JP2015004045A - Blue luminescent silicate phosphor and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blue luminescent silicate phosphor which is excited at a wavelength around 400 nm that is a luminescent wavelength of a near-UV LED to strongly emit light, and which shows little change in the luminescent intensity by changes in an excitation wavelength, and to provide a production method for easily obtaining the blue luminescent silicate phosphor.SOLUTION: The blue luminescent silicate phosphor is represented by compositional formula of BaEuZrSiO(where x, y and δ satisfy 0.001≤x≤0.5, 2.5≤y≤6.0 and -0.1≤δ≤0.2). In the formula, Eu comprises both of Euand Er, and a ratio (Eu/Eu+Eu) of Euin the whole Eu is 10% to 90%.

Description

  The present invention relates to a blue-emitting silicate phosphor that exhibits high-luminance blue light emission when excited by near ultraviolet to violet light, and a method for producing the same.

  The white LED is produced by combining a blue or near-ultraviolet LED (LD) and a phosphor. White LEDs have been developed mainly for backlight applications such as cellular phones because of their low luminous efficiency, but in recent years, they have been attracting attention as next-generation lighting as the luminous efficiency increases.

  As a method for configuring the white LED, a method of combining a blue LED and a yellow phosphor, a method of combining a near ultraviolet LED and blue, green, and red phosphors have been proposed.

Specifically, in the near ultraviolet LED excitation method, a purple LED having an emission center wavelength of 405 nm (or more) is used as an excitation source. This is because (i) purple LED is used at the consumer level for optical pickup of Blu-ray (registered trademark) disk and is relatively low cost, (ii) the phosphor emission and LED emission wavelength Stoke loss at the time of wavelength conversion can be suppressed by being closer, (iii) it is more advantageous to use a long wavelength (low energy) LED as an excitation source when considering the photodegradation of resin and peripheral members, etc. From the point of view. Therefore, in the white LED using the near-ultraviolet LED excitation method, a blue phosphor that is excited around 405 nm, which is the emission center wavelength of the LED, and emits light efficiently is required, and has been used in conventional fluorescent lamps (Ca , Sr) ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₀ O ₁₇ : Eu (BAM) and the like have been used.

  For example, Non-Patent Document 1 describes the excitation spectrum and emission spectrum of BAM improved for the near ultraviolet LED excitation system.

BaZrSi ₃ O ₉ : Eu is known as one of phosphors that emit blue light under near-ultraviolet excitation, and Ba _0.99 ZrSi ₃ O ₉ : 0.01Eu is described in Non-Patent Document 2. Yes.

Patent Document 1 discloses (Ba, Sr) _0.99 ZrSi ₃ O ₉ : 0.01Eu, and Patent Document 2 discloses (Ba _(1-xy) Sr _x Eu _y ) (Sn It has been disclosed that by replacing the Ba site with Sr and the Zr site with Sn as a composition of _1-z Zr _z ) Si ₃ O ₉ , the emission intensity is increased in near-ultraviolet excitation.

Japanese Patent Publication No. 48-38550 JP 2008-63550 A

Taguchi Tsunemasa "All about white LED lighting technology", Industrial Research Committee, p. 110 G. Blasse, A.M. Brill, Journal of Solid State Chemistry, 1970, vol. 2, p105-108

  However, when viewing the excitation spectrum of BAM described in Non-Patent Document 1, the excitation intensity rapidly decreases around 400 nm with a peak at about 380 nm. In addition, since the excitation intensity corresponds to the emission intensity at that wavelength, this indicates that the change in the emission intensity due to the change in the excitation wavelength is large. In this way, when there is a sudden change in the emission intensity with respect to the excitation wavelength of the phosphor, the variation in the blue emission intensity due to the variation in the emission wavelength of the ultraviolet LED that is the excitation source also increases, resulting in variations in the color and emission intensity of the white LED. Since it connects, it is not preferable.

Further, Ba _0.99 ZrSi ₃ O ₉ : 0.01Eu described in Non-Patent Document 2, Patent Document 1, and Patent Document 2 is a mixture of BaCO ₃ , ZrO ₂ , SiO ₂ , Eu ₂ O ₃ , It is formed by a solid phase reaction in which heat treatment is performed in a nitrogen-hydrogen mixed gas. The reason for firing in the nitrogen-hydrogen gas is to dope the luminescent center from Eu ₂ O ₃ (Eu ³⁺ ) to Eu ²⁺ into the crystal. In general, in the phosphor Eu ²⁺ is activated, reduced doping ratio of Eu ²⁺ (the ratio of Eu ²⁺ to the total Eu) is higher there is a high brightness phosphor can be obtained. However, in BaZrSi ₃ O ₉ : Eu, ZrO ₂ tends to cause oxygen defects. For this reason, these phosphors fired in a reducing atmosphere, although the ratio of Eu ²⁺ is nearly 100%, have a large amount of self-absorption due to oxygen defects, and are practical because self-absorption of the excitation light and emission mother crystal occurs. High luminous efficiency that can withstand the above was not obtained.

  The present invention has been made in view of such various problems, and is a blue-emitting silicate that emits strong light when excited at around 400 nm, which is the emission wavelength of a near-ultraviolet LED, and has little change in emission intensity due to change in excitation wavelength. An object of the present invention is to provide a phosphor and a production method capable of easily obtaining the blue light-emitting silicate phosphor.

The inventors of the present invention have made extensive studies to solve the above-described problems. As a result, the composition formula of Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2). In the silicate phosphor represented by the formula, Eu in the composition formula contains both Eu ²⁺ and Eu ^3+, and the ratio of Eu ^{2+ in} the total Eu (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) is 10% or more and 90 It was found that the emission intensity is significantly high when the ratio is less than or equal to%. In addition, such a phosphor is obtained by reducing and doping Eu in the form of Eu ^{2+ in} a heat treatment for reduction firing, and then annealing in an atmosphere containing oxygen, thereby changing Eu ²⁺ to Eu ^3+. As a result, the present invention was completed.

That is, the blue light-emitting silicate phosphor according to the present invention has Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2) a blue light-emitting silicate phosphor represented by the composition formula, Eu in the composition formula is contained both ^{Eu 2+} and ^{Eu 3+,} the ^{Eu 2+} of the total Eu The ratio (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) is 10% to 90%.

  Here, the blue light emitting silicate phosphor may be element-substituted with at least one element selected from Mg, Ca, Sr, Ti, Hf, Sn, Ge, La, and Y.

In addition, the method for producing a blue light-emitting silicate phosphor according to the present invention includes Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, − 0.1 ≦ δ ≦ 0.2) a method for producing a blue light-emitting silicate phosphor represented by a composition formula, wherein each starting material containing the constituents represented by the composition formula is weighed, A step of obtaining a mixture in which the constituent components are uniformly dispersed by mixing and stirring the starting materials in a solvent, and a precursor that is a dried product in which the solvent contained in the mixture is removed by drying the mixture. Forming a calcined powder by heat-treating the precursor at a temperature of 700 ° C. to 1400 ° C. in an air atmosphere, and calcining the powder in a reducing atmosphere at 1100 ° C. to 1500 ° C. was heat-treated at the temperature, the Eu as ^{Eu 2+} The method includes a step of doping, and a step of annealing a heat-treated product obtained by heat-treating the calcined powder at a temperature of 500 ° C. to 1500 ° C. in an atmosphere containing oxygen.

Here, the SiO ₂ used as the starting material is preferably a water-soluble silicon compound.

  According to the present invention, there is provided a blue light emitting silicate phosphor that is efficiently excited by a near-ultraviolet LED, particularly a purple LED of around 400 nm mainly used as an excitation source, has little change in emission intensity, and has high emission intensity. In addition, such a silicate phosphor can be produced by a simple method.

It is a figure which shows the excitation light emission spectrum of the fluorescent substance of Example 1, 2 and the comparative example 1. FIG. Examples 1 and 2, a diagram illustrating a XANES spectrum obtained on the basis of X-ray absorption fine structure (XAFS) measurement of Comparative Example 1 ^{(Eu 2+),} and ^{_{Eu 2 O 3 (Eu 3+)}} . It is a figure which shows the excitation light emission spectrum of the fluorescent substance of Example 1 and Comparative Example 1.

Hereinafter, specific embodiments (hereinafter referred to as “present embodiments”) of the blue light-emitting silicate phosphor and the manufacturing method thereof according to the present invention will be described in detail in the following order. Note that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention.
1. 1. Blue light emitting silicate phosphor 2. Manufacturing method of blue light emitting silicate phosphor 2-1. First step 2-2. Second step 2-3. Third step 2-4. Fourth step 2-5. Fifth step Example

<< 1. Blue-emitting silicate phosphor >>
The blue-emitting silicate phosphor according to the present embodiment is obtained using BaCO ₃ , ZrO ₂ , Eu ₂ O ₃ , and SiO ₂ as starting materials, and the composition formula is Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} . It is a blue light emitting silicate phosphor represented. In this blue-emitting silicate phosphor, Eu in its composition formula contains both Eu ²⁺ and Eu ^3+, and the ratio of Eu ²⁺ out of all Eu (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) is 10%. It is characterized by -90%.

  Here, in this blue light-emitting silicate phosphor, “x”, “y”, and “δ” in the composition formula are 0.001 ≦ x ≦ 0.5 and 2.5 ≦ y ≦ 6.0, respectively. , −0.1 ≦ δ ≦ 0.2 is satisfied.

  Specifically, “x” in the composition formula satisfies the range of 0.001 ≦ x ≦ 0.5 as described above. The optimum Eu concentration varies depending on the value of “y”, but when x <0.001, the concentration of Eu as an activator is too low and the emission intensity decreases. On the other hand, when x> 0.5, the emission intensity decreases due to concentration quenching.

  Further, regarding “x” in the composition formula, it is more preferable that the range of 0.005 ≦ x ≦ 0.2 is satisfied. Thus, by setting “x” to satisfy the range of 0.005 ≦ x ≦ 0.2, it is possible to obtain a phosphor exhibiting an even higher emission intensity.

“Y” in the composition formula satisfies the range of 2.5 ≦ y ≦ 6.0 as described above. When y <2.5, it becomes too SiO ₂ poor, a heterogeneous phase (Ba ₂ Zr ₂ Si ₃ O ₁₂ ) is generated, and the emission intensity decreases. On the other hand, when y> 6.0, the effect of increasing the emission intensity is almost lost. However, in the case where the purpose is to leave more SiO ₂ in the phosphor, the composition can satisfy y> 6.0, but it is difficult to avoid a decrease in emission intensity.

Further, regarding “y” in this composition formula, it is more preferable that the range of 3.0 <y ≦ 6.0 is satisfied. Thus, the emission intensity increases by setting y> 3.0. This is considered to be because the generation of Ba ₂ Zr ₂ Si ₃ O ₁₂ , which is a different phase, can be suppressed by making SiO ₂ excessive from the theoretical amount. Moreover, it is considered that the crystal growth is facilitated during the heat treatment by making SiO ₂ excessive from the theoretical amount.

In addition, when SiO ₂ is further excessive, peaks considered to be BaZrSi ₃ O ₉ and SiO ₂ are detected in the XRD pattern, as will be described later. SiO ₂ present in the finally obtained silicate phosphor does not contribute to light emission. Therefore, the optimum amount of SiO _2, a reduction in emission intensity due to a decrease in the ratio of contributing phase and an increase in emission intensity, the emission by the excess SiO ₂ remains in the course of heat treatment due to an excess of SiO ₂ In view of the above, it is determined by the balance of the influence on the emission intensity.

“Δ” in the composition formula represents a deviation of the oxygen amount from the stoichiometry. δ = 0 (stoichiometric composition) is ideal, but it is possible to have a trace amount of oxygen deficiency that does not affect the emission intensity, and Eu ³⁺ and other expensive elements are included in the crystal. Therefore, it is possible to have an oxygen amount that is more than the stoichiometric amount due to charge compensation.

  “Δ” in the composition formula satisfies the range of −0.1 ≦ δ ≦ 0.2 as described above. When δ <−0.1, the amount of oxygen defects becomes excessive and self-absorption increases, causing a decrease in luminance. On the other hand, when δ> 0.2, the structure becomes unstable and similarly causes a decrease in luminance.

In the blue light-emitting silicate phosphor according to the present embodiment, Eu in the composition formula contains both Eu ²⁺ and Eu ³⁺ . That is, Eu which is an activator is contained in a form in which Eu ²⁺ and Eu ³⁺ are mixed. Then, in the blue light-emitting silicate phosphor, the ratio of ^{Eu 2+} of its entire ^{Eu (Eu 2+ / Eu 2+ +} Eu 3+) that is 10% to 90% is important.

If the ratio of Eu ^{2+ in} the total Eu is less than 10%, the concentration of Eu ²⁺ is too low to obtain sufficient light emission intensity. On the other hand, if the ratio of Eu ²⁺ in the total Eu exceeds 90%, that is, Eu ³⁺ decreases, and the emission intensity decreases. In the blue light-emitting silicate phosphor according to the present embodiment, a very high emission intensity can be obtained when the ratio of Eu ^{2+ in} the total Eu is 10% to 90%. This is related to the manufacturing process of this phosphor, and Eu ²⁺ generated by heat treatment in a reducing atmosphere becomes Eu ³⁺ by the subsequent heat treatment in an atmosphere containing oxygen, thereby increasing the emission intensity. . This effect will be described in more detail later.

Further, in the blue light emitting silicate phosphor according to the present embodiment, a part of Ba in the composition formula represented by Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} is Mg, Ca, Sr, etc. The part can be replaced with Ti, Hf, Sn, or the like, and a part of Si can be replaced with Ge or the like. As described above, by element substitution with at least one element selected from Mg, Ca, Sr, Ti, Hf, Sn, Ge, etc., the emission peak wavelength is shifted or the emission intensity is further increased. Can be increased. As described above, this blue light-emitting silicate phosphor obtains the effect of increasing the light emission intensity by mixing Eu ²⁺ and Eu ³⁺ at a predetermined ratio with respect to Eu as an activator. Therefore, even if a part of the elements Ba, Zr, Si, and Eu is substituted, the effect can be obtained without changing.

  In addition, about Eu which is an activator, some Eu can be substituted with La, Y, etc. as a co-activator. Since introduction of a cation having a high valence into the Ba site also leads to suppression of oxygen defects, it is particularly preferable to add La and Y. Thereby, the light emission intensity can be further increased. In addition, as a co-activator, it can also substitute with rare earth elements other than La and Y.

  According to the blue light-emitting silicate phosphor having the above composition, it is efficiently excited by a near-ultraviolet LED, in particular, a purple LED having a wavelength of around 400 nm mainly used as an excitation source. The blue light-emitting silicate phosphor has little change, stably exhibits extremely high light emission intensity, and has high light emission efficiency.

≪2. Method for producing blue-emitting silicate phosphor >>
Next, a method for manufacturing a blue light-emitting silicate phosphor having the characteristic configuration described above will be described in detail.

  The blue light emitting silicate phosphor production method according to the present embodiment includes a first step of obtaining a mixture by weighing a predetermined amount of starting materials and mixing them in a solvent, and a second step of obtaining a precursor by drying the mixture. A third step of obtaining a calcined powder by heat-treating the precursor in an air atmosphere; a fourth step of heat-treating the calcined powder in a reducing atmosphere; and a heat-treated product obtained by heat-treating the calcined powder as oxygen. And a fifth step of annealing in an atmosphere containing Hereinafter, it explains in full detail for every process.

<2-1. First step (mixing step)>
The first step is a mixing step in which starting materials containing constituent components are mixed to obtain a mixture in which the constituent components are uniformly dispersed. More specifically, in the first step, a compound containing each constituent element as a starting material is converted into a composition formula Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2), and weighed at a predetermined ratio so that the ratio is represented by the composition formula, The mixture in which the constituent components are uniformly dispersed is obtained by mixing and stirring.

  In this way, by mixing and stirring the starting materials in a solvent to produce a mixture in which the constituent components are uniformly dispersed, a phosphor in which the constituent components contained in the starting materials are uniformly distributed can be obtained. It becomes a phosphor having high emission intensity.

Among the starting materials, first, the raw metal compounds (raw metal salts) that serve as the Ba source and Zr source include carbonates, oxides, hydroxide salts, acetates, nitrates, chloride salts, and the like of these metal elements. Can be used. Further, as a Zr source, a hydrate of ZrCl ₂ O can also be used. Among them, it is particularly preferable to use BaCO ₃ which is a carbonate as the Ba source and ZrO ₂ which is an oxide as the Zr source from the viewpoint of ease of handling and cost.

As described above, part of the Ba site in the composition formula represented by Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} is Sr, Ca, Mg, etc., and part of the Zr site is Ti, Hf, Sn. In the case of substituting with these, carbonates, oxides, hydroxide salts, acetates, nitrates, chloride salts and the like can be used as the compounds containing these metal elements.

  Note that these starting materials are exemplified in consideration of costs and the like as described above, and the starting materials may be selected so as to be oxides by heat treatment, and the use of other starting materials is hindered. It is not a thing.

In addition, as a europium compound (Eu compound) serving as an Eu source to be added as an activator, an oxide, acetate, nitrate, or the like can be used, or Eu alone can be used. Among these, it is particularly preferable to use Eu ₂ O ₃ which is an oxide from the viewpoint of easy handling and cost. Moreover, La, Y, etc. added as a co-activator can also use the oxide, acetate, nitrate, etc. From the viewpoint of ease of handling and cost, it is particularly preferable to use an oxide.

Moreover, as a silicon compound (Si compound) serving as a Si source, SiO ₂ that is an oxide thereof can be used. The SiO _2, as those fine preferable because a uniform mixed state is obtained. The SiO _2, are commercially available in various particle sizes, it is preferable that an average particle size used fumed silica or a few tens of nm spherical silica of about several nm. In general, the smaller the particle size, the more difficult it is to handle, and the more easily aggregation occurs after drying, which may hinder the uniform reaction in the subsequent reduction firing.

As the SiO _2, in particular, it is preferable to use a water-soluble silicon compound. Specifically, for example, a water-soluble silicon compound in which the ethoxy group of tetraethoxysilane (TEOS) is substituted with a dihydric alcohol such as glycol can be used as the water-soluble silicon compound. Such a water-soluble silicon compound is gelated by forming a siloxane bond by hydrolysis / condensation during the mixing process, and other raw materials are retained in the structure, so that separation of the raw materials is difficult to occur. Therefore, a state in which the raw materials are more uniformly mixed can be easily obtained by the gel body, and the state can be stably maintained. In addition, since the phosphor phase is formed by uniformly reacting with other raw materials through amorphous silica in the course of heat treatment, a good crystalline state can be efficiently obtained from a lower temperature state.

  As this water-soluble silicon compound, for example, TEOS and dihydric alcohol are added as raw materials so as to have a molar ratio of 1: 3 or more, and mixed under a temperature condition of 50 ° C. to 80 ° C. It can be produced by adding a small amount of acid as a catalyst (about 0.2% of the mixed solution) and stirring for about 1 hour.

  As the dihydric alcohol, for example, propylene glycol or the like can be used, and as the acid used as the catalyst, for example, hydrochloric acid or lactic acid can be used.

  In addition, in a water-soluble silicon compound, for example, TEOS and propylene glycol become water-soluble when added so as to have a molar ratio of 1: 3 or more. In the case of storage, it is preferable to mix TEOS and propylene glycol so that the molar ratio is 1: 4 or more.

As described above, the blue light-emitting silicate phosphor according to the present embodiment has the composition formula Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2). Since the atomic ratio (prepared composition ratio) in the raw material to be supplied and the atomic composition ratio of the obtained phosphor are substantially the same, water consisting of the raw material metal salt and the Eu compound weighed so as to obtain the desired raw material blending ratio. It is preferable to weigh and mix the dispersion and the silicon compound, respectively.

Specifically, in the first step, the above-described raw material metal salt, Ba salt and Zr salt, and activator, Eu compound, are added to a solvent such as pure water and stirred to disperse these raw materials. An aqueous solution (aqueous dispersion, slurry) is prepared. On the other hand, for example, a water-soluble silicon compound of SiO _{2 is} prepared as a silicon compound to be a Si source. Then, a water-soluble silicon compound is added and mixed in an aqueous dispersion in which the raw material metal is dispersed so as to obtain a desired composition ratio. Thereby, it can be easily mixed with the aqueous dispersion in which the raw material metal salt is dissolved, and a gel-like mixture in which the constituent components are uniformly dispersed can be formed.

  As a solvent for dissolving the raw material metal salt and the Eu compound, isopropyl alcohol (IPA), ethanol, or the like can be used in addition to the pure water described above.

  Further, the mixing and stirring method is not particularly limited, and for example, a method of rotating and mixing a container body containing raw materials and a solvent (for example, a ball mill) or a mechanical stirring force by fixing a container. The method of mixing (various mixers) can be selected in consideration of the viscosity of the mixture, the solvent type, the mixing amount, and the like.

  In addition, the temperature condition for mixing and stirring is not particularly limited, but the liquid temperature is preferably 20 ° C to 100 ° C, more preferably 20 ° C to 80 ° C. When the temperature is lower than 20 ° C, the stirring efficiency is deteriorated. When the temperature is higher than 100 ° C, water boils and it is difficult to obtain a uniform mixture.

<2-2. Second step (drying step)>
The second step is a drying step for drying the mixture obtained in the first step described above in which the constituent components are uniformly dispersed. In the second step, the mixture obtained in the first step is put into, for example, a hot air dryer and dried to form a precursor which is a dried product from which the solvent contained in the mixture is removed.

  The mixture obtained in the first step contains, as a solvent component, a part of a dihydric alcohol such as ethanol or propylene glycol derived from a water-soluble silicon compound in addition to moisture. Therefore, in this 2nd process, the obtained gel body is dried, the solvent component contained in the mixture is removed, and the fluorescent substance precursor which is the dried material of a mixture is formed.

  It does not specifically limit as drying temperature in a 2nd process, According to the kind of solvent contained in a mixture, it selects suitably. For example, when pure water is used as the solvent, it is preferably dried at a temperature of about 100 ° C.

  In addition, before drying, it is preferable to filter the mixture obtained in the first step to remove in advance a solvent adhering to the surface and a predetermined amount of solvent contained in the mixture. Moreover, since the cake obtained after drying is loosely agglomerated, the precursor can be obtained by crushing by a known crushing method such as a dry ball mill.

<2-3. Third step (temporary firing step)>
The third step is a pre-baking step of pre-baking the phosphor precursor obtained in the second step described above under predetermined heat treatment conditions. In this third step, the solvent component remaining through the second step is removed, and the raw material metal salt such as carbonate in the precursor is decomposed to grow a base crystal. Thereby, the calcined powder in which the oxides derived from the raw material components are uniformly distributed can be obtained.

  As the heat treatment (temporary firing) conditions, a temperature condition of 700 ° C. to 1400 ° C. is set in an air atmosphere. When the heat treatment temperature is less than 700 ° C., decomposition of the raw material metal salt such as carbonate becomes insufficient, and the growth of the base crystal becomes insufficient. On the other hand, if heat treatment is performed at a temperature exceeding 1400 ° C., crystal growth proceeds too much to form a sintered lump, which makes subsequent crushing difficult.

  Moreover, as temperature conditions of this temporary baking, it is more preferable to carry out in the range of 700 degreeC-1200 degreeC. Further, if necessary, the heat treatment may be performed in stages by changing the firing temperature, or the heat treatment may be performed in multiple steps.

<2-4. Fourth step (firing step)>
The fourth step is a firing step in which the calcined powder obtained in the third step described above is reduced and fired under a predetermined heat treatment condition in a reducing atmosphere. In this fourth step, the base crystal is further grown to obtain a BaZrSi ₃ O ₉ crystal phase, and at the same time, the activator Eu is changed from trivalent (Eu ³⁺ ) (for example Eu ₂ O ₃ ) to divalent (Eu ²⁺ ). To the Ba site.

The heat treatment (firing) condition is a temperature condition of 1100 ° C. to 1500 ° C. in a reducing atmosphere. If the heat treatment temperature is less than 1100 ° C., the target crystal phase (BaZrSi ₃ O ₉ ) may not be obtained, and crystal growth may be insufficient, resulting in failure to obtain high emission intensity. On the other hand, when the heat treatment is performed at a temperature exceeding 1500 ° C., the obtained crystal is melted, and strong pulverization is necessary after the heat treatment, and therefore, there is a problem that the emission intensity is reduced due to damage of the crystal due to the pulverization. Arise.

  Here, in this 4th process, it is preferable to add and mix a chloride, fluoride, etc. as a flux with respect to calcined powder, and to carry out reduction baking in the presence of this flux. Thereby, crystal growth and grain growth can be promoted.

Specifically, as the flux, for example, LiF, NaF, KF, LiCl, NaCl, KCl, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , NaHCO ₃ , NH ₄ Cl, NH ₄ I ₂ , MgF _{2, CaF 2, SrF 2,} BaF 2, MgCl 2, CaCl 2, SrCl 2, BaCl 2, MgI 2, CaI 2, SrI 2, BaI 2 , etc. can be mentioned, or these compounds are singly Two or more kinds can be used in combination. These fluxes may be compounds in which part of the oxygen (O) is substituted with F, Cl, I or the like. A composition in which the anion of the flux component is incorporated into the crystal and substituted with oxygen may be used. Further, the flux can also be used during an annealing process described later.

In the fourth step, when reducing firing is performed, for example, in a firing furnace, a mixed gas of hydrogen gas and argon gas (Ar—H ₂ mixed gas) or a mixed gas of hydrogen gas and nitrogen gas (N ₂ —H). ₂ ), etc., can be performed under a reducing atmosphere.

Moreover, in this 4th process, you may make it divide into the temporary baking process in an atmospheric condition, and the main baking process in a reducing atmosphere, and to perform heat processing in multiple times. That is, the calcined powder obtained in the third step is further subjected to a calcining treatment in an air atmosphere to completely form a BaZrSi ₃ O ₉ crystal phase, and then the book in a reducing atmosphere. By performing the baking treatment, Eu that contributes to light emission is reduced and doped to the Ba site. As a result, the desired BaZrSi ₃ O ₉ crystal phase can be reliably obtained, and the activator Eu ²⁺ can be effectively doped into the Ba site. In addition, when heat processing is performed in a plurality of times, crushing can be performed at each step.

  Although it does not specifically limit as processing time of reduction baking, For example, it can be set as 1 hour-24 hours, and it is preferable to set it as 2 hours-4 hours. If the heat treatment time is too short, crystal growth is insufficient and high emission intensity may not be obtained. On the other hand, if the heat treatment time is too long, it may melt, and if it is melted / sintered, strong pulverization is required. The pulverization may damage the crystal, and high luminescence intensity is obtained. It may not be possible.

<2-5. Fifth step (annealing step)>
Here, phosphor particles can be obtained by pulverizing the heat-treated product obtained by reducing and calcining the calcined powder as described above, and the phosphor thus obtained is Eu ^2+. Is reduced and doped at a rate close to 100%, and the resulting XRD pattern is also of BaZrSi ₃ O ₉ and emits blue light. However, the emission intensity in this state is extremely low. This is considered to be because oxygen deficiency causes self-absorption in the blue light-emitting region and absorbs excitation light and self-blue light emission. In general, ZrO ₂ is very susceptible to oxygen defects, and therefore it is difficult to suppress oxygen defects under a reducing atmosphere.

  Therefore, in the present embodiment, as the fifth step, the heat-treated product obtained by reduction firing in the fourth step described above is heat-treated (oxygen annealing) under a predetermined condition in an atmosphere containing oxygen. That is, the fifth step is an annealing step in which oxygen annealing is performed on the obtained heat-treated product.

  As described above, the phosphor after reduction firing obtained in the fourth step has large self-absorption due to oxygen defects and extremely low luminance. Therefore, by annealing the obtained heat-treated product in an atmosphere containing oxygen, oxygen defects can be filled and self-absorption based on the oxygen defects can be suppressed.

In a typical Eu ²⁺ activated phosphors, when high-temperature annealing in an atmosphere containing oxygen after reduction firing Eu ²⁺ is changed to Eu ³⁺ (oxidized) for emitting a hardly shown, the conventional Eu ²⁺ activated phosphors In the manufacturing process, such a high-temperature annealing process in an oxygen atmosphere is not performed. However, unlike a normal Eu ²⁺ activated phosphor, in BaZrSi ₃ O ₉ : Eu constituting the heat-treated product obtained by the reduction firing in the fourth step, the Ba site doped with Eu ²⁺ is SiO ₉ . It has a crystal structure surrounded by ZrO ₆ and is hardly affected by the external atmosphere. Therefore, even after annealing in an atmosphere containing oxygen and filling oxygen defects, Eu ²⁺ is not completely oxidized, and a state in which Eu ²⁺ and Eu ³⁺ exist together at a specific ratio is obtained. It is considered that the maximum emission intensity can be obtained.

As described above, in this embodiment, high-temperature annealing is performed on the heat-treated product after reduction firing in an atmosphere containing oxygen, thereby filling oxygen defects due to reduction and reducing self-absorption, and Eu ²⁺ and Eu ³⁺ are reduced. It is controlled to exist together at a specific ratio. As a result, it has been found that the BaZrSi ₃ O ₉ : Eu with extremely high emission intensity can be obtained, resulting in a very unusual emission behavior.

  In the fifth step, the heat treatment atmosphere may be in the presence of oxygen, and an oxygen-containing atmosphere can be obtained by circulating an oxygen gas of any concentration. The optimum oxygen concentration is not uniquely determined because it varies depending on the calcination conditions and reduction firing conditions of the precursor, that is, depending on the degree of oxygen defects. However, the heat treatment in the air provides a remarkable effect of improving the fluorescence luminance, and the apparatus and the like can be simplified. Therefore, the heat treatment in the air is an industrially advantageous annealing method. This does not limit the annealing process for recovering oxygen defects using an oxygen gas having an arbitrary concentration.

Also, the annealing temperature is not uniquely determined because it changes depending on the degree of oxygen defects and the oxygen concentration in the phosphor (heat-treated product). For example, in the treatment in the air, the annealing temperature is 500 ° C. to 1500 ° C. It is necessary that the temperature range be within the range of 800 ° C to 1300 ° C. When the annealing temperature is less than 500 ° C., Eu ²⁺ oxidation is suppressed, but sufficient oxygen defect recovery effect cannot be obtained. On the other hand, when annealing at a temperature exceeding 1500 ° C., a sufficient oxygen defect recovery effect is obtained, but Eu ²⁺ is excessively oxidized, and the sample is melted, so that a high light emission intensity cannot be obtained.

In this embodiment, the heat treatment product obtained in the fourth step is annealed in the temperature range of 800 ° C. to 1300 ° C. in an oxygen-containing atmosphere. Eu in the composition formula has both Eu ²⁺ and Eu ³⁺ , and a phosphor having a Eu ²⁺ ratio (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) in the total Eu is 10% to 90%. Can do. The phosphor thus obtained has an emission peak derived from the Eu ³⁺ ff transition in the red region of 610 to 630 nm in the emission spectrum.

  The blue light-emitting silicate phosphor manufactured in this way is efficiently excited by a near-ultraviolet LED, particularly a purple LED of around 400 nm mainly used as an excitation source, and changes in emission intensity due to changes in excitation wavelength are small. Therefore, the phosphor exhibits a stable and extremely high emission intensity and a high luminous efficiency.

  In addition, according to the manufacturing method as described above, a blue light-emitting silicate phosphor having high luminous efficiency can be manufactured inexpensively and easily without going through complicated manufacturing steps and without using special manufacturing equipment. Can do.

≪3. Examples >>
Hereinafter, the present invention will be described in detail with reference to examples. In addition, this invention is not limited to the following Example.

  In this example, fluorescence measurements of the phosphors prepared in each of the examples and comparative examples were performed using “F-4500 type spectrofluorometer” manufactured by Hitachi, Ltd., and the emission intensity and emission peak at a wavelength of 405 nm. The excitation spectrum at the wavelength was measured.

Further, the ratio of Eu ²⁺ to Eu ³⁺ (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) in the total Eu was evaluated by an X-ray absorption fine structure (XAFS). Specifically, the sample after 1400 ° C. reduction firing in Comparative Example 1 was used as the Eu ²⁺ standard sample, and Eu ₂ O ₃ (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.99) was used as the Eu ³⁺ standard sample. %) Was used. The measurement results were obtained by performing pattern fitting of the XANES spectrum of each sample from the data of the standard sample using analysis software (Athena) to obtain the ratio of Eu ^{2+ in} the sample.

[Example 1]
(Production of phosphor)
The charged composition is BaZrSi ₃ O ₉ : 0.09Eu + 0.3SiO ₂ , and BaCO ₃ (manufactured by Nippon Chemical Industry Co., Ltd., LSR), ZrO ₂ (first rare element chemical industry, UEP), Eu ₂ O ₃ ( A slurry was obtained by dispersing in a pure water. In addition, a water-soluble silicon compound was used as SiO ₂ among the starting materials. The water-soluble silicon compound is tetraethoxysilane (manufactured by Kanto Chemical Co., Inc.): 22.4 ml (0.1 mol), and 1,2-propanediol (manufactured by Kojundo Chemical Laboratory Co., Ltd.): 29. 3 ml (0.4 mol) was added and mixed for 24 hours with stirring using a hot stirrer so that the liquid temperature became 54 ° C., and then 0.1 ml of hydrochloric acid was added and the liquid temperature further increased to 54 ° C. It was prepared by mixing for 1 hour. Based on the charged composition, a predetermined amount of a water-soluble silicon compound was added to the slurry and mixed at room temperature to obtain a gel body (mixture) in which the raw materials were uniformly dispersed.

  Next, the obtained gel was dried at 100 ° C. for 12 hours and crushed to obtain a precursor.

  Next, the obtained precursor was put into an alumina crucible, and calcined in an air atmosphere at a temperature condition of 800 ° C. for 12 hours to obtain a calcined powder.

Next, the obtained calcined powder was put into an atmosphere furnace, and reduced and fired for 2 hours under a temperature condition of 1400 ° C. in a reducing atmosphere in which Ar-4% H ₂ was circulated in the furnace. Then, the obtained reduced fired product (heat treated product) was crushed.

  Next, the obtained heat-treated product was put in an alumina crucible and subjected to atmospheric annealing treatment at a temperature condition of 1200 ° C. for 1 hour. That is, the phosphor was annealed in an atmosphere containing oxygen to obtain a phosphor.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was subjected to XRD measurement. As a result, XRD diffraction showed a diffraction pattern of BaZrSi ₃ O ₉ described in ICDD (29-0214), and a weak SiO ₂ (cristobalite) phase was confirmed around 2θ = 22 degrees.

  FIG. 1 shows an excitation emission spectrum. The emission intensity was defined as 1 as the emission peak intensity when YAG: Ce (manufactured by Phosfertech) was excited at 455 nm. Furthermore, XAFS measurement was performed, and the valence state of Eu was evaluated by the XANES spectrum. FIG. 2 shows the XANES spectrum.

  As can be seen from the excitation emission spectrum shown in FIG. 1, the emission peak intensity shown in the emission spectrum was a very high luminance of about 3.5 in the YAG: Ce ratio. Further, it can be seen that the excitation spectrum is very stable at a wavelength of about 300 nm to 400 nm and shows a high excitation intensity without variation. From this, it can be seen that there is almost no change in the emission intensity due to the change in the excitation wavelength, and blue light emission with no variation is exhibited.

Further, as can be seen from the XANES spectrum shown in FIG. 2, Eu in the phosphor is in a state where Eu ²⁺ and Eu ³⁺ are mixed, and the ratio of Eu ^{2+ in} the total Eu obtained from the pattern fitting. (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) was 44%. FIG. 3 shows an enlarged view of the emission spectrum. It had an emission spectrum derived from Eu ^{3+ in} the red region of 610 to 630 nm.

[Example 2]
(Production of phosphor)
A phosphor was fabricated in the same manner as in Example 1 except that the atmospheric annealing treatment was performed at a temperature of 1000 ° C. for 1 hour.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
FIG. 1 shows the excitation emission spectrum, and FIG. 2 shows the XANES spectrum.

  As can be seen from the excitation emission spectrum shown in FIG. 1, the emission peak intensity shown in the emission spectrum was very high in luminance at about 3.3 YAG: Ce. Further, it can be seen that the excitation spectrum is very stable at a wavelength of about 300 nm to 400 nm and shows a high excitation intensity without variation. From this, it can be seen that there is almost no change in the emission intensity due to the change in the excitation wavelength, and blue light emission with no variation is exhibited.

Further, as can be seen from the XANES spectrum shown in FIG. 2, Eu in the phosphor is in a state where Eu ²⁺ and Eu ³⁺ are mixed, and the ratio of Eu ^{2+ in} the total Eu obtained from the pattern fitting. Was 49%. The obtained phosphor had an emission spectrum derived from Eu ^{3+ in} the red region of 610 to 630 nm, as in Example 1.

[Example 3]
(Production of phosphor)
A phosphor was fabricated in the same manner as in Example 1 except that the atmospheric annealing treatment was performed at a temperature of 800 ° C. for 1 hour.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was subjected to excitation emission spectrum measurement in the same manner as in Example 1. The emission peak intensity was as high as about 3.2 in the YAG: Ce ratio, and the excitation spectrum was very stable at a wavelength of about 300 nm to 400 nm and showed a high excitation intensity without variation. XANES spectrum measurement was performed in the same manner as in Example 1, and the Eu ²⁺ ratio (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) out of the total Eu obtained from pattern fitting was 72%. The obtained phosphor had an emission spectrum derived from Eu ^{3+ in} the red region of 610 to 630 nm, as in Example 1.

[Example 4]
(Production of phosphor)
The charged composition is BaZrSi ₃ O ₉ : 0.09Eu + 0.3SiO ₂ , and BaCO ₃ (manufactured by Nippon Chemical Industry Co., Ltd., LSR), ZrO ₂ (first rare element chemical industry, UEP), Eu ₂ O ₃ ( Co. Kojundo Chemical Laboratory Co., Ltd.), SiO 2 _(Admatechs Company Limited Co., and the high purity spherical silica SO-E1) dispersed in pure water to obtain a slurry. After drying the slurry, the cake was dried to obtain a precursor. Thereafter, the same operation as in Example 1 was performed to obtain a phosphor powder.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was subjected to excitation emission spectrum measurement in the same manner as in Example 1. The emission peak intensity was as high as about 3.4 in terms of YAG: Ce, and the excitation spectrum was very stable at a wavelength of about 300 nm to 400 nm and showed a high excitation intensity without variation. Performed XANES spectra measured in the same manner as in Example 1, the ratio of ^{Eu 2+} of the total Eu obtained from pattern fitting ^{(Eu 2+} / Eu 2+ + ^{Eu 3+)} was 56%. The obtained phosphor had an emission spectrum derived from Eu ^{3+ in} the red region of 610 to 630 nm, as in Example 1.

[Example 5]
(Production of phosphor)
The charging composition is BaZrSi ₃ O ₉ : 0.09Eu, 0.05La + 0.3SiO ₂ , and the starting materials are BaCO ₃ (manufactured by Nippon Chemical Industry Co., Ltd., LSR), ZrO ₂ (first rare element chemical industry, UEP), Eu. ₂ O ₃ (manufactured by High Purity Chemical Laboratory Co., Ltd.), La ₂ O ₃ (manufactured by High Purity Chemical Research Laboratory), SiO ₂ (manufactured by Admatechs Co., Ltd., high purity spherical silica SO-E1) is purified water Dispersed into a slurry. After drying the slurry, the cake was dried to obtain a precursor. Thereafter, the same operation as in Example 1 was performed to obtain a phosphor powder.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was subjected to excitation emission spectrum measurement in the same manner as in Example 1. The emission peak intensity was as high as about 3.6 in the YAG: Ce ratio, and the excitation spectrum was very stable at a wavelength of about 300 nm to 400 nm and showed a high excitation intensity without variation. Performed XANES spectra measured in the same manner as in Example 1, the ratio of ^{Eu 2+} of the total Eu obtained from pattern fitting ^{(Eu 2+} / Eu 2+ + ^{Eu 3+)} was 50%. The obtained phosphor had an emission spectrum derived from Eu ^{3+ in} the red region of 610 to 630 nm, as in Example 1.

[Comparative Example 1]
(Production of phosphor)
In Comparative Example 1, a phosphor was obtained in the same manner as in Example 1 except that the atmospheric annealing treatment was not performed. That is, in the same manner as in Example 1, the reduced calcined product (heat treated product) obtained by reducing and calcining the calcined powder was crushed to obtain a phosphor.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
When XRD measurement was performed on the obtained phosphor, the XRD diffraction showed the diffraction pattern of BaZrSi ₃ O ₉ described in ICDD (29-0214) as in Example 1, and further, around 2θ = 22 degrees. A weak SiO ₂ (cristobalite) phase was confirmed.

  On the other hand, when fluorescence measurement was performed, as shown in the excitation emission spectrum of FIG. 1, the emission peak intensity was extremely low, unchanged from YAG: Ce. Moreover, in the excitation spectrum, the variation (change) in excitation intensity was large over about 300 nm to 400 nm, and the excitation intensity was low.

Further, when XAFS measurement was performed, the Eu ²⁺ ratio was found to be almost 100% from the pattern fitting of the XANES spectrum shown in FIG. As described above, as a standard sample for the sample Eu ^2+, it was calculated Eu ²⁺ ratio of the sample of Example. FIG. 3 shows an enlarged view of the emission spectrum, but no emission spectrum derived from Eu ³⁺ that is clearly distinguishable from the measurement background was observed.

[Comparative Example 2]
(Production of phosphor)
In Comparative Example 2, the heat-treated product obtained by reduction firing was put in an alumina crucible and operated in the same manner as in Example 1 except that air annealing was performed at 400 ° C. for 1 hour. A phosphor was prepared.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was evaluated in the same manner as in Example 1, but the excitation emission spectrum and the XANES spectrum were not different from those in Comparative Example 1. This is probably because Eu ²⁺ was not oxidized because the atmospheric annealing was performed at a low temperature. As in Comparative Example 1, an emission spectrum derived from Eu ³⁺ that was clearly distinguishable from the measurement background was not observed.

[Comparative Example 3]
(Production of phosphor)
In Comparative Example 3, the heat-treated product obtained by reduction firing was put in an alumina crucible and operated in the same manner as in Example 1 except that it was subjected to atmospheric annealing treatment at 1550 ° C. for 1 hour. The body was made.

(Fluorescence measurement, Eu ²⁺ ratio evaluation)
The obtained phosphor was evaluated in the same manner as in Example 1, but the obtained phosphor was melted and did not show blue light emission derived from Eu ²⁺ .

That is, the blue light-emitting silicate phosphor according to the present invention has Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2) is a blue light emitting silicate phosphor, obtained by annealing Eu after doping as Eu ²⁺ by heat treatment in a reducing atmosphere , Eu contains both Eu ²⁺ and Eu ³⁺ and is characterized in that the ratio of Eu ²⁺ out of all Eu (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) is 10% to 90%.

Claims (6)

Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2) A blue-emitting silicate phosphor,
Eu in the composition formula contains both Eu ²⁺ and Eu ^3+, and the ratio of Eu ²⁺ out of all Eu (Eu ²⁺ / Eu ²⁺ + Eu ³⁺ ) is 10% to 90%. Blue light emitting silicate phosphor.   2. The blue-emitting silicate phosphor according to claim 1, wherein the blue-emitting silicate phosphor is element-substituted with at least one element selected from Mg, Ca, Sr, Ti, Hf, Sn, Ge, La, and Y. 3. 3. The blue-emitting silicate phosphor according to claim 1, wherein the emission spectrum has an emission peak derived from Eu ³⁺ . Ba _1-x Eu _x ZrSi _y O _{3 + 2y + δ} (where 0.001 ≦ x ≦ 0.5, 2.5 ≦ y ≦ 6.0, −0.1 ≦ δ ≦ 0.2) A blue light emitting silicate phosphor manufacturing method comprising:
A step of weighing each starting material containing the component represented by the above composition formula, and mixing and stirring each starting material in a solvent to obtain a mixture in which the component is uniformly dispersed;
Drying the mixture to form a precursor that is a dried product from which the solvent contained in the mixture has been removed;
Heat-treating the precursor at a temperature of 700 ° C. to 1400 ° C. in an air atmosphere to obtain calcined powder;
Heat treating the calcined powder at a temperature of 1100 ° C. to 1500 ° C. in a reducing atmosphere to dope Eu as Eu ²⁺ ;
And annealing the heat-treated product obtained by heat-treating the calcined powder in an oxygen-containing atmosphere at a temperature of 500 ° C. to 1500 ° C. A method for producing a blue-emitting silicate phosphor, comprising: The method for producing a blue-emitting silicate phosphor according to claim 4, wherein the SiO ₂ used as the starting material is a water-soluble silicon compound.   The part of the starting material is element-substituted with at least one element selected from Mg, Ca, Sr, Ti, Hf, Sn, Ge, La, and Y. A method for producing the blue-emitting silicate phosphor according to claim 5.

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