Co-doped Transparent Glass Ceramics Research Articles

Color tunable emission and temperature sensing performance in Dy3+/Sm3+ co-doped transparent oxyfluoride glass ceramics containing K3YF6 nanocrystals

This paper presents the preparation and characterization of transparent oxyfluoride glass ceramics (GCs) that contain nanocrystals of K3YF6 co-doped with Dy3+ and Sm3+. The study investigates the luminescence characteristics, the process of energy transfer (ET) and the behavior of the ratio-metric temperature sensing. The formation of well-defined nanocrystals of K3YF6 in the glass substrate was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By varying Sm3+ concentration, a tunable emission ranging from pale yellow to orange-red was observed. Energy transfer from Dy3+ to Sm3+ ions was confirmed through fluorescence spectra and decay curves. Sample K3YF6, containing 0.5 mol%Dy3+/1.2 mol%Sm3+, showed an absolute sensitivity (Sa) of 0.635% K−1 and relative sensitivity (Sr) of 0.401% K−1. These findings underscore the promising applications of K3YF6: Dy3+, Sm3+ GCs in multicolor displays and high-performance temperature sensing devices.

Synthesis and up-conversion luminescence properties of Ho3+-Yb3+ co-doped glass ceramics with perovskite structure

By using melt solidification crystallization method, Ho3+-Yb3+ co-doped transparent glass ceramics (GCs) containing LaTiO3 microcrystal were successfully prepared. The structure of the GCs was characterized by X-ray diffraction (XRD), which proved that LaTiO3 microcrystal was precipitated in the precursor glass (PG). The structures of PG and GCs were studied by infrared spectrum, which showed that a new absorption peak appeared in the GCs, which was attributed to the stretching vibration of the Ti-O bond in the [TiO6] octahedral group, and it further demonstrated the precipitation of the LaTiO3 microcrystal. By studying the up-conversion luminescence (UCL) properties, it is found that there were three emission peaks at 546, 652 and 484 nm, which are attributed to the 5F4/5S2 → 5I8, 5F5 → 5I8 and 5F3 → 5I8 transitions of Ho3+, respectively, and the optimal doping concentrations of Ho3+ and Yb3+ were determined. The chrominance coordinate of Ho3+-Yb3+ co-doped glass ceramic (GC) is situated in the green light area and the color purity is as high as 98.03 %. The researches above show that Ho3+-Yb3+ co-doped GCs with LaTiO3 microcrystal have a wide application prospect in green luminescence.

Enhanced up-conversion luminescence of Tb3+-Yb3+ doped glass ceramics by doping Li+

Tb3+-Yb3+ co-doped transparent glass ceramics (GCs) containing Y2Ti2O7 crystal phases were synthesized by the melt crystallization. The light transmittance of GCs in the visible region reached 78%, and the average grain size was 278 nm under the optimal heat treatment conditions (720 °C/2 h). The GCs exhibited greater up-conversion luminescence intensity than precursor glass, and the reason for this result was explained in accordance with the Judd-Ofelt theory. Moreover, the introduction of Li+ did not change the crystalline phase of GCs. The emission intensity of the green light of the 8% Li + doped GCs was significantly enhanced by nearly 4.48 times under 980 nm excitation. The XRD refinement results suggest that the enhanced luminescence intensity is correlated with the change of the Y2Ti2O7 crystal lattice caused by Li+ doping. The relevant luminescence mechanism was elucidated. The results suggest that Li+ doped transparent GCs open novel avenues for green UC applications.

Effects of coordination field environment on the fluorescence properties of transparent ZnGa2O4 glass-ceramics doped with Mn2+ and Cr3+ ions

The transparent ZnGa2O4 glass-ceramics doped with Mn2+/Cr3+ ions were prepared by a one-step crystallization method. The visible light fluorescence properties of Mn2+ ions in 6-coordination and 4-coordination environments and the visible light fluorescence properties of Mn2+/Cr3+ ions co-doped in transparent ZnGa2O4 glass-ceramics were studied. The results manifest that in the parent glass, Mn2+ ions mainly occupy the network former in the form of Hexa-coordination, and the luminescence center can emit orange-yellow light at ~600 nm. In transparent ZnGa2O4 glass-ceramics, Mn2+ ions and Cr3+ ions appear at the four-coordination site (Zn site) and six-coordination site (Ga site) in ZnGa2O4 spinel, respectively, and they can radiate green (510 nm) and red light (688 nm), respectively. An energy transfer mechanism of Mn2+→Cr3+ exists in ZnGa2O4: Mn2+/Cr3+ and different colors of luminescence can be produced by changing the molar ratios of components and test conditions. CIE results show that Mn2+-single-doped parent glass and glass-ceramics can be used in orange-yellow and green light displays, while Mn2+/Cr3+ co-doped transparent ZnGa2O4 glass-ceramics can be used as ideal materials for the green and red light displays.

Luminescence and energy transfer of Sm3+/Eu3+ co-doped transparent glass ceramics

Luminescence and energy transfer of Sm3+/Eu3+ co-doped transparent glass ceramics

Up-conversion luminescence transparent CaNb2O6 glass ceramics for temperature monitoring

To explore new up-conversion luminescent materials with high sensitivity for optical thermometry, Yb3+/Tm3+ co-doped transparent CaNb2O6 glass ceramics are successfully prepared using the traditional melting and controlling crystallization. Its structure, micro-morphology and luminescence characteristics are studied comprehensively by means of XRD, Raman, TEM and a fluorescence spectrometer. The results show that the luminescence intensity of glass ceramics is significantly higher than that of glasses under 980 nm laser excitation. A dual-mode temperature measurement based on fluorescence intensity ratios (FIR, I690/I796 and I690/I651) is realized by using the different temperature dependence of emission peaks of Tm3+. In a wide temperature range (298 − 573 K), the highest absolute sensitivity (Sa-max) of 0.42‰ K−1 and the supreme relative sensitivity (Sr-max) of 2.65% K−1 based on thermal coupling energy levels (TCELs) are gained. Furthermore, using non-thermal coupling energy levels (NTCELs), Sr-max and Sa-max reach 0.23% K−1 and 20.49% K−1, respectively. This work indicates that the CaNb2O6 glass ceramics as a new type of up-conversion luminescent material have great application prospects in the field of optical thermometry.

Crystallization behavior and enhanced fluorescence properties of Yb3+/Ho3+/Tb3+ co-doped transparent glass-ceramics containing oxyapatite-type Na3YSi2O7 crystals

The Yb3+/Ho3+/Tb3+ co-doped Na2O-Y2O3-SiO2 system transparent glass-ceramics containing oxyapatite-type Na3YSi2O7 (NYS) crystals were prepared. The structure of the crystal was characterized by XRD and TEM. The most suitable heat treatment process was confirmed by DSC and TEM results. The strongest emission peak in the fluorescence spectra relates to the Tb3+: 5D4→7F5 transition. In the CIE chromaticity diagram, the luminescence is concentrated in the green area. The emission intensity of the glass-ceramic is increased by 7 times compared with the precursor glass. The increase in emission intensity is caused by the entry of rare-earth ions into the Na3YSi2O7 grains to replace the positions of Y3+ ions. The fluorescence properties of the glass-ceramics containing Na3YSi2O7 crystals were tested at different temperatures. It is demonstrated that the luminescent materials show good thermal stability. The obtained glass-ceramic would be a candidate material for green diode elements.

Color-tunable luminescence and temperature sensing in Ce3+/Tb3+ co-doped transparent oxyfluoride glass-ceramics containing Na1.5Y2.5F9 nanocrystals

Transparent glass-ceramics (GCs) containing Na1.5Y2.5F9 nanocrystals doped with Ce3+/Tb3+ were synthesized by melt-quenching approach. The nanocrystal structure was determined by X-ray diffraction, and its distribution and morphology were observed by transmission electron microscope. Luminous characteristics, energy transfer, and temperature sensing performance were investigated. Under 312 nm light excitation, the Ce3+/Tb3+ co-doped Na1.5Y2.5F9 GCs exhibited a blue emission (Ce3+: 424 nm) and sensitized a green emission (Tb3+: 546 nm). The emission color can be adjusted from blue (0.1643, 0.0826) to green (0.2891, 0.5243) via adding Tb3+ ions. The energy transfer efficiencies from Ce3+ to Tb3+ can reach 33.3%. The temperature sensitivity of sample Na1.5Y2.5F9: 0.5Ce3+, 0.1 Tb3+ and sample Na1.5Y2.5F9: 0.5Ce3+, 1.0 Tb3+ were compared. Based on the fluorescence intensity ratio of the Ce3+ and Tb3+ emission, the absolute sensitivity, relative sensitivity, temperature resolution, and thermal repeatability were estimated to be 0.768% K−1, 0.603% K−1, 0.049 K, and 0.993, respectively. The results indicate that Na1.5Y2.5F9: Ce3+, Tb3+ GCs have immense application prospects for multicolor displays and temperature sensors.

Quantitative relationship between microstructure and optical properties of Er3+-Yb3+ co-doped glass-ceramics containing pyrochlore-type crystalline phases

Er3+-Yb3+ co-doped transparent glass-ceramics (GCs) containing Y2Ti2O7 crystalline phase were prepared by the melting crystallization method. The qualitative relationship between light transmittance and three-dimensional structure parameters of glass-ceramic was studied according to the principle of stereology under different heat treatment conditions. As indicated by the research results, the light transmittance decreased with the increase in the equivalent spherical diameter (D3S) and specific surface area per unit volume of the grains (SV). However, the light transmittance increased linearly with the increase in the discrete grains (SVP) and the mean free distance (λ). The up-conversion luminescence intensity was found to be most vigorous under Er3+ and Yb3+ doping concentrations of 0.5% and 0.9%, respectively, at 980 nm excitation. Considering the correlation between pump power and up-conversion emission intensity, the up-conversion luminescence mechanism was explored. As revealed by the results of color purity and chromaticity coordinates, Er3+-Yb3+ co-doped GCs containing Y2Ti2O7 have promising applications in green up-conversion luminescence.

Synthesis and up-conversion luminescence properties of Ho3+-Yb3+ co-doped glass ceramics containing Sr3Gd(PO4)3

Ho3+-Yb3+ co-doped transparent glass ceramics containing Sr3Gd(PO4)3 were successfully prepared by the melt crystallization method. The best condition of the thermal treatment was determined to be 780 °C/3 h by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The transmittance of glass ceramic was approximately 81% in the visible region. From to the up-conversion emission spectra, the strong green emission (543 nm), weak red (654 nm) and blue emission (483 nm) due to the 5F4/5S2, 5F5, 5F3 → 5I8 transitions of Ho3+ can be observed. In addition, the optimum doping concentration of Ho2O3 and Yb2O3 was 0.3% and 0.8%, respectively. By comparing 0.3%Ho2O3-0.8%Yb2O3 co-doped with 0.3%Ho2O3 doped glass ceramic, the green and red up-conversion luminescence intensity were improved by about 33 times and 21 times, respectively. These results indicated that Ho3+-Yb3+ co-doped transparent glass ceramic containing Sr3Gd(PO4)3 have potential applications in the field of green up-conversion luminescence.

Up-conversion luminescence properties of Ho3+-Yb3+ Co-doped transparent glass ceramics containing Y2Ti2O7

Ho3+-Yb3+ co-doped transparent glass ceramics (GCs) containing Y2Ti2O7 crystal phase were prepared by the melting crystallization method. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The combination of the XRD and SEM results showed that Y2Ti2O7 crystals precipitated in the glass matrix, and the optimal heat treatment condition of GCs was determined to be 730℃/2 h by XRD, SEM, differential scanning calorimetry (DSC) and transmittance curves. Under 980 nm excitation, when the doping concentration of Ho2O3 is 0.3%, the emission intensity is the strongest at 543 nm due to the 5F4/5S2→5I8 transition of Ho3+. The energy transfer from Yb3+ to Ho3+ can be observed through the fluorescence spectra of Ho3+-Yb3+ co-doped GCs. The optimal doping concentrations of Ho2O3 and Yb2O3 are 0.3% and 0.6%, respectively. Ho3+-Yb3+ co-doped transparent GCs containing Y2Ti2O7 crystal phase have potential applications in green up-conversion luminescence.

Preparation, structure and temperature dependence of spectral properties of Yb3+/Er3+ doped Sr5(PO4)3F transparent glass ceramics

The Sr5(PO4)3F transparent glass ceramics (GCs) were achieved for the first time by crystallizing from low-cost lead-free borate glasses. The structure, optical and Up-conversion luminescence characteristics of Yb3+/Er3+ co-doped transparent GCs were studied. The results show that the luminescence properties of Sr5(PO4)3F transparent GCs are distinctly improved compared with precursor glass, which stands to benefit from both low phonon energy environment of Sr5(PO4)3F GCs and the unique structural features of fluorapatite. Under the 980 nm laser, the optical temperature measurement performance of GC samples was evaluated based on the fluorescence intensity ratio by using thermal coupling energy level of Er3+ ion. In this wide temperature range from 303 K to 653 K, the maximum relative sensitivity and maximum absolute sensitivity obtained are 1.26% K−1 and 0.31% K−1, respectively. It is expected to be applied in the field of optical temperature sensing.

Preparation and up-conversion luminescence properties of Er3+-Yb3+ doped glass ceramics

The molybdate precursor glass was prepared by the melting-annealing method. After heat treatment of the precursor glass, the glass ceramics containing NaBi(MoO4)2 crystal phase were successfully synthesized. The transmittance of the precursor glass and glass ceramics and up-conversion emission spectra at 980 nm were measured and analyzed. The effect of Er3+-Yb3+ doped concentration on the up-conversion luminescence intensity of glass ceramic samples was studied, and finally the best doped concentrations of Er3+ and Yb3+ were 0.6% and 1.0%, and the doped concentration ratio is 3:5. The Er3+-Yb3+ co-doped transparent glass ceramics containing NaBi(MoO4)2 have potential applications in green up-conversion luminescence.

Opposite temperature luminescent behaviours of Tb3+ and Pr3+ co-doped BaMoO4 glass ceramics for temperature sensing

Tb3+/Pr3+ co-doped transparent glass ceramics (GC) containing BaMoO4 nano-crystalline phase were synthesized and characterized by differential scanning calorimetry, X-ray diffraction, transmittance spectra, and high-resolution transmission electron microscope. The excitation spectra of the sample for the characteristic emission of Tb3+ and Pr3+ ions show a strong broad bands in between 250–300 nm, which are attributed to Pr3+/Tb3+−Mo6+ charge transfer transitions. Under 266 nm excitation, the luminescent intensities of Tb3+: 5D4 → 7F5 (543 nm) and Pr3+: 3P1 → 3H5 (527 nm) show opposite temperature dependences, as the former decreases due to thermo-quenching while the latter increases due to thermo-coupling of 3P0 and 3P1 emissive levels of Pr3+. This leads to a strong temperature dependent luminescent intensity ratio, which is adopted for temperature sensing. Improved relative temperature sensitivity is achieved by making use this novel opposite temperature dependences of two dopants in a single GC sample. The scheme is subject to further optimization in choosing composition and dopants, and promising for application as optical-fiber temperature sensors.

Ultra-broadband near-infrared photoluminescence in Er3+-Ni2+co-doped transparent glass ceramics containing nano-perovskite KZnF3

In this article, ultra-broadband photoluminescence in near-infrared is achieved in KZnF3 glass ceramics doped with Er3+and Ni2+ ions. Er3+-Ni2+ co-doped fluorosilicate glass and glass ceramics embedded with perovskite nanocrystals were fabricated and efficient energy transfer (ET) from Er3+ to Ni2+ ions was confirmed by luminescence spectra and decay curves. In the glass ceramic samples, Ni2+ ions were effectively sensitized by Er3+, and ultra-broadband photoluminescence from 1400 to 2300 nm was observed when a 980 nm laser was used as a pump, as shown in Fig. 1. The temperature and humidity stability of the glass ceramic samples was characterized from the measured transmittance. These results demonstrated that Ni2+-Er3+ co-doped glass ceramics have significant potential for application in optical communication and broadband amplifiers.

Energy transfer and control of color luminescence in Dy3+/Tb3+ co-doped transparent oxyfluorosilicate glass ceramics containing LiYF4 nanocrystals

Dy3+/Tb3+ co-doped oxyfluoride glass ceramics (GC) containing lithium tetrafluoroyttrium (LiYF4) and yttrium fluoride (YF3) nanograins were prepared by a traditional melt-quenching approach. The crystalline phases and morphologies of the GCs were investigated. The GCs showed enhanced green emission from Tb3+ ions and the quenching of Dy3+ emission because of the efficient energy transfer from Dy3+ to Tb3+ ions. The electric dipole-dipole interactions were responsible for the energy transfer mechanism between Dy3+ and Tb3+ ions. The energy transfer efficiencies of these glass ceramics were calculated from their decay curves. The Dy3+/Tb3+ co-doped oxyfluoride GCs with various visible emissions were found to be potential candidates for white-light emitting diode applications.

Preparation, luminescence properties and energy transfer of Tm3+ and Tm3+-Eu3+ doped glass-ceramics containing NaY(MoO4)2

A series of Tm3+ mono-doped and Tm3+-Eu3+ co-doped transparent glass-ceramics (GCs) containing NaY(MoO4)2 crystal phase was synthesized by melt quenching and glass crystallization. The optimal heat treatment condition, crystal structure, microscopic morphology, transmittance, luminescent properties and energy transfer of samples were studied using DSC, XRD, SEM, spectrophotometer and fluorescence spectrometer, respectively. When the Tm3+ mono-doped concentration is 0.4%, the emission intensity is the strongest at 456 ​nm due to 1D2→3F4 transition of Tm3+. Energy transfer from Tm3+ to Eu3+ is observed by fluorescence spectra of Tm3+-Eu3+ co-doped GCs, and the optimal doping concentrations of Tm3+ and Eu3+ are 0.4% and 1.3%, respectively. In addition, the Tm3+-Eu3+ co-doped GCs can achieve tunable emission from blue to purple by adjusting the doping concentration of Eu3+. These results indicate that Tm3+ mono-doped and Tm3+-Eu3+ co-doped GCs have potential applications in the field of color display.

Structure, luminescence and energy transfer of Eu2,3+/Tb3+ co-doped transparent glass ceramics containing α-Ca3(PO4)2 nanocrystals

Eu2,3+/Tb3+ co-doped transparent glass ceramics containing α-Ca3(PO4)2 nanocrystals were prepared through a phase-separation-controlled crystallization route. The XRD and TEM results revealed that α-Ca3(PO4)2 nanocrystals dispersed uniformly in the CaO–P2O5–SiO2–Al2O3–ZrO2 glass matrix, and grew gradually with increasing heat-treated temperature. Optical spectroscopy analysis confirmed the self-reduction of Eu3+ to Eu2+ in the Eu-doped samples, and the luminescence was tuned with increasing heat-treated temperature and doping concentration. Noticeably, Eu2+, Tb3+ and Eu3+ ions respectively behaved as the blue, green and red luminescent centers, and thus various emitting colors were easily obtained through adjusting the doping concentrations of rare earth ions. Besides, the energy transfer mechanism between Eu2+, Tb3+ and Eu3+ was discussed.

Effects of La3+ on the enhancement NIR quantum cutting and UC emissions in Nd3+–Yb3+ co-doped transparent silicate glass-ceramics for solar cells

Near-infrared (NIR) quantum cutting (QC) and upconversion (UC) emission of Nd3+–Yb3+ co-doped in Si–Al–Ba–La transparent silicate glass-ceramics (SGC) were prepared. Influence of La3+ on the enhancement NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ in SGC were investigated. Thereby, NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ were increased strongly with increasing concentration of LaF3 from 5 up to 25 mol. %. The value of NIR QC emission intensity of the co-doped Nd3+–Yb3+ band centered at ~890, 947, 1071, 1339 and 1430 nm is maximized when the concentration of LaF3 reaches 25 mol. %. At the same time, with the increasing concentration of Yb3+, NIR QC emission intensity of the co-doped Nd3+–Yb3+ bands centered at ~890, 1071, 1339 and 1430 nm of Nd3+ and 947 nm of Yb3+ were gradually increased and reaches its maximum at 2.5 mol. % Yb3+, then decreased owing to the self-quenching effect. In addition, NIR QC mechanism and energy transfer (ET) processes between 2F5/2 → 2F7/2 transition of Yb3+ and transitions of Nd3+ are discussed.

Luminescence and energy transfer studies of Eu3+-Tb3+ co-doped transparent glass ceramics containing BaMoO4 crystallites

The Tb3+ mono-doped and Eu3+-Tb3+ co-doped transparent glass-ceramics (GCs) were fabricated via melt-quenching technique and subsequent heating. The crystal structural and luminescence properties of the samples were systematically investigated via X-ray diffraction (XRD), scanning electron microscope (SEM), transmittance, excitation and emission spectra, and fluorescence lifetime, respectively. The emission spectra of Tb3+ mono-doped GCs are composed of several sharp emission lines about at 410 nm, 436 nm, 488 nm, 545 nm, 587 nm and 622 nm, respectively. Among them, when the Tb3+ mono-doped concentration is 0.7mol%, the brightest green light is generating at 545 nm due to 5D4→7F5 transition of Tb3+ ions. The effective energy transfer from Tb3+ to Eu3+ was observed by fluorescence spectra and fluorescence lifetimes of Eu3+-Tb3+ co-doped GCs. In addition, the emission of Eu3+-Tb3+ co-doped GCs from light green-white-yellow can be achieved by adjusting the doping concentration of Eu3+ and Tb3+. These results indicate that Eu3+-Tb3+ co-doped GCs have potential applications in the field of white light emitting diodes (w-LEDs).