CN105154078A - Preparation method for fluorescent powder Sr3-3x/2(VO4)2:chi Eu<3+> - Google Patents

Abstract

The invention discloses a preparation method for red fluorescent powder Sr3-3x/2(VO4)2:chi Eu<3+>. The preparation method comprises the following steps: firstly, preparing a Sr <2+> and Eu <3+> nitrate solution; secondly, preparing a citric acid and ammonium metavanadate mixed water solution to be added into the Sr <2+> and Eu <3+> nitrate solution, performing magnetic stirring to enable the mixture to be fully mixed, performing water bath heating at a constant temperature of 80 DEG C till the solution becomes a blue gel-like substance; placing the blue gel-like substance into a muffle furnace, performing constant-temperature calcination for 1 hour at the temperature of 300 DEG C to enable the blue gel-like substance to be boiled and concentrated to obtain a gray-black, fluffy and spumous product, taking out the product, placing the product into the muffle furnace at the temperature of 950 DEG C to allow the product to burn immediately, and annealing for crystallization in air after 10 hours of heat insulation to prepare red fluorescent powder Sr3-3x/2(VO4)2:chi Eu<3+>, wherein chi represents the molar fraction with a value of 0.1.

Description

A kind of red fluorescence powder Sr 3-3x/2(VO 4) 2: χ Eu 3+preparation method

Technical field

The invention belongs to LED fluorescent material preparing technical field, particularly a kind of red fluorescence powder Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺the preparation method of (χ represents molar fraction, and its value is 0.1).

Background technology

Photodiode (LightEmittingDiodes is called for short LED), since coming out from the sixties in 20th century, the development course of existing five more than ten years, is a kind of semiconductor diode, electric energy conversion can be become luminous energy.In recent years, semiconductor lighting has the plurality of advantages such as the life-span is long, service efficiency is high, anti-adverse environment, spectral range are wide, visual range is far away, energy-conserving and environment-protective due to it, has been widely used in the various lighting fields such as advertising signboard lamp, screen, head light, automobile, pilot lamp, ornament lamp.LED is considered to 21 century most valuable new type light source and be expected to replace incandescent light.White light LED fluorescent powder technology of preparing develop in order to main flow, simultaneously also bring fluorescent material development field with new opportunities and challenges.The approach realizing white light LEDs at present mainly contains following three kinds: the first, ruddiness, green glow and blue-light LED chip three are packaged together, by spacing color mixed principle, then mate by a certain percentage, make the light of three kinds of colors be mixed into white light.The sharpest edges of this kind of white light LEDs do not need to carry out spectrum conversion, and luminous all from photodiode, therefore, Minimal energy loss, efficiency is also the highest.But in order to keep the stable of color, usually needing photochromicly to compensate three kinds, add reaction circuit respectively and cause circuit complicated, also can cause loss in efficiency simultaneously.Therefore the combination of three-primary color LED chip realizes white light and is often restricted.The second, blue light conversion hysteria white light LEDs.Topmost or the yttrium aluminum garnet (Y of this type LED fluorescent material ₃al ₅o ₁₂: Ce ³⁺), the preparation method of this kind of fluorescent material adopts solid reaction process and coprecipitation method substantially, and its advantage is that making is simple, cost is lower, and efficiency is higher.This is the most frequently used one of current white light LEDs production method.The white light LEDs that this blue gold-tinted is composited is owing to lacking ruddiness component, and spectrum is wide not, and the white light colour rendering index be thus compounded to form is not high (generally below 80).The third, ultraviolet conversion hysteria fluorescent material.Substantially identical with blue light conversion hysteria, ultraviolet conversion hysteria utilizes ultraviolet LED excitation light source to produce white light, namely by UV-light (200 ~ 370nm) the excitated fluorescent powder luminescence that purple pipe sends, the light that various fluorescent material sends carries out certain proportion and is obtained by mixing required white light.The advantage of this method is that the selection of high-efficiency fluorescence body is very abundant, can obtain that colour rendering index is high, light efficiency is high and the fluorescent material of various correlated(color)temperature.But when applying, the efficiency of conversion of red fluorescence powder, far below green and blue colour fluorescent powder, causes color developing poor owing to lacking ruddiness usually, therefore the poor efficiency of red fluorescence powder and shortcoming have become the important factor of restriction white light LEDs development.Research is applicable to the novel red luminescent material that UV-LED tube core excites and seems even more important.And europium ion Eu ³⁺characteristic peak be between 595nm ~ 620nm at emission wavelength, bright ruddiness can be issued.Therefore, study the LED that effectively can be excited by ultraviolet and have very important meaning with europium ion-doped red fluorescence powder to luminescent material research field.According to the difference to temperature requirement in the reaction state of initial stage material and preparation process, fluorescent material preparation method mainly can be divided into high temperature solid-state method, coprecipitation method, hydrothermal synthesis method, solution combustion method, chemical gaseous phase deposition, surface diffusion method, sol-gel method, microemulsion method, Microwave-assisted firing method, arc process, solvent evaporated method etc.Fluorescent material consist of host inorganic compounds and luminescence center, host inorganic compounds exists as matrix, and build specific space lattice, luminescence center is normally doped in parent lattice by activator.Usually, matrix compounds should possess following condition: the cationic extranuclear electron configuration in (1) matrix compounds should reach filled shell electronic structure, physical properties and chemical property more stable; (2) optically zwitterion must be all transparent; (3) certain case be not occupied should be had in parent lattice.At present, the compound as fluorescent material matrix mainly comprises: oxide compound and composite oxides, as aluminate, and borate, silicate, phosphoric acid salt etc.After a large amount of By consulting literatures, find that alkaline earth metal vanadate class has been proved to be good selection, because they can absorb strong ultraviolet, due to VO ₄ ^3-and good strong interaction between the active level of rare earth ion coupling, energy efficient is transferred to rare earth ion.Alkaline earth metal vanadate class M ₃(VO ₄) ₂(M=Ca, Sr, Ba), can well be applied to solid-state illumination, light fixture, X-ray detector and laser apparatus.This patent employing sol-gel method combines with combustion method, and (claiming colloidal sol combustion method) has synthesized fluorescent material Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺series of samples, fluorescent material matrix selects vanadate, and activator is based on rare earth element europium ion, and citric acid selected by ignition dope, effectively can be excited to prepare by UV-light, and emission wavelength is the red light fluorescent material between 595nm ~ 620nm, have studied europium ion Eu ³⁺doping content and annealing temperature are to the performance impact of fluorescent material, utilize spectrophotofluorometer, X-ray powder diffractometer (XRD), scanning electronic microscope (SEM), study its luminescent properties, phase structure, surface topography, the development of this result of study on new LED fluorescent material research and development field produces actively impact.

Summary of the invention

The object of this invention is to provide a kind of red fluorescence powder Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺the preparation method of (χ represents molar fraction, and its value is 0.1), this novel red luminescent material is applicable to UV-LED tube core and excites.

Concrete steps are:

(1) 3.1743gSr (NO is taken ₃) ₂with 0.2230gEu (NO ₃) ₃6H ₂o dissolves in 10mL deionized water respectively, to form Sr ²⁺nitrate solution and Eu ³⁺nitrate solution.

(2) 5.4439g citric acid is dissolved in 40mL deionized water, then adds the ammonium meta-vanadate of 1.1694g and dissolve, finally add the Sr that step (1) is obtained ²⁺nitrate solution and Eu ³⁺nitrate solution, magnetic agitation fully mixes, and at constant temperature 80 DEG C of heating in water bath, becomes blue gel shape material to solution.

(3) the blue gel shape material that step (2) obtains is put into retort furnace 300 DEG C of calcining at constant temperature 1 hour, blue gel shape material seethes with excitement, concentrated, obtain that grey black is fluffy, spumescence product, product is taken out, put into 950 DEG C of retort furnaces, product is ignition immediately, is incubated annealing crystallization in atmosphere after 10 hours, obtained red powder fluorescent material Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺, wherein, χ represents molar fraction, and its value is 0.1.

Colloidal sol combustion method is adopted to prepare Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺fluorescent material, this is because this methods combining advantage of solution combustion method and sol-gel method, fluorescent material is one-step synthesis, preparation of raw material is become solution, the homogeneity of molecular level can be obtained in a short period of time, when forming gel, reactant is likely and is uniformly mixed on a molecular scale.High temperature annealing makes that synthetic sample impurity is few, crystal structure is effective, thus promotes that more activator ion enters host matrix lattice, forms luminescence center, improves fluorescence intensity.

At Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺in fluorescent material, Sr _3-3x/2(VO ₄) ₂for host matrix, Eu ³⁺for rear-earth-doped ion (activator), its principle of luminosity is: by colloidal sol combustion method, rear-earth-doped ion Eu ³⁺enter Sr ₃(VO ₄) ₂host matrix lattice, replaces part Sr ²⁺, occupy its position, substantially do not cause the change of the crystal structure properties such as parent lattice space structure.The luminescence of fluorescent material is all the characteristic emission of dopant ion substantially, and host matrix plays a part to build particular space structure, has continuous print absorption band at the rare earth element that the extreme ultraviolet of spectrum is all, and this corresponds to the transition of out-shell electron.Eu ³⁺during by ultraviolet excitation, Eu ³⁺symmetry centre is only departed from, electric dipole transition a little in residing crystallography position ⁵d ₀→ ⁷f ₂account for leading, send red fluorescence.Positive trivalent La rear earth ion also has d-f transition, and this Transition Spectra is broadband, luminous intensity comparatively high.Eu ³⁺rare earth ion 5d track is in skin, and its d-f transition affects comparatively large by crystal field, therefore its emmission spectrum is wideband spectrum, and band position is subject to the impact of crystal field, and its band position all has from ultraviolet region to visible region.

Accompanying drawing explanation

Fig. 1 is the emmission spectrum of the red fluorescence powder that the embodiment of the present invention obtains, and excitation wavelength is 280nm.

Fig. 2 is the excitation spectrum of the red fluorescence powder that the embodiment of the present invention obtains, and emission wavelength is 618nm.

Embodiment

embodiment:

(1) 3.1743gSr (NO is taken ₃) ₂with 0.2230gEu (NO ₃) ₃6H ₂o dissolves in 10mL deionized water respectively, to form Sr ²⁺nitrate solution and Eu ³⁺nitrate solution.

(2) 5.4439g citric acid is dissolved in 40mL deionized water, then adds the ammonium meta-vanadate of 1.1694g and dissolve, finally add the Sr that step (1) is obtained ²⁺nitrate solution and Eu ³⁺nitrate solution, magnetic agitation fully mixes, and at constant temperature 80 DEG C of heating in water bath, becomes blue gel shape material to solution.

(3) the blue gel shape material that step (2) obtains is put into retort furnace 300 DEG C of calcining at constant temperature 1 hour, blue gel shape material seethes with excitement, concentrated, obtain that grey black is fluffy, spumescence product, product is taken out, put into 950 DEG C of retort furnaces, product is ignition immediately, is incubated annealing crystallization in atmosphere after 10 hours, obtained red powder fluorescent material Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺, wherein, χ represents molar fraction, and its value is 0.1.

The Sr that the present embodiment is obtained _3-3x/2(VO ₄) ₂: χ Eu ³⁺(χ represents molar fraction, and its value is 0.1), fluorescent material can be excited by the ultraviolet high efficiency of 280nm, and emmission spectrum is 595nm to 620nm broadband emission (see accompanying drawing 1) in visible region, corresponding to Eu ³⁺ion ⁵d ₀arrive ⁷f ₂energy level transition, show stronger emissive porwer.Setting emission wavelength is the excitation spectrum that 618nm obtains fluorescent material is the broadband excitation peak (see accompanying drawing 2) that a main peak is positioned at 280nm, illustrates that this fluorescent material effectively can be excited by UV-light.

Claims (1)

1. a red fluorescence powder Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺preparation method, it is characterized in that concrete steps are:

(1) 3.1743gSr (NO is taken ₃) ₂with 0.2230gEu (NO ₃) ₃6H ₂o dissolves in 10mL deionized water respectively, to form Sr ²⁺nitrate solution and Eu ³⁺nitrate solution;

(2) 5.4439g citric acid is dissolved in 40mL deionized water, then adds the ammonium meta-vanadate of 1.1694g and dissolve, finally add the Sr that step (1) is obtained ²⁺nitrate solution and Eu ³⁺nitrate solution, magnetic agitation fully mixes, and at constant temperature 80 DEG C of heating in water bath, becomes blue gel shape material to solution;

(3) the blue gel shape material that step (2) obtains is put into retort furnace 300 DEG C of calcining at constant temperature 1 hour, blue gel shape material seethes with excitement, concentrated, obtain that grey black is fluffy, spumescence product, product is taken out, put into 950 DEG C of retort furnaces, product is ignition immediately, is incubated annealing crystallization in atmosphere after 10 hours, obtained red powder fluorescent material Sr _3-3x/2(VO ₄) ₂: χ Eu ³⁺, wherein, χ represents molar fraction, and its value is 0.1.