Regulated morphology/phase structure and enhanced fluorescence in YF₃:Eu³⁺,Bi³⁺via a facile method

Abstract

A simple and facile hydrothermal method has been developed to enhance the fluorescence performance of YF 3 : xEu 3+ , y%Bi 3+ (x = 0-0.2, y = 0-1.5) via optimizing the concentration of Eu 3+ and Bi 3+ and regulating the morphology/phase structure by controlling the amount of HNO 3 . The evolutionary mechanism of the micro-topography and microstructure for the samples has been proposed, and the fluorescence and decay properties of the samples have been investigated. It was found that the fluorescence intensity of the sample has been enhanced greatly after added the opportune amount of Bi 3+ . The optimum concentrations of Eu 3+ and Bi 3+ for fluorescence are x = 0.125 and y = 0.5%, respectively. The significant enhancement in fluorescence performance could be obtained in the sample with the desired morphology at the optimum volume of HNO 3 (VHNO3 = 11 mL). IntroductionIn recent years, lanthanide ions doped inorganic crystals with controllable shapes and sizes have attracted considerable attention because of their potential technological applications in biomedical imaging, anti-fake label and illumination. 1 Among these inorganic materials, fluoride-containing host materials are the most captivating due to their low vibration energy, minimization of the quenching of the correlative excited state of the rare-earth ions and good optical transparency at a wide wavelength region. 2,3 Meanwhile, fluoride-containing materials possess good solubility, adequate thermal and environmental stabilities. These excellent physicochemical properties are in favor of the optical applications of the materials. 4 In comparison with other fluorescent host materials, YF 3 is considered as one of the most important host materials that has been intensively studied in recent years. 5,6 It has been known that trivalent rare earth ions can easily substitute for Y 3+ in the YF 3 because of their similar ionic radii of lanthanide. Moreover, the consummate matrix of YF 3 is conducive to lanthanides doping thus promoting the high efficiency emission of down/up conversion materials without additional charge compensation. 5,7Among rare earth ions, Eu 3+ has been frequently used as an activator due to its intense emission caused by 5 D 0 → 7 F 2 transition in red spectral region. A number of investigations have been carried out to improve the fluorescence efficiency of Eu-containing materials by doping metal ions (e.g. Ln 3+ -doped calcium fluoride nanocrystals, NaxEu 3+ (2−x)/3 MoO 4 , etc.), 4,8,9 employing various synthesis techniques (e.g. a facile arginine-assisted hydrothermal synthesis, electrospinning, etc.) 10,11 and optimizing the stoichiometric ratio of the materials (e.g. Eu 1-x Bi x VO 4 , BaLa 2−x−y ZnO 5 : xBi 3+ ,yEu 3+ , etc.). 12,13 Eu 3+ has also been introduced into YF 3 to obtain laser materials with excellent emission. For example, Shao et al. studied YF 3 : Eu 3+ micro-single crystals, 7 and Fu et al. fabricated Eu 3+ -doped YF 3 microcrystals with uniform grains. 14 These studies control the morphology of crystal grains t...

SiO2@TiO2:Sm3+ with Diverse Phase Structure and Morphology: Photoluminescence and Simulated Solar Light‐Activated Photodegradation Properties

“…It can be seen that the variation tendency of decay lifetime of cs‐3 series is not consistent with that of the luminescence intensity. The decay properties of the products are determined by some factors including surface defects, morphology, special junctions of the crystal grains, the number of luminescence centers, and so on . Therefore, this unusual phenomenon is the result of the above factors.…”

Enhancing Luminescence and X-ray Absorption Capacity of Eu3+:LaF3 Nanoparticles by Bi3+ Codoping

“…It is well-known, for example, that Bi 3+ can act as a sensitizer to enhance lanthanide (Eu 3+ , Tb 3+ , Sm 3+ , and Dy 3+ ) emissions, through Bi 3+ → Ln 3+ energy transfer in different Ln-based hosts. − However, very few reports have been devoted to the Bi 3+ → Ln 3+ energy-transfer process in Bi 3+ ,Ln 3+ codoped fluorides. To the best of our knowledge, the only related fluoride system reported is YF 3 :Eu 3+ ,Bi 3+ although the analysis of the Bi 3+ → Eu 3+ energy-transfer process in the material does not seem to be correct because of the clear contamination of the nominally Eu 3+ free sample with Eu 3+ …”

“…To the best of our knowledge, the only related fluoride system reported is YF 3 :Eu 3+ ,Bi 3+ although the analysis of the Bi 3+ → Eu 3+ energy-transfer process in the material does not seem to be correct because of the clear contamination of the nominally Eu 3+ free sample with Eu 3+ . 16 On the other hand, because of the high atomic number (Z) of lanthanides (Z = 57−71), Ln:phosphors have additionally been proposed as contrast agents for X-ray computed tomography (CT) in medical diagnosis. 17 Codoping with Bi 3+ is, therefore, not only interesting for the Ln 3+ emission enhancement but also because the high atomic number of Bi (Z = 83) is expected to increase the X-ray attenuation capacity of the material and, consequently, the contrast in the CT image.…”

Monodisperse, shape-selective synthesis of YF3:Yb3+/Er3+ nano/microcrystals and strong upconversion luminescence of hollow microcrystals

“…[21][22][23] The structure and crystalline phase of YF 3 has been found to have a signicant control over its emissive performance. [24][25][26] So far, several YF 3 nano-and microstructures have been synthesized using a variety of methods to investigate their unprecedented shape-and size-dependent up/down-conversion emission properties. [21][22][23][24][25][26][27][28][29] A majority of the adopted synthetic methods require organic surfactants to control the structure.…”

“…[24][25][26] So far, several YF 3 nano-and microstructures have been synthesized using a variety of methods to investigate their unprecedented shape-and size-dependent up/down-conversion emission properties. [21][22][23][24][25][26][27][28][29] A majority of the adopted synthetic methods require organic surfactants to control the structure. Shao et al 30 reported a simple surfactant-free HNO 3 -assisted hydrothermal method to nely tune the structure of YF 3 :Eu 3+ to generate various shapes.…”