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The electromagnetic field in finite crystals
ii
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOLIDS
cannot be explained with the help of phonon excitation; however this peak can be attributed to the defect frequency originating from the replacement of gaffium atom by sulphur in the U17 mode of vibration. The frequency of this defect-induced vibrational mode is calculated by taking a modified molecular model approach, and is found to be 166.9 cm’, which is in reasonably
Vol. 28, No.4
(0.1 psec). The temperature dependence of the static quadrupole frequency is given by the relation vQ(T) = 130 [1 —(1.9 x I (T5)T1~5] MHz. Received 2May 1978 Revised 5 August 1978 8.
AN INVESTIGATION OF FeCoCrO 4 BY
good agreement with the experimentally observed value of 175 cm’.
MOSSBAUER SPECTROSCOPY M.P. Gupta and A.P.B. Sinha, National Chemical Laboratory, Poona-8, India; and S.K. Date, Tata Institute of Fundamental Research, Bombay-S, India.
Received 30 May 1978 5.
THE ELECTROSTATIC POTENTIAL IN A CRYSTALLINE SLAB
A. Redlack and J. Grindlay, Physics Department, University of Waterloo, Waterloo, Ontario, Canada. The electrostatic potential in a crystalline slab of point charges is expressed as a sum of three types of terms, an intrinsic term, microscopic fringing terms and a macroscopic term. Received7May 1978 6.
THE ELECTROMAGNETIC FIELD IN FINITE CRYSTALS A Redlack and J. Grindley, Physics Department, University of Waterloo, Waterloo, Ontario, Canada.
The spinel FeCoCrO4 has been studied between 4.2 and 538 K. Characteristic Mossbauer spectra of paramagnetic, magnetic and electronic relaxation types have 3~ions been observed. The Mossbauer parameters for Fe situated at tetrahedral (A) and octahedral (B) sites have been calculated. The cation distribution in magnetic and paramegnetic phases is found to be approximately Fe~ 3~]O 5Co~5 [Co~5Fe~5Cr 4.The Néel temperature has been determined by the temperature scanning method to be3lO±5K.
9.
-
2H20 M. Lynch, G. Kokoszka and P. Szydlik, State University of New York, Plattsburgh, NY 12901, U.S.A.
The electromagnetic potentials of a finite crystalline slab of oscillating point charges are separated into parts with distinct properties. One part is the Ewald potential. Received I May 1978 Revised 28 July 1978 7.
ELECTRIC—QUADRUPOLE INTERACTION 181Ta IN f.c.t. ZrH AT 197 R.L. Rasera, Argonne National Laboratory, Argonne, IL 60439, U.S.A. and Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21228, U.S.A.; and G.K. Shenoy, B.D. Dunlap, and D.G. Westlake, Argonne National Laboratory, Argonne, IL 60439, U.S.A.
Time-differential perturbed gamma-ray angular 181Ta correlation have been carried outthe ontemperimpurities inexperiments c-phase zirconium hydride over ature range from 20 to 588 K. A static, slightly asyinmetric electric quadrupole interaction is found at all temperatures. The static nature of the pattern indicates the absence of significant hydrogen diffusion at these temperatures on the time scale of the experiment
Received 3 January 1978 Revised 28 July 1978 EPR OF A MIXED METAL TWODIMENSIONAL SYSTEM: Mn1 ~Co,(HCOO)2
An X.band EPR study of Mn1 ~Co~(HCOO)2 2H2O has been carried out for 0.0 ~fc~ 0.99. Although some temperature dependent effects were noted, the dominant result was a strong inverted U-shaped dependence in the Mn(II) resonant linewidth with increasing Co(II) concentration. The data suggest the presence of both isotropic and anisotropic exchange interactions between the dissimilar metal ions. A phenomenological theoretical model is proposed which requires only one adjustable parameter to fit the Iinewidth vs concentration data. Received 30 November 1977 .
10.
Revised 5 August 1978 THE EFFECT OF DIFFERENT DIELECTRIC FUNCTIONS ON A MODEL PSEUDO. POTENTIAL CALCULATION OF PHONON DISPERSION RELATIONS OF HCP METALS S.P. Singh and S.S. Kushwaha, Department of Physics, Banaras Hindu University, Varanasi221005, India.
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOLIDS
cannot be explained with the help of phonon excitation; however this peak can be attributed to the defect frequency originating from the replacement of gaffium atom by sulphur in the U17 mode of vibration. The frequency of this defect-induced vibrational mode is calculated by taking a modified molecular model approach, and is found to be 166.9 cm’, which is in reasonably
Vol. 28, No.4
(0.1 psec). The temperature dependence of the static quadrupole frequency is given by the relation vQ(T) = 130 [1 —(1.9 x I (T5)T1~5] MHz. Received 2May 1978 Revised 5 August 1978 8.
AN INVESTIGATION OF FeCoCrO 4 BY
good agreement with the experimentally observed value of 175 cm’.
MOSSBAUER SPECTROSCOPY M.P. Gupta and A.P.B. Sinha, National Chemical Laboratory, Poona-8, India; and S.K. Date, Tata Institute of Fundamental Research, Bombay-S, India.
Received 30 May 1978 5.
THE ELECTROSTATIC POTENTIAL IN A CRYSTALLINE SLAB
A. Redlack and J. Grindlay, Physics Department, University of Waterloo, Waterloo, Ontario, Canada. The electrostatic potential in a crystalline slab of point charges is expressed as a sum of three types of terms, an intrinsic term, microscopic fringing terms and a macroscopic term. Received7May 1978 6.
THE ELECTROMAGNETIC FIELD IN FINITE CRYSTALS A Redlack and J. Grindley, Physics Department, University of Waterloo, Waterloo, Ontario, Canada.
The spinel FeCoCrO4 has been studied between 4.2 and 538 K. Characteristic Mossbauer spectra of paramagnetic, magnetic and electronic relaxation types have 3~ions been observed. The Mossbauer parameters for Fe situated at tetrahedral (A) and octahedral (B) sites have been calculated. The cation distribution in magnetic and paramegnetic phases is found to be approximately Fe~ 3~]O 5Co~5 [Co~5Fe~5Cr 4.The Néel temperature has been determined by the temperature scanning method to be3lO±5K.
9.
-
2H20 M. Lynch, G. Kokoszka and P. Szydlik, State University of New York, Plattsburgh, NY 12901, U.S.A.
The electromagnetic potentials of a finite crystalline slab of oscillating point charges are separated into parts with distinct properties. One part is the Ewald potential. Received I May 1978 Revised 28 July 1978 7.
ELECTRIC—QUADRUPOLE INTERACTION 181Ta IN f.c.t. ZrH AT 197 R.L. Rasera, Argonne National Laboratory, Argonne, IL 60439, U.S.A. and Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21228, U.S.A.; and G.K. Shenoy, B.D. Dunlap, and D.G. Westlake, Argonne National Laboratory, Argonne, IL 60439, U.S.A.
Time-differential perturbed gamma-ray angular 181Ta correlation have been carried outthe ontemperimpurities inexperiments c-phase zirconium hydride over ature range from 20 to 588 K. A static, slightly asyinmetric electric quadrupole interaction is found at all temperatures. The static nature of the pattern indicates the absence of significant hydrogen diffusion at these temperatures on the time scale of the experiment
Received 3 January 1978 Revised 28 July 1978 EPR OF A MIXED METAL TWODIMENSIONAL SYSTEM: Mn1 ~Co,(HCOO)2
An X.band EPR study of Mn1 ~Co~(HCOO)2 2H2O has been carried out for 0.0 ~fc~ 0.99. Although some temperature dependent effects were noted, the dominant result was a strong inverted U-shaped dependence in the Mn(II) resonant linewidth with increasing Co(II) concentration. The data suggest the presence of both isotropic and anisotropic exchange interactions between the dissimilar metal ions. A phenomenological theoretical model is proposed which requires only one adjustable parameter to fit the Iinewidth vs concentration data. Received 30 November 1977 .
10.
Revised 5 August 1978 THE EFFECT OF DIFFERENT DIELECTRIC FUNCTIONS ON A MODEL PSEUDO. POTENTIAL CALCULATION OF PHONON DISPERSION RELATIONS OF HCP METALS S.P. Singh and S.S. Kushwaha, Department of Physics, Banaras Hindu University, Varanasi221005, India.