Color‐Tunable Up‐Conversion Emission and Infrared Photoluminescence and Dielectric Relaxation of Er³⁺/Yb³⁺ Co‐Doped Bi₂Ti₂O₇ Pyrochlore Thin Films

Abstract

The color‐tunable up‐conversion (UC) emission and infrared photoluminescence and dielectric relaxation of Er3+/Yb3+ co‐doped Bi2Ti2O7 pyrochlore thin films prepared by a chemical solution deposition method have been investigated. The pyrochlore phase structure of Bi2Ti2O7 can be stabilized by Er3+/Yb3+ co‐doping. Intense color‐tunable UC emission and infrared photoluminescence can be detected on the thin films excited by a 980 nm diode laser. Two UC emission bands centered at 548 and 660 nm in the spectra can be assigned to 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ ions, respectively. A Stokes infrared emission centered at 1530 nm is due to 4I13/2 → 4I15/2 transition of Er3+ ions. The dependence of UC emission intensity on pumping power indicates that the UC emission of the thin films is a two‐photon process. The thin films also exhibit a relatively high dielectric constant and a low dissipation factor as well as a good bias voltage stability. Temperature‐ and frequency‐dependent dielectric relaxation has been confirmed. This study suggests that Er3+/Yb3+ co‐doped Bi2Ti2O7 thin films can be applied to new multifunctional photoluminescence dielectric thin‐film devices.

Red-orange photoluminescence and dielectric relaxation of Eu3+-doped Bi2Ti2O7 pyrochlore structure thin films

“…With relatively high permittivity, low dielectric loss, and low sintering temperature, Bi 2 Ti 2 O 7 is a promising candidate material for the integrated capacitor applications [3,4]. Pyrochlore structure bismuth titanate thin film has also been used as a buffer layer to improve the electrical properties of In addition, recent studies suggested that Bi 2 Ti 2 O 7 is a potential host material for rare earth photoluminescence [8,9], because of its wide band gap, high refractive index, and low phonon energy [10]. Furthermore, doping with rare earth ions such as La 3þ has been proved to be an effective method to improve the electrical properties of Bi 2 Ti 2 O 7 [11].…”

Synthesis and Up‐conversion Luminescence of Yb3+/Ln3+ (Ln = Er,Tm,Ho) Co‐Doped Strontium Cerate by Pechini Method

“…Then a non‐radiative decay takes place in the Er 3+ ion through the populated state to the 2 H 11/2 , 4 S 3/2 levels, and then the green 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 emissions occur. Alternatively, the ion can further relax and populate the 4 F 9/2 level, which can lead to the red 4 F 9/2 → 4 I 15/2 emission . The whole process of Sr 2 CeO 4 :Yb 3+ /Er 3+ can be expressed as following formulas: (1) 2 F 7/2 (Yb 3+ ) + 980 nm photon → 2 F 5/2 (Yb 3+ ); (2) 2 F 5/2 (Yb 3+ ) + 4 I 15/2 (Er 3+ ) → 2 F 7/2 (Yb 3+ ) + 4 I 11/2 (Er 3+ ) (ET1); (3) 4 I 11/2 (Er 3+ ) → 4 I 13/2 (Er 3+ ); (4) 2 F 5/2 (Yb 3+ ) + 4 I 13/2 (Er 3+ ) → 2 F 7/2 (Yb 3+ ) + 4 F 7/2 (Er 3+ ) + 4 F 9/2 (Er 3+ ) (ET2); (5) 4 F 7/2 (Er 3+ ) → 2 H 11/2 (Er 3+ ) + 4 S 3/2 (Er 3+ ) + 4 F 9/2 (Er 3+ ), 4 F 9/2 (Er 3+ ) → 4 I 15/2 (Er 3+ , red); and (6) 2 H 11/2 (Er 3+ ) + 4 S 3/2 (Er 3+ ) → 4 I 15/2 (Er 3+ , green).…”

“…It is well known that UC efficiency is mainly dependent on the host material and doping ion, especially the former, a change of the host can enhance or decrease significantly the UC luminescent properties for it can strongly influence the transitions of the lanthanides, therefore ongoing research is mainly concerned with the quest for host materials with increased conversion efficiencies. The UC luminescence of rare earth ions has been investigated in various matrices, such as Gd 2 O 3 , In 2 O 3 , Bi 2 Ti 2 O 7 , NaGdF 4 , and NaYF 4 , etc. Among which NaYF 4 :Er 3+ ,Yb 3+ has been proved to give the strongest UC emissions.…”

Dependence of the up-conversion emission of Li+ co-doped Y2O3:Er3+ films with dopant concentration

“…In spite of this unique characteristic, the Er 3 þ UC emission studies on films have been focused mainly to the preparation of Er 3 þ and Yb 3 þ co-doped films of materials such as Bi 2 Ti 2 O 7 , Y 2 Ti 2 O 7 , ZnO, Y 3 Al 5 O 12 , among others. These films are deposited by methods such as chemical solution deposition, sol gel, radio-frequency magnetron sputtering, dip coating among others [11][12][13][14].…”