Hydrothermal synthesis of NaY(WO4)2:Tb3+ powders with assistance of surfactant and luminescence properties

Abstract

NaY(WO 4 ) 2 :Tb 3? powders with different sizes and morphologies were synthesized by the hydrothermal process. The surfactants and reaction times have obvious effects on sizes and morphologies of samples. When there is the addition of an equimolar combination of oleic acid and oleylamine and the reaction time of 10 h, uniform morphology of octahedron can be formed. As indicated by the FTIR spectra, the enhanced adsorption of oleic acid in the presence of oleylamine leads to the good formation of octahedral NaY(WO 4 ) 2 :Tb 3? powders. Surfactants will selectively absorb on the surface of the growing particles via physical and chemical effects, which leads to different growing rates along corresponding directions and induces the formation of octahedral morphology. Under the ultraviolet excitation, NaY(WO 4 ):Tb 3? powders show dominant green emission originating from the 5 D 4 ? 7 F 5 transition of Tb 3? ions.

Facile hydrothermal crystallization of NaLn(WO4)2 (Ln=La-Lu, and Y), phase/morphology evolution, and photoluminescence

“…The hydrothermal route generally shows substantial advantages over the aforementioned techniques in that it allows better control of the crystallite size, size distribution, particle morphology, and composition of the product, and is thus one of the most commonly used techniques for Ln tungstate preparation [6,11]. In addition, various chelates and surfactants (such as citric acid, ethylene diamine tetraacetic acid (EDTA), cetyltrimethyl ammonium bromide (CTAB), polyvinylpyrrolidone (PVP), ethylene glycol (EG), and oleic acid) have been tested to regulate the morphology of the hydrothermal product [2,5,6]. Through hydrothermal reaction at 200 °C for 24 hours in the presence of a small amount of EDTA-2Na, Liu et al [12] obtained a product that can be transformed into NaLa(WO 4 ) 2 microspindles by annealing at 600 °C for 2 hours.…”

“…NaLn(WO 4 ) 2 is a frequently employed host in the field of luminescence [15,16]. Through hydrothermal reaction at 160 °C for 10 hours and in the presence of oleic acid and oleylamine, Liu et ) under ultraviolet excitation were produced by Sun et al [2] through calcining at 600 °C for 2 hours the product synthesized via hydrothermal reaction at 200 °C for 24 hours. Relative to the host lattices of NaLn(WO 4 ) 2 (Ln=La, Gd, and Y), NaLu(WO 4 ) 2 is much less studied and its crystals are largely produced by the top seeded solution growth (TSSG) technique [18][19][20][21][22].…”

“…Taking Ln=La and Lu for example, the temperature-and time-course phase and morphology evolutions during hydrothermal reaction and subsequent calcination were thoroughly investigated, and the encountered intermediate phases were characterized in detail by the combined techniques of elemental analysis, Fourier transform infrared (FTIR) absorption, and thermogravimetry/differential scanning calorimetry (TG/DSC) to reveal their composition and local coordination. Photoluminescence of NaEu(WO 4 ) 2 and NaTb(WO 4 ) 2 was also investigated comparatively for the as-synthesized and calcination products. We believe that the outcome of this work may have wide implications to the study and application of lanthanide tungstates.…”

“…Lanthanide tungstates are attracting much interest due to their remarkable properties such as high density and high threshold of mechanical, chemical, thermal, and optical damages, and are consequently finding wide applications in the fields of solid lasers, quantum electronics, scintillators, and so forth [1][2][3]. The compounds may exhibit a wide emission band ranging from the visible to mid-infrared region, owing to the electronic transitions within the tungstate group, and are known as a type of self-activated luminescent material [4].…”

Crystal Structure of NaLuW2O8·2H2O and Down/Upconversion Luminescence of the Derived NaLu(WO4)2:Yb/Ln Phosphors (Ln = Ho, Er, Tm)

“…Rare-earth (RE) tungstates have long been a focus of research interest due to their high theoretical densities and excellent resistance to mechanical, chemical, thermal and optical damages. The compounds are currently finding wide applications in the multifaceted fields of solid lasers, quantum electronics, scintillation, and lighting and display. − Scheelite-type RE tungstates (ARE­(WO 4 ) 2 , A = an alkali ion) are of special interest because of the outstanding chemical and physical stabilities arising from their compact tetragonal crystal structure (space group: I -4). , The NaRE­(WO 4 ) 2 of RE = La, Gd, Lu, and Y, for example, are frequently employed as phosphor hosts, since these RE ions have a vacant (La 3+ and Y 3+ ), half-filled (Gd 3+ ), or full-filled (Lu 3+ ) 4f shell. The smaller RE ions of Ho, Er, Tm and Yb are especially suitable for NaLu­(WO 4 ) 2 doping, since they and Lu have similar ionic radii, which allows for minimal lattice distortion.…”