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Low temperature heat capacities and thermal properties of DyAl2, ErAl2 and LuAl2
vi
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
similar to a baseball seam in real space. One of these series is attributed to the orbit ~ around the junction of four electron arms. Received 26 May 1976 Revised 20 August 1976 5.
CYCLOTRON RESONANCE IN LEAD ii, ANISOTROPY, LINE SHAPE, RELAXATION TIME AND IDENTIFICATION OF THE ORBITS —
Vol. 20, No.9~
ties, it was necessary to evaluate the lattice heat capacity. The lattice term, CL was obtained from the Cp data of LuA12 by a method of interpolation which gave values of CL for an arbitrary RA12 compound. Using this “interpolated lattice blank”, excess entropies associated with the crystal field and magnetic terms were computed throughout the series. These values are quite close to R In (2J + 1). The results also indicate that, for the compounds studied, the degeneracy of the lowest ground state is completely lifted. In addition, the magnetic con-
Yoshichika Onuki, Hiroyoshi Suematsu and Sei-ichi Tanuma, The Institute for Solid State Physics, The University of Tokyo, Roppongi, Minato-ku, Tokyo 106, Japan. Through experimentation and analysis of the cyclotron resonance, the [110] arm in the electron Fermi
tribution to the heat capacity of the magnetically ordered RA12 phases was found to exhibit an exponen-
The heat capacities of the compounds DyAI2, ErA12 and LuA12 were measured in an adiabatic calorimeter from approximately 5 to 300 K. The compounds DyA12 and ErAI2 show C~anomalies at 58.0 K and 10.2 K, respectively, which are attributed to the destruction of magnetic order. In order to separate the crystal field and magnetic contributions from the measured heat capaci-
and F. Senftle and C. Alexander, U.S. U.S.A. Geological Survey, Reston, VA 22092,
tial dependence below the temperature corresponding 3”2 dependence aboveto this temperature. the spin wave energy gap and a T Detailed calculations were performed to characterize the influence of cubic crystal field in ErAl on the ~I15/2 3~ion. It is2 concluded surface of lead has been found to be a corrugated cylinground state multiplet of the Er der having different shapes of longitudinal cross section that the magnetic ordering in ErA1 2 takes place within cut by various planes including the axis of the arm. The the r~ quartet state. Smoothed values of heat capacity, resonance amplitude of the orbit ~ on the [1101 arm is entropy and related thermodynamic functions are tabualso dependent on the crystallographic differences of the lated. surfaces, even for the same orientation of the magnetic Received 25 June 1976 field. The best fitting of the theoretical overall line shape to the observed one of the orbit ~has been obtained by 7. CHEMICAL BONDING AND X-RAY considering the decrease of relaxation time for higher EMISSION SPECTRA ANALYSIS FOR indices of harmonic resonance. The second and third NIOBIUM CARBIDE, NITRIDE, AND OXIDE harmonics are well understood in terms of the theory of surface impedance by Chambers and by Tsuji et al. The Michèle Gupta, V.A. Gubanov and D.E. Ellis, rapid broadening of the line shapes of much higher Department of Physics, Northwestern harmonics is attributed to the relation between the University, Evanston, IL 60201, U.S.A. cyclotron orbit radius and the range of dislocation strain A molecular orbital description of (NbX6)~clusters field. Identification of the orbit w has also been made. with X = C, N, and 0 has been obtained in the Hartree— Received 26 May 1976 Fock—Slater model. Effects of spin polarization and Revised 20 August 1976 self-consistent iterations on energy levels and charge distribution are explored; comparison is made to band 6. LOW TEMPERATURE HEAT CAPACITIES structure results. The calculated X-ray emission spectra AND THERMAL PROPERTIES OF DyA12, are in reasonably good agreement with experiment. ErA12 AND LuAI2 Received 8 July 1976 T. Inoue, S.G. Sankar, R.S. Craig and W.E. Wallace, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, 8. ANISOTROPIC MAGNETIC SUSCEPTIU.S.A.; and K.A. Gschneidner, Jr., Ames BILITY OF ERBIUM AND YTTERBIUM IN Laboratory, USERDA and Department of ZIRCON, ZrSiO4 Materials Science and Engineering, Ames, IA A.N. Thorpe, C. Briggs and T. Tsang, Howard 50011, U.S.A. University, Washington, D.C. 20059, U.S.A.;
Magnetic susceptibility measurements have been made for both Er- and Yb-doped (- 10~ppm) zircon single crystals with the magnetic field perpendicular and parallel to the [001] axis. Large susceptibility anisotropies were found in both cases. Our observed ansio-
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
similar to a baseball seam in real space. One of these series is attributed to the orbit ~ around the junction of four electron arms. Received 26 May 1976 Revised 20 August 1976 5.
CYCLOTRON RESONANCE IN LEAD ii, ANISOTROPY, LINE SHAPE, RELAXATION TIME AND IDENTIFICATION OF THE ORBITS —
Vol. 20, No.9~
ties, it was necessary to evaluate the lattice heat capacity. The lattice term, CL was obtained from the Cp data of LuA12 by a method of interpolation which gave values of CL for an arbitrary RA12 compound. Using this “interpolated lattice blank”, excess entropies associated with the crystal field and magnetic terms were computed throughout the series. These values are quite close to R In (2J + 1). The results also indicate that, for the compounds studied, the degeneracy of the lowest ground state is completely lifted. In addition, the magnetic con-
Yoshichika Onuki, Hiroyoshi Suematsu and Sei-ichi Tanuma, The Institute for Solid State Physics, The University of Tokyo, Roppongi, Minato-ku, Tokyo 106, Japan. Through experimentation and analysis of the cyclotron resonance, the [110] arm in the electron Fermi
tribution to the heat capacity of the magnetically ordered RA12 phases was found to exhibit an exponen-
The heat capacities of the compounds DyAI2, ErA12 and LuA12 were measured in an adiabatic calorimeter from approximately 5 to 300 K. The compounds DyA12 and ErAI2 show C~anomalies at 58.0 K and 10.2 K, respectively, which are attributed to the destruction of magnetic order. In order to separate the crystal field and magnetic contributions from the measured heat capaci-
and F. Senftle and C. Alexander, U.S. U.S.A. Geological Survey, Reston, VA 22092,
tial dependence below the temperature corresponding 3”2 dependence aboveto this temperature. the spin wave energy gap and a T Detailed calculations were performed to characterize the influence of cubic crystal field in ErAl on the ~I15/2 3~ion. It is2 concluded surface of lead has been found to be a corrugated cylinground state multiplet of the Er der having different shapes of longitudinal cross section that the magnetic ordering in ErA1 2 takes place within cut by various planes including the axis of the arm. The the r~ quartet state. Smoothed values of heat capacity, resonance amplitude of the orbit ~ on the [1101 arm is entropy and related thermodynamic functions are tabualso dependent on the crystallographic differences of the lated. surfaces, even for the same orientation of the magnetic Received 25 June 1976 field. The best fitting of the theoretical overall line shape to the observed one of the orbit ~has been obtained by 7. CHEMICAL BONDING AND X-RAY considering the decrease of relaxation time for higher EMISSION SPECTRA ANALYSIS FOR indices of harmonic resonance. The second and third NIOBIUM CARBIDE, NITRIDE, AND OXIDE harmonics are well understood in terms of the theory of surface impedance by Chambers and by Tsuji et al. The Michèle Gupta, V.A. Gubanov and D.E. Ellis, rapid broadening of the line shapes of much higher Department of Physics, Northwestern harmonics is attributed to the relation between the University, Evanston, IL 60201, U.S.A. cyclotron orbit radius and the range of dislocation strain A molecular orbital description of (NbX6)~clusters field. Identification of the orbit w has also been made. with X = C, N, and 0 has been obtained in the Hartree— Received 26 May 1976 Fock—Slater model. Effects of spin polarization and Revised 20 August 1976 self-consistent iterations on energy levels and charge distribution are explored; comparison is made to band 6. LOW TEMPERATURE HEAT CAPACITIES structure results. The calculated X-ray emission spectra AND THERMAL PROPERTIES OF DyA12, are in reasonably good agreement with experiment. ErA12 AND LuAI2 Received 8 July 1976 T. Inoue, S.G. Sankar, R.S. Craig and W.E. Wallace, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, 8. ANISOTROPIC MAGNETIC SUSCEPTIU.S.A.; and K.A. Gschneidner, Jr., Ames BILITY OF ERBIUM AND YTTERBIUM IN Laboratory, USERDA and Department of ZIRCON, ZrSiO4 Materials Science and Engineering, Ames, IA A.N. Thorpe, C. Briggs and T. Tsang, Howard 50011, U.S.A. University, Washington, D.C. 20059, U.S.A.;
Magnetic susceptibility measurements have been made for both Er- and Yb-doped (- 10~ppm) zircon single crystals with the magnetic field perpendicular and parallel to the [001] axis. Large susceptibility anisotropies were found in both cases. Our observed ansio-