CN107603594A

CN107603594A - Prepare Y2Ti2O7@SiO2The method of core-shell structure up-conversion

Info

Publication number: CN107603594A
Application number: CN201710808061.4A
Authority: CN
Inventors: 陈中胜; 肖双喜; 谢宗波; 黄海清; 黄国林
Original assignee: East China Institute of Technology
Current assignee: East China Institute of Technology
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2018-01-19

Abstract

The present invention discloses one kind and prepares Y₂Ti₂O₇@SiO₂The method of core-shell structure up-conversion；Comprise the following steps：(1) it is standby go out single dispersing SiO₂Microballoon；(2) with SiO₂Microballoon is core, and synthesis Y is coated using sol-gal process₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺@SiO₂(Re=Er, Ho) core-shell structure.

Description

Prepare Y2Ti2O7@SiO2The method of shell-core structure up-conversion

Technical field

The present invention relates to the preparing technical field of shell-core structure, more particularly to one kind to prepare Y₂Ti₂O₇@SiO₂Shell-core knot The method of structure up-conversion.

Background technology

Silica such as inexpensively, easily forms spherical particles, chemical stability and optical clear due to its unique property Property, it is widely used in preparing shell-core structure material.When in SiO₂One layer of luminescent material is coated on microballoon, can be formed a kind of new Shell-core structure luminescent material.This new composite has single dispersing, spherical morphology, soilless sticking, particle size distribution range The features such as narrower and shell thickness is easily controllable, are advantageous to improve its bulk density, increase luminosity and the scattering for reducing light, Advantage is had more for the practical application of luminescent material.Further, since cheap SiO₂Microballoon instead of the higher rare earth hair of cost Luminescent material, product cost is greatly reduced, this has great significance to the practical application for expanding luminescent material.Therefore, this side The research in face has been obtained for many researchers and paid attention to, with SiO₂Microballoon is shell-nuclear structure fluorescent material prepared by core, such as Y₂O₃:Eu³⁺@SiO₂、Gd₂O₃:Eu³⁺@SiO₂、YVO₄:Eu³⁺@SiO₂And GdPO₄:Eu³⁺@SiO₂Deng.However, so far, these The research of aspect is mainly using down-conversion luminescent material as shell, and in SiO₂The research of micro-spheres up-conversion luminescent material is fresh Appear in the newspapers.

The content of the invention

It is an object of the invention to overcome the deficiencies in the prior art, adapts to real needs, and open one kind prepares Y₂Ti₂O₇@ SiO₂The method of shell-core structure up-conversion.

In order to realize the purpose of the present invention, the technical solution adopted in the present invention is：

Open one kind prepares Y₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：It includes following step Suddenly：

（1）It is standby go out single dispersing SiO₂Microballoon；

（2）With SiO₂Microballoon is core, and synthesis Y is coated using sol-gal process₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺@SiO₂（Re=Er, Ho）Shell-core structure.

Step（1）Implemented by St ber methods, it is specific as follows：

A. by ammoniacal liquor, absolute ethyl alcohol and deionized water by certain than well mixed, the concentrated ammonia liquor is 95ml~100ml, anhydrous Ethanol is 70ml~80ml, deionized water 15ml~20ml)；

B. tetraethyl orthosilicate 5ml~10ml stirrings 24h is added；

C. centrifuge；

D. it is dried to white powder.

Step（2）Implemented using sol-gal process, be specially：

（ⅰ）With n (CA)/n (Y³⁺+Er³⁺+Yb³⁺+Li⁺+Ti⁴⁺)=2.5, keep n (Y³⁺+Er³⁺+Yb³⁺+Li⁺)=n(Ti⁴⁺), Er³⁺、 Yb³⁺And Li⁺The doping concentration of ion is respectively 1.0,7.5 and 10.0mol%；Add 1.0g polyethylene glycol（Crosslinking agent）, formed saturating Bright colloidal sol；

（ⅱ）By step（1）The SiO of preparation₂Microballoon is added to step（ⅰ）In the colloidal sol of preparation, the SiO₂The amount that microballoon adds For 0.1g~0.3g；

（ⅲ）The pH value for adding weak aqua ammonia/dust technology regulation system is not less than 6；Stirring 12h obtains suspension at room temperature；

（ⅳ）Suspension is centrifuged successively, dried；

（ⅴ）1.0h is calcined in Muffle furnace.

The room temperature refers in the environment of 15 degrees Celsius to 22 degrees Celsius.

The step（ⅴ）In, to be calcined in 600~1000 DEG C of temperature in Muffle furnace.

During calcining 600~1000 DEG C are warming up to 5 DEG C/min speed.

Step（ⅴ）In, calcined at a temperature of 800~1000 DEG C.

Step（ⅲ）The middle pH value for adding weak aqua ammonia/dust technology regulation system is to 6.0,7.0 or 8.0.

The beneficial effects of the present invention are：

The present invention：

（1）Using St ber methods, using tetraethyl orthosilicate as base stock, list is successfully prepared in ethanol-ammoniacal liquor-aqueous systems Scattered, spherical SiO₂Particle, its average grain diameter are 201nm.

（2）Y is successfully synthesized using collosol and gel cladding process₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺@SiO₂（Re=Er and Ho）Shell- Composite is changed on nuclear structure.Research shows, the pH value of precursor solution produces important influence to cladding process, pH= When 7.0, Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺Particle energy is complete, is uniformly coated on SiO₂On microballoon, the compound particle of gained is same With preferable dispersiveness and sphericity, shell Y₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺The thickness of material is 20nm or so.

（3）Upconversion emission test shows, composite is changed on shell-core structure and maintains upper conversion nano crystalline substance accordingly Efficient Upconversion luminescence.What is more important, the relatively cheap SiO of use₂Microballoon instead of rare earth material costly, Had great significance to saving material, reducing cost.This method is equally applicable to other Re₂Ti₂O₇@SiO₂It is prepared by structure, And propose the formation mechenism of such shell-core structure.

Brief description of the drawings

Fig. 1 is Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂The technology of preparing route map of shell-core structure；

Fig. 2 is SiO₂Y under microballoon and different calcining heats₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂The FT-IR spectrograms of shell-nuclear particle；

Fig. 3 is the Y of pH=7.0₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂The TG-DSC curve maps of presoma xerogel；

Fig. 4 is Y under different calcining heats₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂XRD spectrum；

Fig. 5（a）For the uncoated SiO under low multiplication factor₂The field emission scanning electron microscope figure of microballoon；

Fig. 5（b）For the uncoated SiO under high-amplification-factor₂The field emission scanning electron microscope figure of microballoon；

Fig. 5（b）Upper right corner illustration is SiO₂Microspherulite diameter distribution map；

Fig. 6（a）For pH=1.0 when cladding after product field emission scanning electron microscope figure；

Fig. 6（b）For pH=4.0 when cladding after product field emission scanning electron microscope figure；

Fig. 6（c）For pH=7.0 when, the field emission scanning electron microscope figure of product after the cladding under low multiplication factor；

Fig. 6（d）For pH=7.0 when, the field emission scanning electron microscope figure of product after the cladding under high-amplification-factor；

Fig. 6（d）Upper right corner illustration is the grain size distribution of microballoon after cladding（Calcining heat is 800 DEG C）；

Fig. 7（a）For SiO uncoated after 800 DEG C of calcining 1.0h₂The transmission electron microscope photo figure of microballoon；

Fig. 7（b）For Fig. 7（a）Corresponding SEAD style;

Fig. 8（a）For pH=4.0 when precursor solution cladding after sample transmission electron microscope picture；

Fig. 8（b）The transmission electron microscope picture of sample after precursor solution cladding when for pH=7.0, multiplication factor being 25000；

Fig. 8（c）The transmission electron microscope picture of sample after precursor solution cladding when for pH=7.0, multiplication factor being 40000；

Fig. 8（d）The high resolution electron microscopy figure of shell when for calcining heat being 800 DEG C；

Fig. 9 is that calcining heat is 800 DEG C, excitation wavelength 980nm, and exciting power is the Y under the conditions of 230mW₂Ti₂O₇:Er³⁺, Yb³⁺,Li⁺Nanocrystalline and Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂The upper conversion spectrogram of shell-core structure；

Figure 10 is that calcining heat is 800 DEG C, excitation wavelength 980nm, and exciting power is the Y under the conditions of 800mW₂Ti₂O₇:Ho³⁺, Yb³⁺,Li⁺Nanocrystalline and Y₂Ti₂O₇:Ho³⁺,Yb³⁺,Li⁺@SiO₂The upper conversion spectrogram of shell-core structure；

Figure 11 is shell-core structure Re₂Ti₂O₇@SiO₂Formation mechenism schematic diagram；

In 2 in figure：(a) SiO not calcined₂Microballoon, 700 DEG C of (b), 800 DEG C of (c), 900 DEG C of (d), 1000 DEG C of (e)；

In Fig. 4:(c) 600 DEG C, 700 DEG C of (d), 800 DEG C of (e), 900 DEG C of (f), 1000 DEG C of (g), (a) Y₂Ti₂O₇Standard card, (b) SiO without calcining₂Microballoon.

Embodiment

The present invention is further described with reference to the accompanying drawings and examples：

Embodiment 1：One kind prepares Y₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, referring to Fig. 1, it includes following step Suddenly：

（1）It is standby go out single dispersing SiO₂Microballoon；

This step is implemented by St ber methods, specific as follows：

A. by ammoniacal liquor, absolute ethyl alcohol and deionized water by necessarily than well mixed specifically, the concentrated ammonia liquor is 98ml, anhydrous second Alcohol is 76ml, deionized water 18ml)；

B. tetraethyl orthosilicate 8.5ml stirrings 24h is added；

C. centrifuge；

D. it is dried to white powder and produces monodispersed SiO₂Microballoon.

（2）With SiO₂Microballoon is core, and synthesis Y is coated using sol-gal process₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺@SiO₂（Re =Er,Ho）Shell-core structure；

This step（2）Implemented using sol-gal process, be specially：

（ⅱ）By step（1）The SiO of preparation₂Microballoon is added to step（ⅰ）In the colloidal sol of preparation, SiO₂Microballoon add amount be 0.2g

（ⅲ）The pH value for adding weak aqua ammonia/dust technology regulation system is not less than 6, and its preferable pH value is 6.0,7.0 or 8.0； 15 degrees Celsius to 22 degrees Celsius of the 12h of stirring at room temperature obtains suspension；

（ⅳ）Suspension is centrifuged successively, dried；

（ⅴ）600~1000 DEG C of calcining 1.0h are warming up to 5 DEG C/min speed in Muffle furnace, it is preferred that this step In preferably calcined at a temperature of not less than 800 DEG C.

Embodiment 2, part same as Example 1 repeat no more, and difference is：

In step a, the concentrated ammonia liquor is 95ml, absolute ethyl alcohol 70ml, deionized water 15ml；

In step b, tetraethyl orthosilicate 5ml stirrings 22h is added；

Step（ⅱ）In, the SiO₂The amount that microballoon adds is 0.1g.

Embodiment 3, part same as Example 1 repeat no more, and difference is：

In step a, the concentrated ammonia liquor is 100ml, absolute ethyl alcohol 80ml, deionized water 20ml；

In step b, tetraethyl orthosilicate 10ml stirrings 26h is added；

Step（ⅱ）In, the SiO₂The amount that microballoon adds is 0.3g.

Through Y made from the methods described of the embodiment of the present invention 1₂Ti₂O₇@SiO₂Shell-core structure is analyzed as follows：

1st, infrared spectrum analysis

Fig. 2 gives not thermally treated SiO₂Shell-core structure Y after particulate, calcining₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂'s FT-IR is composed；In Fig. 2 (a), 3450cm is located at center⁻¹Wide and strong absworption peak belongs to the Si-O-H and surface moisture on surface Hydroxyl（O-H）Stretching vibration absworption peak, 1638cm⁻¹Peak come from hydroxyl in hydrone（O-H）Flexural vibrations；1384cm⁻¹ The peak at place is COO⁻The absorption of symmetrical stretching vibration.In 801 and 1110cm⁻¹Neighbouring absorption is originated from Si-O-Si keys Symmetrical flexible and nonsymmetrical vibration, 950cm⁻¹The absworption peak at place belongs to Si-OH key symmetrical stretching vibrations, 465cm⁻¹The suction at place Receive the flexural vibrations peak that peak is Si-O keys.This shows, the SiO of preparation₂Contain substantial amounts of hydroxyl in the surface of particulate（O-H）, especially It is the presence of substantial amounts of Si-OH keys, the metal cation that can be bonded in sol system, this is to forming Y₂Ti₂O₇:Er³⁺,Yb³⁺, Li⁺@SiO₂Shell-core structure plays vital effect.

As can be seen that 950cm from Fig. 2 (b) ~ (e)⁻¹The absworption peak at place（The symmetrical stretching vibration of Si-OH keys）Disappear completely Lose, show that Si-OH keys are destroyed.And in 563cm⁻¹New absworption peak is formed, this belongs to Ti-O keys in pyrochlore constitution Stretching vibration, (Y, Er, Yb)-O stretching vibration peaks are in 469cm⁻¹Place, the two absworption peaks are the feature of titanate pyrochlore constitution Absworption peak.Amorphous Si O₂Si-O-Si keys（801 and 1110cm⁻¹）Do not change, the flexural vibrations peak of Si-O keys 465cm⁻¹There occurs overlapping with (Y, Er, Yb)-O stretching vibration peaks.In addition, with the raising of calcining heat, 3450cm⁻¹、 1638cm⁻¹And 1384cm⁻¹The intensity of absworption peak gradually reduces, and this shows that calcining heat while crystallinity is improved, reduces H in air₂O and CO₂Absorption.Result above shows Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺Shell and SiO₂Pass through chemistry between core The effect of key is combined together.

2nd, TG-DT A spectrum

Fig. 3 is the TG-DSC curves of presoma xerogel calcination process in air atmosphere of precursor solution pH=7.0.Thermogravimetric Curve shows that sample is continuous weightless until 500 DEG C or so：30 DEG C to 110 DEG C, weightlessness is 7.7%, corresponding to physisorbed molecules The volatilization of water, show 69.5 DEG C of endothermic peak；110 ~ 500 DEG C, weightlessness is 5.0%, corresponding to the combustion of metal citrate complex compound Burn and decompose.When calcining heat is higher than 500 DEG C, the weight of sample is about 87.3%, is kept approximately constant.Compared to uncoated Presoma xerogel, in SiO₂Presoma weightlessness after microsphere surface cladding is obviously reduced, and product is remaining after high-temperature calcination Weight substantially increases, and this is due in SiO₂In presoma after micro-spheres, core SiO₂The weight of microballoon is occupied an leading position （Weight change after before calcination is smaller）, and clad Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺The thinner thickness of gel, shared matter Measure smaller.

3rd, Phase Structure Analysis

Fig. 4 gives the SiO without calcining₂Y after sample and different temperatures calcination processing₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺@SiO₂ The X-ray diffracting spectrum of sample.As seen from the figure, SiO₂Particle and calcining heat only have one for the spectrogram of 600 DEG C of products Wider disperse diffraction maximum, illustrate that both are amorphous mechanism.Shell Materials start to crystallize at 700 DEG C, and 800 DEG C of crystallizations are good It is good, it is the Y of cubic system pyrochlore constitution₂Ti₂O₇Phase（Fdm, JCPDSNo.41-0413）, its（222）、（400）、（331）、（440）With（622）Diffraction maximum etc. serial crystal face is recorded.In addition, with the rise of calcining heat, Y is represented₂Ti₂O₇Structure is spread out The position for penetrating peak does not change, but diffracted intensity gradually strengthens, and diffraction peak width narrows, and illustrates the increasing with calcining heat Add, the crystallite dimension increase of shell, but represent core SiO₂Diffraction maximum remain as the diffraction maximum of disperse（As figure asterisk marks Position）, illustrate SiO₂Microballoon is impalpable structure always.

4th, field emission scanning electron microscope is analyzed

4.1 uncoated SiO₂The field emission scanning electron microscope map analysis of microballoon

Fig. 5 (a) and (b) sets forth uncoated SiO₂The field emission scanning electron microscope result of particle, the illustration in Fig. 5 (b) For uncoated SiO₂The grain size distribution of microballoon.It can be seen that uncoated SiO₂Surface is smooth, spherical in shape, single point Dissipate, soilless sticking, microspherulite diameter distribution relative narrower, average grain diameter 202nm.

The field emission scanning electron microscope map analysis of product after cladding

Fig. 6 gives the stereoscan photograph figure of sample after the claddings of different pH precursor solutions.

Illustration in Fig. 6 (d) for pH=7.0 when cladding after sample particle diameter distribution（Sample calcining heat is 800 DEG C）.

With amorphous Si O₂Microballoon is core, and shell-core structure functional material, precursor solution are prepared using sol-gal process Formation of the pH value to shell played important function.It has been investigated that when only the pH value of precursor solution is more than 6, ability Formation forms uniform shell, and when pH value is less than 6, it cannot get uniform shell-core structure.Can from Fig. 6 (a) and 6 (b) Go out, when pH=1.0,4.0, in addition to obtaining spherical pattern, also part fine granularity material shows Y₂Ti₂O₇:Er³⁺, Yb³⁺,Li⁺Particle is not coated to SiO completely₂On microballoon.When Fig. 6 (c) shows the pH=7.0 of precursor solution, the grain after cladding Son remains in that good spherical morphology, in single dispersing, non-agglomerated；From Fig. 6 (d) it can be found that part coat after microballoon On have a small gap, while some microballoons protrude a fritter, and this is probably the SiO due to during cladding₂Microballoon sticks together, but Mechanical force when being milled after calcining, their coupling part is destroyed, so as to form this structure.In addition, after cladding The average grain diameter of microballoon is 224nm, than uncoated SiO₂Microballoon is big, show the pH value by optimizing colloidal sol, can incite somebody to action Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺Particle is coated on SiO completely₂Core-shell structure is formed on microballoon.Research finds, neutral or alkalescent Condition helps to activate SiO₂Microsphere surface, more active Si-OH are produced, are advantageous to gel in SiO₂On microballoon Even cladding.

5th, transmission electron microscope analysis

In order to further illustrate SiO₂Micro-spheres forward and backward pattern and coating thickness, to uncoated SiO₂Microballoon, difference Sample after the precursor solution cladding of pH value carries out transmission electron microscope analysis.

Uncoated SiO₂The transmission electron microscope picture of microballoon

Fig. 7 gives uncoated SiO₂The transmission electron microscope photo of microballoon.Fig. 7 (a) can be seen that uncoated SiO₂Particle table Face is smooth, spherical in shape, and average grain diameter is 201nm or so, and the value is consistent with obtaining result with ESEM, shows SiO₂Microballoon exists Forward and backward average grain diameter is calcined not change.According to corresponding diffraction spot Fig. 7 (a), it can be determined that, after 800 DEG C of calcining 1.0h SiO₂Microballoon is undefined structure, consistent with XRD analysis result.

The transmission electron microscope picture of product after cladding

The precursor solution coated Si O of different pH value₂Transmission electron microscope photo after microballoon, through calcining sample is as shown in Figure 8（Sample Calcining heat is 800 DEG C）.

Such as Fig. 8 (a), during precursor solution pH=4.0, part nano-particle is is coated on SiO₂On microballoon, do not formed Uniform shell-core structure, the result with scanning electron microscopic observation（Fig. 6 (b)）Unanimously.However, the pH of precursor solution=7.0 when （From Fig. 8 (b)）, certain contrast be present in the core and shell of the compound particle of gained.When amplifying observation multiple improves, such as scheme Shown in 8 (c), the contrast of core particle and shell becomes apparent from.Between contrast difference be due to core particle and clad not Caused by material.It may determine that accordingly, Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺Luminescent material is successfully coated on SiO₂Microballoon On, the average thickness of shell is about 20nm or so.According to high resolution electron microscopy Fig. 8 (d) of shell, lattice fringe is high-visible, says Product complete crystallization corresponding to bright, its interplanar distance is 0.292nm, belongs to Y₂Ti₂O₇'s（222）Crystal face.In addition, some shells- The shell of nuclear structure has small gap, and some shells protrude a fritter, these topographical properties and the knot of FE-SEM observations above Fruit（Fig. 6 (d)）Unanimously.

6th, the up-conversion luminescence performance evaluation of shell-core structure

Referring to Fig. 9, in order to compare influence of the coating function to sample up-conversion luminescence, identical doping concentration is tested（Er³⁺, Yb³ ⁺And Li⁺Doping concentration be respectively 1.0,7.5 and 10.0mol%）With Y under identical calcining heat₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺Receive Rice is brilliant and its up-conversion luminescence of shell-core structure is composed, as shown in Figure 9.It can be seen that coat forward and backward sample upper turn Change and penetrate position, luminous intensity does not have notable difference：Feux rouges can be obtained（~660nm）With two green glows（~524nm、~ 545nm）Transmitting band, it is respectively belonging to Er³⁺Ion⁴ F _9/2→⁴ I _15/2With（² H _11/2,⁴ S _3/2）→⁴ I _15/2Radiation transistion.

Similarly, Y under identical doping concentration and identical calcining heat is tested₂Ti₂O₇:Ho³⁺,Yb³⁺,Li⁺It is nanocrystalline and its The upconversion emission of shell-core structure, as shown in Figure 10, it is observed that bright green glow（~550nm）And feux rouges（~660nm） Transmitting, corresponds respectively to Ho³⁺Ion（⁵ F ₄,⁵ S ₂）→⁵ I ₈With⁵ F ₅→⁵ I ₈Energy level transition, coat the transmitting peak position of forward and backward sample Put and do not change with intensity.Therefore, by up-conversion Y₂Ti₂O₇:Er³⁺,Yb³⁺,Li⁺And Y₂Ti₂O₇:Ho³⁺,Yb³⁺,Li⁺Bag It is layed onto SiO₂On the surface of microballoon, nanocrystalline efficient Upconversion luminescence is maintained.On the other hand, use is relatively cheap SiO₂Microballoon instead of rare earth material costly, have certain meaning to saving material, reducing cost.

7th, the formation mechenism of shell-core structure

Based on shown above, sol-gal process is equally applicable to prepare the Re of other rare earth titanates₂Ti₂O₇@SiO₂Structure. As it was previously stated, SiO₂The surface of microballoon plays key effect there is substantial amounts of Si-OH during collosol and gel cladding, Therefore, present inventors have proposed Re₂Ti₂O₇@SiO₂The mechanism that shell-core structure is formed, as shown in figure 11.

The pH value of ammoniacal liquor regulation precursor solution is employed in experiment.It can be activated in neutral or weak basic condition, ammoniacal liquor SiO₂Microsphere surface, so as to produce more active Si-OH, be advantageous to siloxanes oxygen atom and the Re in colloidal sol³⁺With Ti⁴⁺Cation forms stronger covalent bond.In the mechanism that the present inventor proposes, each Ti⁴⁺And Re³⁺Cation respectively with its Four and three oxygen atoms formation covalent bonds of surrounding, and each oxygen atom and two cations（Ti⁴⁺And Re³⁺Each one）Bonding. The present inventors have noted that LinJ etc. is preparing Gd₂Ti₂O₇:Eu³⁺@SiO₂During shell-core structure, it is proposed that shell-core structure forms machine Reason, but in the schematic diagram that they provide, Ti⁴⁺Cation and five oxygen atoms of surrounding formation covalent bond, and oxygen atom and neighbour Four near cations（Ti⁴⁺And Re³⁺Each two of sun）Form covalent bond.Therefore, the formation mechenism that the present inventor proposes more meets Chemical bonding rule.

In summary, it is of the invention：

Finally illustrate, what embodiments of the invention were announced is preferred embodiment, but is not limited thereto, this area Those of ordinary skill, easily according to above-described embodiment, understand the spirit of the present invention, and make different amplification and change, but Without departing from the present invention spirit, all within the scope of the present invention.

Claims

1. one kind prepares Y₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：It comprises the following steps：

(1) it is standby go out single dispersing SiO₂Microballoon；

(2) with SiO₂Microballoon is core, is coated and synthesized using sol-gel process

Y₂Ti₂O₇:Re³⁺,Yb³⁺,Li⁺@SiO₂(Re=Er, Ho) shell-core structure.

2. Y is prepared as claimed in claim 1₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Step Suddenly (1) passes throughMethod is implemented, specific as follows：

A. by ammoniacal liquor, absolute ethyl alcohol and deionized water by certain than well mixed, the concentrated ammonia liquor is 95ml~100ml, anhydrous Ethanol is 70ml~80ml, deionized water 15ml~20ml；

B. tetraethyl orthosilicate 5ml~10ml stirrings are added；

C. centrifuge；

D. it is dried to white powder.

3. Y is prepared as claimed in claim 2₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Institute It is 22h~26h to state step (b) mixing time.

4. Y is prepared as claimed in claim 1₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Step Suddenly (2) are implemented using sol-gel process, are specially：

(I) is with n (CA)/n (Y³⁺+Er³⁺+Yb³⁺+Li⁺+Ti⁴⁺)=2.5, keep n (Y³⁺+Er³⁺+Yb³⁺+Li⁺)=n (Ti⁴⁺), Er³ ⁺、Yb³⁺And Li⁺The doping concentration of ion is respectively 1.0,7.5 and 10.0mol%；1.0g polyethylene glycol is added, is formed transparent molten Glue；

The SiO that (II) prepares step (1)₂Microballoon is added in the colloidal sol prepared to step (I), the SiO₂The amount that microballoon adds For 0.1g~0.3g；

The pH value that (III) adds weak aqua ammonia/dust technology regulation system is not less than 6；Stirring 12h obtains suspension at room temperature；

(IV) is centrifuged, dried successively to suspension；

(V) calcines 1.0h in Muffle furnace.

5. Y is prepared as claimed in claim 4₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Institute Room temperature is stated to refer in the environment of 15 degrees Celsius to 22 degrees Celsius.

6. Y is prepared as claimed in claim 4₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Institute State in step (V), to be calcined in 600~1000 DEG C of temperature in Muffle furnace.

7. Y is prepared as claimed in claim 6₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Forge During burning 600~1000 DEG C are warming up to 5 DEG C/min speed.

8. Y is prepared as claimed in claim 7₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Step Suddenly in (V), calcined at a temperature of 800~1000 DEG C.

9. Y is prepared as claimed in claim 4₂Ti₂O₇@SiO₂The method of shell-core structure up-conversion, it is characterised in that：Step Suddenly pH value of weak aqua ammonia/dust technology regulation system is added in (III) to 6.0,7.0 or 8.0.