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Knight shifts and magnetic susceptibilities of the inter-metallic compounds CeCu4 and CeCu5
ii
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOLIDS Vol. 29, No.8
agreed well with the peak energy of the 780 nm absorption band which has been attributed to N~. Received 17 November 1977 Revised 20 December 1978 4.
X-RAY K-ABSORPTION EDGE SHIFTS IN TRANSITION ELEMENTS K.S. Srivastava, R.L. Shrivastava, O.K. Harsh and V. Kumar, Department of Physics, Lucknow University, Lucknow-7 (U.P.), India.
It has been found that a striking correlation exists between the plasmon energy in solids and the chemical shifts of the X-ray K-absorption edges of the transition elements Cr, Cu, Ni, Co, Zn and their compounds. Fairly good agreement between the calculated values of the plasmon energies and the observed values of the chemical shifts has been obtained. Received 1 December 1977 Revised 17 December 1978 5.
KNIGHT SHIFTS AND MAGNETIC SUSCEPTIBILITIES OF THE INTERMETALLIC COMPOUNDS CeCu4 AND CeCu 5 Iuliu Pop, Elena Rus, Mann Coldea and
Olivia Pop, Physics Department, ClujNapoca University, 3400 Cluj-Napoca, Romania. The magnetic susceptibility and Knight shift of the compounds CeCu4 and CeCu5 have been measured over the temperature ranges 80—800 K and 140—400 K, respectively. The most important contributions to the magnetic susceptibility are the Curie—Weiss term, expressing the paramagnetism of the localized f. electrons, and a temperature independent term, which have both been determined. The phenomenological exchange integral ~ between the 4f-electron spins and conduction electron spins was found — 10.43 x 3eV for CeCu 3eV to forbeCeCu l0 4 and 3.9 x l0 5. A reversal in the sign of the s—f coupling for CeCu5 is noted.
uniaxial anisotropy, is calculated in the context of the mean-field approximation. The tricritical temperature decreases as 0 increases, and finally vanishes for 0 larger than a certain critical angle. In the (H11, H1, T) space there is a line of tricritical points which separates two phase smoothly joining surfaces of first and of second order transitions. Received 8 August 1978
7.
DIFFUSIVITY PERMEABILITY AND SOLUBILITY OF HYDROGEN IN PLATINUM
Hiroji Katsuta and Rex B. McLellan, Department of Mechanical Engineering and Materials Science, William Marsh Rice University, Houston, TX 77001, U.S.A. The permeability time-lag method has been used to measure the temperature dependence of the diffusivity of hydrogen in platinum in the temperature range 558 to 936°C.In this temperature range the diffusivity D was found to be represented by the Arrhenius relation, 7exp (—i-) — D = (6.47 ±1.73) x 10 where Q = 26.3 ±2.3 kJ/mol. Measurements of the absolute permeation flux in the steady state condition yield values for the permeability coefficient and the solubiity. The solubility values obtained from the permeability flux determinations show discrepancies when compared to solubiities determined by direct equilibration techniques. This discrepancy is briefly discussed. Received 17 October 1978
8.
MAGNETIC STUDIES ON LOW-SPIN K3Mn(CN)6 D. Gosh and R.K. Mukherjee, Magnetism Department, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700 032, India.
Received 8 August 1978 6.
METAMAGNETIC MODEL IN A FIELD OF ARBITRARY DIRECTION R.F.S. Andrade and S.R. Salinas, Instituto de Fisida da Universidade de S. Paulo, C.P. 20516, cao Paulo SP. Brazil.
The free energy of a metamagnetic model, in a magnetic field making an angle 0 with the direction of
This work reports measurements on single crystals of K3Mn(CN)6, of the magnetic susceptibilities and their anisotropies between 300—60 K. The crystal field model has been extended to include molecular overlap effects for this highly covalent low-spin compound. The magnetic data explain the occurrence of the hot bands around 18,000 cm’ reported earlier. Received 1 August 1978
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOLIDS Vol. 29, No.8
agreed well with the peak energy of the 780 nm absorption band which has been attributed to N~. Received 17 November 1977 Revised 20 December 1978 4.
X-RAY K-ABSORPTION EDGE SHIFTS IN TRANSITION ELEMENTS K.S. Srivastava, R.L. Shrivastava, O.K. Harsh and V. Kumar, Department of Physics, Lucknow University, Lucknow-7 (U.P.), India.
It has been found that a striking correlation exists between the plasmon energy in solids and the chemical shifts of the X-ray K-absorption edges of the transition elements Cr, Cu, Ni, Co, Zn and their compounds. Fairly good agreement between the calculated values of the plasmon energies and the observed values of the chemical shifts has been obtained. Received 1 December 1977 Revised 17 December 1978 5.
KNIGHT SHIFTS AND MAGNETIC SUSCEPTIBILITIES OF THE INTERMETALLIC COMPOUNDS CeCu4 AND CeCu 5 Iuliu Pop, Elena Rus, Mann Coldea and
Olivia Pop, Physics Department, ClujNapoca University, 3400 Cluj-Napoca, Romania. The magnetic susceptibility and Knight shift of the compounds CeCu4 and CeCu5 have been measured over the temperature ranges 80—800 K and 140—400 K, respectively. The most important contributions to the magnetic susceptibility are the Curie—Weiss term, expressing the paramagnetism of the localized f. electrons, and a temperature independent term, which have both been determined. The phenomenological exchange integral ~ between the 4f-electron spins and conduction electron spins was found — 10.43 x 3eV for CeCu 3eV to forbeCeCu l0 4 and 3.9 x l0 5. A reversal in the sign of the s—f coupling for CeCu5 is noted.
uniaxial anisotropy, is calculated in the context of the mean-field approximation. The tricritical temperature decreases as 0 increases, and finally vanishes for 0 larger than a certain critical angle. In the (H11, H1, T) space there is a line of tricritical points which separates two phase smoothly joining surfaces of first and of second order transitions. Received 8 August 1978
7.
DIFFUSIVITY PERMEABILITY AND SOLUBILITY OF HYDROGEN IN PLATINUM
Hiroji Katsuta and Rex B. McLellan, Department of Mechanical Engineering and Materials Science, William Marsh Rice University, Houston, TX 77001, U.S.A. The permeability time-lag method has been used to measure the temperature dependence of the diffusivity of hydrogen in platinum in the temperature range 558 to 936°C.In this temperature range the diffusivity D was found to be represented by the Arrhenius relation, 7exp (—i-) — D = (6.47 ±1.73) x 10 where Q = 26.3 ±2.3 kJ/mol. Measurements of the absolute permeation flux in the steady state condition yield values for the permeability coefficient and the solubiity. The solubility values obtained from the permeability flux determinations show discrepancies when compared to solubiities determined by direct equilibration techniques. This discrepancy is briefly discussed. Received 17 October 1978
8.
MAGNETIC STUDIES ON LOW-SPIN K3Mn(CN)6 D. Gosh and R.K. Mukherjee, Magnetism Department, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700 032, India.
Received 8 August 1978 6.
METAMAGNETIC MODEL IN A FIELD OF ARBITRARY DIRECTION R.F.S. Andrade and S.R. Salinas, Instituto de Fisida da Universidade de S. Paulo, C.P. 20516, cao Paulo SP. Brazil.
The free energy of a metamagnetic model, in a magnetic field making an angle 0 with the direction of
This work reports measurements on single crystals of K3Mn(CN)6, of the magnetic susceptibilities and their anisotropies between 300—60 K. The crystal field model has been extended to include molecular overlap effects for this highly covalent low-spin compound. The magnetic data explain the occurrence of the hot bands around 18,000 cm’ reported earlier. Received 1 August 1978