Energy transfer in rare earth ion clusters and fluorescence from rare-earth-doped La sub 1. 85 Sr sub 0. 15 CuO sub 4 superconductors
Laser spectroscopy of rare earth ions in solids was used to study mechanisms of non-resonant energy transfer within rare earth clusters, and to detect insulating, impurity phases in rare-earth-doped La{sub 1.85}Sr{sub 0.15}CuO{sub 4} superconductors. The mechanisms of phonon-assisted, non-resonant energy transfer were studied in well-defined dimer sites in Er{sup 3+}:SrF{sub 2} and Pr{sup 3+}:CaF{sub 2}. Application of a magnetic field to Er{sup 3+}:SrF{sub 2} greatly increased the energy-transfer rate. The magnetic field dependence in Er{sup 3+}:SrF{sub 2} indicates that the mechanism of non-resonant energy transfer is a two-phonon, resonant process (Orbach process). Application of a magnetic field to Pr{sup 3+}:CaF{sub 2} had no effect on the energy-transfer rate because no significant Zeeman splittings occurred. The temperature dependence of the energy-transfer rate in Pr{sup 3+}:CaF{sub 2} showed the mechanism to be a one-phonon-assisted process at low temperatures and predominantly an Orbach process above 10 K. In the second part of this thesis, laser spectroscopy of a Eu{sup 3+} probe ion is developed to detect impurity phases in La{sub 1.85}Sr{sub 0.15}CuO{sub 4} superconductors. Two impurity phases were found in polycrystalline La{sub 1.85}Sr{sub 0.15}CuO{sub 4}: unreacted La{sub 2}O{sub 3} starting material, and a La-silicate phase, which formed from contamination during sintering.
- Research Organization:
- Wisconsin Univ., Madison, WI (USA)
- OSTI ID:
- 5302323
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COPPER COMPOUNDS
CUPRATES
SUPERCONDUCTORS
ERBIUM IONS
CRYSTAL DOPING
LANTHANUM COMPOUNDS
PRASEODYMIUM IONS
STRONTIUM COMPOUNDS
DOPED MATERIALS
ENERGY TRANSFER
LASER SPECTROSCOPY
SOLID CLUSTERS
ALKALINE EARTH METAL COMPOUNDS
CHARGED PARTICLES
IONS
MATERIALS
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties