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Electrical conductivity and optical absorption changes related to the 3800 Å band of CaO:Ca
Solid State Communications,
Vol. 7, pp. i—vu, 1969.
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids ‘J. Phys. Chem. Solids (to be published)’ should be cited in references to material quoted from this section prior to the publication of the relevant article. 1.
ELECTRICAL CONDUCTIVITY AND OPTICAL ABSORPTION CHANGES RELATED CaO: Ca TO THE 3800 BAND OF D.F. Winterstein and E.F. Sieckmann
A
(Physics Department, Idaho, Moscow, Idaho) University of Simultaneous measurements of electrical current and optical absorption in CaO Ca crystals as a function of temperature after light irradiation at liquid nitrogen temperature (INT) have supported the view that an apparent upward shift of about 0.13 eV in the F’-band heating the crystal is actually causedenergy by the upon formation of a new color center of unknown structure, labeled F~.The apparent shift in the F’ band occurred simultaneously with a change in the current-vs.-temperature slope. The F~band was stable in the dark at room temperature and below, but bleached easily when the crystal was irradiated in the absorption band and when it was heated to 170°C. -~
(Received 5 August 1968) (Revised 13 January 1969)
2.
PREPARATION MAGNETIC AND OPTICAL PROPERTIES OF FERRI MAGNETS IN THE RbMgF3—RbCoF3 SYSTEM M.W. Shafer and T.R. McGuire (IBM Watson Research Center, Yorktown Heights, New York)
Previously reported ABF3-type ferrimagnets with hexagonal BaT1O3 structure contain 2 + the as the predominant magnetic ion.allThis Ni paper reports the discovery of new ferrimagnetic compositions in the RbMgF 3 —RbCoF~system 2~is the only magnetic ion. Phase where Co studies on this system show that at high temperatures the hexagonal phase is stable to about 70 per cent RbCOFa. Single crystals were grown over this compositional range and their magnetic and optical properties studied. Compositions containing in excess of about 35 per cent RbCoF 3 are ferrimagnetic and their magnetic moments (as high as 24 em~/g) 2~concentration. and Curie temperatures (up to The magnet36°Kvary ization datawith areCo consistent with a model of a 3 ~ ferrimagnetic spin arrangement. The B—B interaction, which is the resultant of the 900 C~?~ —F—Co2~ and the direct Co2~—Co2~interactions appears to be positive. Anistropy measurements at 4.2°Kyielded values from 2.2 x 10~ to 8.9 ~ 3 for K. Optical absorption ergs/cm data were10~e used to determine the magnitude of the crystal field parameter Dq (87O—880cm’) and the spin orbit interaction constant A (190cm’). From the Dq values it is concluded that the strength of the crystalline field acting on the Co2~ion in the hexagonal structure, where ~ of the CoF 6 octahedra share ~ces, is not too different from that in ‘cubic’ KCoF3 and RbCoF~where they share corners. (Received 27 January 1969) (Revised 25 February 1969)
Vol. 7, pp. i—vu, 1969.
Pergamon Press.
Printed in Great Britain
Abstracts of Articles to be Published in The Journal of Physics and Chemistry of Solids ‘J. Phys. Chem. Solids (to be published)’ should be cited in references to material quoted from this section prior to the publication of the relevant article. 1.
ELECTRICAL CONDUCTIVITY AND OPTICAL ABSORPTION CHANGES RELATED CaO: Ca TO THE 3800 BAND OF D.F. Winterstein and E.F. Sieckmann
A
(Physics Department, Idaho, Moscow, Idaho) University of Simultaneous measurements of electrical current and optical absorption in CaO Ca crystals as a function of temperature after light irradiation at liquid nitrogen temperature (INT) have supported the view that an apparent upward shift of about 0.13 eV in the F’-band heating the crystal is actually causedenergy by the upon formation of a new color center of unknown structure, labeled F~.The apparent shift in the F’ band occurred simultaneously with a change in the current-vs.-temperature slope. The F~band was stable in the dark at room temperature and below, but bleached easily when the crystal was irradiated in the absorption band and when it was heated to 170°C. -~
(Received 5 August 1968) (Revised 13 January 1969)
2.
PREPARATION MAGNETIC AND OPTICAL PROPERTIES OF FERRI MAGNETS IN THE RbMgF3—RbCoF3 SYSTEM M.W. Shafer and T.R. McGuire (IBM Watson Research Center, Yorktown Heights, New York)
Previously reported ABF3-type ferrimagnets with hexagonal BaT1O3 structure contain 2 + the as the predominant magnetic ion.allThis Ni paper reports the discovery of new ferrimagnetic compositions in the RbMgF 3 —RbCoF~system 2~is the only magnetic ion. Phase where Co studies on this system show that at high temperatures the hexagonal phase is stable to about 70 per cent RbCOFa. Single crystals were grown over this compositional range and their magnetic and optical properties studied. Compositions containing in excess of about 35 per cent RbCoF 3 are ferrimagnetic and their magnetic moments (as high as 24 em~/g) 2~concentration. and Curie temperatures (up to The magnet36°Kvary ization datawith areCo consistent with a model of a 3 ~ ferrimagnetic spin arrangement. The B—B interaction, which is the resultant of the 900 C~?~ —F—Co2~ and the direct Co2~—Co2~interactions appears to be positive. Anistropy measurements at 4.2°Kyielded values from 2.2 x 10~ to 8.9 ~ 3 for K. Optical absorption ergs/cm data were10~e used to determine the magnitude of the crystal field parameter Dq (87O—880cm’) and the spin orbit interaction constant A (190cm’). From the Dq values it is concluded that the strength of the crystalline field acting on the Co2~ion in the hexagonal structure, where ~ of the CoF 6 octahedra share ~ces, is not too different from that in ‘cubic’ KCoF3 and RbCoF~where they share corners. (Received 27 January 1969) (Revised 25 February 1969)