- Email: [email protected]
Ferrimagnetic structure of Mn2Co2C
ii
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
Fe1~phase has been carried out in the temperature range 700- 1350°C using solid state electrochemical techniques. The results confirm the presence of three wustite regions separated by order disorder transitions. Partial molar enthalpies and entropies of solution of oxygen in. Fe1_~Oare reported. -
(Received 29 April 1968) (Revised 18 September 1968) 5.
MAGNETO-ACOUSTIC INVESTIGATION OF THE FERMI SURFACE AND SPIN SPLITTING OF THE LANDAU LEVELS IN p-TYPE AND n-TYPE PbTe \V. Schllz (Philips Zentrallaboratorium Hamburg, Hamburg 54, Vogt-Kollnstr.30)
Quantum oscillations of the magnetoacoustic attenuation have been measured in p-type and n-type samples of lead telluride. From the periods of these oscillations, measured as a function of the angle ~ between the direction of magnetic field and the [100] axis of the crystal, the shape of the Fermi surface has been investigated as a function of the carrier concentration. A strong non-ellipsoidal behavior was observed for both p-type and n-type material. Furthermore, spin splitting of the Landau levels was measured. The splitting was found to be around ~ the Landaulevel spacing and decreases slightly with decreasing carrier concentration. (Received 14 August 1968) (Revised 17 September 1968) 6.
ON THE THERMODYNAMIC PROPERTIES OF THE SOLID ELECTROLYTE RbAg4I5 H. Wiedersich and W. V. Johnston (Science Center, North Americal Rockwell Corporation, Thousand Oaks, California 91360, U. S. A.)
The non-random distribution of Ag~ions on three crystallographically nonequivalent sets of tetrahedral sites in RbAg4I5 is a consequence of both site energy differences and mutual repulsion of silver ions on nearest neighbor sites. A method similar to the quasicheniical approximation, used in the theory of order-disorder transformations, has been applied to obtain the configurational entropy and excess specific heat associated with the disorder of the silver ions. Site energy differences of —~0.027 and ‘~0.042 eV between the different types of silver sites and a mutual repulsion energy between silver ions on
Vol.6, No.12
nearest neighbor sites of ~0. 035 eV accounts well for the experimentally observed quantities. The configurational entropy is an appreciable fraction (~10%at 300°K) of the total entropy content. (Received 4 September 1968) 7.
OPTICAL CONDUCTWITY IN ALKALI METALS H. B~1ttnerand E. Gerlach (BattelleInstitut e. V., Frankfurt am Main, Germany)
It is shown that the Mayer Naby peak in the optical conductivity of alkali metals arises from transitions from the Fermi sea to the Brillouin zone boundaries. (Received 29 May 1968) (Revised 14 August 1968) 8.
STRUCTURAL AND MAGNETIC PROPERTIES OF NON-STOICHIOMETRIC PRASEO-DYMIUM MONOPHOSPHIDE Enrico Franceschi and Giorglo L. Olcese (Istituto di Chimica fisica, Universita’ di Genova, Genova, Italy)
An investigation on the occurrence of nonstoichiometry in solid praseodymium monophosphide was carried out by evaluating the variation of the lattice constant and density with the cornposition. A range of solid solution by vacancies in the phosphorus sub-lattice was found between the compositions corresponding to PrP and PrPO.B5 phases. Magnetic properties and their dependence on non-stoichiornetry were determined in the temperature range 4.2° 500°K:for the quasi-stoichiometric phases there is no evidence of magnetic ordering and a superconducting transition seems to occur below 7°K, while an antiferromagnetic coupling of praseodymium ions becomes possible when the interionic distances decrease by introduction of vacancies in the phosphorus sub-lattice. -
(Received 5 August 1968) (Revised 13 September 1968) 9.
FERRIMAGNETIC STRUCTURE OF Mn2Co2C N. S. Satya Murthy, R. J. Begum, C. S. Somanathan, B. S. Srinivasan and M. R. L. N. Murthy (Bhabha Atomic ReSearch Centre, Trombay, Bombay 74, India)
Vol. 6, No. 12
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
The carbidewith Mn2Co2C to be ferrimagnetic a Néel temperature has been found of 535°C by means of neutron diffraction. It has a cubic unit cell with an Mn atom at the cube carner and the carbon atom at the body centre. The face centre sites are taken up by the other Mn and the two Co atoms in a statistical manner. The Mn moments are aligned antiparallel to each other while the two Co moments are parallel to the corner Mn moment. The most reasonable
0~Bfor the corner Mnfor values atom, the 3. moments 36 ~B for are: the4.face centre Mn and 1.24 ~B for each Co atom. The smaller moments of the face centre atoms arise from the Influence of the carbon atom. Polarized neutrons were used to choose a structure having cubic syrnmetry over one of tetragonal symmetry. (Received 20 August 1968)
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
Fe1~phase has been carried out in the temperature range 700- 1350°C using solid state electrochemical techniques. The results confirm the presence of three wustite regions separated by order disorder transitions. Partial molar enthalpies and entropies of solution of oxygen in. Fe1_~Oare reported. -
(Received 29 April 1968) (Revised 18 September 1968) 5.
MAGNETO-ACOUSTIC INVESTIGATION OF THE FERMI SURFACE AND SPIN SPLITTING OF THE LANDAU LEVELS IN p-TYPE AND n-TYPE PbTe \V. Schllz (Philips Zentrallaboratorium Hamburg, Hamburg 54, Vogt-Kollnstr.30)
Quantum oscillations of the magnetoacoustic attenuation have been measured in p-type and n-type samples of lead telluride. From the periods of these oscillations, measured as a function of the angle ~ between the direction of magnetic field and the [100] axis of the crystal, the shape of the Fermi surface has been investigated as a function of the carrier concentration. A strong non-ellipsoidal behavior was observed for both p-type and n-type material. Furthermore, spin splitting of the Landau levels was measured. The splitting was found to be around ~ the Landaulevel spacing and decreases slightly with decreasing carrier concentration. (Received 14 August 1968) (Revised 17 September 1968) 6.
ON THE THERMODYNAMIC PROPERTIES OF THE SOLID ELECTROLYTE RbAg4I5 H. Wiedersich and W. V. Johnston (Science Center, North Americal Rockwell Corporation, Thousand Oaks, California 91360, U. S. A.)
The non-random distribution of Ag~ions on three crystallographically nonequivalent sets of tetrahedral sites in RbAg4I5 is a consequence of both site energy differences and mutual repulsion of silver ions on nearest neighbor sites. A method similar to the quasicheniical approximation, used in the theory of order-disorder transformations, has been applied to obtain the configurational entropy and excess specific heat associated with the disorder of the silver ions. Site energy differences of —~0.027 and ‘~0.042 eV between the different types of silver sites and a mutual repulsion energy between silver ions on
Vol.6, No.12
nearest neighbor sites of ~0. 035 eV accounts well for the experimentally observed quantities. The configurational entropy is an appreciable fraction (~10%at 300°K) of the total entropy content. (Received 4 September 1968) 7.
OPTICAL CONDUCTWITY IN ALKALI METALS H. B~1ttnerand E. Gerlach (BattelleInstitut e. V., Frankfurt am Main, Germany)
It is shown that the Mayer Naby peak in the optical conductivity of alkali metals arises from transitions from the Fermi sea to the Brillouin zone boundaries. (Received 29 May 1968) (Revised 14 August 1968) 8.
STRUCTURAL AND MAGNETIC PROPERTIES OF NON-STOICHIOMETRIC PRASEO-DYMIUM MONOPHOSPHIDE Enrico Franceschi and Giorglo L. Olcese (Istituto di Chimica fisica, Universita’ di Genova, Genova, Italy)
An investigation on the occurrence of nonstoichiometry in solid praseodymium monophosphide was carried out by evaluating the variation of the lattice constant and density with the cornposition. A range of solid solution by vacancies in the phosphorus sub-lattice was found between the compositions corresponding to PrP and PrPO.B5 phases. Magnetic properties and their dependence on non-stoichiornetry were determined in the temperature range 4.2° 500°K:for the quasi-stoichiometric phases there is no evidence of magnetic ordering and a superconducting transition seems to occur below 7°K, while an antiferromagnetic coupling of praseodymium ions becomes possible when the interionic distances decrease by introduction of vacancies in the phosphorus sub-lattice. -
(Received 5 August 1968) (Revised 13 September 1968) 9.
FERRIMAGNETIC STRUCTURE OF Mn2Co2C N. S. Satya Murthy, R. J. Begum, C. S. Somanathan, B. S. Srinivasan and M. R. L. N. Murthy (Bhabha Atomic ReSearch Centre, Trombay, Bombay 74, India)
Vol. 6, No. 12
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
The carbidewith Mn2Co2C to be ferrimagnetic a Néel temperature has been found of 535°C by means of neutron diffraction. It has a cubic unit cell with an Mn atom at the cube carner and the carbon atom at the body centre. The face centre sites are taken up by the other Mn and the two Co atoms in a statistical manner. The Mn moments are aligned antiparallel to each other while the two Co moments are parallel to the corner Mn moment. The most reasonable
0~Bfor the corner Mnfor values atom, the 3. moments 36 ~B for are: the4.face centre Mn and 1.24 ~B for each Co atom. The smaller moments of the face centre atoms arise from the Influence of the carbon atom. Polarized neutrons were used to choose a structure having cubic syrnmetry over one of tetragonal symmetry. (Received 20 August 1968)