan.
Thermoelectric power in antiferromagnetic semiconductors is calculated in the vicinity of the Néel temperature by assuming the presence of the welldefined propagating modes (magnon) and a temperature-dependent magnon velocity. Carriers are specified by the mobile carriers in a broad band with an isotropic effective mass. Magnons and carriers are coupled via the sd-interaction. Anomaly near TN does not result from the diffusion term Sdjff and it isWhich 5drag ascribed to the magnon-drag contribution is obtained from Sdrag
=
~R(q)c~ g
(q)/3e,
where R(q) is the momentum transfer ratio between the magnon system and carriers. cm(q) denotes the specific heat of the magnon q. The assumed temperature dependence of the magnon velocity makes Sdrag divergent at TN with TN T+ +0 and it might be removed in consideration of the magnon frequency spreading. Apart from this divergence the calculation provides a qualitative explanation for the anomalous —
Received 31 July 1972 Revised 5 January 1973
feature in MnTe. 6.
THERMAL EXPANSION OF ALKALI HAUDES ABOVE 300°K. K. K. Srivastava and H. D. Merchant, Department of Metallurgical Engineering, Indian Institute of Technology, Kanpur, India.
Received 6November 1972
8.
GENERALIZED FUNN OPERATORS WITH APPUCATIONS TO MULTI-COMPONENT ALLOYS