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Title: Magnetic properties of rare-earth metallofullerenes

Abstract

Bulk amounts of La C[sub 82] and Gd C[sub 82] have been isolated in pure form from various hollow fullerenes. Magnetization data for these powder samples, an isolated La C[sub 82] isomer and a Gd C[sub 82] isomer, have been obtained employing a SQUID magnetometer at temperatures ranging from 3 to 300 K. For La C[sub 82] the inverse susceptibility as a function of temperature follows a Curie-Weiss law. The effective magnetic moment per La C[sub 82] is 0.38 [mu][sub B]. For Gd C[sub 32] the magnetization data fall on a universal curve which is fitted to a Brillouin function in correspondence with the Gd[sup 3+] free ion ground state values of J = 3.38 and g = 2. 33 refs., 6 figs.

Authors:
; ; ;  [1]
  1. (Power Reactor and Nuclear Fuel Development Corp., Tokai (Japan))
Publication Date:
OSTI Identifier:
6494257
Alternate Identifier(s):
OSTI ID: 6494257
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry; (United States); Journal Volume: 99:7
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 47 OTHER INSTRUMENTATION; GADOLINIUM COMPLEXES; MAGNETIC SUSCEPTIBILITY; MASS SPECTRA; LANTHANUM COMPLEXES; CURIE-WEISS LAW; FULLERENES; GROUND STATES; ISOMERS; MAGNETIZATION; MAGNETOMETERS; RARE EARTHS; SOOT; TEMPERATURE DEPENDENCE; CARBON; COMPLEXES; ELEMENTS; ENERGY LEVELS; MAGNETIC PROPERTIES; MEASURING INSTRUMENTS; METALS; NONMETALS; PHYSICAL PROPERTIES; RARE EARTH COMPLEXES; SPECTRA 360600* -- Other Materials; 400201 -- Chemical & Physicochemical Properties; 360606 -- Other Materials-- Physical Properties-- (1992-); 440800 -- Miscellaneous Instrumentation-- (1990-)

Citation Formats

Funasaka, Hideyuki, Sugiyama, Kenji, Yamamoto, Kazunori, and Takahashi, Takeshi. Magnetic properties of rare-earth metallofullerenes. United States: N. p., 1995. Web. doi:10.1021/j100007a005.
Funasaka, Hideyuki, Sugiyama, Kenji, Yamamoto, Kazunori, & Takahashi, Takeshi. Magnetic properties of rare-earth metallofullerenes. United States. doi:10.1021/j100007a005.
Funasaka, Hideyuki, Sugiyama, Kenji, Yamamoto, Kazunori, and Takahashi, Takeshi. Thu . "Magnetic properties of rare-earth metallofullerenes". United States. doi:10.1021/j100007a005.
@article{osti_6494257,
title = {Magnetic properties of rare-earth metallofullerenes},
author = {Funasaka, Hideyuki and Sugiyama, Kenji and Yamamoto, Kazunori and Takahashi, Takeshi},
abstractNote = {Bulk amounts of La C[sub 82] and Gd C[sub 82] have been isolated in pure form from various hollow fullerenes. Magnetization data for these powder samples, an isolated La C[sub 82] isomer and a Gd C[sub 82] isomer, have been obtained employing a SQUID magnetometer at temperatures ranging from 3 to 300 K. For La C[sub 82] the inverse susceptibility as a function of temperature follows a Curie-Weiss law. The effective magnetic moment per La C[sub 82] is 0.38 [mu][sub B]. For Gd C[sub 32] the magnetization data fall on a universal curve which is fitted to a Brillouin function in correspondence with the Gd[sup 3+] free ion ground state values of J = 3.38 and g = 2. 33 refs., 6 figs.},
doi = {10.1021/j100007a005},
journal = {Journal of Physical Chemistry; (United States)},
number = ,
volume = 99:7,
place = {United States},
year = {Thu Feb 16 00:00:00 EST 1995},
month = {Thu Feb 16 00:00:00 EST 1995}
}
  • Endohedral lanthanide metallofullerenes and their water-soluble biocompatible derivatives have been synthesized. The effect that fast-neutron irradiation has on the stability and nuclear physical properties of endohedral metallofullerenes that are used as magnetocontrast materials ({sup 46}Sc, {sup 140}La, {sup 141}Nd, {sup 153}Sm, {sup 152}Eu, {sup 154}Eu, {sup 153}Sm, {sup 160}Tb, {sup 169}Yb, {sup 170}Tm (isomers I and III), and {sup 177}Lu) is studied. Our hypothesis, according to which carbon-shell relaxation is based on the fast nonradiative processes of an electron shake-off type, is confirmed.
  • For the series {ital R}Co{sub 5} ({ital R}=rare-earth atom) various parameters occurring in the two-sublattice model of rare-earth{endash}transition-metal intermetallics (local magnetic moments, intersublattice exchange fields, crystal field parameters, as well as magnetic hyperfine fields and electric field gradients) are calculated within the framework of the local-spin-density approximation (LSDA) and the full-potential linear-muffin-tin-orbital theory. Special emphasis is given to a determination of the crystal field parameter {ital A}{sup 0}{sub 2}. It is shown that it is absolutely indispensable to include the 5{ital p} states at the {ital R} site into the valence band and to avoid any spherical approximation for themore » effective potential. The quantity {ital A}{sup 0}{sub 2} depends on the orientation of the aspherical 4{ital f} charge density, in contrast to a basic assumption of the two-sublattice model. As a result, the experiments in general yield some kind of average effective values which are different for different experiments. Application of the LSDA introduces rather large uncertainties for {ital A}{sup 0}{sub 2} which cannot be totally removed but at least drastically reduced by physically motivated measures. {copyright} {ital 1996 The American Physical Society.}« less
  • Single crystals of LiErF/sub 4/ and LiHoF/sub 4/ have been grown and their magnetic properties measured from 1.3 to 300/sup 0/K. LiHoF/sub 4/ turned out to be a nearly ideal Ising ferromagnet with T/subC/ = 1.30 plus-or-minus 0.05 K and a saturation magnetization along the crystalline c axis of (6.98 plus-or-minus 0.02) ..mu../subB/. In LiErF/sub 4/ no ordering was observed, but extrapolation indicates that below 0.5 K it will be ferromagnetic with the magnetic moments in the crytalline ab plane. From the susceptibilities the crystal-field parameters B/subm//subn/ with (n, m) = (2,0), (4.0), (4,4), (6,0), (6,4) have been extracted givingmore » for Er/sup 3 +/ in LiErF/sub 4/: 430., -985., 1185., -5., 740. + i135. (cm/sup -1/) and for Ho/sup 3 +/ in LiHoF/sub 4/: 470.,-825., 1050., -10., 760. + i150. (cm/sup -1/). The exchange constants were found to be small compared to the dipole interactions. Furthermore the /sup 7/Li NMR spectra have been obtained in these materials as well as in LiTbF/sub 4/ thereby determining the second-order crystal-field parameters at the Li site: q = 0.0363, 0.0354, and 0.0343 A/sup -3/ for the Er, Ho, and Tb compound, respectively. The crystal-field parameters are compared to values calculated from point charges, showing agreement at the Li sites but not at the rare earth sites. (AIP)« less
  • A comparative study of the magnetic properties of a few members of the Ln {sub 0.5}Sr{sub 0.5}CoO{sub 3} family with different radii of the A-site cations, <r{sub A} >, in the range 1.19-1.40 A has been carried out. The apparent T {sub c} (where the magnetization undergoes an abrupt increase) decreases markedly with <r{sub A} > as well as the size-disorder arising from the mismatch in the size of the A-site cations. The value of the magnetization at low temperatures decreases markedly with decrease in <r{sub A} > or increase in size-disorder, suggesting that the relative proportion of the ferromagneticmore » (FM) species decreases relative to that of the paramagnetic (PM) species. Such a variation of the FM/PM ratio with composition and temperature is evidenced from the Moessbauer spectra of La{sub 0.5}Sr{sub 0.5}CoO{sub 3} as well. The variation of the FM/PM ratio with <r{sub A} > and size-disorder, as well as a local-probe study using {sup 59}Co Nuclear magnetic resonance spectroscopy suggest that electronic phase separation is an inherent feature of the Ln {sub 0.5}Sr{sub 0.5}CoO{sub 3} type cobaltates, with the nature of the different magnetic species in the phase-separated system varying with <r{sub A} > and size disorder. - Graphical abstract: Variation of (a) T {sub c} and (b) FC magnetization at 1000 Oe with <r{sub A} > at 120 K in Ln {sub 0.5}Sr{sub 0.5}CoO{sub 3} and Dy{sub 0.34}Nd{sub 0.16}Sr{sub 0.40}Ca{sub 0.10}CoO{sub 3}.« less
  • Rare earth elements (R) react with hydrogen at elevated temperatures to form hydrides with compositions approaching RH/sub 3/. Intermetallic compounds involving the rare earths in chemical union with Mn, Fe, Co or Ni absorb copious quantities of hydrogen rapidly and dissociatively at room temperature. In all the hydrides RH/sub 3/ and in many of the hydrogenated intermetallics the proton density exceeds that in condensed elemental hydrogen. The presence of such large amounts of hydrogen significantly modifies various physical properties of the host metal. In the elemental rare earths hydrogenation produces a loss in metallic conduction and greatly weakens exchange. Magneticmore » ordering is suppressed by as much as 250 degrees. In contrast hydrogenation of intermetallics may either strengthen or weaken exchange, the latter predominating numerically in the systems studied to date. Contrasting behavior is exhibited by the isostructural pair of compounds Y/sub 6/Mn/sub 23/ and Th/sub 6/Mn/sub 23/. Th/sub 6/Mn/sub 23/ exhibits Pauli paramagnetism whereas Y/sub 6/Mn/sub 23/ is ferromagnetic. Hydrided Th/sub 6/Mn/sub 23/ and Y/sub 6/Mn/sub 23/ are ferromagnetic and paramagnetic, respectively. The weakening of exchange in RH/sub 3/ is a simple consequence of the depopulation of the conduction band to form anionic hydrogen. Elucidation of the magnetic behavior of the hydrided intermetallics requires detailed band structure information, which is non-existent at present.« less