Structure, upconversion photoluminescence, and dielectric properties of Ho3+- and Yb3+-codoped tetragonal tungsten bronze Sr4La2Ti4Nb6O30. (April 2015)

• Record Type: Journal Article
• Authors: Wei, T.; Li, C.P.; Zhou, Q.J.; Li, Z.P.; Li, P.; Wu, J.; Yang, X.F.
• Is Part Of: Materials research bulletin. Volume 64(2015:Apr.)
• Page Start: 395
• Page End: 400
• Publication Date: 2015-04
• Subjects: 78.55.-m -- 77.84.-s; Ceramics -- Luminescence -- Dielectric properties; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2014.12.067
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: TTB-type SLTN: Ho-Yb x with space group P 4/ mbm was determined. UC photoluminescence of SLTN: Ho-Yb x ceramics was first reported. Bright UC green emission was observed at room temperature. Two-photon energy transfer process was confirmed for the UC processes. Temperature stability of dielectric permittivity was improved for SLTN: Ho-Yb x . Abstract: Ho 3+ - and Yb 3+ -codoped Sr4 La2 Ti4 Nb6 O30 (Sr4 La1.94– x Ho0.06 Yb x Ti4 Nb6 O30, abbreviated as SLTN: Ho-Yb x ) ceramics have been synthesized, and their structural, up-conversion (UC) photoluminescence, and dielectric properties have been carefully investigated. Through Rietveld structural refinement, SLTN: Ho-Yb x samples are determined as single tetragonal tungsten bronze (TTB) phase with space group P 4 /mbm in which larger Sr 2+ ions fill the A2 -sites, relative smaller La 3+, Ho 3+, and Yb 3+ ions occupy the A1 -sites, while Ti 4+ and Nb 4+ ions fill the B-sites. Under 980 nm near infrared (NIR) excitation, bright UC green emission, relatively weak red and near-infrared (NIR) emissions, originating from 5 F4 / 5 S2 → 5 I8, 5 F5 → 5 I8, and 5 F4 / 5 S2 → 5 I7 transitions of Ho 3+ ions, are confirmed for SLTN: Ho-Yb x . Two-photon energy transfer process is proved through pumping laser power dependence of emission intensity measurement. Furthermore, the influence of Ho 3+ - and Yb 3+ - ions on the dielectric properties of SLTN: Ho-Yb x is also investigated and the temperature stability of dielectric permittivity is improved.