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Phosphors that can emit broadband light from visible to near infrared (NIR) may have applications in the fields like white-light illumination and NIR vessel visualization, the investigation on single phase extra-broadband visible-NIR emitting phosphor is of great significance. Herein, an extra-broadband phosphor with tunable visible-NIR emission from 500 nm to longer than 900 nm (bandwidth >400 nm) was successfully prepared, which originates from the emission of Ce3+ (peaking at 573 nm), Cr3+ (peaking at 750 nm) and energy transfer from Ce3+ to Cr3+ in Y 3 MgAl 3 SiO 12 garnet. The influences of Ce3+/Cr3+ doping concentration and working temperature were discussed systematically by luminescence spectra and decay curves. A visible-NIR full-spectrum phosphor-converted light emitting diode (pc-LED) fabricated with a 460 nm LED chip and Y 3 MgAl 3 SiO 12 :0.03Ce3+, 0.01Cr3+ can generate bright white light and broadband NIR light simultaneously. The co-doping of Ce3+ can perfectly compensate for the missing spectrum of Cr3+ in the visible region, thanks to the extra-broadband emission of Ce3+ in visible region and Cr3+ in NIR region, multifunctional advanced applications may be realized for the prepared phosphors. [ABSTRACT FROM AUTHOR]

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]

Eu3+-activated La2CaB10O19 phosphors with nominal chemical formulae La2−xEuxCaB10O19 and La2Ca1−2xEuxNaxB10O19 were prepared. The luminescence properties under VUV-UV excitation were investigated. Luminescence spectra reveal Eu3+ ions occupy both Ca2+ and La3+ sites in all samples. The O2−→ Eu3+ charge transfer bands (CTBs) and the 5D0→7F0 emissions of Eu3+ at Ca 2+ site and La3+ site are identified, respectively. The schematic energy levels for Eu3+ in two sites were achieved. Luminescence decays of the 5D0→7F0 transitions were measured for both sites. [ABSTRACT FROM AUTHOR]

Phosphors of Eu activated BaMg(BO) were prepared by a high-temperature solid-state reaction technique. The phase purity was characterized by powder X-ray diffraction (XRD). The luminescence properties in the VUV-vis range as well as the decay curves have been investigated. The results demonstrate that the band near 176 nm in the VUV excitation spectra can be ascribed to host-related absorption. The charge-transfer bands (CTBs) of O → Eu in BaMg(BO):Eu are at about 231 nm. The emission intensity of the D→F transition (594 nm) is dominant upon excitations at 172 nm or 231 nm (CTB), while that of D→F transition (613 nm) is dominant when excitations are at 395 nm (the F→L transition of Eu) or at other f-f transitions. [ABSTRACT FROM AUTHOR]

Abstract: This report presents the luminescence properties of Ce3+ and Pr3+ activated Sr2Mg(BO3)2 under VUV–UV and X-ray excitation. The five excitation bands of crystal field split 5d states are observed at about 46729, 44643, 41667, 38314 and 29762cm−1 (i.e. 214, 224, 240, 261 and 336nm) for Ce3+ in the host lattice. The doublet Ce3+ 5d→4f emission bands were found at about 25840 and 24096cm−1 (387 and 415nm). The influence of doping concentration and temperature on the emission characteristics and the decay time of Ce3+ in Sr2Mg(BO3)2 were investigated. For Pr3+ doped samples, the lowest 5d excitation band was observed at about 42017cm−1 (238nm), a dominant band at around 35714cm−1 (280nm) and two shoulder bands were seen in the emission spectra. The excitation and emission spectra of Ce3+ and Pr3+ were compared and discussed. The X-ray excited luminescence studies show that the light yields are ∼3200±230 and ∼1400±100photons/MeV of absorbed X-ray energy for the samples Sr1.86Ce0.07Na0.07Mg(BO3)2 and Sr1.82Pr0.09Na0.09Mg(BO3)2 at RT, respectively. [ABSTRACT FROM AUTHOR]

The fabrication of rare earth luminescent materials with monodispersed and hierarchical morphology is of great importance due to their various applications. In this report, monodispersed hierarchical Yb(OH) x F 3−x microcrystals assembled by nanorod arrays were synthesized by a mild hydrothermal route. Calcination of Yb(OH) x F 3−x resulted in the formation of Yb 6 O 5 F 8 with the retention of morphology. The crystallographic structure relationship between Yb(OH) x F 3−x and Yb 6 O 5 F 8 and the transformation mechanism from Yb(OH) x F 3−x to Yb 6 O 5 F 8 were disclosed. The upconversion emission properties of the Er 3+ doped samples were investigated. It can be found that Yb 6 O 5 F 8 : 5%Er 3+ exhibited an intense red light upconversion emission with the strongest peaks around 658 nm while Yb(OH) x F 3−x : 5%Er 3+ shows no upconversion emission. [ABSTRACT FROM AUTHOR]

Yb 3+ and Tb 3+ singly doped and Tb 3+ –Yb 3+ co-doped Ca 5 (BO 3 ) 3 F phosphors were prepared by a solid state reaction method. The luminescence emission and excitation spectra as well as the luminescence decay curves were investigated. The emission bands of Yb 3+ ion are located around 1000 nm, matching well with the optimal response of Si-based solar cells. Tb 3+ can be a sensitizer for Yb 3+ in the host. The energy transfer from Tb 3+ to Yb 3+ was investigated, the energy transfer mechanism was proposed as cooperative energy transfer. Tb 3+ concentration dependent quantum efficiency was calculated and the maximum efficiency approached 115.5%. [ABSTRACT FROM AUTHOR]

Abstract: The spectroscopic properties of Na3Gd(PO4)2 and Na3Gd(PO4)2:Ce3+ phosphors in the VUV–UV spectral range were investigated. Five excitation bands of Ce3+ ions at Gd3+ sites are observed at wavelengths of 205, 246, 260, 292, and 321nm. Doublet Ce3+ 5d→4f emission bands are observed at 341 and 365nm with a decay constant τ 1/ e around 26ns. The X-ray excited luminescence of Na3Gd0.99Ce0.01(PO4)2 at room temperature shows a photon yield of ∼17,000photons/MeV of absorbed X-ray energy. [ABSTRACT FROM AUTHOR]

Abstract: The phosphors NaGdFPO4:Ln 3+ and GdPO4:Ln 3+ (for Ln3+=Ce3+ and Tb3+) were prepared by solid-state reaction technique, the VUV–vis spectroscopic properties of the phosphors were investigated, and we vividly compare the luminescence of Ce3+ and Tb3+ in the hosts. For phosphors GdPO4:Ln 3+, the band near 155nm in VUV excitation spectrum is assumed to be the host-related absorption, and for NaGdFPO4:Ln 3+ the absorption is moved to longer wavelength, near 170nm, showing the P–O bond covalency increased after fluoridation. The f–d transitions of Ce3+ and Tb3+ in the host lattices are assigned and corroborated, and it was found that the 5d states are with lower energy in NaGdFPO4:Ln 3+ than those in GdPO4:Ln 3+. For fluoridation of GdPO4:Ln 3+ to NaGdFPO4:Ln 3+, the energy change of Ln 3+ (Ln=Ce, Tb) 5d states is consistent with that of host-related absorption. [Copyright &y& Elsevier]

A series of Ce3+ and Dy3+ doped LiY 9 (SiO 4) 6 O 2 phosphors was prepared by conventional high temperature solid state reaction method. The dominant emission of Dy3+ originates from the 4F 9/2 → 6H 13/2 (yellow emission) electric dipole transition while that of Ce3+ locates in the blue region. The concentration quenching for Dy3+ emission was investigated by luminescence spectra and decay curves, the main mechanism responsible for the energy transfer between Dy3+ ions was determined by the Inokuti-Hirayama model. Energy transfer from Ce3+ to Dy3+ as well as the temperature sensing property was studied in detail. Thanks to the different thermal responses between Ce3+ and Dy3+ in the host, the highest sensing sensitivity was calculated to be 0.43% K−1. The results demonstrate that LiY 9 (SiO 4) 6 O 2 : Ce3+, Dy3+ may be a potential candidate for a luminescent ratiometric thermometer. [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]

We present novel near-infrared (NIR) Cr 3+ -doped non-gallate super-long-persistence phosphors (Zn 1+x Al 2-2x Ge x O 4 :Cr 3+ ) by Germanium substitution in the original ZnAl 2 O 4 :Cr 3+ . Unlike the negligible NIR persistent luminescence of ZnAl 2 O 4 :Cr 3+ upon UV or visible light excitation, the Ge substituted phosphors feature strong and super-long-persistent luminescence at approximately 650–750 nm for more than 120 h. The relation between the Ge substitution and the defect trapping states is investigated systematically. The experimental results combined with the first-principles calculations reveal that Ge Zn ○○ and Ge Al ○ in the spinel structure would introduce shallow and deep defect states in the band gap to serve as new efficient traps, which are mainly responsible for the strong and super-long-persistent luminescence upon UV or visible light excitation. The present advanced phosphors is an alternative candidate for applications in biomedical imaging and night-vision surveillance. [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]

Novel red-emitting phosphors, Sr 3 LaTa 3 O 12 :Eu3+ (SLTO:Eu3+), have been successfully synthesized for use in white light-emitting diodes (w-LEDs) and latent fingerprint (LFP) visualization applications. The crystalline structure, bandgap, and photoluminescence (PL) of the SLTO:Eu3+ phosphors were thoroughly investigated. Under 395 nm excitation, SLTO:Eu3+ phosphors emitted orange-red light at the wavelength of 616 nm due to the 5D 0 -7F 2 transition of Eu3+ ions. The optimal doping concentration of the phosphor is x = 0.30 and the neighbor ions interaction is the most critical factor in the concentration quenching mechanism of the SLTO:Eu3+ phosphor. Furthermore, the SLTO:0.30Eu3+ phosphor exhibit higher thermal stability compared to the conventional red phosphor (Sr 2 Si 5 N 8 :Eu2+). The packaged w-LED showed a correlated color temperature (6887 K), excellent color rendering index (95), and Commission International de l'Eclairage (CIE) coordinates of (0.305, 0.334). The SLTO:0.30Eu3+ phosphor effectively detected level 1–3 structures of LFPs under ultraviolet irradiation, and ultimately detected LFPs in various daily life circumstances. These findings indicate that the SLTO:0.30Eu3+ phosphor might be a viable option for w-LED lighting applications and LFPs visualization. • Sr 3 LaTa 3 O 12 :Eu3+ phosphors are firstly synthesized via solid-state reaction. • The phosphor emits bright red light excited by 395 nm. • The phosphor exhibits good thermal stability and high color purity. • Sr 3 LaTa 3 O 12 :Eu3+ phosphors has potential to be used for w-LED application and LFPs visualization. [ABSTRACT FROM AUTHOR]

Ultra-broadband Vis-NIR (visible to near-infrared) tunable emitting phosphors are considered to the most promising fluorescent materials, such as for the applications in general lighting, NIR spectroscopy, plant growth lighting, and etc. Herein, Ce3+-Cr3+ co-doped Mg 3 Y 2 Ge 3 O 12 phosphors were prepared. Ultra-broadband Vis-NIR luminescence of Ce3+/Cr3+ ranging from ∼500 nm to >900 nm can be observed, which can be tuned with changes of doping concentration or experimental temperature. The energy transfer processes of Ce3+-Cr3+ are investigated by applying the excited state dynamics principle. Interestingly, broadband high-sensitivity temperature sensing performance is obtained for the Ce3+-Cr3+ co-doped Mg 3 Y 2 Ge 3 O 12 phosphors at high temperatures, achieving visible to near-infrared temperature regulation. A single phase phosphor-converted light emitting diode (pc-LED) was fabricated by combining blue LED chip with Mg 3 Y 2 Ge 3 O 12 :Ce3+,Cr3+ phosphors. The interesting results indicate that the prepared phosphors may realize multifunctional advanced applications. • We obtained ultra-broadband Vis-NIR luminescence of Ce3+/Cr3+ ranging from ∼500 nm to >900 nm. • A broadband high-sensitivity temperature sensing performance with S r from 1.38% K−1 to 0.85% K−1 is obtained. • A full-spectrum pc-LED fabricated by only using Mg 3 Y 2 Ge 3 O 12 :Ce3+,Cr3+ can generate white light and broadband NIR light. [ABSTRACT FROM AUTHOR]

Deep-red light emitting phosphors play vital roles in phosphor-converted light emitting diodes (pc-LEDs) for indoor plant growth and full-spectrum applications. Recently, Mn4+ activated red/deep-red phosphors have attracted considerable interests due to the advantages of cheap price and excellent luminescence properties. Herein, a series of (Gd,La) 2 (Zn,Mg)TiO 6 :Mn4+ phosphors were synthesized through high temperature solid state reaction. Morphology, structure and luminescence properties of the as-prepared phosphors were investigated. More importantly, the influences of Mg2+/La3+ doping on structure, luminescence spectra, decay curves and thermal quenching were discussed in detail. It is found that a certain amount of Mg2+ contributes positively to the emission intensity and can improve the luminescence thermal stability of Mn4+, while the doping of La3+ exhibits a negative effect. By employing the prepared phosphor as deep-red component, a full-spectrum high performance white LED with low correlated color temperature (4287 K) and extremely high color rendering index (Ra = 97.9) can be fabricated. The results indicate that the as-prepared phosphors may be potential for full-spectrum lightings and indoor plant growth after further improvement. • A deep-red phosphor (Gd,La) 2 (Zn,Mg)TiO 6 : Mn4+ with emission in the 650–800 nm range was prepared and investigated. • The influence of Mg2+ and La3+ on Gd 2 ZnTiO 6 : Mn4+ phosphor was discussed by temperature dependent luminescence and decay curves. • A full-spectrum high performance white pc-LED with low CCT and extremely high CRI could be successfully obtained. [ABSTRACT FROM AUTHOR]

The phosphors, fluorapatites M5(PO4)3F (M=Ca, Sr, Ba) activated with Dy3+ ions, were prepared by a high-temperature solid-state reaction technique. The VUV-UV excitation spectra and emission spectra under VUV/UV excitation were measured. The phosphors show broad and strong absorption near 172 nm and intensive emission with the chromaticity coordinates entering the white light region. Hence, the phosphors may be considered as suitable candidates for Hg-free lamps. [ABSTRACT FROM AUTHOR]

Abstract: The spectroscopic properties of Ce3+, Pr3+ and Tb3+ activated SrB4O7 in VUV–vis range were investigated. The split 5d levels for Ce3+ in the host lattice are discussed and an environmental factor F c is used to explain the crystal field splitting (CFS). The photon cascade emission (PCE) process was observed in Pr3+ doped SrB4O7, and the quantum efficiency of PCE is estimated. An empirical relationship between the lowest spin-allowed f–d transition energy [W fd(n)] and n-value for 4f n -series Ln3+ (Ln=Ce, Pr, Tb) ions in SrB4O7 is proposed. [Copyright &y& Elsevier]

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]