Summary of the invention
An object of the present invention is to provide a kind of stable height and the good rareearth blue fluorescent material of luminous intensity, this material can make the fine rareearth blue fluorescent powder of granularity.
Another object of the present invention provides a kind of preparation method of rareearth blue fluorescent material, this method can make the rareearth blue fluorescent material with above-mentioned premium properties with high purity and composition distribution uniformly, this method is carried out under the condition of gentleness, greatly reduces sintering temperature.
A further object of the invention provides the purposes of rareearth blue fluorescent material.
Be achieved through the following technical solutions above-mentioned purpose of the present invention.
The invention provides a kind of rareearth blue fluorescent material, its composition is represented by following general formula:
(M1)
x(M
2)
yEu
z(M
3)
w(SiO
3)
nCl
mSiO
2Wherein, M1 is the alkali metal that is selected from sodium, potassium, rubidium or its combination, M2 is the alkali earth metal that is selected from magnesium, calcium, strontium, barium or its combination, M3 is selected from the thulium of yttrium, lanthanum, terbium, cerium or its combination, x=0.05-0.3, y=0.05-0.3, z=0.001-0.05, w=0-0.5, n=0.1-0.5, m=x+2y+2z+3w-2n.
Be more preferably, M1 is potassium or rubidium, and M2 is calcium or strontium, and M3 is yttrium or terbium.x=0.1-0.2,y=0.1-0.2,z=0.005-0.05,n=0.15-0.3。
Rareearth blue fluorescent material of the present invention is more preferably granularity in the scope of 20-100nm.
The present invention also provides a kind of method for preparing rareearth blue fluorescent material, and this method may further comprise the steps:
Prepare colloidal sol in order to following method (a) or method (b):
(a) water-soluble alkali metal salts of mixed chemical calculated amount and excessive hydrochloric acid stir and obtain homogeneous solution A,
In this solution A, add capacity tetraalkyl orthosilicate Si (OR)
4, R is C in the formula
1-C
4Alkyl stirs until the colloidal sol C that forms homogeneous transparent,
(b) water-soluble alkali metal salts of mixed chemical calculated amount and excessive hydrochloric acid stir and obtain homogeneous solution A,
Additionally mixed capacity tetraalkyl orthosilicate Si (OR)
4And hydrochloric acid, R is C in the formula
1-C
4Alkyl stirs hydrolysis, obtains the sol B of homogeneous transparent,
Solution A is added in the sol B, stir the colloidal sol C that obtains homogeneous transparent;
The pH value of gained vitreosol C is less than 7, and to alkaline earth salt that wherein adds stoichiometric quantity and rare earth metal salt, described alkaline earth salt and rare earth metal salt are water-soluble salts or can be transformed into water-soluble salt under acidic conditions, stir so that mix; Add excessive reductant and stirring, leave standstill and obtain wet gel;
Drying, with the xerogel that obtains under non-oxidizing atmosphere in 500-800 ℃ of thermal treatment, obtain rareearth blue fluorescent material.
The method that the present invention prepares rareearth blue fluorescent material also comprises the step that the rareearth blue fluorescent material that obtains is washed, filters, dries and grinds.
In a better example of the present invention, prepare that tetraalkyl orthosilicate is methyl silicate Si (OCH in the method for rareearth blue fluorescent material
3)
4Or tetraethoxy Si (OC
2H
5)
4Water-soluble alkali metal salts is selected from alkalimetal silicate, alkali metal halide, alkaline carbonate, base metal nitrate and alkali metal phosphate, alkaline earth salt is selected from alkaline earth metal halide and alkaline earth metal carbonate, and rare earth metal salt is selected from rare earth element halogenide and rare-earth metal nitrate.Reductive agent is selected from POTASSIUM BOROHYDRIDE, sodium borohydride and inferior sodium phosphate.
The present invention also provides the purposes of rareearth blue fluorescent material in following field: optical transfer agricultural film with light conversion agent, demonstration and illumination with fluorescent material, anti-fake fluorescent material and coating fluorescent material.
Rareearth blue fluorescent material stability of the present invention is high, and luminous intensity is good, can make the fine rareearth blue fluorescent powder of granularity.The present invention prepares the sol-gel method of described rareearth blue fluorescent material and can carry out under the condition of gentleness, greatly reduces sintering temperature, can make highly purified fluorescent material, has avoided introducing owing to high sintering temperature the problem of impurity effectively.And the sol-gel liquid phase reduction that the present invention adopts is compared with traditional high temperature solid-state reduction method, and each feed composition mixes more even, and the fluorescent material group that makes becomes to be more evenly distributed, and can make the finer fluorescent material of granularity.Rareearth blue fluorescent material of the present invention is of many uses, for example can be used as optical transfer agricultural film with light conversion agent, demonstration and illumination with fluorescent material, anti-fake fluorescent material and coating fluorescent material.
Embodiment
A kind of rareearth blue fluorescent material, its composition is represented by following general formula:
(M1)
x(M2)
yEu
z(M3)
w(SiO
3)
nCl
mSiO
2Wherein, M1 is the alkali metal that is selected from sodium, potassium, rubidium or its combination, M2 is the alkali earth metal that is selected from magnesium, calcium, strontium, barium or its combination, M3 is selected from the thulium of yttrium, lanthanum, terbium, cerium or its combination, x=0.05-0.3, y=0.05-0.3, z=0.001-0.05, w=0-0.5, n=0.1-0.5, m=x+2y+2z+3w-2n.
In rareearth blue fluorescent material of the present invention, europium is as the fluorescence-activation source, and the rare earth metal that is selected from yttrium, lanthanum, terbium and cerium is as the sensitized fluorescence agent.The adulterated fluorescent material of divalent europium of the present invention can exist stable in the airly, and the blue-fluorescence of this material is kept functionally.In being doped with the silicate of divalent europium, described divalent europium occupies the part case of silicate.The reason that these divalent europiums are able to stable existence may be: described silicate particulate is encapsulated in the silica network that is formed by the tetraalkyl orthosilicate hydrolytic polymerization and is fixedly secured, thereby has advantages of excellent stability.
Rareearth blue fluorescent material of the present invention makes with aforesaid sol-gel liquid phase reduction.The mechanism that this method is possible is as follows: in colloidal sol, alkaline-earth metal ions and silicate ion form alkaline earth metal silicate on the one hand, reductive agent is reduced into divalent europium with trivalent europium ion under acidic conditions on the other hand, divalent europium combines with silicate ion, formation is doped with the silicate of europium ion, these silicate particulates are encapsulated in the silica network that is formed by the tetraalkyl orthosilicate hydrolytic polymerization, divalent europium can comparatively stably be present in the colloidal sol, and alkalimetal ion plays the effect of charge compensation agent simultaneously.After warm processing in the gel process, divalent europium is securely fixed in the above-mentioned silica network with the form of above-mentioned silicate.
Compare with sol-gel liquid phase reduction of the present invention, in the high-temperature sintering process of routine, have only the divalent europium that reduction is obtained to occupy the part case of silicate or aluminate by high temperature sintering in reducing atmosphere.
Prepare in the method for blue RE fluorescent material in the present invention, add an alkali metal salt with stoichiometric quantity, purpose is to introduce alkalimetal ion.Because most of an alkali metal salts are all water-soluble, so those skilled in the art can select suitable water-soluble alkali metal salts as raw material at an easy rate, as long as they can not have a negative impact to the luminescent properties of gained blue RE fluorescent material.These water-soluble alkali metal salts for example comprise: alkalimetal silicate, alkali metal halide (better being fluorochemical and muriate), alkaline carbonate, base metal nitrate and alkali metal phosphate, but be not limited thereto.
In preparation method of the present invention, the tetraalkyl orthosilicate of employing it is believed that and can form the silica network by hydrolytic polymerization.Tetraalkyl orthosilicate can be methyl silicate, tetraethoxy, positive silicic acid propyl ester and butyl silicate, better is methyl silicate or tetraethoxy, preferably tetraethoxy.
Among the preparation method of the present invention, the implication of excessive hydrochloric acid is that the add-on of hydrochloric acid can make the pH value of colloidal sol keep less than 7, is more preferably the pH value that makes colloidal sol and keeps less than 3.The pH value of colloidal sol remained on two effects in the above-mentioned scope: the one, prevent precipitation to occur in the colloidal sol effectively or gel occurs too early; The 2nd, reductive agent only could be reduced into divalent europium with trivalent europium ion effectively under acidic conditions.
In the method for the invention, introduce alkaline earth salt and rare earth metal salt (comprising europium salt and the rare earth metal salt that is selected from yttrium, lanthanum, terbium, cerium or its combination) with stoichiometric quantity, purpose is to introduce the associated metal ion.Because method of the present invention is a liquid phase reduction, therefore alkaline earth salt and the rare earth metal salt that uses should be water-soluble salt or can be transformed into water-soluble salt under acidic conditions.For example, alkaline earth salt can be an alkaline earth metal halide, better is fluorochemical and muriate, also can be alkaline earth metal carbonate, and carbonate is convertible into soluble salt under acidic conditions; Rare earth metal salt can be a rare earth element halogenide, better is fluorochemical and muriate, can also be rare-earth metal nitrate etc.
Reductive agent can be any reductive agent that trivalent europium ion can be reduced into divalent europium and can not have a negative impact to the luminescent properties of obtained fluorescent material, and these reductive agents are well known to a person skilled in the art.Reductive agent can for example be POTASSIUM BOROHYDRIDE, sodium borohydride or inferior sodium phosphate.
Among the preparation method of the present invention, the temperature of dry wet gel is well known to those skilled in the art, is generally 60-200 ℃.In the inventive method, thermal treatment to xerogel is carried out under non-oxidizing atmosphere, and non-oxidizing atmosphere is well known to those skilled in the art, for example comprises inert atmosphere (as nitrogen), reducing atmosphere (as hydrogen) etc., consider from the cost aspect, preferably nitrogen.The thermal treatment temp of xerogel is 500-800 ℃, is preferably 550-650 ℃.This thermal treatment temp is lower than the sintering temperature in the conventional high temperature sintering method widely, has therefore saved energy consumption, has simplified processing unit.
Further specify the present invention by the following examples.But should be understood that these embodiment are exemplary, the present invention does not limit to this.
Embodiment 1
In 20ml 12M hydrochloric acid (containing 0.24mol HCl), drip 20ml 2.5M K
2SiO
3The aqueous solution (contains 0.05mol K
2SiO
3), stir and obtain homogeneous solution.Add the 1.1mol tetraethoxy in this solution, stir until the colloidal sol that forms homogeneous transparent, the pH value of this colloidal sol is about 1.In gained colloidal sol, add 0.10molCaCl
2With 0.005mol EuCl
3, stirred 5 minutes.Then, add the 0.01mol POTASSIUM BOROHYDRIDE, stirred 20 minutes.This colloidal sol is airtight, under 60 ℃, left standstill 12 hours, obtain wet gel.Make this wet gel in 120 ℃ dry 6 hours down, with the xerogel that obtains under nitrogen atmosphere in 650 ℃ of thermal treatments 1 hour, obtain rareearth blue fluorescent material.Determine the composition of gained fluorescent material to be K with X diffractometer and atomic absorption spectrometry
0.1Ca
0.1Eu
0.005(SiO
3)
0.15Cl
0.01SiO
2
With distilled water wash three times of this fluorescent material, washing with alcohol twice is filtered, is dried, and with ball mill grinding 1 hour and screening, obtains blue colour fluorescent powder.Measure the fluorescence spectrum of this fluorescent material with the Cary-E fluorescence spectrophotometer, the emission spectrum of this fluorescent material is positioned at the wavelength region of 380-470nm (being blue light-emitting), and fluorescence intensity is about 500a.u..
Fig. 2 shows transmission electron microscope (TEM) Photomicrograph of this fluorescent material, and the granularity of fluorescent material is in the scope of 20-100nm, and mean particle size is about 50 nanometers.This shows, rareearth blue fluorescent material of the present invention can be made the fine fluorescent material of granularity, this is because after the gel drying and thermal treatment that sol-gel method makes, obtain harder gel or crystal macrobead, these gels or granule interior have a large amount of micropores, can obtain nano_scale particle behind ball milling.And the material that makes with high-temperature sintering process is because interior solid, even also can not get nano_scale particle through grinding highly.
In air, left standstill 90 days at the fluorescent material that obtains, redeterminate its fluorescence intensity, find that fluorescence intensity does not almost change.
Embodiment 2
The aqueous solution that adds the listed an alkali metal salt of table 1 in the hydrochloric acid of the listed consumption of table 1 stirs and obtains homogeneous solution.In this solution, add the listed tetraalkyl orthosilicate Si (OR) of table 1
4, stirring until the colloidal sol that forms homogeneous transparent, the pH value of this colloidal sol is about 2.In gained colloidal sol, add listed alkaline earth salt and the Eu salt of table 1, stirred 5 minutes.Then, add the listed reductive agent of table 1, stirred 20 minutes.This colloidal sol is airtight, under 40 ℃, left standstill 24 hours, obtain wet gel.Make this wet gel in 60 ℃ dry 12 hours down, with the xerogel that obtains under nitrogen atmosphere in 550 ℃ of thermal treatments 45 minutes, obtain rareearth blue fluorescent material.Determine the composition of fluorescent material to be shown in table 2 with X diffractometer and atomic absorption spectrometry.
By embodiment 1 identical mode wash, filter, dry, grind, aftertreatment such as screening, obtain fluorescent material.The mean particle size of this fluorescent material is about 50 nanometers.Press the identical mode of embodiment 1, the emission spectrum that records this fluorescent material is positioned at the wavelength region of 380-470nm, and fluorescence intensity is 600a.u..Gained fluorescent material was left standstill in air 90 days, redeterminate fluorescence intensity, find that fluorescence intensity does not almost change.
Embodiment 3
Undertaken by embodiment 2 described methods, different is wet gel is in 200 ℃ of dryings 2 hours, with the gained xerogel under hydrogen atmosphere in 500 ℃ of thermal treatments 30 minutes.Raw materials used and consumption is as shown in table 1.The composition of gained fluorescent material, emission spectrum wavelength region, fluorescence intensity and stability thereof are as shown in table 2.
Embodiment 4
Undertaken by embodiment 2 described methods, different is wet gel is in 150 ℃ of dryings 6 hours, with the gained xerogel under nitrogen atmosphere in 800 ℃ of thermal treatments 1 hour.Raw materials used and consumption is as shown in table 1.The composition of gained fluorescent material, emission spectrum wavelength region, fluorescence intensity and stability thereof are as shown in table 2.
Embodiment 5-10
Undertaken by embodiment 1 described method, used raw material and consumption thereof are as shown in table 1.The composition of gained fluorescent material, emission spectrum wavelength region, fluorescence intensity and stability thereof are as shown in table 2.Fig. 1 is the fluorescence spectrum figure of the fluorescent material of the embodiment 8 that records with the Cary-E fluorescence spectrophotometer, and wherein the curve on the left side is that wavelength is the fluorescent powder excitation line that the light monitoring of 425nm records down; The curve on the right is to be the fluorescent material line of departure that the light of 330nm records as excitaton source with the wavelength.As seen from the figure, the emission spectrum of the fluorescent material of embodiment 8 is positioned at the wavelength region of 380-470nm, and fluorescence intensity is about 1000a.u..
Table 1
| Embodiment | ?????HCl ??(mol;ml) | An alkali metal salt (M1 salt) (mol) | ???????????Si(OR)
4????????????(mol)
| Alkaline earth salt (M2 salt) (mol) | Activator Eu salt (mol) | Rare earth metal salt (M3 salt) (mol) | Reductive agent (mol) |
| ????1 | ??0.24????20 | ????K
2SiO
3????0.05
| ????Si(OEt)
4??????1.1
| ??CaCl
2????0.10
| ????EuCl
3?????0.005
| ????--???????????-- | ????KBH
4??????0.01
|
| ????2 | ??0.48????40 | ????K
2CO
3?????0.10
| ????Si(OEt)
4??????1.3
| ??CaCl
2????0.26
| ????EuCl
3?????0.01
| ????--???????????-- | ????KBH
4??????0.02
|
| ????3 | ??0.38????30 | ????KCl??????????0.16 | ????Si(OEt)
4??????1.4
| ??CaCO
3????0.20
| ????EuCl
3?????0.02
| ????YCl
3???????0.1
| ????KBH
4??????0.03
|
| ????4 | ??0.72????60 | ????RbCl?????????0.30 | ????Si(OMe)
4??????1.48
| ??BaCO
3????0.30
| ????EuCl
3?????0.05
| ????YCl
3???????0.005
| ????NaH
2PO
2??0.09
|
| ????5 | ??0.24????20 | ????RbCl?????????0.05 | ????Si(OMe)
4??????1.1
| ??SrCl
2????0.05
| ????EuCl
3?????0.005
| ????TbF
3???????0.05
| ????KBH
4??????0.01
|
| ????6 | ??0.29????20 | ????RbNO
3???????0.12
| ????Si(OMe)
4??????1.25
| ??SrCl
2????0.16
| ????EuCl
3?????0.03
| ????--???????????-- | ????NaBH
4?????0.08
|
| ????7 | ??0.34????30 | ????Na
2SiO
3????0.07
| ????Si(O(n-Pr)
4???1.38
| ??BaCl
2????0.18
| ????EuCl
3?????0.025
| ????LaCl
3??????0.2
| ????NaBH
4?????0.04
|
| ????8 | ??0.48????40 | ????NaCl??????????0.10 | ????Si(O(s-Pr)
4???1.5
| ??CaCl
2????0.12
| ????Eu(NO
3)
3?0.003
| ????TbCl
3??????0.3
| ????NaBH
4?????0.01
|
| ????9 | ??0.38????30 | ????NaF???????????0.08 | ????Si(O(n-Bu)
4???1.16
| ??MgCO
3????0.08
| ????Eu(NO
3)
3?0.001
| ????Ce(NO
3)
3??0.03
| ????NaH
2PO
2??0.005
|
| ????10 | ??0.96????80 | ????K
3PO
3??????0.08
| ????Si(O(t-Bu)
4???1.5
| ??MgCl
2????0.28
| ????EuF
3??????0.04
| ????CeCl
3??????0.5
| ????NaH
2PO
2??0.1
|
Table 2
| Embodiment | The composition of fluorescent material | Emission spectrum wavelength (nm) | Fluorescence intensity (unit: a.u.) | Stability |
| ????1 | ?K
0.1Ca
0.1Eu
0.005(SiO
3)
0.15Cl
0.01·SiO
2 | ????380-470 | ????500 | Leave standstill 90 days in air after, fluorescence property does not almost change |
| ????2 | ?K
0.2Ca
0.26Eu
0.01(SiO
3)
0.3Cl
0.14·SiO
2 | ????380-470 | ????600 |
| ????3 | ?K
0.16Ca
0.2Eu
0.02Y
0.1(SiO
3)
0.4Cl
0.1·SiO
2 | ????380-470 | ????400 |
| ????4 | ?Rb
0.3Ba
0.3Eu
0.05Y
0.005(SiO
3)
0.48Cl
0.055·SiO
2 | ????380-470 | ????500 |
| ????5 | ?Rb
0.05Sr
0.05Eu
0.005Tb
0.05(SiO
3)
0.1Cl
0.11·SiO
2 | ????380-470 | ????400 |
| ????6 | ?Rb
0.12Sr
0.16Eu
0.03(SiO
3)
0.25·SiO
2 | ????380-470 | ????600 |
| ????7 | ?Na
0.14Ba
0.18Eu
0.025La
0.2(SiO
3)
0.45Cl
0.25·SiO
2 | ????380-470 | ????400 |
| ????8 | ?Na
0.1Ca
0.12Eu
0.003Tb
0.3(SiO
3)
0.5Cl
0.246·SiO
2 | ????380-470 | ????1000 |
| ????9 | ?Na
0.08Mg
0.08Eu
0.001Ce
0.03(SiO
3)
0.16Cl
0.012·SiO
2 | ????380-470 | ????500 |
| ????10 | ?K
0.24Mg
0.28Eu
0.04Ce
0.5(SiO
3)
0.5Cl
1.38·SiO
2 | ????380-470 | ????500 |
Embodiment 11
In 20ml hydrochloric acid (containing 0.24mol HCl), drip 20ml K
2SiO
3The aqueous solution (contains 0.05molK
2SiO
3), stir and obtain homogeneous solution A.The aqueous solution to the 26.5ml tetraethoxy (contains 1.17molSi (OEt) in addition
4) 10 hydrochloric acid of middle dropping, stir and make its hydrolysis, obtain the sol B of homogeneous transparent.Above-mentioned homogeneous solution A is added in the sol B, stir the colloidal sol C that obtains homogeneous transparent, the pH value of this colloidal sol C is about 3.In gained colloidal sol, add 0.10mol CaCl
2, 0.10mol SrCl
2With 0.01mol EuCl
3, stirred 10 minutes.Then, add the 0.015mol POTASSIUM BOROHYDRIDE, stirred 20 minutes.This colloidal sol is airtight, under 60 ℃, left standstill 12 hours, obtain wet gel.Make this wet gel in 120 ℃ dry 6 hours down, with the xerogel that obtains under nitrogen atmosphere in 650 ℃ of thermal treatments 1 hour, obtain rareearth blue fluorescent material.Determine the composition of gained fluorescent material to be K with X-ray diffractometer and atomic absorption spectrometry
0.1Ca
0.1Sr
0.1Eu
0.01(SiO
3)
0.22Cl
0.08SiO
2
By embodiment 1 identical mode wash, filter, dry, grind, aftertreatment such as screening, obtain fluorescent material.The mean particle size of this fluorescent material is about 50 nanometers.Press the identical mode of embodiment 1, the emission spectrum that records this fluorescent material is positioned at the wavelength region of 380-470nm, and fluorescence intensity is 600a.u..In air, left standstill 90 days at the fluorescent material that obtains, redeterminate its fluorescence intensity, find that fluorescence intensity does not almost change.
Embodiment 12
In 20ml hydrochloric acid (containing 0.24mol HCl), add the 8ml KCl aqueous solution (containing 0.04mol KCl) and the 12ml RbCl aqueous solution (containing 0.06mol RbCl), stir and obtain homogeneous solution A.The aqueous solution to the 28.5ml tetraethoxy (contains 1.3mol Si (OEt) in addition
4) 10 hydrochloric acid of middle dropping, stir and make its hydrolysis, obtain the sol B of homogeneous transparent.Above-mentioned homogeneous solution A is added in the sol B, stir the colloidal sol C that obtains homogeneous transparent, the pH value of this colloidal sol C is about 1.In gained colloidal sol, add 0.2mol CaCl
2, 0.01mol EuCl
3With 0.05mol YCl
3, stirred 10 minutes.Then, add the 0.02mol sodium borohydride, stirred 20 minutes.This colloidal sol is airtight, under 40 ℃, left standstill 24 hours, obtain wet gel.Make this wet gel in 60 ℃ dry 12 hours down, with the xerogel that obtains under nitrogen atmosphere in 550 ℃ of thermal treatments 45 minutes, obtain rareearth blue fluorescent material.Determine the composition of gained fluorescent material to be K with X diffractometer and atomic absorption spectrometry
0.04Rb
0.06Ca
0.2Eu
0.01Y
0.05(SiO
3)
0.3Cl
0.07SiO
2
By embodiment 1 identical mode wash, filter, dry, grind, aftertreatment such as screening, obtain fluorescent material.Press the identical mode of embodiment 1, the emission spectrum that records this fluorescent material is positioned at the wavelength region of 380-470nm, and fluorescence intensity is 550a.u..In air, left standstill 90 days at the fluorescent material that obtains, redeterminate its fluorescence intensity, find that fluorescence intensity does not almost change.
Embodiment 13
Undertaken by embodiment 12 described methods, different is to use 0.02mol YCl
3With 0.03mol LaCl
3Replace 0.05mol YCl
3The gained fluorescent material consist of K
0.04Rb
0.06Ca
0.2Eu
0.01Y
0.02La
0.03(SiO
3)
0.3Cl
0.07SiO
2The emission spectrum of fluorescent material is positioned at the wavelength region of 380-470nm, and fluorescence intensity is 550a.u..In air, left standstill 90 days at the fluorescent material that obtains, redeterminate its fluorescence intensity, find that fluorescence intensity does not almost change.