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Magnetic characteristics of the intermetallic system Gd2Ni17−x Alx
Solid State Communications, Printed in Great Britain.
Vol. 41, No. 9, pp. i-vii,
1982.
0038-1098/82/09000-07$02,00/O Pergamon Press Ltd.
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids J Phys. Chem. Solids (to be published)’ in references the publication
1.
to material
quoted
of the relevant
MdSSBAUER EFFECT IN IRON PICOLINATE-DIMER AND MONOMER C.C. German0 and F.F.T. de Aratijo, Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 1262, 60.000 - Fortaleza, Ceara, Brazil.
A study of the quadrupole doublets of the dimer lFe(pic),(OH) Ia and of the monomer lFe(pic)z(OHz)C1 1,which are asymmetric when observed at room temperature, has been made. For the dimer it has been proposed that this asymmetry was due mainly to effects of spin-spin relaxation between the two bridged iron atoms, antiferromagnetically coupled. Observation of the spectrum at a temperature of 4.2 K in the presence of an external magnetic field up to 18 KG, leads to identification of the sign of the electric field gradient and the relative direction of the fluctuating magnetic field. The observed small area asymmetry has been attributed to the Karyagin-Goldanskii effect. For the monomer, the area asymmetry was attributed to the Karyagin-Goldanskii effect, and the asymmetry of the linewidths was explained in terms of a relaxation mechanism between the Kramers doublets. Received 20 April 198 1
2.
X-RAY LI, L2 AND L3 ABSORPTION OF 4D TRANSITION METALS
LIMITS
K. Maeda, Department of Physics, K&ran University, Higashinada-ku, Kobe 658, Japan. The wavelengths and energies of the L1, Lz and Ls absorption limits in Zr, Nb, Ru, Rh, Pd and Ag metals have been measured and some of the previous reported values have been found to be incorrect. By comparing the energies of the absorption limits with those of the Ly, and L/3,, 15 lines and also with the binding energies obtained by XPS, the electronic transitions corresponding to the respective absorption limits have been clarified. It is concluded that (i) the end level of the electronic transition corresponding to the L1 absorption limit of Zr-Ag is the Sp-like level, and (ii) the end level
should
from this section
be cited prior to
article.
corresponding to either of the Lz and L3 absorption limits of Zr-Pd is the 4d level, while that of Ag is, rather unexpectedly, the top of the 5s level. Received 5 May 198 1 3.
MAGNETIC CHARACTERISTICS OF THE INTERMETALLIC SYSTEM GdzNi,,_,Al, Iuliu Pop, Natalia Dihoiu and Marin Coldea, Physics Department, Cluj-Napoca University, 3400 Cluj-Napoca, Roumania.
The magnetic behaviour of the intermetallic compounds GdsNi,,_,Al, (0 < x < 2) has been investigated both in the ferrimagnetic and paramagnetic regions. The unusual temperature dependence of the intensity of magnetization may be interpreted as a second order phase transition of order-order type, i.e. from a colinear to non-colinear ferrimagnetic structure. Received 7 April 198 1 4.
THE INFRARED SPECTRUM OF OH-COMPENSATED DEFECT SITES IN C-DOPED MgO AND CaO SINGLE CRYSTALS F. Freund and H. Wengeler Mineralogisches Institut der Universitit Koh, Ziilpicher Str. 49, D-5000 Koln 1, Fed. Rep. Germany.
The i.r. spectra of OH-compensated point defects in MgO (and CaO) single crystals of various purity grades were reinvestigated. Three distinct groups of i.r. bands appear in the O-H stretching region: A, B and C around 3550 cm-’ (3650 cm-‘), 3300 cm-’ (3450 cm-‘) and 3700 cm-’ (3750 cm-‘). They are assigned as follows: band A to the fully compensated, band B to the half compensated and band C to the overcompensated cation vacancies, [OH’ V,‘H,HO’lX, [OH’ I’,“,,], and [OH’OH’ V&tHO’] ’ , respectively. Upon cooling to 80K the band A shows a complex behavior partly due to the formation of Hz molecules by charge transfer and concomittant O- formation: [O’(H,)~,,O’]X. The O- represent defect electrons or positive holes in the 02- matrix.
Vol. 41, No. 9, pp. i-vii,
1982.
0038-1098/82/09000-07$02,00/O Pergamon Press Ltd.
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids J Phys. Chem. Solids (to be published)’ in references the publication
1.
to material
quoted
of the relevant
MdSSBAUER EFFECT IN IRON PICOLINATE-DIMER AND MONOMER C.C. German0 and F.F.T. de Aratijo, Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 1262, 60.000 - Fortaleza, Ceara, Brazil.
A study of the quadrupole doublets of the dimer lFe(pic),(OH) Ia and of the monomer lFe(pic)z(OHz)C1 1,which are asymmetric when observed at room temperature, has been made. For the dimer it has been proposed that this asymmetry was due mainly to effects of spin-spin relaxation between the two bridged iron atoms, antiferromagnetically coupled. Observation of the spectrum at a temperature of 4.2 K in the presence of an external magnetic field up to 18 KG, leads to identification of the sign of the electric field gradient and the relative direction of the fluctuating magnetic field. The observed small area asymmetry has been attributed to the Karyagin-Goldanskii effect. For the monomer, the area asymmetry was attributed to the Karyagin-Goldanskii effect, and the asymmetry of the linewidths was explained in terms of a relaxation mechanism between the Kramers doublets. Received 20 April 198 1
2.
X-RAY LI, L2 AND L3 ABSORPTION OF 4D TRANSITION METALS
LIMITS
K. Maeda, Department of Physics, K&ran University, Higashinada-ku, Kobe 658, Japan. The wavelengths and energies of the L1, Lz and Ls absorption limits in Zr, Nb, Ru, Rh, Pd and Ag metals have been measured and some of the previous reported values have been found to be incorrect. By comparing the energies of the absorption limits with those of the Ly, and L/3,, 15 lines and also with the binding energies obtained by XPS, the electronic transitions corresponding to the respective absorption limits have been clarified. It is concluded that (i) the end level of the electronic transition corresponding to the L1 absorption limit of Zr-Ag is the Sp-like level, and (ii) the end level
should
from this section
be cited prior to
article.
corresponding to either of the Lz and L3 absorption limits of Zr-Pd is the 4d level, while that of Ag is, rather unexpectedly, the top of the 5s level. Received 5 May 198 1 3.
MAGNETIC CHARACTERISTICS OF THE INTERMETALLIC SYSTEM GdzNi,,_,Al, Iuliu Pop, Natalia Dihoiu and Marin Coldea, Physics Department, Cluj-Napoca University, 3400 Cluj-Napoca, Roumania.
The magnetic behaviour of the intermetallic compounds GdsNi,,_,Al, (0 < x < 2) has been investigated both in the ferrimagnetic and paramagnetic regions. The unusual temperature dependence of the intensity of magnetization may be interpreted as a second order phase transition of order-order type, i.e. from a colinear to non-colinear ferrimagnetic structure. Received 7 April 198 1 4.
THE INFRARED SPECTRUM OF OH-COMPENSATED DEFECT SITES IN C-DOPED MgO AND CaO SINGLE CRYSTALS F. Freund and H. Wengeler Mineralogisches Institut der Universitit Koh, Ziilpicher Str. 49, D-5000 Koln 1, Fed. Rep. Germany.
The i.r. spectra of OH-compensated point defects in MgO (and CaO) single crystals of various purity grades were reinvestigated. Three distinct groups of i.r. bands appear in the O-H stretching region: A, B and C around 3550 cm-’ (3650 cm-‘), 3300 cm-’ (3450 cm-‘) and 3700 cm-’ (3750 cm-‘). They are assigned as follows: band A to the fully compensated, band B to the half compensated and band C to the overcompensated cation vacancies, [OH’ V,‘H,HO’lX, [OH’ I’,“,,], and [OH’OH’ V&tHO’] ’ , respectively. Upon cooling to 80K the band A shows a complex behavior partly due to the formation of Hz molecules by charge transfer and concomittant O- formation: [O’(H,)~,,O’]X. The O- represent defect electrons or positive holes in the 02- matrix.