Light Display Systems Research Articles

Well-defined Gd(OH)CO3, Gd2O(CO3)2·H2O, and Gd2O3 compounds with multiform morphologies and adjustable particle sizes: Synthesis, formation process, and luminescence properties

A variety of monodisperse size-tunable Gd(OH)CO3 nanospheres and Gd2O(CO3)2·H2O microplates have been synthesized via a facile homogeneous precipitation route with a mixing solvent of isopropanol (IPA) and H2O. The morphology and particle size of the gadolinium compounds can be tuned in a controlled manner by simply adjusting the volume ratio of IPA/H2O in solvent or reaction temperature and time. Both the amorphous Gd(OH)CO3 nanospheres and crystalline Gd2O(CO3)2·H2O microplates have been transformed into cubic phase of Gd2O3 after a calcination process in air. Interestingly, the Gd2O3 products perfectly inherit the well-defined morphology, good unifomity and dispersity of the precursor samples except for a shrinkage in particle size due to crystallization and coalescence at high temperature. The Gd2O3:Eu3+ and Gd2O(CO3)2·H2O:Tb3+ samples show red and green emission colors under ultraviolet excitation, and Gd2O3:Yb,Ln3+ (Ln = Er and Ho) samples exhibit characteristic orange-red and green emissions when excited at near-infrared (NIR) excitation. The morphology- and particle size-dependent luminescence performances of phosphors are studied in detail. Moreover, the light emitting diode (LED) devices fabricated with the corresponding down-conversion or up-conversion phosphors can display dazzling characteristic multicolor emissions, revealing that the as-synthesized luminescent materials have potential application prospect in the fields of LEDs, light display systems, and optoelectronic devices.

Characterization and Photoluminescence Property of a New Eu3+ -doped Phosphor of the K2 [Al(B5 O10 )] Prepared by Precursor Method

A new phosphor of the K2[Al(B5O10)]:Eu3+ was prepared by annealing of the as-prepared of the precursor of K2[Al(B5O10)]∙4H2O:Eu3+ at 300–400 °C, and which has been synthesized under facile hydrothermal conditions. All the samples were characterized by the EDS, XRD, FT-IR, and SEM. A systematic study on their luminescent properties has been performed by the PL and PLE. A series of influencing factors on the luminescent properties were also investigated. The PL and PLE studies reveal that the phosphor of K2[Al(B5O10)]:Eu3+ with optimal luminescent intensity and higher red-orange ratio were obtained by sintering the precursor at 400 °C for 5.5 h, with 9% doping concentration, which suggests that it might as a potential application of the light display systems.

Uniform and Well-Dispersed LuBO₃ Hollow Microspheres: Synthesis, Formation and Photoluminescence Properties.

A hard template strategy is developed to fabricate the LuBO3: Eu3+/Tb3+ hollow microspheres using a novel multi-step transformation synthetic route for the first time with polystyrene (PS) spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process, and a calcination process. The results show that the as-obtained LuBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.8 μm and shell thickness of about 80 nm. When used as luminescent materials, the emission colors of LuBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet (UV) light, which might have potential applications in the field such as light display systems and optoelectronic devices.

High aspect ratio Ca6Si6O17(OH)2 nanowires: Green hydrothermal synthesis, formation mechanism, optical and photoluminescence properties

Calcium silicate 1D nanostructures have aroused widespread concern and become widely available for drug delivery, and photoluminescence host, etc., which however have traditionally been synthesized via high temperature based molten salt synthesis or solution-based techniques, in the presence of organic template or solvents. Herein, a facile controllable green hydrothermal route (200 °C, 12.0 h) to uniform high aspect ratio high purity Ca6Si6O17(OH)2 nanowires (diameter: 20.0–120.0 nm, aspect ratio: 60.0–350.0) has been developed for the first time by using abundant CaCl2·2H2O and Na2SiO3·9H2O as raw materials, in the absence of any organic stabilizer, template, or directing agent. Effects of process parameters such as molar ratio of reactants, reaction time, temperature, reactant concentration, and dropping rate on the hydrothermal products were investigated in detail, and an intrinsic highly anisotropic structure induced hydrothermal formation mechanism of the high aspect ratio Ca6Si6O17(OH)2 nanowires was proposed. The Ca6Si6O17(OH)2 nanowires exhibited a transparent characteristic from the ultraviolet to visible range, and the Ca6Si6O17(OH)2:1.2%Tb3+ nanophosphors demonstrated the strongest photoluminescence emission intensity. With the doping molar percentage of Tb3+ changing from 0.5% to 1.5%, the quantum yields (QYs) varied within the range of 43%–72%, definitely suggesting the Ca6Si6O17(OH)2 nanowires as a great promising host candidate for green-emitting luminescent materials in light display systems, and optoelectronic devices, etc.

Facile Synthesis and Down-Conversion Emission of RE3+-Doped Lutetium Oxide Nanoparticles.

Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles have been successfully synthesized by a facile homogeneous precipitation method with subsequent sintering process. The crystal structure, morphology and luminescence properties of the as-prepared samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra. Upon ultraviolet (UV) and low-voltage electron beam excitation, Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles show strong red (Eu3+,5D0 → 7F2), green (Tb3+,5D4 → 7F5), and green (Ho3+,5S2 → 5I8) emissions. They exhibit a good advantage of multicolor emissions in the visible region, and endow these kinds of materials with potential application in many fields, such as light display systems, optoelectronic devices and biological imaging.

Large-scale fabrication of porous YBO3 hollow microspheres with tunable photoluminescence.

Hollow lanthanide-doped compounds are some of the most popular materials for high-performance luminescent devices. However, it is challenging to find an approach that can fabricate large-scale and well-crystallized lanthanide-doped hollow structures and that is facile, efficient and of low cost. In this study, YBO3: Eu3+/Tb3+ hollow microspheres were fabricated by using a novel multi-step transformation synthetic route for the first time with polystyrene spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process and a calcination process. The results show that the as-obtained YBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.65 µm and shell thickness of about 160 nm. When used as luminescent materials, the emission colours of YBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet light, which might have potential applications in fields such as light display systems and optoelectronic devices.

Facile hydrothermal-thermal conversion synthesis of CaSiO3 nanowires as promising structure and function integrated photoluminescent host candidate

A facile green low-cost controllable hydrothermal-thermal conversion (HTC) process for the uniform high aspect ratio CaSiO3 nanowires has been developed using abundant CaCl2·2H2O and Na2SiO3·9H2O as raw materials without any organic additive. The nanowires exhibited a transparent characteristic from the ultraviolet to visible region, and the CaSiO3:1.2%Tb3+ nanophosphors with well preserved 1D morphology demonstrated strong green luminescence with CIE coordinates of (x=0.3144, y=0.5912). The present work definitely reveals the nanowires as a promising structure and function integrated host candidate for green-emitting luminescent materials in light display systems and optoelectronic devices.

Synthesis and luminescent properties of uniform monodisperse LuPO4:Eu3+/Tb3+ hollow microspheres.

Uniform monodisperse LuPO4:Eu3+/Tb3+ hollow microspheres with diameters of about 2.4 µm have been successfully synthesized by the combination of a facile homogeneous precipitation approach, an ion-exchange process and a calcination process. The possible formation mechanism for the hollow microspheres was presented. Furthermore, the luminescence properties revealed that the LuPO4:Eu3+ and LuPO4:Tb3+ phosphors show strong orange-red and green emissions under ultraviolet excitation, respectively, which endows this material with potential application in many fields, such as light display systems and optoelectronic devices. Since the synthetic process can be carried out at mild conditions, it should be straightforward to scale up the entire process for large-scale production of the LuPO4 hollow microspheres. Furthermore, this general and simple method may be of much significance in the synthesis of many other inorganic materials.

Synthesis and photoluminescence properties of Sr0.95Ba0.05La2-xO4:xRE3+(RE=Eu,Er,Ce and Ho) for WLEDs application

The Sr0.95Ba0.05La2-xO4:xRE3+(RE = Eu,Er,Ce and Ho) phosphors are synthesized through high temperature solid-state reaction method at steps of 1000, 1100, 1200 °C. The impact of temperature on phase structures, functional group, luminescence properties and decay lifetime are investigated. The prepared Sr0.95Ba0.05La2-xO4 phosphors exhibit abundant luminescent properties with doping of different RE3+ ions under ultraviolet–visible and infrared excitation (980 nm) excitation. The Sr0.95Ba0.05La2-xO4:xEr3+ particles characterize red emission (4F9/2 → 4I15/2) through up-conversion emissions at 980 nm NIR irradiation. The chromaticity (CIE 1931) colour coordinates of the titled phosphors have also been evaluated. The merits of multicolor emissions in the visible region endow the synthesized material by UV irradiation reveals potential candidate in the field of light display systems, lasers and optoelectronic devices.

Covering the optical spectrum through different rare-earth ion-doping of YAG nanospheres produced by rapid microwave synthesis

In this work, YAG:RE3+ (RE = Pr3+, Tm3+, Tb3+, Ce3+, Eu3+, Nd3+, and Er3+;Yb3+) luminescent nanospheres with tunable photoluminescence (PL) emission were prepared by using fast and energy-saving microwave-assisted synthesis (MWAS). The nanopowders were post-annealed at 1100°C for 3h to obtain nanocrystalline phosphors. X-ray diffraction (XRD) analysis confirmed the presence of nanocrystals that were well indexed to the cubic YAG phase. Surface chemical groups were detected using Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) showed that the synthesized samples consist of nanospheres with an average size of ~ 110nm. The effect of aluminum precursors on the morphology of synthesized nanoparticles is discussed. The produced nanophosphors showed strong emission at different wavelengths (ultraviolet, visible and near-infrared) corresponding to different RE3+ ions. Altogether, the merits of spherical morphology and PL emission at various wavelengths endow rare-earth-doped YAG nanoparticles with suitable characteristic for potential applications in the field of nanomedicine (e.g., bioimaging and nanoscintillators), light display systems, optoelectronic devices, and lasers.

Multicolor Tunable Luminescence Based on Tb3+/Eu3+ Doping through a Facile Hydrothermal Route.

Ln3+-doped fluoride is a far efficient material for realizing multicolor emission, which plays an important part in full-color displays, biolabeling, and MRI. However, studies on the multicolor tuning properties of Ln3+-doped fluoride are mainly concentrated on a complicated process using three or more dopants, and the principle of energy transfer mechanism is still unclear. Herein, multicolor tunable emission is successfully obtained only by codoping with Tb3+ and Eu3+ ions in β-NaGdF4 submicrocrystals via a facile hydrothermal route. Our work reveals that various emission colors can be obtained and tuned from red, orange-red, pink, and blue-green to green under single excitation energy via codoping Tb3+ and Eu3+ with rationally changed Eu3+/Tb3+ molar ratio due to the energy transfer between Tb3+ and Eu3+ ions in the β-NaGdF4 host matrix. Meanwhile, the energy transfer mechanism in β-NaGdF4: x Eu3+/y Tb3+ (x + y = 5 mol %) submicrocrystals is investigated. Our results evidence the potential of the dopants' distribution density as an effective way for analyzing energy transfer and multicolor-controlled mechanism in other rare earth fluoride luminescence materials. Discussions on the multicolor luminescence under a certain dopant concentration based on single host and wavelength excitation are essential toward the goal of the practical applications in the field of light display systems and optoelectronic devices.

Single phase GdPO4: Dy3+ microspheres blue, yellow and white light emitting phosphor

Luminescent microspheres, Gd(1−x)DyxPO4 have been synthesized using simple combustion method for the first time. SEM images show that the obtained powders are formed by dispersed microscaled spheres with diameter ranging from 0.5 to 1 μm. The X-ray diffraction, FTIR and Raman spectroscopy studies reveal that the microparticles annealed at 800 °C crystallized in a monoclinic phase with space group P21/n. Under host Gd3+ sensitization, Gd(1−x)DyxPO4 emission spectra of Dy3+ show a broad blue band attributed to transitions 4I15/2 + 4I13/2 + 4I11/2 + 4F9/2 → 6H15/2, a sharp yellow band due to 4F9/2 → 6H13/2 transition, and the little red band of 4F9/2 → 6H11/2 transition. Blue and white emissions have been obtained at low and high Dy3+ concentration, respectively due the energy transfer from Gd3+ to Dy3+. Under direct 4f–4f excitation of Dy3+ in GdDPO4, three bands attributed to 4F9/2 → 6H15/2, 6H13/2, 6H11/2 transitions have been observed resulting in a yellow light emission. The emission bands intensity are discussed as function of GdPO4 structure. They are in well agreement with crystal structure of the host lattice GdPO4 in contrast to reported works. The decay rates for the 4F9/2 level are found to be deviated from exponential to non-exponential nature with increase of Dy3+ concentration. A promising white-light emission for white LED operating under UV excitation is investigated from single-phased phosphor. The obtained results suggest a potential application of GdPO4:Dy3+ microspheres as alternatives to replace bulk materials for many application fields, including light display systems and optoelectronic devices.

Oxalic Acid-Assisted Hydrothermal Synthesis and Luminescent of Hexagonal NaYF4:Ln3+ (Ln = Sm, Eu, Yb/Er) Micro/Nanoplates

Hexagonal NaYF4:Ln3+ micro/nanoplates were successfully synthesized via a hydrothermal method using oxalic acid as a shape modifier. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) have been used to study the morphologies and crystal structure of the products. The effects of the pH values and the molar ratio of oxalic acid to NaOH on the crystal growth have been investigated in detail. The time-dependent experiments have been conducted to investigate the morphology evolution process, and based on the results, a possible growth mechanism was proposed. The photoluminescence properties of 5 mol% Eu3+ and 3 mol% Sm3+ doped NaYF4 and 20 mol% Yb3+/2 mol% Er3+ codoped NaYF4 micro/nanoplates were investigated. The experimental results showed that NaYF4:Ln3+ micro/nanoplates have excellent luminescence and can be potential application in the field of light display systems, lasers, and optoelectronic devices.

One-pot synthesis and photoluminescence properties of core/porous-shell olive-like BaWO4 microstructure by a template-assisted hydrothermal method

Core/porous-shell olive-like crystalline BaWO4 is synthesized by a combined simple hydrothermal method and soft template approach. The prepared product shows an olive-like shape with diameter of ∼2 μm, length of ∼4 μm, and the thickness of the shell of about 65 nm, which are orderly assembled by many nanoparticles. A possible formation mechanism of olive-like BaWO4 microstructure involving interfacial recognization of ions, nucleation, aggregation, in situ growth and Ostwald ripening process is proposed. Polyacrylic acid sodium (PAAS) as a template plays an important role in inducing the nucleation and growth of olive-like BaWO4 microcrystalline. Other shapes of BaWO4 microcrystalline are also fabricated by varying the concentration of PAAS and Ba2+. The olive-like product with a core-shell structure which exists a large number of pores on crystal surface shows excellent photoluminescence property, which have potentially applied prospects in fields such as light display systems etc.

Hydrothermal Synthesis and Luminescence Properties of Monodisperse Spherical CaF<sub>2</sub> and CaF<sub>2</sub>:Ln<sup>3+</sup> (Ln = Eu, Tb, Ce/Tb) Microcrystals

Spherical CaF2 and CaF2:Ln3+ (Ln = Eu, Tb, Ce/Tb) with tunable particle size (about 2.5 µm) have been synthesized by one-step facile and effective hydrothermal method. The spherical structure was highly uniform and well-dispersed. It was found that reaction time, pH value, and reaction temperature have important effects on the controlled synthesis of spherical CaF2. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), photo-luminescence (PL) and luminescence decay curve. Under UV excitation, the CaF2:Eu3+ showed the red emission (5D0→7FJ = 0, 1, 2, 3) and the CaF2:Tb3+ presented the green emission (5D4→7FJ = 6, 5, 4, 3), respectively. Furthermore, Ce3+/Tb3+ co-doped CaF2 showed efficient energy transfer from Ce3+ to Tb3+, which presented strong green photo-luminescence of Tb3+. Due to excellent luminescent properties, the obtained samples can be used in many fields, such as light display systems, optoelectronic devices and biological imaging.

Hydrothermal synthesis and tunable luminescence of CaSiO3:RE3+(RE3+ = Eu3+, Sm3+, Tb3+, Dy3+) nanocrystals

CaSiO3:RE3+ (RE3+=Eu3+, Sm3+, Tb3+, Dy3+) nanocrystals were prepared by facile hydrothermal method with further calcinations. The crystal structure and the effects of annealing temperature on phase transition have been characterized by X-ray diffraction (XRD). The photoluminescence (PL) and PL excitation (PLE) spectra were used to characterize the optical properties of all samples. The effect of Eu3+ and Sm3+ doping concentrations on the luminescent intensity were also investigated in details, respectively. Moreover, the luminescence colors of the Tb3+ and Eu3+ co-doped CaSiO3 samples can be tuned by simply adjusting the relative doping concentrations of the rare earth ions under a single wavelength excitation, which might find potential applications in the fields of light display systems and optoelectronic devices.

Facile synthesis and luminescence properties of Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Tm(3+), Yb(3+)/Ho(3+)) microspheres.

Multicolor and monodisperse Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Ho(3+)) microspheres were prepared through a facile urea-assisted homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. The XRD results reveal that the as-prepared spheres can be well indexed to cubic Y2O3 phase with high purity. The SEM and TEM images show the obtained Y2O3:Ln(3+) samples consist of regular nanospheres with the mean diameter of 350 nm. And the possible formation mechanism is also proposed. Upon ultraviolet and low-voltage electron beams excitation, Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+)) samples exhibit respective bright red (Eu(3+), (5)D0 --> (7)F2), green (Tb(3+), (5)D4 --> (7)F5), blue (Dy(3+), (4)F9/2 --> (6)H13/2), yellow (Sm(3+), (4)G5/2 --> (6)H7/2), green (Er(3+), (4)S3/2 --> (4)I15/2), green (Ho(3+), (5)S2 --> (5)I8), blue (Tm(3+), (1)D2 --> (3)F4) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Y2O3:Ln(3+) (Ln(3+) = Yb(3+)/Er(3+), Yb(3+)/Tm(3+) and Yb(3+)/Ho(3+)) exhibit characteristic up-conversion (UC) emissions of green (Er(3+), (2)H11/2, (4)S3/2, (2)H11/2 --> (4)I5/2), blue (Tm(3+), (1)G4 --> (3)H6) and green (Ho(3+), (5)F4, (5)S2 --> (5)I8), respectively. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the field of light display systems, lasers, and optoelectronic devices.

Study on terbium doped lanthanum oxybromide luminescent nanoribbons and nanofibers

Terbium doped lanthanum oxybromide (LaOBr:Tb3+) nanoribbons and nanofibers were successfully synthesized by double-crucible bromination of the electrospinning-derived La2O3:Tb3+ nanoribbons and nanofibers using NH4Br powders as the bromine source. The structure and morphology of the samples were investigated by X-ray diffractometry and scanning electron microscopy. The results indicated that LaOBr:Tb3+ nanoribbons and nanofibers were pure tetragonal in structure with space group of P4/nmm. The width of LaOBr:Tb3+ nanoribbons were 2.33 ± 0.33 μm and the diameter of LaOBr:Tb3+ nanofibers was 90.08 ± 15.19 nm. The photoluminescent properties of LaOBr:Tb3+ nanoribbons and nanofibers were also characterized systematically. Under the excitation of 253-nm ultraviolet light, LaOBr:Tb3+ nanostructures exhibit the green emission of predominant peak at 543 nm. The optimum doping molar concentration of Tb3+ ions in the LaOBr:Tb3+ nanoribbons is 5 %. Interestingly, the luminescence intensity of LaOBr:5 %Tb3+ nanofibers is obviously greater than that of LaOBr:5 %Tb3+ nanoribbons under the same measuring conditions. Moreover, the luminescence colors of LaOBr:Tb3+ nanostructures are located in the green region in Commission Internationale de L’Eclairage chromaticity coordinates diagram. The mechanism of double-crucible bromination method was also proposed. This new bromination technique not only can inherit the morphology of rare earth oxides precursor, but also can be used to fabricate pure-phase rare earth oxybromide at low temperature compared with conventional high temperature solid state bromination reaction method. LaOBr:Tb3+ nanostructures are promising nanomaterials for applications in the fields of light display systems and optoelectronic devices.

NaY(MoO4)2 microcrystals with controlled faceting and their tunable photoluminescence properties after doping with Eu3+

We present a facile synthesis of NaY(MoO4)2 microcrystals with controlled morphologies and tunable faceting via an ethylenediaminetetraacetic acid (EDTA)-mediated hydrothermal method. Three different types of NaY(MoO4)2 microcrystals, namely, sharp bipyramids, truncated bipyramids, and quasi-cubes, can be selectively produced, and the percentage of {001} and {101} facets in the tetragonal bipyramidal NaY(MoO4)2 microcrystals can be engineered through the judicious choice of an appropriate amount of EDTA. The preferential adsorption of EDTA on {001} facets of the NaY(MoO4)2 crystal is responsible for the morphology evolution of the NaY(MoO4)2 microcrystals from sharp bipyramids to quasi-cubes. The present synthetic approach is also extendable to achieve NaHo(MoO4)2 and NaTb(MoO4)2 microcrystals with different shapes and tunable exposed facets. It is found that the luminescence properties of the NaY(MoO4)2:Eu3+ microcrystals are highly dependent on their shape and size, and the sharp NaY(MoO4)2:Eu3+ bipyramids exhibit the strongest emission intensity due to their larger size, fewer defects and less exposed facets. As such, the sharp NaY(MoO4)2:Eu3+ bipyramids may have potential applications in light display systems as well as optoelectronic devices, while the present EDTA-mediated hydrothermal synthetic strategy represents a potentially general route to the generation of nano/microcrystals with shape- and exposed facet-control.

Hydrothermally derived NaLuF4:Yb3+, Ln3+ (Ln3+ = Er3+, Tm3+ and Ho3+) microstructures with controllable synthesis, morphology evolution and multicolor luminescence properties

A series of NaLuF4:Yb3+, Ln3+ (Ln3+ = Er3+, Tm3+, and Ho3+) microstructures with diverse morphologies and sizes were successfully prepared via a designed hydrothermal route with the assistance of trisodium citrate (Na3Cit). The phases, morphologies, sizes and luminescent properties of the as-prepared products were fully characterized by means of X-ray diffraction (XRD), field scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and up-conversion (UC) photoluminescence spectroscopy, respectively. It can be found that the as-prepared microcrystals can be rationally modified in phase, size and morphology by tuning the pH value, Na3Cit content, and reaction time. Based on the experimental results, the possible formation mechanism of the crystal growth process was proposed. Moreover, a systematic study of the up-conversion (UC) luminescent properties of NaLuF4 has also been performed through doping different rare earth ions (Yb3+/Er3+, Yb3+/Tm3+ and Yb3+/Ho3+). It is found that under 980 nm NIR excitation, the emission intensity and the corresponding luminescent colors of Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+ co-doped NaLuF4 can be precisely modulated by changing the Yb3+ doping concentration. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the fields of light display systems, lasers, and optoelectronic devices.