1. A sulfide phosphor having excellent weather resistance, characterized in that: the molecular deposition film comprises a substrate and a molecular deposition film deposited on the surface of the substrate, wherein the substrate is an alkaline earth sulfide luminescent material, and the molecular deposition film comprises a material with a general formula A_xB_yThe compound of (1), wherein B is at least one selected from O elements and N elements.

2. The sulfide phosphor with good weatherability as claimed in claim 1, wherein: in said A_xB_yIn the formula, B is O element, and A is at least one selected from Si element and Al element.

3. The sulfide phosphor with good weatherability as claimed in claim 1, wherein: in said A_xB_yIn the formula, B is an N element, A is selected from Si elements, and A is_xB_yIs Si₃N₄。

4. The sulfide phosphor with good weatherability as claimed in claim 1, wherein: the molecular deposition film comprises more than two molecular deposition layers, and the two adjacent molecular deposition layers have different substance compositions.

5. The sulfide phosphor with good weatherability as claimed in claim 4, wherein: the molecular deposition layer comprises an oxide molecular deposition layer and a nitride molecular deposition layer, and the oxide molecular deposition layer and the nitride molecular deposition layer are compounded to form the molecular deposition film.

6. The sulfide phosphor with good weatherability as claimed in claim 5, wherein: the oxide molecule deposition layer is directly compounded with the surface of the substrate.

7. The sulfide phosphor with good weatherability as claimed in any one of claims 1 to 6, wherein: the molecular deposition film is formed on the surface of the substrate through plasma enhanced chemical vapor deposition.

8. A chemical deposition method for producing a sulfide phosphor having excellent weatherability, comprising the steps of:

step one, forming plasma through inert gas;

secondly, taking the alkaline-earth sulfide luminescent material as a substrate, and enabling the first reaction gas and the second reaction gas to collide with the plasma to form a molecular structure A_xB_yThe deposition molecule of (a) is deposited on the surface of the substrate and diffused on the surface of the substrate to form a substance composition of (a) on the surface of the substrate_xB_yThereby producing the sulfide phosphor;

in said A_xB_yB is selected from at least one of O element and N element, and the first reaction gas is used for providing and forming the A_xB_yThe second reaction gas ofThe body is used for providing and constituting the A_xB_yO element or N element in (1).

9. The chemical deposition method for producing a sulfide phosphor with excellent weatherability as claimed in claim 8, wherein: the first reaction gas is selected from at least one of SiH4, butyl orthosilicate and trimethylaluminum, and the second reaction gas is selected from N₂O、O₂、NH₃At least one of (1).

10. The chemical deposition method for producing a sulfide phosphor with good weatherability as claimed in claim 9, wherein: in the second step, the gas flow ratio of the first reaction gas to the second reaction gas is 1: 5-200.

Background

The alkaline earth sulfide has a suitable forbidden band width, and is one of excellent luminescent matrix materials. By doping different metal ions, phosphors having emission spectra from the infrared region to the ultraviolet region can be obtained. Therefore, the alkaline earth sulfide luminescent materials have been widely used in the fields of photoluminescence, electroluminescence, cathodoluminescence, and the like. The rare earth ion doped alkaline earth sulfide is a good fluorescent powder, can be effectively excited by ultraviolet light or visible light, and generates an emission peak with wider half-peak width. Therefore, the rare earth ion doped alkaline earth sulfide has the characteristics of absorbing ultraviolet light and partial visible light in solar spectrum components and emitting red light. Therefore, in addition to application to light emitting devices, in recent years, rare earth ion-doped alkaline earth sulfide phosphors are used as light conversion assistants. The organic light conversion film is added into organic polymer resin to manufacture an agricultural light conversion film, so that the light energy utilization rate of crops is improved, and the photosynthesis of plants is promoted.

Alkaline earth sulfides have poor chemical stability and readily react with water, oxygen and carbon dioxide in the air. If exposed to air, the luminous performance of the fluorescent powder is rapidly reduced, which brings great difficulty to the storage and application of the alkaline earth sulfide fluorescent powder. In addition, the phosphor without surface modification has poor dispersibility. Therefore, the alkaline earth sulfide phosphor is subjected to surface modification treatment before application. The coating modification of the alkaline earth sulfide is mainly carried out by coating an oxide or an inert material, and the coating is inert, so that the fluorescent powder can be well protected, and the chemical stability of the fluorescent powder is improved. The chemical vapor deposition method and the physical vapor deposition method are mainly used for the purpose, however, the operation is complicated, the uniformity and the compactness of the coating formed by the method are poor, and the long-acting protection effect on the alkaline earth sulfide is difficult to be realized.

Disclosure of Invention

The invention aims to provide a sulfide phosphor with good weather resistance and a chemical deposition method for preparing the phosphor with good weather resistance, so as to effectively improve the luminous stability of the sulfide phosphor.

According to one aspect of the present invention, there is provided a sulfide phosphor having excellent weather resistance: comprises a substrate and a molecular deposition film deposited on the surface of the substrate, wherein the substrate is an alkaline earth sulfide luminescent material, and the molecular deposition film comprises a general formula A_xB_yThe compound of (1), wherein B is at least one selected from O elements and N elements. Corresponds to the general formula A_xB_yThe materials comprise oxide and nitride, the oxide and nitride generally have simple structures, easily obtained raw materials and stable chemical properties, so that the molecular deposition film formed by the oxide and/or nitride can isolate the alkaline earth sulfide luminescent material from air and water vapor in the environment, and simultaneously, the luminescent performance of the alkaline earth sulfide luminescent material is not influenced. Based on the characteristic of the film with regularly arranged molecular deposition films, the invention can form a compact protective film on the surface of the alkaline earth sulfide luminescent material by depositing the molecular deposition films on the surface of the alkaline earth sulfide luminescent material, thereby playing a powerful and long-acting protection role on the alkaline earth sulfide luminescent material, enabling the alkaline earth sulfide luminescent material to maintain the due luminescent property for a long time and prolonging the service life of a product using the alkaline earth sulfide luminescent material.

The alkaline earth sulfide luminescent material refers to a luminescent material taking alkaline earth sulfide as a matrix, and can be selected from but not limited to MgS: Eu²⁺、CaS:Eu²⁺、SrS:Eu²⁺、BaS:Eu²⁺And the like.

Preferably, the substrate is a powder particle having a particle size of 500nm to 6 μm.

Preferably, in A_xB_yIn the formula, B is O element, and A is at least one selected from Si element and Al element.

The compound containing Al atoms and Si atoms has stable structure and can perform good passivation effect on the surface of the alkaline earth sulfide luminescent material. On the other hand, the raw materials for forming the molecular deposition layer of the compound containing Al atoms and Si atoms are limited, the available raw materials can be flexibly and diversely selected to form the molecular deposition layer corresponding to the elements, the formed molecular deposition layer has high compactness, and the luminous property of the alkaline earth sulfide luminescent material is not adversely affected. Alternatively, A_xB_yComprising SiO₂、Si₃N₄、SiON、Al₂O₃At least one of (1).

Preferably, in A_xB_yIn the formula, B is N element, A is selected from Si element, A_xB_yIs Si₃N₄。

Preferably, the molecular deposition film comprises more than two molecular deposition layers, and the two adjacent molecular deposition layers have different material compositions.

Preferably, the thickness of the molecular deposition layer is 5-50 nm.

Preferably, the molecular deposition layer comprises an oxide molecular deposition layer and a nitride molecular deposition layer, and the oxide molecular deposition layer and the nitride molecular deposition layer are compounded to form the molecular deposition film.

Preferably, the oxide molecule deposition layer is directly composited with the surface of the substrate.

Preferably, the molecular deposition film is formed on the surface of the substrate by plasma enhanced chemical vapor deposition.

Chemical Vapor Deposition (CVD) is a technique in which reaction gases decompose under excited conditions and chemically react to ultimately produce a solid mass that is deposited on the surface of a substrate. In practice, it is a film preparation method in which a mixed gas is interacted with the surface of a substrate under a certain temperature condition, so that some components in the mixed gas are decomposed, and a solid film of a metal or a compound is formed on the surface of the substrate. Compared with other film deposition technologies, the method has the following advantages in process: the chemical composition of the coating can change along with the change of the gas phase composition, thereby obtaining gradient sediment or obtaining a mixed coating. Secondly, the density and the purity of the coating can be controlled, and the coating can be coated on a substrate with a complex shape and on particle materials. Is suitable for coating workpieces with various complex shapes. Because of its good winding and plating performance, it can coat the workpiece with slot, ditch, hole, even blind hole. ③ the deposited layer usually has a columnar crystal structure, which is not resistant to bending, but can be modified by gas-phase perturbation of the chemical reaction by various techniques. And the coating of various metals, alloys, ceramics and compounds can be formed through various reactions. Plasma and laser assistant technology is adopted to promote chemical reaction obviously and the deposition may be performed at relatively low temperature and may be used widely in electronic, photoelectronic, surface modification and other fields. The chemical vapor deposition (PECVD) is a further improvement on the basis of CVD, and the method takes rare earth ion doped alkaline earth sulfide as a powder substrate, takes two gases as reaction sources, and utilizes plasma deposition to prepare an inert protective layer coated in the substrate. Under vacuum pressure, the radio frequency electric field applied on the electrode plate makes the gas in the reaction chamber produce glow discharge to produce great amount of electrons in the glow electricity generating area. These electrons gain sufficient energy under the action of an electric field, and their temperature is high, and they collide with gas molecules, activating them. They are adsorbed on the rare earth ion doped alkaline earth sulfide substrate and undergo a chemical reaction to generate a dielectric film, and the by-products are desorbed from the substrate and are pumped away by a vacuum pump along with the main gas flow. By the method, a high-quality, uniform and compact protective layer is formed on the surface of the rare earth ion doped alkaline earth sulfide fluorescent powder, so that the stability of sulfide in air is improved and the fluorescence property of sulfide is maintained.

According to another aspect of the present invention, there is provided a chemical deposition method for preparing a sulfide phosphor having excellent weatherability, comprising the steps of: step one, forming plasma through inert gas; secondly, taking the alkaline-earth sulfide luminescent material as a substrate, and enabling the first reaction gas and the second reaction gas to collide with the plasma to form a molecular junctionIs formed as A_xB_yThe deposition molecule is deposited on the surface of the substrate and diffused on the surface of the substrate to form a substance composition A on the surface of the substrate_xB_yThereby producing a sulfide phosphor; in A_xB_yWherein B is selected from at least one of O element and N element, and the first reaction gas is used for providing component A_xB_yThe second reaction gas is used to provide component A_xB_yO element or N element in (1).

Preferably, the first reaction gas is selected from SiH₄At least one of N-butyl silicate and trimethyl aluminum, and the second reaction gas is selected from N₂O、O₂、NH₃At least one of (1).

Preferably, in the second step, the gas flow ratio of the first reaction gas to the second reaction gas is 1: 5-200. The flow ratio of the first reactive gas and the second reactive gas determines the species formed in the protective layer film. In the course of the reaction, Ar may be selected₂Or N₂The reaction gases are diluted to adjust a gas flow ratio between the first reaction gas and the second reaction gas.

Drawings

FIG. 1 shows the CaS: Eu prepared in example 3²⁺Red fluorescent powder and uncoated CaS Eu²⁺And (3) a trend change chart of the luminous intensity of the red fluorescent powder in the positive test period.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.

CaS Eu, used in the examples²⁺The red fluorescent powder is CaS Eu which is self-made by adopting the conventional method in the field and has the same batch²⁺Red fluorescent powder with the particle size of 500 nm.

Example 1

Preparation of surface-coated SiO by plasma enhanced chemical vapor deposition₂Film(s)CaS of Eu²⁺The red fluorescent powder is specifically operated as follows:

CaS:Eu²⁺the powder temperature was 200 ℃. SiH₄With Ar₂Or N₂Diluting at 15% concentration and 50cm flow rate³/min；SiH₄And N₂The flow ratio of O determines the material to be formed in the protective layer film, and is usually controlled to be 1:16, N₂O flow rate of about 200cm³And/min. The rf voltage during plasma deposition is a function of the product of the total gas pressure in the chamber and the plate distance. The total pressure of the chamber gases at the above flow conditions was 45Pa, corresponding to an RFV of 60W. Vacuumizing for 3min before deposition, wherein the vacuum degree is 10^-3Pa. The deposition time is 5min to obtain SiO with the thickness of 10 nm₂And a protective layer.

Comparative example 1

Preparation of surface-coated SiO by sol-gel method₂Film CaS Eu²⁺The red fluorescent powder is specifically operated as follows:

25ml of ethanol and 40ml of deionized water were added to the beaker, and 3%, 5% or 10% ethyl orthosilicate was added dropwise at a rate of 0.6ml per minute. Adding 20g of CaS: Eu into the solution²⁺Stirring the powder (500nm) at 60 deg.C for 30min, adding dropwise small amount of ammonia water, adjusting pH to 9-10, stirring for 45min, vacuum drying at 80 deg.C for 2 hr, and calcining at 500 deg.C in muffle furnace for 1 hr to obtain silica-coated CaS²⁺And (4) red fluorescent powder.

Example 2

Preparation of surface-coated Al by plasma enhanced chemical vapor deposition₂O₃Film CaS Eu²⁺The red fluorescent powder is specifically operated as follows:

and N₂The flow rate of O determines the material to be formed in the protective layer, and is usually controlled to be 1:13, N₂O flow rate of about 200cm³And/min. The rf voltage during plasma deposition is a function of the product of the total gas pressure in the chamber and the plate distance. The total pressure of the chamber gases at the above flow conditions was 55Pa, corresponding to an RFV of 100W. Vacuumizing for 3min before deposition, wherein the vacuum degree is 10^{- 3}Pa. The deposition time is 10min, and 15nm Al is obtained₂O₃And a protective layer.

Comparative example 2

Preparation of surface-coated Al by sol-gel method₂O₃Film CaS Eu²⁺The red fluorescent powder is specifically operated as follows:

weighing 1g of aluminum nitrate solution, 5ml of ethanol and 5ml of deionized water to prepare solution a; weighing 8g of ammonium bicarbonate, 5ml of ethanol solution and 5ml of deionized water to prepare solution b;

adding 20g of CaS: Eu to the solution a²⁺Stirring the powder (500nm) at normal temperature for 30min, dropwise adding the solution b, continuously stirring for 30min, cleaning, and drying at 90 deg.C for 1 h; finally, the precursor is placed in a muffle furnace to be calcined for 2 hours at 1000 ℃ to obtain the CaS: Eu coated by the alumina²⁺And (4) red fluorescent powder.

Example 3

Preparation of surface-coated Al by plasma enhanced chemical vapor deposition₂O₃-Si₃N₄Film CaS Eu²⁺The red fluorescent powder is specifically operated as follows:

CaS:Eu²⁺the powder temperature was 150 ℃. N for gaseous trimethylaluminum₂Diluting at 40% concentration and 50cm flow rate³Min; the flow ratio of the first reactive gas and the second reactive gas determines the species formed in the protective layer film, and is generally controlled to be 1:10, N₂O flow rate of about 200cm³And/min. The rf voltage during plasma deposition is a function of the product of the total gas pressure in the chamber and the plate distance. The total pressure of the chamber gases at the above flow conditions was 55Pa, corresponding to an RFV of 60W. Vacuumizing for 3min before deposition, wherein the vacuum degree is 10^-3Pa. The deposition time was 4 min.

Then coating Al with the above₂O₃CaS of Eu²⁺The powder continued to react at 170 ℃. SiH₄With Ar₂Diluting at 30% concentration and 50cm flow rate³/min；SiH₄And NH₃The flow rate ratio of (A) to (B) determines the species formed in the protective layer film, and is usually controlled to be 1:13, and the flow rate of the second reaction gas is about 200cm³And/min. The rf voltage during plasma deposition is a function of the product of the total gas pressure in the chamber and the plate distance. Under the condition of the flow rateThe total pressure of the chamber gases was 55Pa, corresponding to an RFV of 140W. Vacuumizing for 3min before deposition, wherein the vacuum degree is 10^-3Pa. The deposition time is 8min, and Al with a total thickness of 23nm is obtained₂O₃-Si₃N₄And a protective layer.

Test example

Using uncoated CaS Eu²⁺Eu and CaS with coating layer obtained after treatment of red phosphor in example 1, comparative example 1, example 2, comparative example 2 and example 3²⁺The red fluorescent powder is used for carrying out a moisture-resistant deterioration experiment, and the specific experiment setting mode is as follows:

the testing period is 30 days, and the test powder is placed in a temperature box with the temperature of 25 ℃ and the relative humidity of 75% to carry out the moisture-resistant deterioration test. After the coating is finished, the CaS with the coating layer is obtained²⁺Immediately performing fluorescence spectrum test on the red fluorescent powder, performing fluorescence spectrum test on a reference sample entering a positive test period, measuring an emission spectrogram of the reference powder under the test condition that the excitation wavelength is 540nm, recording the generation intensity of the emission spectrum of the reference powder at the position of 640nm, and taking the emission intensity of the reference powder and the CaS, Eu and Eu which are not coated before entering the positive test period²⁺The ratio of the emission intensity of the red fluorescent powder represents the retention rate of the luminescence property of the powder to be tested.

Specific test results are shown in Table 1, and it can be seen from Table 1 that Eu is the same as that of uncoated CaS²⁺Comparing the red phosphors, the CaS of comparative example 1 and comparative example 2 is Eu²⁺The red phosphor showed a significant deterioration and the emission intensity was significantly reduced, and after the end of the positive test period, the CaS: Eu of comparative example 1 and comparative example 2²⁺The luminous intensity of the red fluorescent powder is obviously lowered. In contrast, the CaS: Eu obtained in examples 1, 2 and 3 after completion of coating²⁺The red phosphor can maintain good luminous intensity level, which shows that examples 1, 2 and 3 adopt plasma enhanced chemical vapor deposition method to treat CaS: Eu²⁺The red fluorescent powder is subjected to surface treatment, and CaS and Eu are not treated²⁺The luminescent properties of red phosphors constitute a significant detriment. Examples 1, 2, after entering the positive test phase,3 the prepared CaS of which the surface is coated with a protective film is Eu²⁺The red fluorescent powder can keep good luminous intensity level, and can have the luminous performance retention rate of more than 80% after the positive test period is finished. Wherein, CaS is Eu, which is obtained in example 3²⁺Red fluorescent powder and uncoated CaS Eu²⁺The trend of the emission intensity of the red phosphor in the positive test period is shown in fig. 1.

TABLE 1CaS Eu²⁺Retention of luminous performance of red fluorescent powder

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the present invention.