Search

Ce 3+ , Yb 3+ and Tb 3+ singly doped and Ce 3+ -Yb 3+ , Tb 3+ -Yb 3+ codoped Ca 3 (BO 3 ) 2 phosphors were prepared by a solid state reaction method. The photoluminescence excitation and emission spectra at room temperature were investigated. The emissions of Yb 3+ ion are at around 1000 nm, matching well with the optimal response of Si-based solar cells. When codoped with Ce 3+ or Tb 3+ ion, the absorption is greatly broadened in the ultraviolet-visible region. Energy transfer from Ce 3+ /Tb 3+ to Yb 3+ was investigated, the cooperative energy transfer process is proposed. [ABSTRACT FROM AUTHOR]

A series of novel near-infrared (NIR) long persistent phosphors of Zn 1.2 Al 1.6 Ge 0.2 O 4 : Cr 3+ , Yb 3+ was synthesized by a solid state method. The crystal structure of Zn 1.2 Al 1.6 Ge 0.2 O 4 was identified. Yb 3+ ions were effective codopants for improving the NIR persistent luminescence intensity even after 100 h of decay. The persistent luminescence decay curves and the thermo-luminescence spectra were analyzed. Results indicated that the increase in efficient electron trap concentration induced by doping Yb 3+ ions was a major factor in the improvement of the NIR persistent luminescence. Moreover, short-wave infrared (SWIR = 900–1700 nm) emission of Yb 3+ was be excited by UV and visible light through charge transfer transition of O 2- –Yb 3+ and energy transfer from Cr 3+ to Yb 3+ , respectively. [ABSTRACT FROM AUTHOR]

A new series of red luminescent Cd 2 MgTeO 6 : x Eu3+ (x = 0.5–50 mol%) phosphors was successfully synthesized through a high-temperature solid-phase reaction at 1000 °C. The synthesized phosphors were investigated for their phase purity, surface morphology, elemental distribution, and luminescence properties. Strong orange-red light emission (617 nm) was observed upon excitation at 398 nm, which was attributed to the electric dipole 5D 0 -7F 2 transition of Eu3+. The optimal doping concentration was found to be x = 20 mol%. Concentration quenching mechanism was identified as the interaction of near-neighbor ions. The chromaticity coordinates of all the Cd 2 MgTeO 6 :Eu3+ samples were found to be located in the red region and were almost the same. The Cd 2 MgTeO 6 : 20 mol%Eu3+ phosphors exhibited an unusual thermal quenching behavior, maintaining 102% of the initial intensity, thus possessing excellent thermostability. Moreover, the manufactured white light diode demonstrated a good color rendering index (R a = 89) with the coordinates of (0.344, 0.330) by the Commission International de L'Eclairage (CIE). Additionally, the Cd 2 MgTeO 6 : 20 mol%Eu3+ phosphor was surface-functionalized with oleic acid (OA) (Cd 2 MgTeO 6 : 20 mol%Eu3+@OA) to aid in the identification of Level I-III fingerprint details with high resolution and contrast. Good visualization of the latent fingerprint (LFP) was observed on different substrates. Therefore, Cd 2 MgTeO 6 :Eu3+ phosphors hold great promise for the visualization of w-LEDs and LFPs. • The Cd 2 MgTeO 6 :Eu3+ phosphor has an unusual thermal quenching behavior and excellent thermal stability. • The synthesized phosphors exhibit a high color purity (100%). • The fabricated w-LED exhibits a high color rendering index (R a = 89). • The Cd 2 MgTeO 6 : 20 mol%Eu3+@OA phosphor shows great potential in LFP visualization. [ABSTRACT FROM AUTHOR]

The near-infrared (NIR) luminescence materials have attracted great attention on account of their potential applications in optical imaging field. In this paper, a series of Cr3+ and Nd3+ doped GdY 2 Al 3 Ga 2 O 12 phosphors with luminescence in the biological windows were synthesized using a solid-state reaction method. The crystal field parameters, concentration dependent photoluminescence and persistent luminescence properties of Cr3+ were discussed in detail. Nd3+ ions exhibit perfect NIR to NIR Stokes luminescence in the host. The influence of Nd3+ doping concentration was studied by emission spectra and decay curves. Taking the advantages of both Cr3+ and Nd3+, dual mode phosphors with NIR persistent luminescence and NIR to NIR Stokes luminescence were designed and achieved. Based on the energy transfer process, persistent luminescence and thermo-luminescence curves, the luminescence mechanism was proposed. • The luminescence and persistent luminescence properties of Cr3+ and Nd3+ in the GdY 2 Al 3 Ga 2 O 12 host were investigated. • The energy transfer from Cr3+ to Nd3+ was found, the main mechanism was determined by the Inokuti-Hirayama model. • Dual mode phosphors with NIR persistent luminescence and NIR to NIR Stokes luminescence were successfully obtained. • The luminescence mechanism was discussed and proposed. [ABSTRACT FROM AUTHOR]