CN114933902B - Preparation method and composition of fluorescent compound - Google Patents
Preparation method and composition of fluorescent compound Download PDFInfo
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Abstract
The invention provides a preparation method and a composition of a fluorescent compound. The general formula of the phosphor compound in the preparation method of the invention is k (M1) 0.04‑a M2 a N b O c R d )·X e N f : mRe. The preparation method of the fluorescent compound is a multi-step and multi-stage process method which comprises the steps of introducing micron-sized flake graphite as a crystallization template in a solid phase reaction, removing the flake graphite and simultaneously filling nano fumed silica. The introduction of the micron-sized flake graphite in the technical process of the fluorescent compound has the effect of crystallization control, so that the crystallization of the fluorescent compound is improved, the crystal morphology is ideal, the luminous performance and the attenuation resistance of the fluorescent compound are improved, the practical application performance of the fluorescent compound is improved, and the fluorescent compound can emit green to orange luminescence after being excited by ultraviolet-blue-green light and is applied to the manufacture of LED devices.
Description
Technical Field
The invention belongs to the field of fluorescent bodies, and particularly relates to a preparation method of a nitride and oxynitride fluorescent body with improved luminous performance, in particular to a preparation method and a composition of a fluorescent body compound capable of realizing efficient luminescence through crystal crystallization control.
Background
In the general illumination technology of LEDs, a blue light chip is mainly used to excite a fluorescent powder emitted by yellow to generate yellow light, and the yellow light is mixed with the rest of blue light to obtain white light. The traditional yellow fluorescent powder mainly comprises garnet structural materials (Y, gd) activated by rare earth ions 3 (Al，Ga) 5 O 12 : ce, (YAG for short) and rare earth ion activated alkaline earth metal orthosilicate materials (Sr, ba, ca) 2 SiO 4 Eu. In order to obtain a warm white lighting effect with more excellent application performance, a fluorescent material capable of being used for the complementary color of the warm white lighting effect and obtaining red luminescence under blue light excitation has been found in several nitride matrixes in recent years. The prior art discloses Eu which can be excited by ultraviolet-blue-green light to emit 600-650 nm red light 2+ Activated alkaline earth metal silicon nitride fluorescent material (Ba, sr, ca) 2 Si 5 N 8 . However, this material has a lower lumen efficiency and a greater thermal decay. Another prior art also disclosesEu capable of being excited by ultraviolet-blue-green light to emit 600-700 nm red light 2+ Activated alkaline earth nitride phosphor (Ca, sr) AlSiN 3 . The luminescent property of the material is superior to that of (Ba, sr, ca) 2 Si 5 N 8 Eu materials, the luminous efficiency is improved by about 15 percent, the thermal attenuation is smaller, and the Eu materials become the main stream red fluorescent materials of warm white light illumination schemes. However, the half-width of the emission spectrum of the red fluorescent material is too wide, and in the range of 75-95nm, the requirement of the display backlight source on high color purity is not met, and the red fluorescent material can only be used in the field of illumination light sources but not in the field of display backlight sources.
In addition to the materials that emit red light with little light decay obtained in a crystal lattice that is coordinated entirely by N as an anion, excellent LED fluorescent materials that emit blue to orange have been found in recent years in nitrides and oxynitride materials that are coordinated together by N and O as anions. The lattices coordinated by N as anions have a common characteristic that the lattices have strong covalent property and stable property, are easy to form larger crystal field energy level cleavage under the action of an activator to realize red emission, and have strong structural rigidity, so that materials with better thermal stability and smaller light attenuation, such as alkaline earth metal oxynitride materials (Ba, sr, ca) Si with blue-green emission, are easy to obtain 2 O 2 N 2 Eu is also an ideal blue-green complementary color material in the full spectrum scheme of LED illumination. However, the blue-green part of the luminescent color of the material is not suitable for the requirement of a display backlight source, and the green part is also not suitable for the field of the display backlight source due to the wider half-width of the emission spectrum, and can only be used in the field of LED illumination.
In order to meet the application requirements of the LED display backlight source, the extremely strong covalent nature of the N or N-O serving as an anion coordination lattice is found to enable the atomic stack to be tighter, and narrower crystal field energy level cleavage is formed under the action of an activator more easily to realize narrow-peak-width emission, so that the requirements of the LED backlight and display technology on purer chromaticity and narrower emission peak width of fluorescent powder can be met. The prior art discloses an orange-emitting alpha-sialon material Ca x (Si,Al) 12 (O,N) 16 :yEu(0.75 < x < 1.0,0.04 < y < 0.25). The prior art also discloses a green emitting beta-sialon material Si 6- z Al z O z N 8-z Eu (0 < z < 4.2). The two materials have common structural characteristics, namely, in [ Si, al][O,N] 4 On the basis of a structural matrix formed by tetrahedron three-dimensional co-angular peaks, the luminescence characteristic is obtained by introducing activator ions or alkaline earth metal ions and activator ions into structural void channels of the structural matrix. The material has the most compact bonding mode, extremely strong covalent nature, can generally obtain light emission with a narrow peak, and has excellent stability and attenuation resistance, so that the material becomes a good material for LED display backlight. However, this [ Si, al ]][O,N] 4 The tetrahedron three-dimensional co-angular top compact stacking structure is mainly synthesized by silicon nitride and aluminum nitride raw materials with extremely high stability, extremely high bonding energy is needed to break the stable bond energy of binary nitride to be rebuckly formed into a derivative structure with a void channel, synthesis conditions with extremely high temperature and high pressure are generally needed, the difficulty in equipment and process control is extremely high, and the industrial mass production is not easy.
In addition, this is [ Si, al only][O,N] 4 The tetrahedron structure lacks the existence, stability and support of other heavy metal cations, so that the crystal growth is severely restricted by the fine influence of equipment characteristics, technological process and growth microenvironment, the crystallization state is difficult to control and maintain ideal, and the crystal morphology is often poor, the crystal face development is not ideal, the aggregation and polymorphism occur. Further, the luminescence realized by introducing the activator into the structural gap channel in the material has extremely strong randomness and uncertainty, is extremely sensitive to the crystallization state of crystals restricted by equipment and fine technology, and thus the high-efficiency realization of the luminescence performance is seriously affected, so how to obtain the material with ideal crystallization and high effect of the activator through fine control to realize commercialization is always a practical obstacle to the use of the fluorescent body, and at present, no technology and capability of the commercialization production of the fluorescent body exist in China.
Further, the nitride or oxynitride phosphor excited by the structural void channel with ideal crystallization, better luminous efficiency and smaller thermal attenuation is developed, and the method for manufacturing the phosphor with high application performance has the advantages of simple synthesis process, mild condition and easy industrial mass production, and has important significance for the technical progress and application popularization of the domestic LED display backlight.
Disclosure of Invention
Accordingly, an object of the present invention is to overcome the drawbacks of the prior art and to provide a method and a composition for producing a phosphor compound capable of realizing efficient light emission by controlling crystal crystallization.
An object of the present invention is to provide a method for producing a phosphor compound capable of realizing efficient light emission by crystallization control, the composition of the phosphor compound being represented by the following general formula: k (M1) 0.04-a M2 a N b O c R d )·X e N f : mRe, wherein:
m1 is at least one element selected from Si and Ge, M2 is at least one element selected from Al and Ga, N is nitrogen, O is oxygen, and R is selected from F - 、Cl - X is selected from at least one element of Mg, ca, li, la, Y, and Re is selected from at least one element of Eu, ce, dy, ho, tm, er, pr;
k. a, b, c, d, e, f, m is the molar coefficient: k is more than 0.3 and less than 2.2,0, a is more than 0.03,0.045, b is more than 0.075,0 and less than or equal to c and less than or equal to 0.055,0 and less than or equal to d and less than or equal to 0.002,0 and less than or equal to e and less than or equal to 0.025,0 and less than f and less than 0.025,0, and m is more than 0.025 and less than or equal to 0.025.
Preferably, the phosphor compound emits a light emission spectrum having one or more peaks with a peak wavelength in the range of 505 to 605nm after being excited by ultraviolet-blue-green light having a peak wavelength in the range of 250 to 550 nm.
Preferably, the phosphor compound, wherein 0.8 < k < 1.2,0 < a < 0.025,0.045 < b < 0.055,0.ltoreq.c < 0.005,0.ltoreq.d < 0.0015 and 0.045 < b+c+d < 0.062, e=0, f=0, 0 < m < 0.0015; preferably, M1 is Si, M2 is Al, N is N, O is O, R is F - Ion, re is Eu; and/or, preferably, 0.95.ltoreq.k.ltoreq. 1.05,0.001.ltoreq.a.ltoreq. 0.02,0052.ltoreq.b.ltoreq. 0.054,0.ltoreq.c.ltoreq. 0.0035,0.ltoreq.d.ltoreq.0.0013, and 0.052 < b+c+d.ltoreq.0.0588, e=0, f=0, 0 < m.ltoreq.0.0013.
Preferably, the phosphor compound, wherein 1.8 < k < 2.2,0 < a < 0.025,0.045 < b < 0.055,0 < c < 0.005,0 < d < 0.002 and 0.05 < b+c+d < 0.055,0 < e < 0.015,0 < f < 0.01,0 < m < 0.0035; preferably, M1 is selected from Si, M2 is Al, N is N, O is O, R is F - Ions, re is Eu, X is Ca; and/or, preferably, k is more than or equal to 1.95 and less than or equal to 2.05,0.0005 a is more than or equal to 0.02,0.052 b is more than or equal to 0.054,0 c is more than or equal to 0.0033,0 d is more than or equal to 0.0017, and 0.052 is more than or equal to b+c+d is more than or equal to 0.059,0 e is more than or equal to 0.0133,0 f is more than or equal to 0.0089,0 m is more than or equal to 0.0033.
The above-mentioned method for producing a phosphor compound which realizes efficient luminescence by crystallization control, comprising the steps of:
(1) According to k (M1) 0.04-a M2 a N b O c R d )·X e N f : weighing raw materials according to element proportion of mRe, and uniformly mixing;
(2) Weighing flake graphite with the particle size of 10-100 microns in a proper proportion, placing the flake graphite into the mixture obtained in the step (1), and then placing the mixture into a shearing crusher for fully and uniformly mixing to obtain a composite material;
(3) Placing the composite material obtained in the step (2) into high-temperature high-pressure pressing equipment to perform high-temperature solid-phase reaction, and then crushing, screening and acid washing to obtain a fluorescent body sintered material coated with flake graphite;
(4) Weighing nanoscale fumed silica powder with a proper proportion, and fully mixing the nanoscale fumed silica powder with the phosphor sintering material coated with the flaky graphite obtained in the step (3) to obtain a secondary mixture;
(5) And (3) placing the secondary mixture obtained in the step (4) into a resistance furnace, and performing low-temperature heat treatment in an air atmosphere to obtain the high-efficiency luminous phosphor compound.
According to the method for preparing the fluorescent body, which realizes high-efficiency luminescence through crystallization control, the sources of elements in the step (1) are as follows: the M1 element adopts a nitride raw material, the M2 element adopts a nitride raw material or a nitride raw material and an oxide raw material, the X element adopts a nitride raw material or a carbonate raw material or an oxide raw material or a hydroxide raw material, and the Re element adopts a nitride raw material or an oxide raw material or a fluoride raw material or a chloride raw material.
According to the method for preparing the fluorescent body, which realizes high-efficiency luminescence through crystallization control, the adding proportion of the flake graphite with the particle size of 10-100 microns in the step (2) is 0.001-25%, preferably 0.5-10%.
According to the method for preparing the fluorescent body, which is provided by the invention, high-efficiency luminescence is realized through crystallization control, wherein the atmosphere of the high-temperature solid-phase reaction is nitrogen atmosphere or mixed atmosphere of nitrogen and hydrogen; the reaction pressure is 1-2000 atm, preferably 10-200 atm; the reaction temperature is 1200-2500 ℃, preferably 1600-2300 ℃; and/or the reaction time is from 4 to 16 hours, preferably from 6 to 12 hours; and/or
In the step (3), the post-processing step includes: placing the crushed and sieved material into an acid solution with the molar concentration of 1-10% for stirring and washing for 1-4 hours, filtering acid liquor, washing for 1-4 times by using deionized water or ethanol, and drying to obtain the fluorescent compound; preferably, the acid is selected from one or more of the following: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid.
According to the method for preparing a fluorescent substance by crystallization control to realize efficient luminescence, in the step (4), the addition ratio of the nano-scale fumed silica is 0.001% -10%, preferably 0.5% -3%.
According to the method for preparing the fluorescent body, which is provided by the invention, high-efficiency luminescence is realized through crystallization control, wherein in the step (5), the air atmosphere of the secondary mixture is subjected to low-temperature heat treatment, and the atmosphere is an atmospheric air atmosphere; the reaction temperature is 400-1000 ℃, preferably 550-750 ℃; and/or the reaction time is 16 to 32 hours, preferably 20 to 30 hours.
Another object of the present invention is to provide a phosphor composition comprising at least the phosphor compound according to the production method of the present invention.
The invention aims to provide a group of preparation methods of nitride and oxynitride phosphors, which can emit green and orange light under the excitation of ultraviolet-blue-green light (especially 400-470 nm), and the technical scheme that flake graphite is introduced as a crystallization template in the high-temperature high-pressure synthesis process enables the phosphor to be more ideal to form columnar crystals with more complete crystallization, more ideal crystal face development and larger and more uniform crystal particle size, thereby remarkably improving the luminous efficiency and attenuation resistance of the phosphor.
The invention relates to a method for preparing a fluorescent material capable of realizing high-efficiency luminescence by crystallization control, wherein the group of nitride or oxynitride fluorescent material with improved luminescence performance is an ultraviolet-blue-green light excitable luminescent material, and the general formula is k (M1 0.04-a M2 a N b O c R d )·X e N f : mRe, wherein: m1 is at least one element selected from Si and Ge, M2 is at least one element selected from Al and Ga, N is nitrogen, O is oxygen, and R is selected from F - 、Cl - X is selected from at least one element of Mg, ca, li, la, Y, and Re is selected from at least one element of Eu, ce, dy, ho, tm, er, pr; k. a, b, c, d, e, f, m is the molar coefficient: k is more than 0.3 and less than 2.2,0, a is more than 0.03,0.045, b is more than 0.075,0 and less than or equal to c is more than 0.055,0 and less than or equal to d is more than 0.002,0 and less than or equal to e is more than 0.025,0 and less than f is more than 0.025,0 and less than 0.025. The nitride or oxynitride phosphor is a group of [ Si, al ]][O,N]And the 4 tetrahedron three-dimensional co-angular roof stack, rare earth activated ions or alkaline earth metal ions and rare earth activated ions are filled in the luminous structure of the structural void channel. The structural material is mainly composed of Si 3 N 4 AlN raw material synthesis, due to Si 3 N 4 AlN has extremely strong covalent property, requires extremely high temperature to open a bonding bond for chemical combination, and in addition, the sialon structure is a structure with stronger covalent property, and requires extremely high pressure to ensure Si 3 N 4 Sialon, which has a stronger binding force with AlN, is synthesized and remains stable, so that such nitride or oxynitride phosphors require high-temperature and high-pressure synthesis conditions, Typically at 1900 to 2500 c and at a pressure of 10 to 200 atmospheres. The solid phase reaction under the high temperature and high pressure condition is often excessive and difficult to control, and forms crystallization defects such as tiny polycrystal formed by overgrowth of multipoint crystal nucleus, irregular crystal development or round edge formed by incomplete crystal development, and general agglomeration formed by irregular particles or plate-shaped columnar particles. The invention aims at the nitride or oxynitride fluorescent material, and Si is introduced by taking the flake graphite with inert and stable temperature and atmospheric pressure as a crystallization template 3 N 4 The crystallization behaviors of the raw materials such as AlN in the high-temperature high-pressure solid phase reaction process are controlled and inherited by the flaky graphite template, so that the phosphor with ideal crystallization, larger and more uniform crystals, columnar crystal and crystal face development positions, crystal aggregation reduction and other crystallization characteristics is obtained.
The principle of the technical scheme is described as follows: the general technical process of the nitride or oxynitride light-emitting structure is Si 3 N 4 Solid phase reaction of a small amount of AlN and trace activated ions, alkaline earth metal ions and oxygen (with or without) raw materials at 1900-2500 ℃ and 10-200 atmospheric pressure, solid-liquid-solid reaction under the synthesis condition is random and difficult to control, extremely polycrystalline nucleus growth is often caused by excessive melting, fine crystal agglomeration is easy to form, irregular granular and crystal face incompletely developed disordered crystals and extremely serious crystal agglomeration are also extremely easy to form in the solid-liquid-solid reaction under high pressure, and the characteristics seriously influence the luminous performance of the product. The invention discovers that graphite has excellent physical and chemical inertia under the conditions of 1900-2500 ℃ and 10-200 atmospheric pressure, does not participate in the chemical reaction of Si-Al-O-N-rare earth metal-alkaline earth metal and does not influence the progress of the chemical reaction, and flake graphite with certain particle size can become a good crystallization control medium by the excellent and stable flake two-dimensional crystallization habitAnd a crystallization template. Under the technical scheme provided by the invention, si 3 N 4 After a small amount of AlN and trace activated ions, alkaline earth metal ions and oxygen (or no) raw materials are fully mixed with a certain amount of flaky graphite with a certain particle size, the raw materials of the sialon begin to melt and the growth process of the sialon crystals in a liquid phase under the reaction condition of 1900-2500 ℃ and 10-200 atm, the stable inert flaky graphite crystals with a certain amount and a certain particle size which are uniformly mixed in the raw materials are just used as crystal seeds and supports for the growth of the sialon crystals, the crystal templates are used, the constituent elements Si, al, N, O (or no) of the sialon fluorescent body and alkaline earth metals (or no) and Eu in the solid-liquid-solid reaction are used as crystal nuclei to grow layer by layer around the flaky graphite crystals according to the stacking rule of the sialon structure, and finally the sialon crystals coating the flaky graphite are formed. On the one hand, the existence of the flaky graphite provides uniform seed crystals, fine disordered growth of polycrystalline nuclei is avoided, the effect of larger and more uniform crystallization of the sialon crystals can be obtained, on the other hand, the flaky crystal habit of the flaky graphite also provides a crystal template for the growth of the sialon crystals, plugs Long Chengfen are stacked layer by layer on the whole surface network of the flaky crystal until the whole columnar crystal coating the flaky graphite crystal is formed, and the specific development preferential and strong crystal face of the flaky graphite also enables the growth of the sialon crystal to continue the growth in the direction until the dominant single crystal rather than agglomerated and interpenetrated polycrystalline grains are formed. Therefore, the crystal nucleus and the crystallization template of the flake graphite play a role in controlling crystallization during high-temperature high-pressure solid phase reaction synthesis, a uniform columnar monocrystal dominant product with perfect crystallization is formed, irregular particles and crystallization defect particles are reduced, and the agglomeration phenomenon of the irregular granular particles and the plate columnar particles is obviously reduced. On the basis, through the subsequent air low-temperature treatment process provided by the invention, stable lamellar graphite crystal nuclei coated in the sialon crystal are oxidized in long-time low-temperature (oxidation temperature of C) air annealing to form carbon dioxide gas to be separated, and meanwhile, gaps formed in the sialon crystal due to separation of fine graphite crystal nuclei are uniformly mixed into sintering materials to be filled and repaired by high-fluidity nano fumed silica before low-temperature treatment, and the nano fumed silica is prepared The material has similar permeability and refraction, the complete combination of the material and the sialon crystal does not influence the luminous performance of the sialon structure, and finally a group of nitride or oxynitride fluorescent bodies with controlled crystallization are obtained, and the luminous performance and the anti-attenuation performance of the material are obviously improved due to the remarkably improved crystallization state.
Before the technical scheme of the invention, the luminous body filled with the [ Si, al ] [ O, N ]4 tetrahedron three-dimensional co-angular peaks, rare earth activated ions or alkaline earth metal and rare earth metal ions in the structural gap channel needs the synthesis condition of extremely limited high temperature and high pressure, has the characteristics of strong luminous randomness and uncertainty, has extremely high difficulty in equipment and process control, and is easy to cause excessive and uncontrolled growth of luminous crystals to form various defects so as to influence luminous performance. In the technical scheme of the invention, the graphite flakes which are stable and inert in the temperature, pressure and inert atmosphere of the sialon synthesis can play roles of crystallization control and crystallization templates during the synthesis and growth of the sialon crystals for the first time, and the graphite flakes with a certain quantity and grain diameter in the raw materials can be used as crystal nuclei and dominant crystal habit control factors to enable the sialon crystals to grow into columnar single crystals with larger and more uniform grains, so that the existence of tiny irregular grains is obviously reduced, the crystal face development is more perfect and ideal, and the interpenetration agglomeration and fusion agglomeration phenomena of irregular grains and columnar grains are obviously reduced. The implementation of the control technical means for adding the flake graphite plays a role in improving and controlling the crystal state of the sialon crystal to form the sialon crystal coated with the flake graphite more ideal in crystallization, and on the other hand, the flake graphite has the characteristic that the flake graphite is easy to be completely oxidized at the carbon oxidation temperature in the air and is removed in the form of carbon dioxide gas; in addition, the pure sialon crystal with better crystal face development and more regular and ideal crystal form can reduce the thermal vibration amplitude and disturbance of the lattice structure in the excited state, thereby playing the role of improving the thermal attenuation resistance of the fluorescent body, and the existence of the high-stability nano silicon dioxide inlaid and modified in the form of points, lines and planes in the crystal also plays the role of structural pinning and further plays the role of improving the thermal attenuation resistance of the fluorescent body; the implementation of the technical scheme is easy to realize the industrial mass production of the high-performance fluorescent body. According to the preparation method of the fluorescent body, crystallization control is achieved in the high-pressure synthesis process of the plug Long Gaowen by introducing the micron-sized flake graphite, so that efficient luminescence is achieved, the nitride or oxynitride sialon fluorescent body is prepared by a multi-step high-temperature solid-phase reaction method improved by introducing the micron-sized flake graphite, and after the fluorescent body is excited by ultraviolet-blue-green light with the emission peak wavelength ranging from 250 nm to 550nm, the fluorescent body emits one or more peak light emission spectrums with the peak wavelength ranging from 505 nm to 605nm, and can display luminescence from green to orange, so that the fluorescent body is applied to manufacturing of LED devices.
As a further improvement of the present invention, the present invention provides a method for producing a phosphor capable of achieving efficient light emission by crystallization control, the nitride or oxynitride phosphor wherein M1 is Si, M2 is Al, N is N, O is O, R is F - Ion, re is Eu; K. a, b, c, d, e, f, m is the molar coefficient: k is more than 0.8 and less than 1.2, a is more than 0 and less than 0.025,0.045, b is more than 0.055,0 and less than 0.005,0 and less than d is more than or equal to 0.0015, b+c+d is more than 0.045 and less than 0.062, e=0, f=0, and m is more than 0 and less than 0.0015.
As a further improvement of the present invention, the present invention provides a method for producing a phosphor for realizing efficient light emission by crystallization control, wherein M1 is selected from Si, M2 is Al, N is N, O is O, R is F-ion, re is Eu, and X is Ca; K. a, b, c, d, e, f, m is the molar coefficient: k is more than 1.8 and less than 2.2,0, a is more than 0.025,0.045, b is more than 0.055,0 and less than or equal to c is more than 0.005,0 and less than or equal to d is less than 0.002, and 0.05 and less than or equal to b+c+d is more than 0.055,0, e is more than 0.015,0, f is more than 0.01,0, m is more than 0.0035.
As a further improvement of the present invention, the present invention provides a method for producing a phosphor capable of achieving efficient light emission by crystallization control, the nitride or oxynitride phosphor wherein M1 is Si, M2 is Al, N is N, O is O, R is F - Ion, re is Eu; K. a, b, c, d, e, f, m is the molar coefficient: k is more than or equal to 0.95 and less than or equal to 1.05,0.001 a is more than or equal to 0.02,0.052 b is more than or equal to 0.054,0 c is more than or equal to 0.0035,0 d is more than or equal to 0.0013, b+c+d is more than 0.0588, e=0, f=0, and m is more than 0 and less than or equal to 0.0013.
As a further improvement of the present invention, the present invention provides a method for producing a phosphor capable of achieving efficient light emission by crystallization control, wherein M1 is selected from Si, M2 is Al, N is N, O is O, R is F - Ions, re is Eu, X is Ca; K. a, b, c, d, e, f, m is the molar coefficient: k is more than or equal to 1.95 and less than or equal to 2.05,0.0005 a is more than or equal to 0.02,0.052 b is more than or equal to 0.054,0 c is more than or equal to 0.0033,0 d is more than or equal to 0.0017, and 0.052 is more than or equal to b+c+d is more than or equal to 0.059,0 e is more than or equal to 0.0133,0 f is more than or equal to 0.0089,0 m is more than or equal to 0.0033.
The invention provides a preparation method of a nitride or oxynitride fluorescent material capable of realizing high-efficiency luminescence through crystallization control, the raw materials are compounds or simple substances of the following elements, and the elements are represented by a chemical composition formula k (M1) 0.04- a M2 a N b O c R d )·X e N f : the mole ratio range of mRe is as follows:
M1：0.0001～0.09；
M2：0～0.05；
N：0.0001～0.12；
O：0～0.03；
R：0～0.002；
X：0～0.025；
Re：0.0001～0.025；
wherein: m1 represents one or more elements of Si and Ge;
m2 represents one or more elements of Al and Ga;
R represents F - 、Cl - A compound of one or more elements;
a compound wherein X represents one or more elements of Mg, ca, li, la, Y;
compounds of one or more elements of Re represents Eu, ce, dy, ho, tm, er, pr;
the compound of the element represented by M1 adopts the form of nitride and/or oxide and/or metal simple substance as an element source;
the compound of the element represented by M2 adopts the form of nitride and/or oxide and/or metal simple substance as an element source;
the compound of the element represented by R adopts fluoride or chloride form as an element source;
the compound of the element represented by X adopts the form of oxide or nitride or carbonate or hydroxide or halide as an element source;
the compound of Re represents the element in the form of oxide and/or nitride and/or fluoride and/or chloride as the element source;
the preparation process is a multi-step high-temperature solid phase reaction method which is improved by introducing micron-sized flake graphite as a crystallization template to realize a crystallization control technology, and is characterized by comprising the following steps: the first step is according to k (M1 0.04-a M2 a N b O c R d )·X e N f : weighing raw materials according to element proportion of mRe, and uniformly mixing; weighing flake graphite with the particle size of 10-100 microns in a proper proportion, placing the flake graphite into the mixture obtained in the first step, and then placing the mixture into a shearing crusher for fully and uniformly mixing to obtain a composite material; thirdly, placing the composite material obtained in the second step into high-temperature high-pressure pressing equipment to perform high-temperature solid-phase reaction, and then crushing, screening and acid washing to obtain a fluorescent body sintered material coated with the flake graphite; weighing nanoscale fumed silica powder with a proper proportion, and fully mixing the nanoscale fumed silica powder with the fluorescent body sintering material coated with the flaky graphite obtained in the third step to obtain a secondary mixture; and fifth, placing the secondary mixture obtained in the fourth step into a resistance furnace, and performing low-temperature heat treatment in an air atmosphere to obtain the high-efficiency luminous phosphor compound.
As a further improvement of the invention, the method for preparing the nitride or oxynitride fluorescent material with improved luminous performance by introducing micron-sized flake graphite as a crystallization template to realize the crystallization control technology is characterized in that the first step adopts a nitride raw material as an M1 element, adopts nitride or nitride and oxide raw materials as an M2 element, adopts a nitride or carbonate or oxide or hydroxide raw material as an X element, and adopts a nitride or oxide or fluoride or chloride raw material as an Re element.
As a further improvement of the invention, the method for preparing the nitride or oxynitride fluorescent material with improved luminous performance by introducing micron-sized flake graphite as a crystallization template to realize the crystallization control technology is improved by multi-step high-temperature solid phase reaction, and the second step is characterized in that the adding proportion of the flake graphite with the grain size of 10-100 microns is 0.001-25%, preferably 0.5-10%.
As a further improvement of the invention, the method for preparing the nitride or oxynitride fluorescent material with improved luminous performance by introducing micron-sized flake graphite as a crystallization template to realize the crystallization control technology is characterized in that the atmosphere of the high-temperature solid phase reaction is nitrogen atmosphere or mixed atmosphere of nitrogen and hydrogen; the reaction pressure is 1-2000 atm, preferably 10-200 atm; the reaction temperature is 1200-2500 ℃, preferably 1600-2300 ℃; and/or the reaction time is from 4 to 16 hours, preferably from 6 to 12 hours, followed by a post-treatment of the calcined powder. The powder post-treatment step comprises: placing the crushed and sieved material into an acid solution with the molar concentration of 1-10% for stirring and washing for 1-4 hours, filtering acid liquor, washing for 1-4 times by using deionized water or ethanol, and drying to obtain the fluorescent compound; preferably, the acid is selected from one or more of the following: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid.
As a further improvement of the invention, the fourth step of the preparation method of the multi-step high-temperature solid phase reaction, which is improved by taking the micron-sized flake graphite introduced with the nitride or oxynitride fluorescent material with improved luminous performance as a crystallization template to realize crystallization control technology, is characterized in that the addition proportion of the nano-sized fumed silica is 0.001-10%, preferably 0.5-3%.
As a further improvement of the present invention, the present invention provides a preparation method of a multi-step high temperature solid phase reaction improved by introducing micron-sized flake graphite as a crystallization template to realize crystallization control technique, wherein the fifth step is characterized in that the atmosphere of the secondary mixture is a normal pressure air atmosphere by low temperature heat treatment in the air atmosphere; the reaction temperature is 400-1000 ℃, preferably 550-750 ℃; and/or the reaction time is 16 to 32 hours, preferably 20 to 30 hours, thereby obtaining the nitride and oxynitride phosphor having improved light emission performance.
The emission spectrum and the thermal characteristic of the fluorescent body are respectively tested by adopting an F-4500 fluorescent spectrometer and an EX-1000 fluorescent powder thermal quenching analysis system, the components and the morphological characteristics of the fluorescent body are respectively tested by adopting a TD-3500X-ray diffractometer and a KYKY 2800B scanning electron microscope, and the content of halogen elements in the fluorescent body is tested by adopting a TAS-986 atomic absorption spectrometer.
According to the technical scheme of the invention, micron-sized flake graphite is used as a crystallization template to be introduced, in the process of extremely high temperature and high pressure compression of a light-emitting structure with a group of [ Si, al ] [ O, N ]4 tetrahedron three-dimensional co-angular peaks and rare earth activated ions filled in a structural gap channel, due to the existence of a certain number of flake graphite with a certain particle size and inert and stable in the synthesis process, raw material particles grow by taking flake graphite crystals as crystal nuclei and templates in the solid-liquid-solid phase reaction process formed by the light-emitting structure, and finally, the improvement effect of crystallization characteristics of larger and more uniform light-emitting crystal grains, more ideal crystal form and crystal face development and obviously reduced aggregation of the light-emitting crystals is obtained, and then, a group of nitride or oxynitride fluorophor with more ideal crystal growth and obviously improved luminous efficiency and thermal attenuation resistance can be obtained through a post-treatment process of removing graphite and crystal modification. Compared with the same type of fluorescent body prepared by the conventional simple high-temperature high-pressure synthesis process, the fluorescent body has obvious difference in crystallization morphology and functional effect, and the technical scheme of the invention is a remarkable innovation in product morphology and realization function.
Past [ Si, al ][O,N] 4 The tetrahedron three-dimensional co-angular crown forms a structural matrix, then the simple high-temperature high-pressure synthesis of the type of fluorescent body formed by introducing an activating agent into a gap channel of the structural matrix, the solid-liquid-solid phase crystallization reaction process of the fluorescent structure is often difficult to control at extremely high synthesis temperature (1900-2500 ℃) and extremely high synthesis pressure (10-200 MPa) to generate excessive and degradation phenomena, the undesirable crystallization state is extremely easy to form due to weak deviation of equipment and technology, tiny polycrystal with multi-particle nucleation is presented, various crystals with extremely large-size phase difference and crystal crystallization shapes are easy to form irregular grains, the crystal surface development is poor, circular arc irregular edges are presented, irregular grains are seriously agglomerated, large crystal grains are interpenetrated and agglomerated, and crystals are melted and agglomerated, and other macroscopic crystallization states are presented in the microscopic crystallization state of a luminescent crystal correspondingly, defects, dislocation, slippage, distortion and other microscopic symmetry runaway phenomena are excessive, and the macroscopic and microscopic occupation environments of the activating agent ions in the gap channel of the structure are lost ideal, and the luminescence formed after the excitation is subjected to various weakening, absorption and ideal and microcosmic scale are difficult to realize, so that the practical luminous efficiency of the fluorescent body is achieved, and the practical luminous efficiency is difficult to meet the requirements of a commercial luminous technology.
In order to solve the technical difficulty, the invention provides a new multi-step control process means for realizing crystallization control by taking micron-sized graphite flakes as a crystallization template, wherein micron-sized graphite flakes with stable inertness to synthesis temperature, pressure and atmosphere are firstly introduced in the process of high-temperature high-pressure synthesis, the existence of the graphite flakes plays a role in controlling growth crystal nuclei and crystal habit to obtain nitride or oxynitride crystal powder coated with the graphite flakes and having obviously improved crystal morphology, and then graphite crystal nuclei are removed through oxidation treatment and simultaneously filling modification is assisted by fumed silica, so that a group of nitride or oxynitride fluorescent bodies with obviously improved luminescence performance due to obviously improved crystal morphology are obtained. The implementation of the technical means has the effects of obviously improving the macroscopic and microscopic crystallinity of the luminescent crystal, the idealization of the crystallization of the luminescent structure and the modification and compensation of crystal defects, and the effect of improving the effect of the activator, so that the luminous performance of the luminophor is obviously improved, the ideal development of the luminescent crystal and the existence of the modified and filled fumed silica in the crystal also have the macroscopic and microscopic pinning effect of the structure, and the thermal vibration amplitude of the lattice structure in an excited state is reduced, thereby improving the thermal attenuation resistance of the luminophor. The preparation technical scheme is a remarkable improvement and innovation of the nitride or oxynitride fluorescent body in terms of product morphology and realization function, and the realization of the preparation method is helpful for realizing industrial mass production and commercial application of the high-performance fluorescent body under mild conditions.
The invention may have, but is not limited to, the following benefits:
the preparation process scheme for controlling the synthesis of a group of nitride or oxynitride fluorescent bodies by introducing micron-sized flake graphite as a crystallization template to obtain crystallization control so as to remarkably improve the luminous performance of the nitride or oxynitride fluorescent bodies has remarkable creative and fundamental differences in product morphology, manufacturing method, conditions and performance improvement compared with the traditional preparation process scheme of corresponding nitride or oxynitride fluorescent bodies. The technical scheme of the invention not only improves the luminous performance of the product, but also reduces the harsh conditions of product synthesis, so that the product is easier to be put into practical use for mass production, which is a remarkable progress in the related technical field.
Drawings
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is an X-ray diffraction pattern of the sample of the present invention in example 1 and comparative example 1, wherein a1 is a comparative sample and b1 is a sample of example 1;
FIG. 2 is a scanning electron microscope topography of the samples of example 1 and comparative example 1 of the present invention, wherein a1 is the sample of comparative example 1, and b1 is the sample of example 1;
FIG. 3 is the emission spectra of the samples of example 1 and comparative example 1 of the present invention, wherein a1 is the comparative sample and b1 is the sample of example 1;
FIG. 4 shows the thermal steady state luminous flux decay curves of the samples of examples 1 and comparative example 1 and the samples of examples 2 and comparative example 2 according to the present invention, wherein a1 is the sample of comparative example 1 and b1 is the sample of example 1; a2 is the sample of comparative example 2, b2 is the sample of example 2;
FIG. 5 shows X-ray diffraction patterns of samples of examples 2, 9 and 10 and comparative examples 2, 9 and 10 according to the present invention, wherein a2 is a sample of comparative example 2 and b2 is a sample of example 2; a9 is the comparative example 9 sample, b9 is the example 9 sample; a10 is the sample of comparative example 10, b10 is the sample of example 10;
FIG. 6 is a graph of the morphology of the scanning electron microscope of the samples of the example 2 and the comparative example 2 of the present invention, wherein a2 is the sample of the comparative example 2, and b2 is the sample of the example 2;
FIG. 7 is the emission spectra of the samples of example 2 and comparative example 2 of the present invention, in which a2 is the comparative sample and b2 is the sample of example 2.
Detailed Description
The invention is further illustrated by the following specific examples, which are, however, to be understood only for the purpose of more detailed description and are not to be construed as limiting the invention in any way.
This section generally describes the materials used in the test of the present invention and the test method. Although many materials and methods of operation are known in the art for accomplishing the objectives of the present invention, the present invention will be described in as much detail herein. It will be apparent to those skilled in the art that in this context, the materials and methods of operation used in the present invention are well known in the art, if not specifically described.
The reagents and instrumentation used in the following examples were as follows: reagent:
Si 3 N 4 : high purity grade, available from the japanese UBE company; alN: high purity grade, purchased from japan de shan company; al (Al) 2 O 3 : high-purity grade, purchased from the new material company of the BoKaika Europe; euF (EuF) 3 : high purity grade, purchased from Ganzhou Xinzheng new materials company; s is SiO 2 : analytically pure, purchased from national pharmaceutical group chemical reagent company; caCO (CaCO) 3 CaO: analytically pure, purchased from the national collection of drugs fg group chemical reagent company; caF (CaF) 2 : analytically pure, purchased from national pharmaceutical group chemical reagent company; ca (Ca) 3 N 2 : high purity grade, available from Liaoning Desheng ceramic materials company; eu (Eu) 2 O 3 、CeO 2 : high purity grade, purchased from new material company, hengma high purity, inc; 10-100 micron flake graphite: analytically pure, purchased from Shanghai glass Intelligent technologies.
The emission spectrum and the thermal characteristic of the fluorescent body are respectively tested by adopting a remote photoelectric F-4500 fluorescent spectrometer and an EX-1000 fluorescent powder thermal quenching analysis system, the components and the morphological characteristics of the fluorescent body are respectively tested by adopting a TD-3500X-ray diffractometer accessed by Dandong and an OXFORD KYKY2800B scanning electron microscope of a Zhongkeke instrument, and the content of halogen element R in the fluorescent body is tested by a TAS-986 atomic absorption spectrometer of a Beijing general analysis general instrument.
Example 1
This example is a description of a method for producing a phosphor of the present invention.
Firstly, weighing the raw materials according to the following proportion under the protection of inert gas: si (Si) 3 N 4 1.05 g, alN 0.03 g and Al 2 O 3 0.02 g, euF 3 0.02 g, siO 2 0.05 g, and the raw materials are fully ground and uniformly mixed after being weighed in a glove box according to a molar ratio. Then weighing 0.06 g of flake graphite with the grain diameter of 10-100 microns according to the proportion, fully and uniformly mixing the mixed raw materials and the flake graphite, then filling the composite material into a boron nitride crucible, putting into a pneumatic sintering furnace, and adding the mixture into N 2 Calcination was carried out in an atmosphere at a temperature of 2050℃under a pressure of 125℃for 6 hours. After cooling the sintered body, pulverizing and sieving. Washing in hydrochloric acid solution with the concentration of 8% for 1 hour, washing with water and drying to obtain the fluorescent structure matrix coated with the flake graphite. Then 1.0 g of fluorescent structure matrix coated with flake graphite and 0.008 g of nano fumed silica are weighed according to the following proportion in a glove box, the two are fully and uniformly mixed, and then the secondary mixture is put into a resistance furnace, and the mixture is heated in an air atmosphereCalcining at 600 ℃ for 24 hours, and cooling to obtain the high-efficiency luminous phosphor compound Si 0.0383 Al 0.0017 O 0.0007 N 0.0523 F 0.0003 ：0.00013Eu 2+ The emission wavelength was 545.43nm.
As a comparison, comparative example 1 was also prepared. Weighing the following raw materials in proportion under the protection of inert gas: si (Si) 3 N 4 1.05 g, alN 0.03 g and Al 2 O 3 0.02 g, euF 3 0.02 g, siO 2 0.05 g, and the raw materials are fully ground and uniformly mixed after being weighed in a glove box according to a molar ratio. The mixture is then charged into a boron nitride crucible and placed into a gas pressure sintering furnace in N 2 Calcination was carried out in an atmosphere at a temperature of 2050℃under a pressure of 125℃for 6 hours. After cooling the sintered body, pulverizing, sieving, then washing in hydrochloric acid solution with concentration of 8% for 1 hour, washing with water and drying to obtain phosphor Si of comparative example 1 0.0383 Al 0.0017 O 0.000 7 N 0.0523 F 0.0003 ：0.00013Eu 2+ The emission wavelength was 545.38nm.
FIG. 1 is an X-ray diffraction pattern of the sample of example 1 and comparative example 1, in which a1 is a comparative sample and b1 is a sample of example 1. Diffraction peaks of the two patterns can be matched with (Si.Al) 0.04 (O，N) 0.0533 All diffraction peaks in the standard diffraction pattern of (2) correspond to each other, and no other crystalline impurity phase peak exists, and both of the diffraction peaks show the diffraction peak pattern of the pure crystalline phase structure. However, the diffraction peak intensities and diffraction peak intensity distribution combinations of the diffraction patterns of the samples of example 1 and comparative example 1 are clearly different. Of the three major strong peaks at 27.2 °, 33.8 ° and 36.1 ° of the standard spectrum, the intensities of comparative example 1 were 3500, 3150 and 3350 in this order, the strongest peak was 3500 at 27.2 °, the intensities of example 1 were 4850, 3200 and 5600, respectively, and the strongest peak was 5600 at 36.1 °. As is apparent from the comparison of the diffraction patterns, the sample of example 1 has higher crystallization degree and more ideal crystal development, so that the diffraction intensity of each crystal face is obviously enhanced, and the intensity of the strongest diffraction peak is 1.6 times that of the sample of comparative example 1. The intensity arrangement of the three main strong peaks also changes obviously, and the comparison is carried out The high to low alignment changes of 27.2 °, 36.1 °, and 33.8 ° for the example 1 samples were 36.1 °, 27.2 °, and 33.8 ° for the example 1 samples. The diffraction peaks in the X-ray diffraction pattern represent a set of crystal planes or structure plane network directions, which are represented by crystal plane development characteristics and crystal shape characteristics, and it is apparent that the crystal integrity, plane development characteristics and crystal habit of the light emitting structure crystal in the sample of example 1 are changed differently from those of the sample of comparative example 1. The result of the X-ray diffraction analysis proves that the multi-step process technical scheme provided by the invention, which introduces the flake graphite as a crystallization template, obviously improves the crystallization characteristics of a target product on the basis that the target luminous structure matrix is not damaged and other crystallization impurity phases are not formed, the crystallization degree of a sample is more ideal and the uniformity is better, so that the intensity of diffraction peaks is obviously improved, and the distribution change of the intensity of diffraction peaks also proves that the crystallization of the luminous structure is controlled under the condition that the flake graphite is used as the crystallization template, and the development of a specific dominant crystal form and a dominant crystal face is more ideal, thereby being more beneficial to the realization of high-performance products.
Fig. 2 is a scanning electron microscope topography of the samples of example 1 and comparative example 1, in which a1 is the sample of comparative example 1 and b1 is the sample of example 1. As can be seen from the crystal morphology diagram, the luminophor in the sample of comparative example 1 is crystallized into irregular granules with larger particles, and meanwhile, a plurality of small irregular granular aggregates are also arranged, the crystallization state of the crystal is poor, the crystal face and the crystal form develop poorly, the crystal form and the crystal face edge are smooth granules, the characteristics obviously reflect that the solid-liquid-solid phase reaction of the luminophor crystal is easy to be excessive and lose control under the conventional process of >1900 ℃ and >100 atmospheric pressure, the particles are coarse, the crystallization is poor, the irregular granules are often formed and the aggregation is serious, and the characteristics severely restrict the luminescence performance of the product and cannot meet the commercial use requirements. The sample of the embodiment 1 obtained by the preparation process provided by the invention has the characteristics of remarkably improved and idealized crystallization on the crystal morphology, the crystals are in uniform and smaller columnar morphology, the irregular granular crystals are basically disappeared, the crystals are in columnar shape with good crystal face development and clear edges and corners, and the grain aggregation phenomenon is remarkably reduced. The morphological characteristics under the electron microscope also prove that the multi-step process technical scheme for introducing the flake graphite as the crystallization template provided by the invention obviously improves the crystallization characteristics of a target product, the crystallization degree of a sample is more ideal and the uniformity is better, the crystallization of a light-emitting structure is controlled under the condition that the flake graphite is used as the crystallization template, the development of a specific dominant crystal form and a dominant crystal face is more ideal, and the realization of a high-performance product is more facilitated.
FIG. 3 is a graph showing emission spectra of the phosphor of example 1 and the corresponding pair of example 1, wherein a1 is a comparative sample and b1 is a sample of example 1. Fig. 4 is a thermal steady state luminous flux decay curve for the samples of example 1 and comparative example 1 and example 2 and comparative example 2, where a1 is the comparative sample and b1 is the example 1 sample. Compared with the comparative sample 1, the luminous intensity of the sample in the embodiment 1 is improved by 15%, the light attenuation at the position where the thermal steady state is maintained for 300s is reduced by 0.4%, and the obvious improvement on the luminous performance is consistent with the improvement on the crystal morphology of the sample, which reflects the progress and innovation of the technical scheme provided by the invention in the aspects of product morphology and realization of functions.
Example 2
This example is a description of a method for producing a phosphor of the present invention.
Firstly, weighing the raw materials according to the following proportion under the protection of inert gas: si (Si) 3 N 4 0.73 g of AlN 0.21 g of CaCO 3 0.15 g, euF 3 0.027 g, the above raw materials are weighed according to a molar ratio in a glove box, and then fully ground and uniformly mixed. Then weighing 0.06 g of flake graphite with the grain diameter of 10-100 microns according to the proportion, fully and uniformly mixing the mixed raw materials and the flake graphite, then filling the composite material into a boron nitride crucible, putting into a pneumatic sintering furnace, and adding the mixture into N 2 Calcining at 1900 deg.c under 25 atm for 6 hr. After cooling the sintered body, pulverizing and sieving. Washing in hydrochloric acid solution with the concentration of 8% for 1 hour, washing with water and drying to obtain the fluorescent structure matrix coated with the flake graphite. Then 1.0 g of fluorescent structure matrix coated with flake graphite and 0.008 g of nano fumed silica are weighed according to the following proportion in a glove box, the two are fully and uniformly mixed, then the secondary mixture is put into a resistance furnace, calcined for 24 hours at 600 ℃ in an air atmosphere, and cooledAfter that, the phosphor compound 2 (Si) 0.03 Al 0.01 O 0.0028 N 0.05 F 0.0003 )·Ca 0.0057 N 0.0038 ：0.0005Eu 2+ The emission wavelength was 598.56nm.
As a comparison, comparative example 2 was also prepared. Weighing the following raw materials in proportion under the protection of inert gas: si (Si) 3 N 4 0.73 g of AlN 0.21 g of CaCO 3 0.15 g, euF 3 0.027 g, the above raw materials are weighed according to a molar ratio in a glove box, and then fully ground and uniformly mixed. The mixture is then charged into a boron nitride crucible and placed into a gas pressure sintering furnace in N 2 Calcining at 1900 deg.c under 25 atm for 6 hr. After cooling the sintered body, pulverizing, sieving, then washing in hydrochloric acid solution with concentration of 8% for 1 hour, washing with water, and drying to obtain phosphor 2 (Si) 0.03 Al 0.01 O 0.0028 N 0.05 F 0.0003 )·Ca 0.0057 N 0.0038 ：0.0005Eu 2+ The emission wavelength was 600.78nm.
FIG. 5 shows X-ray diffraction patterns of samples of examples 2, 9 and 10 and comparative examples 2, 9 and 10 according to the present invention, wherein a2 is a sample of comparative example 2 and b2 is a sample of example 2; a9 is the comparative example 9 sample, b9 is the example 9 sample; a10 is the sample of comparative example 10, b10 is the sample of example 10; examples 9 and 10 were each prepared using the procedure provided in example 2 of the present invention, and comparative examples 9 and 10 were each prepared using the procedure provided in comparative example 2 of the present invention. The diffraction peak of several groups of samples in the figure can be equal to that of 2 (Si.Al) 0.04 (O，N) 0.0533 ·Ca 0.0057 N 0.0038 All diffraction peaks in the standard diffraction patterns of (2) correspond to each other, and no other crystallization impurity phase peak exists, so that the diffraction peak patterns of the pure crystal phase structure are all shown. However, the diffraction peak intensities of the diffraction patterns of the samples of examples 2, 9, and 10 and the samples of comparative examples 2, 9, and 10 are clearly different. Of the three major strong peaks at 30 °, 35 ° and 38 ° of the standard spectrum, the diffraction peak intensities of examples 2, 9, 10 were each higher than that of the comparative example 2 sample, and the secondary peak intensities of examples 2, 9, 10 at 34 ° were significantly higher than those of comparative examples 2, 9, 10. This difference in diffraction peak intensitiesThe process provided by the invention, such as example 2, is reflected in that the sample has higher crystallization degree and more ideal crystal development, so that the diffraction intensity is enhanced. The diffraction peaks in the X-ray diffraction pattern represent a group of crystal planes or structural network directions, and are represented by crystal plane development characteristics and crystal shape characteristics, and it is apparent that the enhancement of 34 ° secondary peaks in the samples of examples 2, 9 and 10 particularly clearly shows that the preparation method provided by the invention makes the crystal plane development characteristics and crystal habit of the crystal with a light-emitting structure obviously changed from those of the samples of comparative examples 2, 9 and 10. The result of the X-ray diffraction analysis proves that the multi-step process technical scheme provided by the invention, which introduces the flake graphite as a crystallization template, obviously improves the crystallization characteristics of a target product on the basis that the parent body of the target light-emitting structure is not damaged and other crystallization impurity phases are not formed, the crystallization degree of a sample is more ideal, the intensity of a diffraction peak is improved, and the enhancement of a specific diffraction peak also proves that the crystallization of the light-emitting structure is controlled under the condition that the flake graphite is used as the crystallization template, and the development of a specific dominant crystal form and a dominant crystal face is more ideal, so that the realization of a high-performance product is facilitated.
FIG. 6 is a graph of the morphology of the scanning electron microscope of the samples of example 2 and comparative example 2 of the present invention, wherein a2 is the sample of comparative example 2, and b2 is the sample of example 2. As is evident from the graph, the luminophore in the sample of comparative example 2 is crystallized into extremely fine and uniform long and thin needle shape, and the characteristic of the fine crystal is quite unfavorable for obtaining high-efficiency luminescence property, and severely restricts the luminescence property of the product to meet the commercial use requirement. The sample of the embodiment 2 obtained by the preparation process provided by the invention has the characteristics of remarkably improved and idealized crystallization on the crystal morphology, the crystals are in uniform and smaller columnar morphology, the irregular granular crystals are basically disappeared, the crystals are in columnar shape with good crystal face development and clear edges and corners, and the grain aggregation phenomenon is remarkably reduced. The morphological characteristics under the electron microscope also prove that the multi-step process technical scheme for introducing the flake graphite as a crystallization template provided by the invention obviously improves the crystallization characteristics of a target product, the crystallization degree of a sample is more ideal, uniform and larger wide columnar and thick plate crystals are presented, the crystal granularity is increased by 4-8 times, the crystal face development and combination are completely different from those of comparative example 2, the strengthening phenomenon of a secondary peak of 34 degrees in an X-ray diffraction pattern is also proved, and obviously, the crystallization of a light-emitting structure is controlled under the condition that the flake graphite is used as the crystallization template, the crystal is obviously increased, and the development of a specific dominant crystal form and the dominant crystal face is more ideal, so that the realization of a high-performance product is more facilitated.
FIG. 7 is an emission spectrum of the phosphor of example 2 and corresponding comparative example 2, wherein a2 is a comparative sample and b2 is a sample of example 2. The thermal steady state luminous flux decay curve of fig. 4 also gives the luminous flux decay characteristics at thermal steady state for the samples of example 2 and comparative example 2, where a2 is the comparative sample and b2 is the sample of example 2. Compared with comparative sample 2, the sample in example 2 has the advantages that the crystal morphology of the luminous structure is greatly changed by the flake graphite, so that the emission wavelength of the sample is changed from 600.78nm to 598.56nm, but the luminous intensity of the sample is improved by 20%, the light attenuation at the position where the thermal steady state is maintained for 300s is also obviously reduced by 2%, and the obvious improvement on the luminous performance is consistent with the improvement on the crystal morphology of the sample, thus reflecting the progress and innovation of the technical scheme provided by the invention in the aspects of product morphology and realization function.
Examples 3 to 7
This example is a description of a method for producing a phosphor of the present invention.
The following phosphors were prepared in a similar manner to example 1, with the following table showing the relevant parameters of the raw material amount ratio:
table 1 ratio of the amount (g) of the phosphor raw materials and final light-emitting properties in examples 3 to 7
Table 2 proportion of the amount of sintered body, flake graphite and fumed silica (g) in examples 3 to 7
Examples 8 to 12
This example is a description of a method for producing a phosphor of the present invention.
Comparative examples 9 and 10 of examples 9 and 10 were prepared by a method similar to example 2, and also by a method similar to comparative example 2, and the raw material amount ratio-related parameters are shown in the following table:
TABLE 3 ratio of raw materials (g) to final luminescence of the phosphors in examples 8 to 12
Table 4 the amount ratio (g) of the sintered body, the graphite flakes and the fumed silica in examples 8 to 12
Although the present invention has been described to a certain extent, it is apparent that appropriate changes may be made in the individual conditions without departing from the spirit and scope of the invention. It is to be understood that the invention is not to be limited to the described embodiments, but is to be given the full breadth of the claims, including equivalents of each of the elements described.
Claims (10)
1. A method for producing a phosphor compound, characterized in that the composition of the phosphor compound is represented by the following general formula: k (M1) 0.04-a M2 a N b O c R d )·X e N f : mRe, wherein:
m1 is at least one element selected from Si and Ge, and M2 is at least one element selected from Al and GaAn element, N is nitrogen, O is oxygen, R is F - 、Cl - X is selected from at least one element of Mg, ca, li, la, Y, and Re is selected from at least one element of Eu, ce, dy, ho, tm, er, pr;
k. a, b, c, d, e, f, m is the molar coefficient: k is more than 0.3 and less than 2.2,0, a is more than 0.03,0.045, b is more than 0.075,0 and less than or equal to c and less than or equal to 0.055,0 and less than or equal to d and less than or equal to 0.002,0 and less than or equal to e and less than or equal to 0.025,0 and less than f and less than 0.025,0, and m is more than 0.025 and less than or equal to 0.025.
After the fluorescent compound is excited by ultraviolet-blue-green light with the emission peak wavelength ranging from 250 nm to 550nm, the fluorescent compound emits a light emission spectrum with one or more peaks with the peak wavelength ranging from 505 nm to 605 nm;
the method comprises the following steps:
(1) According to k (M1) 0.04-a M2 a N b O c R d )·X e N f : weighing raw materials according to element proportion of mRe, and uniformly mixing;
(2) Weighing flake graphite with the particle size of 10-100 microns in a proper proportion, placing the flake graphite into the mixture obtained in the step (1), and then placing the mixture into a shearing crusher for fully and uniformly mixing to obtain a composite material;
(3) Placing the composite material obtained in the step (2) into high-temperature high-pressure pressing equipment to perform high-temperature solid-phase reaction, and then crushing, screening and acid washing to obtain a fluorescent body sintered material coated with flake graphite;
(4) Weighing nanoscale fumed silica powder with a proper proportion, and fully mixing the nanoscale fumed silica powder with the phosphor sintering material coated with the flaky graphite obtained in the step (3) to obtain a secondary mixture;
(5) Placing the secondary mixture obtained in the step (4) into a resistance furnace, and performing low-temperature heat treatment in an air atmosphere to obtain the fluorescent compound;
The sources of the elements in the step (1) are as follows: the M1 element adopts a nitride raw material, the M2 element adopts a nitride raw material or a nitride raw material and an oxide raw material, the X element adopts a nitride raw material or a carbonate raw material or an oxide raw material or a hydroxide raw material, and the Re element adopts a nitride raw material or an oxide raw material or a fluoride raw material or a chloride raw material;
the atmosphere of the high-temperature solid-phase reaction is nitrogen atmosphere or mixed atmosphere of nitrogen and hydrogen; the reaction pressure is 10-200 atm; the reaction temperature is 1900-2500 ℃.
2. The method of claim 1, wherein 0.8 < k < 1.2,0 < a < 0.025,0.045 < b < 0.055,0 < c < 0.005,0 < d < 0.0015 and 0.045 < b+c+d < 0.062, e=0, f=0, 0 < m < 0.0015; and/or
The M1 is Si, the M2 is Al, the N is N, the O is O, and the R is F - Ion, re is Eu.
3. The method according to claim 1, wherein, k is more than or equal to 0.95 and less than or equal to 1.05,0.001 a is more than or equal to 0.02,0.052 b is more than or equal to 0.054,0 c is more than or equal to 0.0035,0 d is more than or equal to 0.0013, b+c+d is more than 0.0588, e=0, f=0, and m is more than 0 and less than or equal to 0.0013.
4. The method of claim 1, wherein 1.8 < k < 2.2,0 < a < 0.025,0.045 < b < 0.055,0 < c < 0.005,0 < d < 0.002 and 0.05 < b+c+d < 0.055,0 < e < 0.015,0 < f < 0.01,0 < m < 0.0035; and/or
The M1 is selected from Si, M2 is Al, N is N, O is O, R is F - Ion, re is Eu, and X is Ca.
5. The method according to claim 1, wherein, k is more than or equal to 1.95 and less than or equal to 2.05,0.0005 a is more than or equal to 0.02,0.052 b is more than or equal to 0.054,0 c is more than or equal to 0.0033,0 d is more than or equal to 0.0017, and 0.052 is more than or equal to b+c+d is more than or equal to 0.059,0 e is more than or equal to 0.0133,0 f is more than or equal to 0.0089,0 m is more than or equal to 0.0033.
6. The preparation method of claim 1, wherein the proportion of the flake graphite with the particle size of 10-100 microns added in the step (2) is 0.001% -25% of the mixture.
7. The method according to claim 1, wherein the step (3),
the reaction time is 4-16 hours; and/or
In the step (3), the steps of crushing, sieving and acid washing comprise: placing the crushed and sieved material into an acid solution with the molar concentration of 1-10% for stirring and washing for 1-4 hours, filtering acid liquor, washing for 1-4 times by using deionized water or ethanol, and drying to obtain the fluorescent compound; the acid is selected from one or more of the following: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid.
8. The method according to claim 1, wherein in the step (4), the nano-sized fumed silica is added in an amount of 0.001 to 10% of the sinter.
9. The method according to claim 1, wherein in the step (5), the atmosphere of the secondary mixture is an atmospheric air atmosphere, which is subjected to low-temperature heat treatment in the air atmosphere; the reaction temperature is 400-1000 ℃; and/or the reaction time is 16-32 hours.
10. A phosphor composition comprising at least the phosphor compound according to any one of the preparation methods of claims 1 to 5.
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