Effect of silica coating on the structural and luminescent properties of Sm3+/Yb3+ or Tm3+/Yb3+ co-doped TiO2 nanoparticles

The luminescent characteristics of spherical titanium dioxide (TiO₂) nanoparticles (NP's) doped with Sm³⁺/Yb³⁺ and Tm³⁺/Yb³⁺ with and without a silica coating were analyzed. These nanoparticles were synthesized using the spray pyrolysis technique and coated with silica through a wet chemical process. The Sm³⁺/Tm³⁺ and Yb³⁺ doping induces a triphasic poly-crystalline structure of rutile and anatase TiO₂ and a Sm₂Ti₂O₇/Tm₂Ti₂O₇ cubic phase. A Williamson-Hall analysis was used to monitor the tensions of the NP's crystallites at the various doping concentrations and with addition of the silica shell. The luminescent spectra presented the characteristic emission peaks for the electronic energy levels transitions of the Sm³⁺/Tm³⁺ and Yb³⁺ ions. The Sm³⁺/Yb³⁺ co-doped NP's showed a maximum emission peak in the visible region at 612 nm, associated with ⁴G_5/2 → ⁶H_7/2 transitions of the Sm³⁺ ions. The IR emission peak at 973 nm (²F_5/2 → ²F_7/2) pertaining to Yb³⁺. For the combination of Tm³⁺/Yb³⁺, two emissions associated with Tm³⁺ ions were observed at 440 nm (¹D₂ → ³F₄) and 806 nm (³H₄ → ³H₆). The emission at 973 nm (²F_5/2 → ²F_7/2) is correlated to the Yb³⁺ ions. Silica coating of the NP's resulted in luminescence emission intensity increase of about 4 times.     

Up-conversion emission color tuning in NaLa(MoO4)2: Nd3+/Yb3+/Ho3+ excited at 808 nm

As alternatives to Yb³⁺-sensitized up-conversion (UC) materials excited at 980 nm, Nd³⁺-sensitized UC phosphors irradiated by 808 nm have been used to decrease the absorption of water and alleviate the overheating effect in vivo biological application. Intense red and green UC emissions from ⁵F₅→⁵I₈ and ⁵F₄/⁵S₂→⁵I₈ transitions of Ho³⁺ appeared in Nd³⁺/Yb³⁺/Ho³⁺ tri-doped NaLa(MoO₄)₂ through successive energy transfer Nd³⁺→Yb³⁺→Ho³⁺ under 808 nm excitation, in which Yb³⁺ ions were proven to be the energy transfer bridge between Nd³⁺ and Ho³⁺ by lifetime measurement. The variable emission color and intensity ratios of red to green emissions were realized by adjusting the doping concentration of Yb³⁺, pulse width of the excitation laser and the addition of Ce³⁺ ion, which depends on the different population pathways to the green and red emitting states of Ho³⁺. The chromaticity modulation mechanisms of these approaches were proposed, which provides a feasible strategy to tune the UC emission color.     

Energy transfer and up-conversion luminescence in Er/Yb co-doped transparent glass ceramic containing YF3 nano-crystals

Transparent glass ceramics containing YF₃ nano-crystals were fabricated by heat treatment of the SiO₂–Al₂O₃–NaF–YF₃–LnF₃ (Ln = Er, Yb) glasses. X-ray diffraction and transmission electron microscopy analyses evidenced the homogeneous distribution of spherical YF₃ nano-crystals sized 25–30 nm among the glassy matrix. Energy dispersive X-ray spectroscopy measurement, combined with the Stark splitting of the absorption and emission bands, verified the incorporation of Er³⁺ and Yb³⁺ ions into YF₃ nano-crystals. The infrared to visible up-conversion emission of Er³⁺ intensified with the increasing of Yb³⁺ concentration, ascribing to the increase of the efficiency of non-radiative energy transfer from Yb³⁺ to Er³⁺ which exceeded 45% for the 0.5Er³⁺/1.0Yb³⁺ co-doped sample. The up-conversion luminescence at 545 and 660 nm were affirmed coming from two-photon excitation process.     

Enhancement of up-conversion emission and emerging cool white light emission in co-doped Yb3+/ Er3+: Li2O-LiF-B2O3-ZnO glasses for photonic applications

A series of co-doped (Yb³⁺/Er³⁺): Li₂O-LiF-B₂O₃-ZnO glasses were prepared by standard melt quenching technique. Structural and morphological studies were carried out by XRD and FESEM. Phonon energy dynamics have been clearly elucidated by Laser Raman analysis. The pertinent absorption bands were observed in optical absorption spectra of singly doped and co-doped Yb³⁺/Er³⁺: LBZ glasses. We have been observed a strong up-conversion red emission pertaining to Er³⁺ ions at 1.0 mol% under the excitation of 980 nm. However, the up-conversion and down conversion (1.53 µm) emission intensities were remarkably enhanced with the addition of Yb³⁺ ions to Er³⁺: LBZ glasses due to energy transfer from Yb³⁺ to Er³⁺. Up-conversion emission spectra of co-doped (Yb³⁺/Er³⁺): LBZ glasses exhibits three strong emissions at 480 nm, 541 nm and 610 nm which are assigned with corresponding electronic transitions of ²H_9/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 respectively. Consequently, the green to red ratio values (G/R) also supports the strong up-conversion emission. The Commission International de E′clairage coordinates and correlated color temperatures (CCT) were calculated from their up-conversion emission spectra of co-doped (Yb³⁺/Er³⁺): LBZ glasses. The obtained chromaticity coordinates for optimized glass (0.332, 0.337) with CCT value at 5520 K are very close to the standard white colorimetric point in cool white region. These results could be suggested that the obtained co-doped (Yb³⁺/Er³⁺): LBZ glasses are promising candidates for w-LEDs applications.     

High-accuracy dual-mode optical thermometry based on up-conversion luminescence in Er3+/Ho3+-Yb3+ doped LaNbO4 phosphors

Due to the non-contact and high sensitivity, optical thermometry based on rare earth doped phosphors has been paid much attention to. Herein, dual-mode optical thermometers are designed using up-conversion luminescence of Er³⁺/Ho³⁺-Yb³⁺ doped LaNbO₄ phosphors, which were synthesized for the first time by high-temperature solid-state reaction method. The LaNbO₄:1Er³⁺:10Yb³⁺ and LaNbO₄:1Ho³⁺:10Yb³⁺ phosphors exhibit reliable and excellent thermometric performance by combining fluorescence intensity ratio and decay lifetime for self-calibration. Specifically, the maximal relative sensitivities based on fluorescence lifetime were 0.27 %K⁻¹ and 0.33 %K⁻¹ for LaNbO₄:1Er³⁺:10Yb³⁺ and LaNbO₄:1Ho³⁺:10Yb³⁺ phosphors, respectively. The maximal relative sensitivity is 1.12 %K⁻¹ when using intensity ratio between thermal coupling energy levels in LaNbO₄:1Er³⁺:10Yb³⁺ as a detecting signal. Furthermore, the maximal relative sensitivity reaches as high as 0.98 %K⁻¹ when taking advantage of special non-thermal coupling energy levels in LaNbO₄:1Ho³⁺:10Yb³⁺. These results indicate that Er³⁺/Ho³⁺-Yb³⁺ doped LaNbO₄ phosphors possess great potential in self-calibrated optical thermometric techniques.     

Tuning size and up-conversion luminescence of CeO2:Yb3+/Er3+ nanoparticles through lanthanide doping

Particle size is a critical parameter in up-conversion luminescence tuning and application research. In this study, CeO₂:Yb³⁺/Er³⁺ nanospheres were synthesized via coprecipitation. The average size of these nanospheres gradually decreased as the Yb³⁺ doping concentration increased, which might be attributed to the influence of Yb³⁺ doping on the growth rate of nanospheres by surface charge repulsion. Upon exciting these nanospheres using a 980-nm laser, the corresponding up-conversion red-green emission intensity ratio gradually increased as the Yb³⁺ doping concentration increased, which might be ascribed to two reasons: the strengthened ⁴S_3/2 → ⁴F_9/2 nonradiative relaxation process and the enhanced Er³⁺ → Yb³⁺ energy back-transfer process. To assess the influence of the nonradiative relaxation process on the up-conversion emission red-green ratios, the down-conversion emission spectra and decay curves of CeO₂:x%Yb³⁺/2%Er³⁺ nanospheres that were excited by a 520 nm laser were investigated. To validate how the particle size affects the up-conversion emission, CeO₂:x%Lu³⁺/2%Yb³⁺/2%Er³⁺ nanospheres of various sizes were synthesized by substituting optically active Yb³⁺ using optically inert Lu³⁺. The corresponding up-conversion emission spectra and decay curves were investigated. The experimental results enhanced our understanding of how lanthanide doping affects the up-conversion luminescence tuning of Er³⁺, offering great potential to regulate the morphology and optical properties of the up-conversion luminescence nanoparticles.     

Luminescent properties and energy transfer mechanism of NaGd(MoO4)2:Sm3+, Eu3+ phosphors

Sm³⁺ singly doped NaGd(MoO₄)₂ and Sm³⁺, Eu³⁺ co-doped NaGd(MoO₄)₂ phosphors by using sodium citrate as chelating agent were synthesized via hydrothermal method. The structure and morphology were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). During the synthesis process, the Na₃Cit concentration plays a crucial role in determining the morphology and particle size of the products. The optimal doping concentration in Sm³⁺ singly doped NaGd(MoO₄)₂ phosphor was confirmed. The relevant parameters of energy transfer in the NaGd(MoO₄)₂: Sm³⁺, Eu³⁺ phosphors have been calculated based on the fluorescent dynamic analysis. Finally, on the analysis of luminescent spectra and fluorescent dynamics, the main energy transfer mechanism between Sm³⁺ and Eu³⁺ in NaGd(MoO₄)₂ phosphor is confirmed to be electric dipole-dipole interaction, and energy transfer pathway is from ⁴G_5/2 state of Sm³⁺ to ⁵D₀ state of Eu³⁺ rather than ⁵D₁ of Eu³⁺ ions.     

Synthesis and up-conversion of Er3+ and Yb3+ Co-doped LiY(MoO4)2@SiO2 for optical thermometry applications

Non-contact temperature sensors based on the fluorescence intensity ratio (FIR) have been widely investigated owing to their high sensitivity and reliable real-time monitoring. Herein, the SiO₂-coated LiY(MoO₄)₂@SiO₂:Er³⁺,Yb³⁺ phosphor was investigated as an optical thermometry material, which was synthesized using the conventional solid state reaction and coated by a facile wet chemical route. The effect of surface modification on FIR was systematically characterized by structural analyses and spectral measurements and the temperature-dependent up-conversion FIR was investigated from 303 to 603 K under a 980 nm laser excitation. The results showed that the FIR value was thermally stable and the SiO₂ coating led to a higher FIR sensitivity as well as a higher saturation threshold. This work would pave a way to design interesting optical thermometry materials in up-conversion phosphors with better properties.     

High sensitive Ln3+/Tm3+/Yb3+ (Ln3+ = Ho3+, Er3+) tri-doped Ba3Y4O9 upconverting optical thermometric materials based on diverse thermal response from non-thermally coupled energy levels

Upconversion (UC) optical thermometers using the fluorescence intensity ratio (FIR) technique arising from the thermally coupled energy levels (TCLs) are still suffering from low sensitivity owing to the restriction of small energy gap. In the present study, a strategy to strive for superior temperature sensitivity and signal discriminability is employed with the help of non-thermally coupled energy levels (NTCLs). A novel tri-doped Ba₃Y₄O₉: Ho³⁺/Tm³⁺/Yb³⁺ phosphor with rhombohedral symmetry was successfully prepared via a solid-state reaction method, and the temperature sensing performance was evaluated by analyzing temperature-dependent upconversion emission spectra. The emission intensities of both Ho³⁺ and Tm³⁺ activators can be almost completely restored to their original values when the temperature of the sample is cooled to room temperature. The temperature-dependent FIR between NTCLs can be fitted well by a derived three-term equation with the correlation coefficient above 99.6%, and the FIR of NTCLs exhibits high temperature sensitivity over a wide temperature range owing to the different temperature responses of the NTCLs. The maximum absolute sensitivity S_A and relative sensitivity S_R values reaches as high as 0.0552?K^?1 and 1.49% K^?1, respectively, which are much higher than those of the previously reported bulk UC optical temperature sensing materials. Moreover, the emission bands of NTCLs are well separated, which endows the material a good signal discriminability for temperature detection. Excellent temperature sensing performance is also demonstrated in Er³⁺/Tm³⁺/Yb³⁺ tri-doped Ba₃Y₄O₉, evidencing the validity of this strategy. These results indicate that the present UC materials can be potential candidates for optical temperature sensors, and the present strategy will provide a thought for developing other innovative UC temperature sensing materials.     

Tailorable Multicolor Up‐conversion Emissions in Tm3+/Ho3+/Yb3+ Co‐Doped LiLa(MoO4)2

Using a modified sol–gel method, LiLa(MoO₄)₂: Tm³⁺/Ho³⁺/Yb³⁺ phosphors with tailorable up‐conversion (UC) emission colors were prepared. Under the excitation of a 980 nm laser diode, up‐conversion red and green emissions in Ho³⁺/Yb³⁺ co‐doped and blue emission in Tm³⁺/Yb³⁺ co‐doped LiLa(MoO₄)₂ were observed, respectively. The intensities of the RGB (red, green, and blue) emissions could be controlled by varying concentrations of Tm³⁺ or Ho³⁺, and the optimal composition was also determined. In Tm³⁺/Ho³⁺/Yb³⁺ co‐doped LiLa(MoO₄)₂, the UC emission colors could be tuned from blue through white to yellow by adjusting the concentrations of Tm³⁺ or Ho³⁺. The UC excitation mechanisms were also investigated based on the power dependence of UC luminescence intensity.     

Design and preparation of white light emission from up-conversion transitions in Er3+/Tm3+/Yb3+ co-doped cubic zirconia single crystals

High-quality cubic YSZ crystals were designed with various contents of Er³⁺, Tm³⁺ and Yb³⁺ to produce white light emission, and grown by the optical floating zone method. The up-conversion luminescence spectra of the crystals under 980 nm laser irradiation show three distinct groups of emission peaks at ∼473 nm (blue) generated by the Tm^{3+ 1}G₄→³H₆ transition, 531 and 547 nm (green) from the Er^{3+ 2}H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions, and 640 and 662 nm (red) from the Er^{3+ 4}F_9/2 → ⁴I_15/2 transition. The optical power curve obtained by plotting the up-conversion luminescence intensity against the laser power shows that the blue emission involves a three-photon process, whilst both the green and red emissions are the results of two-photon processes. Overall white light emission was observed with the crystal prepared with 0.05 mol% Er₂O₃, 0.5 mol% Tm₂O₃ and 2.0 mol% Yb₂O₃, and this crystal is suitable for use in highly efficient white light emission devices.     

Preparation and infrared to visible upconversion luminescence of Yb2O3:Ho3+ nanocrystalline powders

Yb₂O₃:Ho³⁺ nanocrystalline powders were synthesized through a solid state reaction method. X-ray diffraction analysis and field emission scanning electron microscopy were used to analyze the phase composition and morphology of the powders. Then under the 980 nm excitation of laser diode, the fluorescence of the crystals was studied via a fluorescence spectrometer. The green and red emissions centered on 551 and 668 nm were observed, and the green band dominated the emission spectrum. The effect of the concentration of Ho³⁺ on the upconversion luminescence intensity was discussed and the possible upconversion emission mechanism was explained. It indicates that like other metal oxide nanoparticles, Yb₂O₃ could also be a potential host material for doping to prepare the upconversion phosphor.     

Synthesis,crystal structure,photoluminescence of Ba3Y2(BO3)4:Er3+ and thermal expansion of Ba3Y2(BO3)4

The Ba₃Y_2–xEr_x(BO₃)₄ (х = 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) phosphors were obtained by crystallization from a melt. The Ba₃Y₂(BO₃)₄ crystal structure was refined from single crystal X-ray diffraction data to R = 0.037. Its anisotropic atomic displacement parameters for all atoms were refined for the first time. The borate crystallizes in the orthorhombic crystal system, space group Pnma with unit cell parameters a = 7.673(1), b = 16.44(1), c = 8.977(2) Å, V = 1132.3(3) ų, Z = 4. These phosphors are isotypical to those of the A₃M₂(BO₃)₄ (A = Ca, Sr, Ba, M = Ln, Y, Bi) family. The crystal structure contains the isolated BO₃ triangles, two general and a special one independent crystallographic sites for large cations, which are disordered over sites. Thermal behavior of Ba₃Y₂(BO₃)₄ was investigated by high-temperature X-ray powder diffraction and thermal expansion coefficients are calculated in a wide temperature range. An inflections of temperature dependencies of the unit cell parameters is observed in a range 600–740 °C. Luminescence spectra, excitation and kinetic curves of the Ba₃Y₂(BO₃)₄:Er³⁺ series are reported. A maximum luminescence intensity is observed for the x = 0.1 sample. According to vibrational spectroscopy data no structural changes upon activation of the Ba₃Y₂(BO₃)₄ matrix with the Er ions are observed.     

Synthesis and photoluminescence properties of CaGd2(MoO4)4:Eu3+ red phosphors

The novel red-emitting Eu³⁺ ions activated CaGd₂(MoO₄)₄ phosphors were prepared by a citrate sol–gel method. The X-ray diffraction patterns confirmed their tetragonal structure when the samples were annealed above 600 °C. The photoluminescence excitation spectra of CaGd₂(MoO₄)₄:Eu³⁺ phosphors exhibited the charge transfer band (CTB) and intense f–f transitions of Eu³⁺ ion. The optimized annealing temperature and Eu³⁺ ion concentration were analyzed for CaGd₂(MoO₄)₄:Eu³⁺ phosphors based on the dominant red (⁵D₀→⁷F₂) emission intensity under NUV (394 nm) excitation. All decay curves were well fitted by the single exponential function. These luminescent powders are expected to find potential applications such as WLEDs and optical display systems.     

Tunable emission of single-phased NaY(WO4)2:Sm3+ phosphor based on energy transfer

A series of NaY(WO₄)₂:Sm³⁺ phosphors were prepared by high temperature solid state reaction. When excited by ultraviolet and blue light, their emission spectra cover entirely visible light region, due to intrinsic luminescence of WO₄^2- group as well as Sm³⁺ 4f-4f transitions. White light emission was obtained from NaY_0.99Sm_0.01(WO₄)₂ phosphor under radiation of 265 nm UV light, and intense yellow and red emission from ⁶H_{J(J=5/2, 7/2, 9/2)} transitions were observed when pumped Sm^{3+ 4}G_5/2 by 405 nm blue light. With incorporation of Sm³⁺ into NaY(WO₄)₂ host, higher-level emission from Sm³⁺ at 650 nm was generated by energy transfer from WO₄^2- to Sm³⁺ under excitation of 265 nm. The corresponding energy transfer mechanism was demonstrated to be a dipole-dipole interaction. In addition, tunable emission from blue to white and, finally, to red was realized by increasing Sm³⁺ doping concentration. The band gap of NaY(WO₄)₂ calculated from diffuse reflection spectra indicates a semiconducting character. All these results show that NaY_1−xSm_x(WO₄)₂ phosphor provides promising application for conversion of frequencies emitted by UV or blue LEDs.     

Structural,magnetic, vibrational and impedance properties of Pr and Ti codoped BiFeO3 multiferroic ceramics

Single-phase (Bi_1−xPr_x)(Fe_1−xTi_x)O₃ ceramics (x=0.03, 0.06, and 0.10 as BPFT-3, BPFT-6 and BPFT-10, respectively) were synthesized by conventional solid state reaction method. The effect of varying Pr and Ti codoping concentration on the structural, magnetic, dielectric and optical properties of the BPFT ceramics have been investigated. X-ray diffraction indicated pure rhombohedral phase formation for BPFT-3 and BPFT-6 ceramics, however, a structural phase transition from a rhombohedral to an orthorhombic phase has been observed for BPFT-10 ceramic. The maximum remnant magnetization of 0.1824 emu/g has been observed in BPFT-6. With increasing codoping concentration the room temperature dielectric measurements showed enhancement in dielectric properties with reduced dielectric loss. UV–vis diffuse reflectance spectra demonstrated the strong absorption of light in the visible region for a band gap variation 2.31–2.34 eV. Infrared spectroscopy indicated the shifting of Bi/Pr–O and Fe/Ti–O bonds vibrations and change in Fe/Ti–O bond lengths. Decrease in the conductivity on increasing Pr and Ti concentration in BFO is attributed to an enhancement in the barrier properties leading to suppression of lattice conduction path arising due to lattice distortion as confirmed from impedance analysis.     

Broad-scope dual-mode modulation thermometry based on up-conversion phosphor GaNbO4: Yb3+/Er3+

Fluorescence temperature measurement technology has set off another upsurge in non-contact temperature measurement, but still suffers from the large error for single-mode thermometry. Herein, in a broad temperature range of 93–633 K, a dual-mode modulation thermometry based on up-conversion phosphor of GaNbO₄:Yb³⁺/Er³⁺ is realized with the maximum relative sensitivity (S_r) of 11.7% K⁻¹ (93 K) and 13.1% K⁻¹ (123 K), respectively. GaNbO₄:Yb³⁺/Er³⁺ phosphors were synthesized by high temperature solid-state method. The structure, surface morphology and the optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The fluorescence intensity ratio (FIR) readout method based on Er³⁺ thermal-coupled energy level (TCL) and non-thermal-coupled energy level (NTCL) was used to achieve the dual-mode temperature measurement with high temperature resolution and good repeatability in GaNbO₄:5 mol% Yb³⁺ and 5 mol% Er³⁺ phosphors. All the results show that GaNbO₄:Yb³⁺/Er³⁺ phosphors have great application potential in high sensitivity broadband thermometry.     

Up-conversion luminescence and optical thermometry properties of transparent glass ceramics containing CaF2:Yb3+/Er3+ nanocrystals

A series of Yb³⁺/Er³⁺ codoped transparent oxyfluoride glass ceramics with various amounts of Yb³⁺ have been successfully fabricated and characterized. Under 980 nm laser prompting, the samples produce intense red, green and blue up-conversion emissions, and the emission intensities increase with Yb³⁺ concentration and heat treatment temperature. Before losing good transparency in the visible region, optimum emission intensities are obtained for the sample with 25 mol% of Yb³⁺ at a heat treatment temperature of 680 °C. A possible up-conversion mechanism is proposed from the dependence of emission intensities on pumping power. The fluorescence intensity ratio between the two thermally coupled levels ²H_11/2 versus ⁴S_3/2 was measured with the laser output power of 57 mW to avoid the possible laser induced heating effect. The fluorescence intensity ratio values in the temperature range from 295 K to 723 K can be well fitted with the equation: A exp (−∆E/k_BT), where A = 6.79 and ∆E=876 cm⁻¹. The relative temperature sensitivity at 300 K was evaluated to be 1.4% K⁻¹. All the results suggest that the Yb³⁺/Er³⁺ codoped CaF₂ glass ceramics is an efficient up-conversion material with potential in optical fiber temperature sensing.     

Upconverting luminescence based dual-modal temperature sensing for Yb3+/Er3+/Tm3+: YF3 nanocrystals embedded glass ceramic

Yb³⁺/Er³⁺/Tm³⁺ doped transparent glass ceramic containing orthorhombic YF₃ nanoparticles was successfully synthesized by a melt-quenching method. After glass crystallization, tremendously enhanced (about 5000 times) upconversion luminescence, obvious Start-splitting of emission bands as well as long upconversion lifetimes of Er³⁺/Tm³⁺ confirmed the incorporation of lanthanide activators into precipitated YF₃ crystalline environment with low phonon energy. Furthermore, temperature-dependent upconversion luminescence behaviors of glass ceramic were systematically investigated to explore its possible application as optical thermometric medium. Impressively, both fluorescence intensity ratio of Er³⁺: ²H_11/2 → ⁴I_15/2 transition to Er³⁺: ⁴S_3/2 → ⁴I_15/2 one and fluorescence intensity ratio of Tm³⁺: ³F_2,3 → ³H₆ transition to the combined Tm³⁺: ¹G₄ → ³F₄/Er³⁺: ⁴F_9/2 → ⁴I_15/2 ones were demonstrated to be applicable as temperature probes, enabling dual-modal temperature sensing. Finally, the thermal effect induced by the irradiation of 980 nm laser was found to be negligible in the glass ceramic sample, being beneficial to gain intense and precise probing signal and detect temperature accurately.     

Color-tunable up-conversion emission in Y2O3:Yb3+, Er3+ nanoparticles prepared by polymer complex solution method

Abstract

Powders of Y₂O₃ co-doped with Yb³⁺ and Er³⁺ composed of well-crystallized nanoparticles (30 to 50 nm in diameter) with no adsorbed ligand species on their surface are prepared by polymer complex solution method. These powders exhibit up-conversion emission upon 978-nm excitation with a color that can be tuned from green to red by changing the Yb³⁺/Er³⁺ concentration ratio. The mechanism underlying up-conversion color changes is presented along with material structural and optical properties.

PACS

42.70.-a, 78.55.Hx, 78.60.-b