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Site-selective spectroscopy of erbium-doped SrTiO 3 , Sr 2 </mml:…

1995; American Physical Society; Volume: 51; Issue: 9 Linguagem: Inglês

10.1103/physrevb.51.5649

1095-3795

Laurel J. Knott, Nigel J. Cockroft, John C. Wright,

Microwave Dielectric Ceramics Synthesis

The fluorescence spectra of erbium-doped strontium titanate were investigated as a function of sample preparation in order to probe the solid-state defect equilibrium. Erbium dopants double as donor dopants and as optical probes that reflect the variety of defect compensation mechanisms of strontium titanate. Erbium sites were correlated within the strontium titanate phases as a function of cation stoichiometry, dopant concentration, and annealing conditions. Unlike previously studied rare-earth ions, one erbium site apiece was assigned to the ${\mathrm{Sr}}_{2}$${\mathrm{TiO}}_{4}$ and ${\mathrm{Sr}}_{3}$${\mathrm{Ti}}_{2}$${\mathrm{O}}_{7}$ phases, while the ${\mathrm{SrTiO}}_{3}$ phase supported four sites. The relative distribution of two of the latter sites showed unprecedented sensitivity to ${\mathrm{SrTiO}}_{3}$ stoichiometry and preparation conditions. The observed changes in the site distribution do not agree with simple solid-state defect equilibrium models.