Effect of Calcination Temperature on Up-Conversion Photoluminescence of the GdAlO₃: Er³⁺,Yb³⁺Phosphor

Abstract

GdAlO 3 :1.5%Er 3+ ,8%Yb 3+ phosphors were prepared by calcining the precipitate precursor at different temperatures. Effects of calcination temperature on the phase composition, morphology, light absorption and up-conversion photoluminescence properties of the phosphors were investigated. It was found that the phosphors prepared at a temperature between 1000 and 1400 • C kept perovskite structure. With increasing calcination temperature, the crystallinity of the phosphor improved along with the increased particle size. The absorption at 977 nm increased while the concentration of residual OH − decreased with increasing calcination temperature. Under 980 nm excitation, the intensity of green emission at a wavelength of 546 nm increased nearly linearly with increasing calcination temperature when the calcination temperature of the phosphor was between 1000 and 1300 • C, accompanied by gradually decreased ratio of red-to-green emission. Based on the FT-IR spectra and energy levels of Er 3+ and Yb 3+ , possible reasons causing changes in green emission intensity and the ratio of red-to-green with the calcination temperature of the phosphor were discussed. The nearly linear response of the red-to-green emission ratio of the GdAlO 3 :Er 3+ ,Yb 3+ phosphor to the calcination temperature at which it endured during preparation makes the precipitate precursor GdAlO 3 :Er 3+ ,Yb 3+ to be a promising candidate for upconversion thermal history sensing material. In recent years, frequency up-conversion materials that convert infrared to visible light have attracted much attention for their potential applicability in many fields, such as solid-state lasers, biological fluorescence labels, fiber-optic amplifiers, and photovoltaic devices. 1−4Most of the up-conversion photoluminescence (UCPL) materials that have been extensively studied are rare-earth doped halides, oxyhalides and glasses.1,5−6 Although the conversion efficiency of the fluoridebased UCPL materials has been improved to a considerable level, the application is still greatly restricted because of high production cost and poor chemical stability. Therefore, it is of great significance to seek for new hosts with high-conversion efficiency. It is well established that suitable host material for UCPL should have low intrinsic phonon energy because the phonons (or lattice vibration) of the host can provide non-radiative decay ways to suppress UCPL. 29 It was found that the GdAlO 3 :Er 3+ ,Yb 3+ phosphors prepared by different methods showed unlike morphologies and particle sizes, which led to distinct absorption strengths for 980 nm radiation. Moreover, the concentration of residual CO 3 2− and OH − species in the GdAlO 3 :Er 3+ ,Yb 3+ phosphors prepared by different methods was quite different. Since vibrational frequencies of these species were significantly higher than that of GdAlO 3 host, the existence of these species resulted in multi-phonon non-radiative relaxation of the excited states of Er 3+ ion. Therefore, green UCPL intensity and the z E-mail: sryan@fuda...

Sustainably Adjusting the Up-Conversion White-Emitting Luminescence Properties of GdAlO3: Er3+/Yb3+/Tm3+ Phosphors

“…The higher the concentration of OH − impurity in the phosphor the higher the probability of 4 I 11/2 → 4 I 13/2 , 4 S 3/2 → 4 F 9/2 , 3 F 2 → 3 H 4 , and 3 H 5 → 3 F 4 non-radiative transitions. The concentration of surface OH − groups in the phosphor decreased gradually when the calcination temperature increased as shown in our previous work (Deng et al, 2014a ). From the energy level diagram, it can be seen that the blue emission process needed three non-radiation transitions.…”

“…In our previous research on GAP, it was found that the ratio of the red to green emissions intensity can be modified after changing the Er 3+ /Yb 3+ doping concentration and laser power. Apart from this, the particle size and the content of impurity groups adsorbed on the surface of the GAP phosphors calcined at different temperatures will also affect the intensity and proportion of red/green emissions in UCPL (Deng et al, 2014a , b ). In this paper, Yb 3+ was used to sensitize Er 3+ , Tm 3+ in GdAlO 3 to obtain the UC white light, and the doping concentration of Er 3+ and Yb 3+ ions, the calcination temperature of the precursor, the laser power of the excitation light source, and Li + doping were changed to adjust the intensity and relative proportion of red, green, and blue emissions.…”

Improving Upconversion Photoluminescence of GdAlO3:Er3+, Yb3+ Phosphors via Ga3+, Lu3+ Doping

“…0.08 (x=0.00,0.01,0.03,0.05) phosphors. All of the phosphor spectra match the standard data for perovskite GdAlO 3 (PDF#46-0395) [19], and no other impurities were detected. Compared to the pattern of the Gd 0.91 AlO 3 :…”

“…Otherwise, from the schematic diagram, it is seen that the 4 I 11/2 → 4 I 13/2 and 4 S 3/2 → 4 F 9/2 nonradiative transitions of Er 3+ play a key role in determining the green emission intensity and the ratio of red-to-green emission of UCPL spectra. In our previous work [17,19], we showed that the energy gaps of 4 I 11/2 → 4 I 13/2 and 4 S 3/2 → 4 F 9/2 of Er 3+ are about 3600 cm −1 and 3140 cm −1 ; these values are close to the vibrational frequency of OH − (3460 cm −1 ). The decrease in the OH − concentration in the phosphor had a marked influence on reducing the 4 I 11/2 → 4 I 13/2 and 4 S 3/2 → 4 F 9/2 nonradiative transitions.…”

Novel erbia-yttria co-doped zirconia fluorescent thermal history sensor

“…The temperature dependence of the crystallization rate constant, that follows an Arrhenius type relation [30], predicts a strong dependence on temperature of the microstructural state of the material which might thus pass on its fluorescence properties. Numerous studies carried out on the lanthanide activator ions Eu 3+ (in Al 2 O 3 [14], ZrO 2 [31], YAG [32], Y 2 O 3 [13,33,34], YVO 4 [35], CaY 2 Si 3 O 12 [36]), Er 3+ (in SiO 2 [25], GdAlO 3 [26], ZrO 2 [37], Gd 2 TiO 7 [38]), Tb 3+ (in Y 2 O 3 [14,34], Y 2 SiO 5 [12]), Pr 3+ (in PbO-Sb 2 O 3 -B 2 O 3 [39]) and Ce 3+ (in YAG [40]), have shown that their emission intensity at room temperature, initially nonexistent or weak, is greatly improved with the increase of crystallinity resulting from annealing at high temperature, typically in the range 1073-1573 K. This effect, that goes along with the sharpening of emission peaks and generally an increase of the luminescence lifetime [12-14, 32, 34, 38], results mainly from the coarsening of the average crystal size, the uniformization of the crystal field as well as the reduction of the number of crystal defects and residual organic groups acting as luminescence quenchers [12,33,34,38]. Figure 1 shows the x-ray diffraction patterns and the fluorescence spectra of the YSZ:Er 3+ phosphor powder produced by a sol-gel route at the Institut Clément Ader and CIRIMAT [21] in the initial state and after further annealing at 1373 K for 2 h.…”