Facile Synthesis and Effect of Eu, Tb Co-doping On the Tunable Luminescent Properties of YBO 3
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Facile Synthesis and Effect of Eu, Tb Co-doping On the Tunable Luminescent Properties of YBO3
Xianwen Zhang1 , Archis Marathe1 , Sandeep Sohal2 , Mark Holtz2 , Marauo Davis3 , Louisa J. Hope-Weeks3 and Jharna Chaudhuri1 1
Department of Mechanical Engineering, Texas Tech University, Lubbock,Texas, USA. Department of Physics, Texas Tech University, Lubbock, Texas, USA. 3 Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, Texas, USA. 2
ABSTRACT Eu3+/Tb3+co-doped YBO3 three-dimensional (3D) microstructures have been hydrothermally prepared by adjusting solvent and the molar ratio of Y3+ to B (Y/B) at 180 °C. The whole process was carried out under alkaline conditions without the use of any surfactant or catalyst. Characterizations of the samples are carried out using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The photoluminescence (PL) colors of YBO3 sample co-doped with Eu3+ and Tb3+ under ultraviolet excitation can be tuned from red, through yellow and green-yellow, to green by changing the relative doping concentrations of the two activator ions. These phosphors with multicolor emissions in the visible region be potentially used as labels for light-display systems, optoelectronic devices and biological molecules. INTRODUCTION Rare earth orthoborates LnBO3 (Ln =Y, La, Gd, Lu, and Sc) are an important series of PL materials due to low toxicity, strong luminescence intensity, high chemical stability and high ultraviolet and optical damage thresholds [1, 2]. Among them, YBO3 has been proved to be a very effective host crystal for the luminescence of europium ions (Eu3+) and terbium (Tb3+) ions and has been used as red and green emitting phosphors in the plasma display panels (PDPs), fluorescent lamps and bioimaging materials. Recently, a new generation of light-emitting diodes (LEDs) has exhibited much attraction in the field of solid-state lighting, owing to their high efficiency in converting electrical energy to light, long duration and lifetime, good reliability, energy savings and environmental friendliness [3-6]. A near ultraviolet (UV) LED coated with multicolor phosphors was introduced due to the superior color uniformity with high color rendering [7, 8]. Compounds co-doped with Tb3+ and Eu3+ have been extensively studied due to the tunability of the luminescence wavelength. The energy transfer from Tb3+ to Eu3+ plays an important role in luminescent materials [9-11], while the inverse transfer of energy from Eu3+ to Tb3+ is not significant [12]. Even though there are many studies investigating synthesis and optical properties of YBO3 doped with a single rareearth element, there are few exploring the co-doping of two or more rare-earth elements in the same host crystal. The fine-tuning of the excitation and emission spectra of phosphors can be obtained conveniently by mean of co-doping [13, 14]. Recently, we reported on an efficient surfactant and template-free hydrothermal approach to synthesi
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