Preparation of Transparent Red-Emitting YVO₄:Eu Nanophosphor Suspensions

Abstract

Inorganic nanophosphors are in high demand for advanced flexible and transparent display devices. [1][2][3][4] Because inorganic nanophosphors do not show any scattering effect in the visible region, transparent luminescent matrices can be fabricated by embedding inorganic nanophosphors on transparent matrices, such as glass and plastics.5-8 However, nanophosphors agglomerate easily. Accordingly, the preparation of monodispersed inorganic nanophosphors is essential for the formation of transparent suspensions.YVO4:Eu is a well-known bright red-emitting phosphor that is used in cathode ray tubes (CRTs) and fluorescent lamps. 9,10Normally, micron-sized YVO 4 :Eu phosphors are prepared by solid state reactions.11-13 Nano-sized YVO4:Eu phosphors have been prepared by sonochemical methods, hydrothermal reactions and polymer complex processing methods.14-19 YVO 4 : Eu thin films have been prepared through various techniques such as pulsed laser deposition (PLD), chemical vapor deposition (CVD), and electrochemical method. [20][21][22] In general, these techniques need expensive and complicated equipment set-ups, and complicated processing. Colloidal YVO 4 :Eu phosphors can be synthesized and stabilized by sodium hexametaphosphate. 23,24The preparation of colloids makes possible an alternative approach to fabrication of YVO 4 :Eu thin films by dispersion of colloidal YVO 4 :Eu phosphors in polymer matrix. 25 However, there are few reports on the preparation of YVO4:Eu nanophosphors for transparent suspensions. This paper reports a simple synthetic method for YVO 4 :Eu nanophosphors and its transparent suspensions. A simple and room temperature processing method for fabrication of the transparent and flexible YVO4:Eu thin film is also reported. Figure 1 shows the powder X-ray diffraction (XRD) patterns of the as-prepared YVO 4 :Eu nanophosphors. A series of Bragg reflections in the XRD pattern can be indexed perfectly as tetragonal YVO 4 (JCPDS 17-0341, a = 0.7119 nm, c = 0.6289 nm). Since the mole fraction of europium to yttrium is only 0.05, the europium ion is expected to occupy the yttrium sites in YVO4. Moreover, the ionic radius of Eu 3+ (0.095 nm) is slightly larger than that of Y 3+ (0.089 nm), allowing easy insertion into the yttrium site in YVO4. 26 No other peaks were observed in the XRD pattern, indicating that YVO 4 :Eu had been successfully synthesized.

Preparation and Photoluminescence Properties of Transparent Red-Emitting Suspension of BaMoO4:Eu3+,Na+Nanophosphor for a Three-Band White LED

“…On the other hand, nanophosphors agglomerate easily in solvents, and little is known regarding the preparation of a suspension of inorganic nanophosphors. [17][18][19][20] This paper reports the first simple method for preparing a transparent suspension of BaMoO 4 :Eu 3+ ,Na + nanophosphors and the feasibility of this BaMoO 4 :Eu 3+ ,Na + suspension for a threeband white LED. Figure 1 shows the powder X-ray diffraction (XRD) patterns of the BaMoO 4 :Eu 3+ ,Na + phosphor prepared by a hydrothermal process at 80°C.…”

Sonochemical Synthesis and Properties of YVO4:Eu3+ Nanocrystals for Luminescent Security Ink Applications

“…Regarding the references on synthesis of YVO 4 :Eu 3+ nanoparticles by wet-chemical method [12][13][14][15][16][17][18][19][20][21][38][39][40][41][42], we use three different routes to synthesize YVO 4 :Eu 3+ nanoparticles, which are thermal stirring, microwave methods, and ultrasonic methods, in order to compare the luminescent level of the nanoparticles. According to the published results, the best doping level of Eu 3+ in YVO 4 for luminescence properties is 5 mol% [38,[43][44][45][46][47][48][49][50][51][52][53][54][55]. We use YVO 4 :Eu 3+ nanoparticles to produce ink for PS JET 300 V inkjet printer.…”

Preparation and Photoluminescence of GdVO4:Eu Nanophosphors for Flexible and Transparent Displays

“…Transparent suspensions of small amounts of YVO 4 :Eu nanophosphors in hexane have been prepared using surfactant-assisted hydrothermal reactions in a waterhexane bilayer system. 15 In this system, most of the YVO 4 :Eu nanophosphors aggregated in the water phase that is not adequate for the flexible and transparent displays. New methods for the large-scale synthesis of nanophosphors are required that can prepare phosphors in single organic solvent phase.…”