The Preparation And Photoluminescence Properties Of Two Kinds Of Rare-earth Sc Oxides

Among the large number of luminescent materials,rare earth luminescent materials are used extensively to lighting and display device by reason of their outstanding performances,such as their good photochemical stability,the strong emission band,lower toxicity and high monochromaticity.Therefore,rare earth luminescent materials have become one of the most attractive topics in materials sciences in recent years.In general,the micro/nanometer structure with controllable shape,good dispersion and uniform size plays a vital role in properties of the rare materials,and rational control over these affecting factors can help us to better understand the observed complex phenomena of crystal growth and reveal the underlying fundamental theories and principles to realize the design of functional materials.As a result,the preparation of a novel rare earth luminescent material with controllable morphology and size provides significant benefit to the development of luminescent materials.Among the several preparation methods,as a typical soft chemical method,hydrothermal method is promising for preparation of functional materials due to the merit of mild reaction condition and environmentally friendly;and various morphologies can be obtained by adopting hydrothermal method,so it is an ideal method at the present.ScVO₄ microcrystals with various and controllable morphologies were prepared by means of hydrothermal method.And monodisperse morphologies from one-dimensional to three-dimensional were obtained by changing either the pH value,the amount of additives or time,such as dodecahedron,micron-rods,pancake-like hierarchical structures,the polyhedron of chocolate-like and cooky-shape.It has shown the formative and growing mechanism of phases and morphologies,which can help us to further understand the nature of crystal growth.And we can create the novel materials with good performance according to chemical and physical properties as desired.Beyond that,in the aspect of luminescence,firstly,we focus on discussing flexibly adjustment for multicolor emissions?yellow?white?orange?red?of ScVO₄:Dy³⁺/Eu³⁺phosphors through controlling the doping ratio of Dy³⁺to Eu³⁺under single wavelength excitation.And the multicolor luminescence of phosphor is also obtained via adopting different excitation wavelengths at constant doping concentration.Secondly,based on the structural characteristics of ScVO₄,LaVO₄ and ScPO₄ crystals,the relationship between luminescence properties of La_xSc_1-xVO₄:Eu³⁺and the host lattice distortion was studied.And doping of PO₄^3-hindered efficient energy transfer process from VO₄^3-to Eu³⁺to influence luminescence properties of the mixed crystal Sc?VO₄?_1-x?PO₄?_x:Eu³⁺.The modulation of the electronic band gap through doping Bi³⁺ions into the host lattice will result in controllable multicolor emissions for Sc?VO₄?_1-x?PO₄?_x:1%Bi³⁺phosphor,which provides a new path toward tunable phosphors.What's more,the tunable down/up conversion multicolor luminescence of ScVO₄:Ln³⁺?Ln=Sm,Eu,Dy,Ho,Er,Tm,Yb/Er,Yb/Ho,Yb/Tm?were obtained.We have realized the transformation from boehmite-type?-ScOOH crystal to diaspora-type?-ScOOH crystal under mild conditions by changing pH values of the initial solution.And ScBO₃ crystal was synthesized via one-step hydrothermal method using?-ScOOH as the precursor,then their morphology also transforms from cooky-shaped to rhombus.We systematically studied the changing mechanisms of phase and morphology.In the end,Sc₂O₃ crystal was synthesized via subsequently calcinations process using ScOOH as the precursor.What's more,we found that the luminescence property of?-ScOOH:Tb³⁺phosphor is better than that of?-ScOOH:Tb³⁺phosphor via doping Tb³⁺.