CN105670629A - Low temperature synthesis method for infrared excitation up-conversion nano material NaGdF4:Yb3+/Tm3+ - Google Patents

Abstract

The invention belongs to the field of preparation of hybrid nano materials and relates to a low temperature synthesis method for an infrared excitation up-conversion nano material NaGdF4:Yb3+/Tm3+. The infrared excitation up-conversion spherical nano material NaGdF4:Yb3+/Tm3+ is synthesized at low reaction temperature and through simple steps. The crystal form of the nano material is a hexagonal crystal form with small phonons, size distribution is uniform, and the diameter is smaller than 100 nm. The technology is simple, operation is convenient, reaction temperature is low, cost is low, energy consumption is small, purity of the synthesized material is high, luminous efficiency and strength are high, and the nano material can be used in various fields of fluorescent display, biological fluorescent labeling, laser devices and the like .

Description

A kind of infrared excitation up-conversion nano material NaGdF4:Yb3+/Tm3+Low-temperature synthetic method

Technical field:

The invention belongs to the preparation field of hybrid nano-material, the preparation method relating to the upconversion fluorescence nano material of one kind of multiple rare earth ion codopes, particularly a kind of infrared excitation up-conversion nano material NaGdF₄:Yb³⁺/Tm³⁺Low-temperature synthetic method, adopt relatively low reaction temperature and simple step to synthesize the NaGdF of infrared excitation₄:Yb³⁺/Tm³⁺Upper conversion ball shaped nano material, its crystal formation is the hexagonal structure that phonon is little, and even size distribution, diameter is about 100nm.

Background technology:

Up-conversion is that a class will be changed into low-energy long-wave radiation the luminescent material of high-octane shortwave radiation, the sixties in last century, Auzel proposed conversion concept, initial thirties years, its research is concentrated mainly on glass fluoride, from the nineties in last century, up-conversion nano material research achieves development at full speed, by two-photon or multi-photon mechanism, the exciting light of long wave is converted into the transmitting light of shortwave by up-conversion luminescent material, what generally use is that the infrared light of 980nm is as exciting light, it has deeper light penetration depth, to biological tissue almost without damage, fluorescence background is little, and up-conversion stable chemical nature, absorb and the scope of transmitting band is narrower, relative to semiconductor-quantum-point fluorescent material, the advantages such as fluorescent stability is good. therefore, up-conversion is at solid state laser, solaode, biomarker, and the aspect such as data storage has potential using value.

In general, up-conversion is generally made up of host material, activator and sensitizer, the difference of host material and excited ion, and the mechanism of photon transition is also incomplete same. Rare earth ion has the level structure of division, and owing to 4f layer electronics is by the electronic shield effect of outer layer, the metastable energy level life-span is long, up-conversion luminescence efficiency is high, it is often used as activator, the rare earth ion doped up-conversion of single, its conversion efficiency depends on the distance between active ions and absorption cross-section, when the excessive concentration of dopant ion, interionic due to cross-relaxation, can produce fluorescent quenching, be substantially reduced conversion efficiency, introduce the agent of quick China and then can obtain higher conversion efficiency, Yb³⁺There is less ionic radius, excited state structure single in infrared region (²F_7/2→²F_5/2) and good photoabsorption cross-section, it is often used as the agent of quick China and is doped in substrate, be one of the most frequently used sensitized ions.Host material provides suitable crystalline field for active ions, will have the crystal type close with dopant ion and relatively low phonon energy, mainly have fluoride, chloride, oxide etc., and fluoride has low phonon energy, but hygroscopic, poor chemical stability; The relatively low vibration level of chloride is low, and multi-phonon relaxation is few, adds relaxation process, but poor stability; Oxide synthesis condition is ripe, stable performance, but phonon energy is high, causes that luminous efficiency is low. Therefore, prepare conversion hybridized nanometer host material on the rare earth that phonon energy is low, chemical stability good, preparation technology is simple, luminous efficiency is high and remain a major challenge in this field.

At present, the preparation method of up-conversion luminescent material has high temperature solid-state method, combustion method, sol-gel method, microemulsion method and solvent-thermal method etc., wherein high temperature solid-state method is to prepare a kind of traditional method that phosphor is the more commonly used, this synthetic method step is simple, the luminous efficiency of synthetic sample is high, but preparation process energy consumption is high, and the response time is long, sample granularity differs, and product morphology is irregular; The combustion synthesis time is short, but experiment condition requires height, and sample is without specific morphology, and fluorescence efficiency is low; Sol-gel method process control, product are reunited less, but the method remains a need for through high-temperature process; Microemulsion method can pass through kind and the consumption of control table surface-active agent, controls size and the form of nano materials, but the introducing of emulsifying agent can affect the luminosity of material; Solvent-thermal method is the important method of synthesizing inorganic nano material, but prepares for rare earth upconversion nano material for solvent method, and desired reaction temperature higher (300 DEG C), the response time is longer, and up-conversion fluorescence intensity is weak. Rare earth fluoride NaGdF₄There is relatively low phonon energy, assist in up-conversion luminescence process in multi-phonon relaxation and can reduce radiationless transition probability, Enhanced Radiation Reduced Blast transition probability. Additionally, Gd³⁺Lattice structure has energy transmission effect, can effectively reduce the cross relaxation of rare earth activation ion, increase its luminous efficiency and intensity. Therefore, a kind of infrared excitation up-conversion nano material NaGdF is sought₄:Yb³⁺/Tm³⁺Low-temperature synthetic method, hydrothermal reaction at low temperature in employing, by control F^-With lanthanide ion (Ln³⁺) ratio, effectively control purity and the crystal phase structure of product, synthesis of high purity, hexagonal crystal system spherical NaGdF₄:Yb³⁺/Tm³⁺Up-conversion.

Summary of the invention:

It is an object of the invention to the shortcoming overcoming prior art to exist, seek to design a kind of infrared excitation up-conversion nano material NaGdF₄:Yb³⁺/Tm³⁺Low-temperature synthetic method, by the Yb of big concentration³⁺Ion is as sensitizer and Tm³⁺Active ions adulterate wherein, are effectively controlled distribution of sizes and the form of material on the one hand by the method for fractional steps, on the other hand, effectively reduce the cross relaxation between rare earth ion, improve Tm³⁺Fluorescence intensity reduce up-conversion fluorescence efficiency.

To achieve these goals, the present invention specifically includes the following step:

(1), 10mL concentrated nitric acid is joined in 100mL volumetric flask, constant volume, obtaining percent by volume after shaking up is 10% salpeter solution;

(2), 141.414mgGd is weighed successively₂O₃、39.4mgYb₂O₃、3.85mgTm₂O₃, by Gd₂O₃、Yb₂O₃And Tm₂O₃Three kinds of rare earth oxides are dissolved in the salpeter solution that step (1) is prepared, and under 80 DEG C of heating conditions, magnetic agitation is to being completely dissolved, and obtain the rare earth nitrate solution of clarification;

(3), measure in oleic acid 5ml addition small beaker, then measure in 16ml ethanol addition small beaker, oleic acid and ethanol are stirred into uniform solution, then 251.1mgNaF white powder is joined in uniform solution, continue to be uniformly mixing to obtain mixed solution;

(4), rare earth nitrate solution prepared by step (2) is added dropwise in mixed solution prepared by step (3), limit dropping stirring, under room temperature, magnetic agitation obtains milky white liquid in 5 minutes;

(5), being transferred in the politef high-pressure hydrothermal reaction kettle of 100mL by milky white liquid prepared by step (4), be tamping bottleneck with poly tetrafluoroethylene, at 150 DEG C, laser heating naturally cools to room temperature after reacting 9 hours;

(6) after politef high-pressure hydrothermal reaction kettle naturally cools to room temperature, flat bottoms at politef high-pressure hydrothermal reaction kettle has white solid to precipitate, reacted solution is transferred in centrifuge tube, with the centrifuge rotating speed at room temperature centrifugation 5 minutes with 6000rpm/min, the supernatant liquid of centrifuge tube is taken out, add 6ml ethanol purge three times, obtain pure white solid product;

(7) white solid product vacuum drying 6 hours at 40 DEG C step (6) obtained, obtain being smaller in size than the NaGdF of 100 nanometers₄:Yb³⁺/Tm³⁺, its crystalline structure is hexagonal crystal system, and 980nm excites its up-conversion fluorescence for doping Tm³⁺Characteristic emission peak.

Compared with prior art, its technique is simple, and easy to operate, reaction temperature is low, and cost is few, less energy consumption for the present invention, and the material purity of synthesis is high, and luminous efficiency and intensity are big, can be applicable to the numerous areas such as fluorescence display, biological fluorescent labelling and laser instrument.

Accompanying drawing illustrates:

Fig. 1 is the NaGdF that the present invention synthesizes₄:Yb³⁺/Tm³⁺Transmission electron microscope picture.

Fig. 2 is the NaGdF that the present invention synthesizes₄:Yb³⁺/Tm³⁺Electron scanning electron microscopic picture.

Fig. 3 is the NaGdF that the present invention synthesizes₄:Yb³⁺/Tm³⁺X ray diffracting spectrum.

Fig. 4 be 980nm infrared ray excited under, the present invention synthesis NaGdF₄:Yb³⁺/Tm³⁺Up-conversion fluorescence spectrum.

Fig. 5 is the GdF of the 2-in-1 one-tenth of the embodiment of the present invention₃:Yb³⁺/Tm³⁺X ray diffracting spectrum.

Fig. 6 is the GdF of the 2-in-1 one-tenth of the embodiment of the present invention₃:Yb³⁺/Tm³⁺Transmission electron microscope picture.

Fig. 7 is the sample transmission electron microscopic picture of the embodiment of the present invention 5 preparation.

Detailed description of the invention:

Below by specific embodiment, and the present invention is further elaborated in conjunction with accompanying drawing.

Embodiment 1:

The present embodiment synthesis NaGdF₄:Yb³⁺/Tm^3+'sConcretely comprise the following steps:

(1), 10mL concentrated nitric acid is joined in 100mL volumetric flask, constant volume, obtaining percent by volume after shaking up is 10% salpeter solution;

(2) 141.414mg (0.78mmol) Gd, is weighed successively₂O₃、39.4mg(0.2mmol)Yb₂O₃、3.85mg(0.02mmol)Tm₂O₃, by Gd₂O₃、Yb₂O₃And Tm₂O₃Three kinds of rare earth oxides are dissolved in the salpeter solution that step (1) is prepared, and under 80 DEG C of heating conditions, magnetic agitation is to being completely dissolved, and obtain the rare earth nitrate solution of clarification;

(3), measure oleic acid 5ml and add in small beaker, measure 16ml ethanol again and add in small beaker, oleic acid and ethanol are stirred into uniform solution, then 251.1mg (6mmol) NaF white powder is joined in uniform solution, continue to be uniformly mixing to obtain mixed solution;

(4), rare earth nitrate solution prepared by step (2) is added dropwise in mixed solution prepared by step (3), limit dropping stirring, under room temperature, magnetic agitation obtains milky white liquid in 5 minutes;

(5), being transferred in the politef high-pressure hydrothermal reaction kettle of 100mL by milky white liquid prepared by step (4), be tamping bottleneck with poly tetrafluoroethylene, at 150 DEG C, laser heating naturally cools to room temperature after reacting 9 hours;

(6) after politef high-pressure hydrothermal reaction kettle naturally cools to room temperature, flat bottoms at politef high-pressure hydrothermal reaction kettle has white solid to precipitate, reacted solution is transferred in centrifuge tube, with the centrifuge rotating speed at room temperature centrifugation 5 minutes with 6000rpm/min, the supernatant liquid of centrifuge tube is taken out, add 6ml ethanol purge three times, obtain pure white solid product;

(7) white solid product vacuum drying 6 hours at 40 DEG C step (6) obtained, obtain being smaller in size than the NaGdF of 100 nanometers₄:Yb³⁺/Tm³⁺, respectively as depicted in figs. 1 and 2, its crystalline structure is hexagonal crystal system (as shown in Figure 3) for its transmission electron microscope picture and electron scanning electron microscopic picture, and 980nm excites its up-conversion fluorescence for doping Tm³⁺Characteristic emission peak (as shown in Figure 4).

Embodiment 2:

The present embodiment adopts normal stoichiometric proportion NaF:Ln³⁺For 4:1, preparation technology comprises the following steps:

(1) measure 10mL concentrated nitric acid and join in 100mL volumetric flask, constant volume, shake up, preparation obtains the salpeter solution that percent by volume is 10%;

(2) rare earth oxide that precise is a certain amount of, wherein Gd₂O₃141.414mg, 0.78mmol, Yb₂O₃39.4mg, 0.2mmol, Tm₂O₃3.85mg, 0.02mmol, be dissolved in the salpeter solution of step (1) by these three rare earth oxide, and 80 DEG C of lower magnetic agitation to oxides of heating are completely dissolved, and solution obtains rare earth nitrate solution till becoming clarification;

(3) oleic acid 5ml is measured, add after being dissolved with hot water in beaker, the ethanol measuring 16mL again adds in beaker, the two is stirred into uniform solution, continue load weighted NaF (167.4mg, 4mmol) white powder joins in solution, continues to be uniformly mixing to obtain mixed solution;

(4) rare earth nitrate solution prepared by step (2) dropwise join in mixed solution prepared by step (3), limit dropping stirring, under room temperature, magnetic agitation obtains milky white liquid in about 5 minutes;

(5) being transferred to by milky white liquid prepared by step (4) in the politef high-pressure hydrothermal reaction kettle of 100mL, be tamping beaker mouth with poly tetrafluoroethylene, at 150 DEG C, laser heating naturally cools to room temperature after reacting 9 hours;

(6) after politef high-pressure hydrothermal reaction kettle naturally cools to room temperature, white solid is had to precipitate in poly tetrafluoroethylene flat bottoms, reacted solution is transferred in centrifuge tube, the supernatant liquid of centrifuge tube is poured out after 5 minutes with centrifugation under centrifuge 6000rpm/min room temperature, add ethanol in proper amount to clean, clean three times altogether, obtain pure white solid product;

(7) white solid product step (6) obtained, at 40 DEG C, vacuum drying 6 hours, obtain white solid powder.

The present embodiment is analyzed by XRD (accompanying drawing 5) and SEM picture (accompanying drawing 6), it does not have prepare GdF₃:Yb³⁺/Tm³⁺, namely adopt normal stoichiometric coefficient to react, it is impossible to prepare a nanometer NaGdF₄:Yb³⁺/Tm³⁺。

Embodiment 3:

The present embodiment adopts normal stoichiometric proportion NaF:Ln³⁺For 4:1, raising reaction temperature is to 200 DEG C, and other techniques are identical with embodiment 2, and the sample X ray diffracting spectrum prepared is as it is shown in figure 5, sample is consistent with the sample crystal formation that embodiment 2 obtains as can be seen from Figure 5, for GdF₃:Yb³⁺/Tm³⁺, namely adopt normal stoichiometric coefficient to react, raise temperature and can not prepare a nanometer NaGdF₄:Yb³⁺/Tm³⁺。

Embodiment 4:

The present embodiment adopts normal stoichiometric proportion NaF:Ln³⁺For 4:1, the volume ratio changing nitric acid is that 30% all the other techniques are identical with embodiment 2, reaction does not obtain solid sample after terminating, thus prove, normal stoichiometric coefficient is adopted to react, improve the acidity of solution, improve rare earth oxide solubility property wherein, six side NaGdF can not be prepared through this reaction₄:Yb³⁺/Tm³⁺。

Embodiment 5:

The present embodiment increases stoichiometric proportion NaF:Ln³⁺For 12:1, all the other techniques are identical with embodiment 2, and the sample transmission electron microscopic picture obtained is as it is shown in fig. 7, the sample morphology distribution as can be seen from the figure prepared is various, possibly together with the impurity crystal phase of other the unknowns, it does not have obtain spherical NaGdF₄:Yb³⁺/Tm³⁺。

Claims (1)

1. an infrared excitation up-conversion nano material NaGdF₄:Yb³⁺/Tm³⁺Low-temperature synthetic method, it is characterised in that specifically include the following step:

(1), 10mL concentrated nitric acid is joined in 100mL volumetric flask, constant volume, obtaining percent by volume after shaking up is 10% salpeter solution;

(2), 141.414mgGd is weighed successively₂O₃、39.4mgYb₂O₃、3.85mgTm₂O₃, by Gd₂O₃、Yb₂O₃And Tm₂O₃Three kinds of rare earth oxides are dissolved in the salpeter solution that step (1) is prepared, and under 80 DEG C of heating conditions, magnetic agitation is to being completely dissolved, and obtain the rare earth nitrate solution of clarification;

(3), measure in oleic acid 5ml addition small beaker, then measure in 16ml ethanol addition small beaker, oleic acid and ethanol are stirred into uniform solution, then 251.1mgNaF white powder is joined in uniform solution, continue to be uniformly mixing to obtain mixed solution;

(4), rare earth nitrate solution prepared by step (2) is added dropwise in mixed solution prepared by step (3), limit dropping stirring, under room temperature, magnetic agitation obtains milky white liquid in 5 minutes;

(5), being transferred in the politef high-pressure hydrothermal reaction kettle of 100mL by milky white liquid prepared by step (4), be tamping bottleneck with poly tetrafluoroethylene, at 150 DEG C, laser heating naturally cools to room temperature after reacting 9 hours;

(6) after politef high-pressure hydrothermal reaction kettle naturally cools to room temperature, flat bottoms at politef high-pressure hydrothermal reaction kettle has white solid to precipitate, reacted solution is transferred in centrifuge tube, with the centrifuge rotating speed at room temperature centrifugation 5 minutes with 6000rpm/min, the supernatant liquid of centrifuge tube is taken out, add 6ml ethanol purge three times, obtain pure white solid product;

(7) white solid product vacuum drying 6 hours at 40 DEG C step (6) obtained, obtain being smaller in size than the NaGdF of 100 nanometers₄:Yb³⁺/Tm³⁺。