Co-doped Phosphors Research Articles

Eu3+ and Tb3+ doped LiCaY5(BO3)6: Efficient red and green phosphors under UV or NUV excitations

Eu3+ and Tb3+ are typical red and green-emitting photoluminescent (PL) activators and rare earth borates are well-known good PL hosts. In this contribution, a recently reported borate LiCaY5(BO3)6 was selected as the host to study the Eu3+ and Tb3+ photoluminescence systematically. LiCa(Y1-xEux)5(BO3)6 (0 ≤ x ≤ 1), LiCa(Y1-yTby)5(BO3)6 (0 ≤ y ≤ 1) and LiCa(Y0.88-zTb0.12Euz)5(BO3)6 (0.01 ≤ z ≤ 0.07) were synthesized by solid state reactions and the powder X-ray diffraction proved the high purity and crystallinity by quantifying the unit cell volume expansion when replacing Y3+ with Eu3+ and Tb3+. Charge transfer band and f-f transitions of Eu3+ in ultraviolet (UV) and near UV range are both intense because there exists a strongly noncentrosymmetric site in the host. Concentration quenching effect was also observed at x = 0.30 and 0.50 when excited by CTB and 392 nm, respectively. For Tb3+, strong f-d and weak f-f transitions were observed along with the typical green emission, and the concentration quenching occurs at y = 0.12 and 0.30, respectively. It is interesting to observe the Tb3+ to Eu3+ energy transfer in co-doped phosphors, thus the color tunable emissions from green to yellow, and to red were realized by manipulating the dopant concentrations. A preliminary trial to combine these borates with NUV LED chips gave typical red, green, and warm white lights, indicating the potentials as LED-pumped phosphors.

Photoluminescence performance of Tb3+/Eu3+ doped Bi2Sn2O7 phosphors

Tb3+/Eu3+ doped Bi2Sn2O7 phosphors were synthesized by a co-precipitation method. XRD patterns indicate that Tb3+/Eu3+ doped Bi2Sn2O7 have a single phase. TEM images indicate that the phosphors are irregular particles with the size of several nanometers. Tb3+ or Eu3+ singly doped Bi2Sn2O7 phosphors show characteristic photoluminescence of Tb3+/Eu3+ ions while they are excited. And Tb3+/Eu3+ codoped Bi2Sn2O7 phosphors show tunable photoluminescence because of Tb3+ → Eu3+ energy transfer. The light can move from green region to yellowish-red region via yellow region by changing Eu3+ concentration.

Ce3+ luminescence, near-UV excitation enhancement of Tb3+ emission via energy transfer in Y4Zn4(SiO4)5:Ce3+,Tb3+ phosphor for white LED application

The luminescence property of phosphors plays an important role in the performance of phosphor-converted white light-emitting-diode (pc-WLED). In this paper, we report a simple energy-transfer (ET) strategy to enhance Tb3+ emission under near-UV excitation in Y4Zn4(SiO4)5 (YZS) doped with Ce3+/Tb3+ phosphor. The luminescence properties of YZS:Ce3+ based on crystal structure of YZS were investigated. The ET mechanism from Ce3+ to Tb3+ was also discussed in detail. The color of emitted light can be adjusted from blue to green by introducing Tb3+ ions into YZS:Ce3+. More importantly, the Tb3+ emissions under near-UV excitation are enhanced evidently, and the excitation spectrum for the Ce3+,Tb3+ co-doped phosphor matches well with the emission of near-UV chip. The selected green phosphor and commercial red, blue phosphors were coated on a 365-nm chip to fabricate a WLED device. The WLED shows an outstanding performance (Ra = 93.5 and CCT = 4769 K), indicating that YZS:Ce3+,Tb3+ phosphors have potential applications in near-UV pc-WLED as a green-emitting component.

Down conversion studies in Ce3+ and Yb3+ doped Ca2SiO4 phosphors from agricultural waste: Si based solar cell applications

Ca2SiO4 phosphors activated with Ce3+/Yb3+ ions were prepared by the solid-state reaction method by extracting the raw materials from the agricultural waste of egg shells and rice husk. The XRD spectra reveal that the prepared phosphors have monoclinic structure. The introduction of Yb3+ ions led to decrease in intensities of Ce3+ ions at 381 nm. Conversely, the NIR emission intensity of Yb3+ ion at 980 nm is found to increased up to 0.5 mol % of Yb3+ ions and then decreases. The results indicate that there would be co-operative energy transfer between Ce3+ and Yb3+ ions. The lifetime is found to decrease from 12 to 6 μs when the concentration of Yb3+ is increased from 0.1 to 2.0 mol %. The results indicate that the Ce3+ and Yb3+ co-doped Ca2SiO4 phosphors could be useful for spectral down-conversion applications.

Up-Converting Luminescence and Temperature Sensing of Er3+/Tm3+/Yb3+ Co-Doped NaYF4 Phosphors Operating in Visible and the First Biological Window Range.

Accurate and reliable non-contact temperature sensors are imperative for industrial production and scientific research. Here, Er3+/Tm3+/Yb3+ co-doped NaYF4 phosphors were studied as an optical thermometry material. The typical hydrothermal method was used to synthesize hexagonal Er3+/Tm3+/Yb3+ co-doped NaYF4 phosphors and the morphology was approximately rod-like. The up-conversion emissions of the samples were located at 475, 520, 550, 650, 692 and 800 nm. Thermo-responsive emissions from the samples were monitored to evaluate the relative sensing sensitivity. The thermal coupled energy level- and non-thermal coupled energy level-based luminescence intensity ratio thermometry of the sample demonstrated that these two methods can be used to test temperature. Two green emissions (520 and 550 nm), radiated from 2H11/2/4S3/2 levels, were monitored, and the maximum relative sensing sensitivities reached to 0.013 K−1 at 297 K. The emissions located in the first biological window (650, 692 and 800 nm) were monitored and the maximum relative sensing sensitivities reached to 0.027 (R692/650) and 0.028 K−1 (R692/800) at 297 K, respectively. These results indicate that Er3+/Tm3+/Yb3+ co-doped NaYF4 phosphors have potential applications for temperature determination in the visible and the first biological window ranges.

A potential temperature sensing material: Studies of structure and temperature-sensitive photoluminescent properties of Nb5+, Sm3+ doped YTaO4

Non-contact luminescence temperature measurement technology shows a broad application prospect in medical, high-temperature environment and other fields, which has attracted people's attention for its high-precision, real-time response and so on. In this work, Nb5+, Sm3+ single-doped and co-doped YTaO4 phosphor was designed. YTaO4 with M-type and M′-type structures can be obtained by adjusting the synthesis conditions. The structure and composition of the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM). The photoluminescent properties of NbO43− group and Sm3+ ions in M-type and M′-type YTaO4 matrix were studied. Due to the different thermal responses of Nb5+ and Sm3+ ions, the fluorescence intensity ratio between them can be used as temperature detecting signal. In the range of 77–500 K, the maximum relative sensitivity of the YTaO4: Nb5+, Sm3+ reaches 1.15 %K−1 at 450 K, indicating that the Nb5+ and Sm3+ co-doped M-type YTaO4 phosphors can be used as optical temperature sensor. This research may provide guidance for the design of other rare earth doped luminescent materials for temperature detection.

Improved photoluminescence in Eu3+ doped LaVO4 phosphor via co-doping of Li+/Ca2+ ions

This paper investigates the structural and optical properties of Eu3+ doped LaVO4 phosphor via co-doping of Li+ and Ca2+ ions. The unit cell volume and particles size vary with Li+ and Ca2+ ions. The Eu3+ doped phosphor emits intense red color at 613 nm due to Eu3+ ion on excitation with 266, 355 and 394 nm. The photoluminescence intensity of Eu3+ doped phosphor is enhanced up to 2.1 and 4.5 times via co-doping of Li+ and Ca2+ ions, respectively. Therefore, the Eu3+, Li+, Ca2+ co-doped LaVO4 phosphor may be suitable candidate for the development of display devices and white light emitting diodes.

Synthesis and enhanced photoluminescence of the BaSiF6:Dy3+ phosphors by Li+ doping via combustion method

Undoped BaSiF6, Dy3+ doped BaSiF6, and Dy3+, Li+ co-doped BaSiF6 phosphors were synthesized through a gel-combustion method. The prepared samples were characterized by powder x-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive x-ray spectroscopy (EDS), and photoluminescence (PL) techniques. The XRD data revealed that both the Dy3+ doped and Li + co-doped BaSiF6 phosphors exhibited a single-phase structure belonging to the space group R3m‾ which matched well with the standard JCPDS files (No. 002–6613). FTIR spectra showed absorption bands at 3417 cm−1, 1640 cm−1, and 1620 cm−1 corresponding to water molecules. EDS analysis confirmed the chemical composition of the prepared samples. The PL emission spectra of BaSiF6:Dy3+ by different co-doping concentrations of Li+ exhibited prominent emission peaks at 490 nm, 572 nm, 672 nm and 758 nm. The incorporation of Li+ is beneficial for enhancing the photoluminescence intensity. The optimum Li+ amount was 8% for BaSiF6:Dy3+ and then started to decrease. The enhancement could be due to the occurrence of oxygen vacancies due to the incorporation of Li + ions. The x = 0.301 and y = 0.361 coordinates of this phosphor with varying Li+ dopant concentration determined by the Commission Internationale de l'Eclairage (CIE - 1931) were in the white range. The present work demonstrates how a simple and effective method can be used to prepare novel nanophosphors for applications in the field of visible light emitting devices with enhanced white emission.

Fluorescence intensity ratio optical thermometer YNbO4: Pr3+, Tb3+ based on intervalence charge transfer

Currently, due to the advantages of fast response, remote operations and good stability, non-contact optical temperature measurement technology based on fluorescence intensity ratio (FIR) has attracted intensive attention. Here, we successfully developed a novel Pr3+, Tb3+ co-doped YNbO4 phosphor which can be used as a non-contact optical thermometer. Under excitation at 295 nm, Pr3+, Tb3+ co-doped YNbO4 emits red light from Pr3+ (1D2 → 3H4) and green light from Tb3+ (5D4 → 7F5), simultaneously. Based on strong dependence of the emission intensity on temperature, the FIR of red and green emissions is designed as detection signal to accurately monitor temperature. The maximum absolute and relative sensitivities reached as high as 0.0125 K−1 at 508 K and 1.01% K−1 at 478 K, respectively. The luminous color of this phosphor is sensitive to the temperature, which provides the possibility for visualization of temperature measurement. There was little change in the luminescence intensity of Pr3+, Tb3+ co-doped phosphors after they went through five heating-cooling cycles. It is proved that the multi-phonon relaxation from 3P0 to 1D2 and intermediate charge transfer are responsible to the temperature-dependent luminescence of the phosphors. Optical thermometer based on the current phosphors show the advantages of high sensitivity, high precision and good repeatability. This indicates Pr3+, Tb3+ co-doped phosphors have potential application value in optical temperature sensing field.

Extremely intense green up-conversion luminescent and ultra-high temperature sensitivity in Er3+/Yb3+ co-doped BiTa7O19 phosphors

Er3+/Yb3+ co-doped BiTa7O19 phosphors with bright pure green emission were synthesized first by a solid-state reaction method. The lattice structure and morphology of the synthesized samples was determined by X-ray diffraction (XRD) and field emission scan electronic microscope (FESEM). These samples’ up-conversion luminescence (UCL) and optical temperature sensing behavior were investigated by photoluminescence spectroscopy under 980 nm laser diode (LD) excitation. The optimum values of Er3+ and Yb3+ doping concentration were 10 mol % and 40 mol %, respectively. Further optimizing the preparation process of (Bi0·5Er0.1Yb0.4)Ta7O19, the green UCL integrated intensity of (Bi0·5Er0.1Yb0.4)Ta7O19 is up to 1.32 times than that of commercial NaYF4: Er3+/Yb3+ phosphors under 980 nm LD 35.71 W/cm2 excitation. In addition, all Er3+/Yb3+ co-doped BiTa7O19 phosphors have a good green monochromaticity (Sgr), and the Sgr reached 0.98–0.99. Based on the fluorescence intensity ratio (FIR) of the transition emission of the thermally coupled 2H11/2 and 4S3/2 levels to the ground state, the maximum absolute sensitivity (SA) of optimized (Bi0·5Er0.1Yb0.4)Ta7O19 is calculated as high as 0.01624 K−1 at 475 K, which is much higher than other reported materials. These results indicate that BiTa7O19: Er3+/Yb3+ may have potential applications in biological imaging, fluorescent labels, and optical temperature sensors.

Enhancing luminescence intensity and improving thermostability of red phosphors Li3Ba2La3(WO4)8:Eu3+ by co-doping with Sm3+ ions

Co-doping with Sm3+ ions into the Eu3+-doped phosphors can bring interesting properties due to the energy transfer of Sm3+→Eu3+. Herein, Sm3+/Eu3+ co-doped phosphors Li3Ba2La3(WO4)8:xSm3+/yEu3+ were synthesized to witness this fact. Upon excitation of 404 nm light, Sm3+/Eu3+ co-doped phosphors show the characteristic emissions of both Sm3+ and Eu3+. The intensity of Sm3+ emission decreases along with the improving Eu3+ concentration, whereas the intensity of Eu3+ emission gets promoted. For Li3Ba2La2.87Sm0.08Eu0.05(WO4)8, the quantum yield reaches up to 53%. Moreover, co-doping Sm3+/Eu3+ phosphor Li3Ba2La2.87Sm0.08Eu0.05(WO4)8 possess better fluorescence thermostability than sole Eu3+ doping phosphor Li3Ba2La2.87Sm0.08Eu0.05(WO4)8, by a factor of about two. The total PL integral intensity at 450 K of Li3Ba2La2.87Sm0.08Eu0.05(WO4)8 remains 83% of that at 300 K, ensuring its applications in high power White Light Emitting Diodes (WLED).

Synthesis and luminescence properties of NaBaPO4:Tm3+,Dy3+ white-light emitting phosphors with enhanced brightness by Li+ co-doping

In this paper, a series of NaBaPO4:Tm3+, Dy3+, Li+ (NBPO) single-doped and co-doped phosphors were synthesized successfully by the traditional high-temperature solid state reaction method. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and fluorescent decay curves. The XRD results showed that samples NaBaPO4: Tm3+, Dy3+ were matched well with the standard profile NaBaPO4.White light emission can be achieved by simply adjusting the doping concentration of Tm3+ and Dy3+ ions in NaBaPO4 host. The CIE coordinates (0.3192,0.2951) of phosphor NBPO: 0.01 Tm3+, 0.04Dy3+ was closest to the coordinates of ideal white light. The enhanced emission intensity was achieved by doping Li+ ions. When the Li+ ions doping concentration was 0.01, the emission intensity reached the maximum, which was 2.2 times the emission intensity of the non-doped Li + phosphor. The results demonstrated the promising application of NaBaPO4: Tm3+, Dy3+, Li+ phosphor for near-UV white LEDs.

Multicolor emission and energy transfer dynamics in thermally stable Ca2Ga2SiO7:Tb3+/Eu3+ for warm w-LEDs application

Tb3+/Eu3+ co-doped CGS phosphor was prepared successfully through solid-state reaction technique and their structural, and emission properties were inspected in depth. X-ray diffraction (XRD) represented single-phase tetrahedral structure of Ca2Ga2SiO7 having P4¯21m space group. The emission profile for Tb3+/Eu3+ co-doped CGS phosphor exhibited peaks in the different spectral regions (blue, green, orange, and red region) under 374 nm excitation. The energy transfer from Tb3+ to Eu3+ was ascribed to dipolar- dipolar interaction as confirmed by Dexter and Reisfeld theory with 49.5% ET efficiency. The emission color of the CGS phosphor can be modulated over a vast spectral region passing via white light region by appropriately regulating Eu3+ concentration. The obtained CIE chromaticity coordinates were (0.445, 0.416) with CCT value of 2966 K, indicating warm white light emission. The emission intensity for Tb3+/Eu3+ co-doped CGS phosphor at 423 K was 85.26% of that at 298 K, indicating strong thermal stability and potential applicability for w-LEDs application.

Mn4+, Bi3 + Co-Doped K0.5La0.5SrMgTeO6 Far-Red Emitting Phosphor

A series of Mn4+ doped KmLamSr2–2mMgTeO6 phosphors and Mn4+, Bi3+ co-doped phosphors were prepared by high-temperature solid-state reaction method. It is found that the non-luminous Sr2MgTeO6: Mn4+ begins to glow when the Sr2+ sites are partially replaced by K+ and La3+ ions. The K0.5La0.5SrMgTeO6: Mn4+ phosphor gives the strongest emission peaking at 692 nm, in which half of the Sr2+ ions are replaced by La3+ and K+ ions. The optimal doping concentration of Mn4+ in K0.5La0.5SrMgTeO6 is 0.7% in mole. As the concentration of Mn4+ continues to increase, the dipole-dipole interaction-induced luminescence concentration quenching occurs. Moreover, the emission intensity of the phosphor can be further increased by 69% when co-doping Bi3+ with a concentration of 1% in a mole. The properties of the developed phosphor indicate that it has potential application prospects in plant growth LED.

Tunable Luminescence of Ce3+/Eu2+ Activated in Single-Phase Li2BaSiO4 Phosphor via Energy Transfer

A series of Ce3+,Eu2+ co-doped Li2BaSiO4 cyan-green phosphors were synthesized by a high temperature solid phase method. The crystal structure, morphology, luminescent properties and temperature characteristics of the corresponding samples were systematically studied. The main peaks of the emission spectra of Li2BaSiO4:Ce3+,Eu2+ were shifted from 400 nm to 500 nm by adjusting the Ce3+,Eu2+ co-doping concentration. And a series of phosphors with continuous changes from blue to cyan green were obtained, which effectively compensated for the gap between the white LED at 470–510 nm region. The energy transfer efficiency and mechanism of Ce3+,Eu2+ in Li2BaSiO4 were studied by fluorescence lifetime. The highest energy transfer efficiency was 46.01%, and the energy transfer mechanism was determined to be electric dipole-electric dipole transition. Finally, fabricating a white LED device which coated blue, green-yellow, red and as-prepared cyan phosphors on the surface of ultraviolet chip (350 nm), and the device exhibited excellent luminescence characteristics (Ra = 95.2, CCT = 3105 K). The results show that the Li2BaSiO4:Ce3+,Eu2+ phosphor developed can be regard as single-component tunable color luminescent materials under the excitation of near ultraviolet light.

Tunable photoluminescence and temperature sensing properties of Ce3+, Eu2+ co-doped Ca2-xSrxMgSi2O7 phosphors

A series of Ca2-xSrxMgSi2O7: Ce3+, Eu2+ (x = 0, 0.5, 1, 1.5, 2) phosphors were synthesized on the basis of high temperature solid-state reaction strategy. Its phase composition, optical spectral properties, fluorescence lifetime and temperature sensitivity were investigated in detail. Under excitation at 342 nm, the emission spectra of Ca2MgSi2O7: Ce3+, Eu2+ exhibit a purple emission band (Ce3+ ions) and a green emission band (Eu2+ ions). The emission band of Ce3+ overlaps with the excitation band of Eu2+, indicating that there may be energy transfer (ET) between the two ions. The decreasing fluorescence lifetime of Ce3+ with increasing Eu2+ concentration further proves the existent of ET process in Ca2MgSi2O7: Ce3+, Eu2+ phosphor. In addition, Ca2-xSrxMgSi2O7: Ce3+, Eu2+ solid solution was designed and synthesized by Sr2+ substituting Ca2+. As Sr2+ gradually replaced Ca2+, the blue-shift of Ce3+ and Eu2+emission band were caused by the change of crystal field. With the increase of temperature, the fluorescence intensity of Ce3+ and Eu2+ emission bands decreased slowly and rapidly, respectively. Hence, in the Ce3+/Eu2+ co-activated Ca2-xSrxMgSi2O7 phosphor, Ce3+ ions and Eu2+ ions can be used as fluorescence intensity ratio (FIR) signals. The maximum relative sensitivity can reach 2.43% K−1 (at 293 K) under 342 nm excitation. The above results indicate that Ca2-xSrxMgSi2O7: Ce3+, Eu2+ phosphors are potential candidates for optical thermometer materials.

Molten salt synthesis and luminescence performance of the Ce3+/Eu2+ doped Sr3Y2Ge3O12 phosphors

The Ce3+ and/or Eu2+ doped inorganic phosphors with the broad excitation bands and efficient visible emission play the important roles in the light emitting diodes. Herein, we synthesized the Ce3+/Eu2+ doped Sr3Y2Ge3O12 phosphors via a molten salt method under a reducing atmosphere. The phosphors were investigated by the X-ray diffraction, scanning electron microscopy, transmission electron microscopy and fluorescence spectrophotometer. The thermal stability of the Sr2.91Ce0.03Eu0.06Y2Ge3O12 phosphor was evaluated in 300–500 K at a temperature interval of 25 K. Upon the excitation at 450 nm, the Sr2.97Ce0.03Y2Ge3O12 and Sr2.97Eu0.03Y2Ge3O12 phosphors emit green and yellow-red light, respectively. The energy transfer process from Ce3+ to Eu2+ occurs in Ce3+/Eu2+ codoped Sr3Y2Ge3O12 phosphors, which results in the tunable luminescence.

Charge compensating effect of alkali metal ions R+ (R = Li, Na, K) on the luminescence enhancement of CaAl11.9P0.1O19.1:Mn4+ red-emitting phosphor

A series of novel Mn4+-doped and Mn4+/R+ co-doped (R = Li, Na, K) CaAl11.9P0.1O19.1 red-emitting phosphors were synthesized by high-temperature solid-state reaction, and their crystal structure, luminescence properties and thermal stability were studied in detail. Under the excitation of the optimal wavelength (396 nm), all phosphors exhibit a strong red-light emission, which corresponds to the 2Eg→4A2g transition of Mn4+. The optimal Mn4+ doping concentration was determined to be x = 0.01 in the CaAl11.9-xP0.1O19.1:xMn4+ phosphor, and excessive dopants will cause concentration quenching due to energy transfer interaction between Mn4+ ions. The alkali metal charge compensation ions Li+, Na+ and K+ co-doped with Mn4+ significantly improve the luminescence intensity of CaAl11.89P0.1O19.1:0.01Mn4+ phosphor, where Na+ co-doped phosphor has the strongest luminescence intensity, and K+ co-doped phosphor has the longest luminescence lifetime. Due to the ion radius of charge compensation ion R+ is closest to that of Ca2+ in the host, it is easier to occupy R+ for the Ca2+ lattice site. R+ can eliminate the positive defects caused by Mn4+ replacing with Al3+, thereby keeping charge valance to be neutral. Moreover, Ca0.9Al11.89P0.1O19.1:0.01Mn4+,0.1Na+ phosphor has excellent color purity (97.0%) and quantum yield (60.7%), indicating that the phosphor has potential application prospects for use in white-light-emitting diodes.

Tunable luminescence property and optical temperature sensing performance of Bi3+ and Sm3+ co-doped Ca2YZr2Al3O12 phosphors

Researches on tunable luminescence and temperature sensitivity of phosphors have become an increasingly popular trend. This paper reports a series of Ca 2 YZr 2 Al 3 O 12 (CYZA):Bi 3+ , Sm 3+ phosphors prepared by solid-state reaction. The phase purity, energy transfer, luminescent properties and temperature sensing performance of the phosphors have been carefully studied. CYZA:Bi 3+ , Sm 3+ phosphors excited by ultraviolet light show tunable color emission, and the color shifts from dark blue to pink due to Bi 3+ →Sm 3+ energy transfer. The related luminescent mechanism of phosphors is also explained. In addition, according to the different thermal sensitivity of Bi 3+ and Sm 3+ , the temperature sensitivity of the phosphors is studied by fluorescence intensity ratio model. The maximum values of absolute sensitivity and relative sensitivity reach up to 0.099% K −1 at 423 K and 0.356% K −1 at 473 K, respectively. These findings indicate that CYZA:Bi 3+ , Sm 3+ phosphors are potential candidates for tunable luminescence and temperature sensing. • The color-tunable property can be obtained in CYZA:Bi 3+ , Sm 3+ phosphors. • Energy transfer from Bi 3+ to Sm 3+ ions. • Different thermal attenuation behaviors of Bi 3+ and Sm 3+ ions. • Temperature sensing performance is investigated by FIR model.

Up-conversion luminescence and temperature sensing properties of Ho3+/Gd3+ co-doped YbNbO4 phosphors

Ho3+/Gd3+ co-doped YbNbO4 phosphors were successfully synthesized by the high-temperature solid-state method. The crystal structure, morphology structure, element distribution, up-conversion luminescence and relative optical temperature sensing properties were investigated. X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) analysis demonstrated that the doping of Ho3+/Gd3+ ions had no change in crystal structure and microstructure of YbNbO4 phosphors. Under the excitation of 980 nm laser radiation, the green and red UC emissions were achieved by prepared phosphors, corresponding to the transitions of (5F4, 5S2)→5I8, 5F5→5I8 of Ho3+ ions. It is observed that the UC luminescence intensity was significantly enhanced for Ho3+/Gd3+ co-doped YbNbO4 samples compared to the mere Ho3+ doped YbNbO4 sample. Moreover, Ho3+/Gd3+ co-doped YbNbO4 samples' temperature sensitivity ranging from 303 to 663 K was calculated based on the fluorescence intensity ratio (FIR) method. The maximum sensitivity reached 0.0078 K−1 at 663 K. These results indicate that the YbNbO4:Ho3+/Gd3+ samples are a promising candidate for optical temperature sensing and up-conversion luminescence.