KR20210140935A - DC fluorescent particle, Method for preparing thereof and fluorescent ink including the same - Google Patents

Abstract

The present invention relates to down-conversion (DC) phosphor particles, and more specifically, to DC phosphor particles with excellent luminescent brightness and low preparing cost without losing a DC fluorescence characteristic due to phase change even at high temperatures, a method for preparing the same, and a fluorescent ink comprising the same. The present invention provides the method for preparing DC phosphor particles, comprising the following steps of (1) dissolving a host precursor mixture comprising titanium (Ti) and silicon (Si), respectively, and a dopant precursor mixture containing europium (Eu) and lithium (Li), respectively in a solvent to prepare a spray solution; (2) heating and inducing a reaction of the spray solution at a predetermined temperature and then drying the same to obtain precursor powder; and (3) heat-treating the precursor powder.

Description

Down-converted phosphor particles, a method for preparing the same, and a fluorescent ink comprising the same

The present invention relates to downconversion phosphor particles, and more particularly, to downconversion phosphor particles, characterized in that they do not lose DC fluorescence characteristics due to phase change even at high temperatures, have excellent luminance, and have a low manufacturing cost, a method for producing the same, and It relates to a fluorescent ink comprising the same.

A phosphor is a material that emits light corresponding to the energy difference when it receives external energy and is excited from the ground state of electrons to an excited state and then returns to the ground state.

Today, phosphors are used in various ways, such as light emitting diodes (LEDs), solar cells, photocatalysts, optical sensors, and semiconductors. According to the change of today's industrial technology, various products are produced, but the problem of the counterfeit product market has come to the fore. In the past, the counterfeit market was dominated by luxury bags and luxury clothing, but now a variety of so-called counterfeit products such as cosmetics, health food, and electronic devices are overflowing. To prevent this, a QR code was introduced into the product, but until recently, until the Board of Audit and Inspection, the QR code means that customs clearance has been completed legally, and the authenticity of the product is unclear, causing confusion among consumers. Therefore, there is a method of using a fluorescent pigment as a technology that can compensate for this.

In addition, a specific pattern and mark are made using a luminescent material, and a fluorescent pigment in a specific pattern is made to emit light in a specific pattern by Near Infrared Ray (NIR) or Ultraviolet (UV) light. As an example of such a method, it is possible to visually determine whether a bill is forged or not.

Rare-earth bases used for phosphor manufacturing are expensive materials compared to their weight. Therefore, there is an economic problem in mass production in the production of current anti-counterfeiting labels and marks. For this reason, it is necessary to develop a fluorescent pigment that can lead to mass production at a lower unit cost. Among the phosphor matrix, TiO ₂ is the most suitable material for the production of anti-counterfeiting products because it has abundant mineral reserves and is inexpensive and stable. Since the _{band gap of TiO 2} is 3.0 ~ 3.2 eV, which is relatively large compared to other parent materials, it absorbs light in the ultraviolet region and can be used in various fields such as solar cells, photocatalysts, and semiconductors. While TiO ₂ has these advantages, it also has fatal disadvantages for phosphor applications.

Depending on the firing temperature, it is largely divided into an anatase phase and a rutile phase. The anatase phase crystallizes in a narrow region of 400~470℃ and is used for phosphors and solar cells. It is not suitable as a phosphor due to change, so it is used as a white paint for paints, paints, inks, sunscreens, etc., and has limited phosphor application. Therefore, there is a need for research and development of DC phosphors that can improve thermal stability and luminance by maintaining anatase phase in phosphor applications.

Laid-Open Patent Publication No. 10-2007-0116590 (2007.12.10.)

The present invention has been devised to solve the above-mentioned problems, and the problem to be solved by the present invention is to produce down-converted phosphor particles with excellent luminance without losing fluorescence properties against high-temperature heat treatment while being able to manufacture at a low cost, and manufacturing the same It is to provide a method and a fluorescent ink comprising the same.

In order to solve the above problems, the present invention is (1) a host precursor mixture comprising titanium (Titanium, Ti) and silicon (Silicon, Si), respectively, europium (europium, Eu) and lithium (Lithium, Li) ) dissolving a dopant precursor mixture containing each in a solvent to prepare a spray solution; (2) heating and reacting the spray solution to a predetermined temperature and drying the spray solution to obtain a precursor powder; and (3) heat-treating the precursor powder.

According to a preferred embodiment of the present invention, step (2) may be performed by a spray pyrolysis method.

In addition, titanium may have a greater mole fraction than silicon in the spray solution.

In addition, the step (3) may be heat-treated at a temperature of 600 ℃ to 750 ℃.

In addition, in step (1), the mole fraction of silicon may be 2 mol% to 30 mol%.

In addition, the spray solution may include the europium and lithium in mole fractions of 2 to 18 mol% and 2 to 8 mol%, respectively.

In addition, the step (2) may be performed at a temperature of 700 ℃ to 1,100 ℃.

In addition, the present invention provides a down-conversion (DC) phosphor composition comprising a parent precursor mixture including titanium and silicon, respectively, and a dopant precursor mixture including europium and lithium, respectively.

According to a preferred embodiment of the present invention, silicon may be included to have a mole fraction of 2 to 30 mol%.

In addition, the present invention provides down-conversion (DC) phosphor particles prepared by reacting the above-described down-conversion (DC) phosphor composition, and comprising a compound represented by the following formula (1).

[Formula 1]

(Ti _1-xyz Si _x Eu _y Li _z )O ₂

In Formula 1, 0.02≤x+y+z≤0.5.

According to a preferred embodiment of the present invention, Chemical Formula 1 may satisfy at least one of the following conditions 1) to 3).

1) 0.02≤x≤0.3

2) 0.02≤y≤0.18

3) 0.02≤z≤0.08.

In addition, the present invention provides a fluorescent ink including the down-conversion (DC) phosphor particles described above.

The downconverted phosphor particles, the method for manufacturing the same, and the fluorescent ink including the same according to the present invention can be manufactured by a simple process and the manufacturing cost can be reduced. The phenomenon does not occur or can be minimized, and there is an effect of remarkably excellent light emission luminance.

Accordingly, it can be widely used in related fields such as a security ink material.

1 is a photograph of a bill applied with anti-counterfeiting ink.
2 is a diagram schematically illustrating down-conversion fluorescence and up-conversion fluorescence.
3 is a schematic diagram showing a method of manufacturing down-converted phosphor particles according to a preferred embodiment of the present invention.
4 is a band gap diagram of _{TiO 2 .}
5 is a PL spectrum according to Eu concentration of _{TiO 2} based DC phosphor particles not containing Si and Li.
6 is a graph showing emission intensity according to heat treatment temperature and Eu concentration of _{TiO 2} based DC phosphor particles not containing Si and Li.
7A is a PL spectrum according to the concentration of Eu and Li of DC phosphor particles.
7B is a graph showing the emission intensity according to the presence or absence of LI in DC phosphor particles.
8 is a graph showing emission intensity according to whether Si and Li are included in DC phosphor particles.
Figure 9a ~ Figure 9d are all TiO ₂ based DC phosphor particles, that do not contain Li TiO ₂ based DC phosphor particles, that do not contain Si TiO ₂ based DC phosphor particles and Si and Li that does not contain Si and Li, respectively It is a graph showing the change of the XRD pattern and crystallite size (D _c ) according to the heat treatment temperature of the TiO _{2 -based DC phosphor particles containing the particles.}

Before describing the present invention in detail, the meaning of the terms used herein is defined.

As used herein, the term “mol fraction” is defined as meaning the molar fraction between metal atoms positioned at the cation lattice site when the parent, activator, deactivator, and dopant constitute the phosphor particle.

Originally, silicon as a metalloid has both metallic and non-metallic properties, but in the present specification, silicon is regarded as a metal. Accordingly, the number of metal atoms for the calculation of the mole fraction includes the number of silicon atoms.

Hereinafter, the present invention will be described in more detail.

As described above, conventional phosphors are down-conversion (DC) phosphors or up-conversion phosphors, which have a high unit cost, such as using a rare earth metal as a matrix. There is a problem in that the fluorescence characteristic is lost or the luminance of light is lowered due to a phase transformation during heat treatment.

In order to solve this problem, the present invention (1) a host precursor mixture containing titanium (Titanium, Ti) and silicon (Si), respectively, europium (europium, Eu) and lithium (Lithium, Li) Preparing a spray solution by dissolving a dopant precursor mixture including each in a solvent, (2) heating and reacting the spray solution to a predetermined temperature and drying the spray solution to obtain a precursor powder It provides a method for producing down-conversion (DC) phosphor particles comprising the steps of obtaining and (3) heat-treating the precursor powder.

The down-conversion (DC) phosphor particles prepared according to the manufacturing method of the present invention include silicon in the metal cation lattice of the matrix, so that no phase change occurs even during high-temperature heat treatment, thereby maintaining excellent down-conversion fluorescence properties.

In particular, preferably, step (2) may be performed by a spray pyrolysis method. In the case of the spray pyrolysis process, an atmospheric pressure process is possible, and there is an advantage in that it can be manufactured in a simple process because it does not need to go through a milling process.

Hereinafter, each step will be described.

3 is a schematic diagram illustrating a method of manufacturing down-converted phosphor particles according to an embodiment of the present invention step by step.

Referring to Figure 3, the parent titanium precursor TTIP (Titanium (IV) isopropoxide, TiC ₁₂ H ₂₈ O ₄ ), the parent silicon Preparing a spray solution containing each of the precursor TEOS (Tetraethyl orthosilicate, SiC ₈ H ₂₀ O ₄ ) and dopant precursors Eu ₂ O ₃ and Li _{2 O;} reacting the spray solution through spray pyrolysis; and heat-treating (calcining) the precursor powder obtained by spray pyrolysis of the spray solution.

(Step 1

The downconversion phosphor particles of the present invention have a titanium dioxide (TiO ₂ ) compound as a parent, and a part of titanium is substituted with silicon (Ti, Si)O ₂ to form a parent. In order to provide a reaction process containing europium and lithium dopants serving as activators and deactivators in such a matrix, a spray solution containing them is first prepared.

The spray solution means that when the solution of the parent and dopant precursor mixture is heated and reacted, the solution is sprayed according to the spray pyrolysis reaction to perform the spray pyrolysis process in a droplet state. In the case of proceeding to a simple liquid phase reaction rather than a spray pyrolysis reaction, although the term “spray” is included, the spray solution is not sprayed. In the present invention, down-conversion phosphor particles cannot be necessarily prepared only by spray pyrolysis, but may also be prepared by a liquid-phase manufacturing method.

In the case of the liquid manufacturing method, the spray solution is heated to 40° C. to 50° C. to form particles by a sol-gel reaction, and the method is thermally decomposed.

The spray solution includes a mixture of the parent titanium precursor and the parent silicon precursor, and further includes a dopant precursor mixture. The dopant refers to a small amount of impurity metal that replaces a part of the metal cation lattice in the matrix, and includes an activator and a co-activator. Accordingly, the dopant precursor mixture includes an activator precursor and a deactivator precursor. The precursor mixture of the parent _{forms a (Ti, Si)O 2} lattice by subsequent thermal decomposition, thereby forming the matrix of the downconverted phosphor particles of the present invention.

The parent titanium precursor is preferably one or more selected from an alkoxide of titanium, titanium sulfate hydrate, TiCl ₄ , and TiO _{2 nanoparticles.} The alkoxide of titanium may be, for example, TTIP described above, but is not necessarily limited thereto, and is not necessarily limited to the alkoxide of titanium. A parent precursor may be selected from coordination compounds capable of stably providing titanium (IV).

The parent silicon precursor supplies Si cations to the titanium oxide matrix to replace a part of Ti with Si in the matrix, and the titanium oxide matrix in which Si is partially substituted has better stability to high temperature.

The parent silicon precursor may be one or more selected from TEOS and other TMOS (Tetramethyl orthosilicate), SiCl ₄ , and SiO ₂ nanoparticles, preferably TEOS, but is not necessarily limited thereto. Among the coordination compounds that can stably provide Si cations, the parent silicon precursor can be selected.

In addition to the parent titanium precursor and the parent silicon precursor, the spray solution also includes a dopant precursor. Among them, the activator precursor includes europium, and may preferably be europium oxide. An example of europium oxide is Eu ₂ O ₃ . The deactivator precursor comprises lithium and may preferably be lithium oxide. An example of lithium oxide is Li ₂ O.

The activator is substituted in the cation lattice site in the matrix like the silicon, receives energy from the parent metal and is excited, then falls to the ground state and emits energy, and determines the energy involved in the luminescence process. It affects the luminous color and luminous efficiency. In the present invention, europium ions (Eu ³⁺ ) serve as an activator.

In addition, the sub-activator is a material added together with the activator in order to improve the luminous efficiency of the phosphor particles. Like the activator, the sub-activator is excited by receiving energy and then falls to the ground state and transfers energy to the activator. In the present invention, lithium ions (Li ⁺ ) serve as a deactivator.

The step (1) preferably includes (1-1) preparing an active solution by dissolving an activator and a deactivator precursor in a solvent, and (1-2) adding the parent precursor mixture to the active solution to form a spray solution. It may be carried out as a method of preparing a spray solution by sequentially performing the steps of preparing a.

In step (1-1), the active solution may be prepared by dissolving the activator and the sub-activator precursor with an acid. For example, the active solution may be an aqueous solution in which an active agent and a de-active agent precursor are dissolved in nitric acid. However, the acid is not necessarily limited to nitric acid.

For example, when Eu ₂ O ₃ as an activator precursor and Li ₂ O as a deactivator precursor are used to prepare an aqueous solution by dissolving the activator precursor and the deactivator precursor in nitric acid, the reaction formulas are the following Reaction Schemes 1 and 2 same.

[Scheme 1]

Eu ₂ O ₃ + 6HNO ₃ → 2Eu(NO ₃ ) ₃ + 3H ₂ O

[Scheme 2]

Li ₂ O + 2HNO ₃ → 2LiNO ₃ + H ₂ O

Here, since the reactions according to Schemes 1 and 2 are both exothermic reactions, it is preferable to dissolve them while cooling by adding distilled water together.

Subsequently, in step (1-2), a spray solution may be prepared by further adding the parent precursor mixture and other additives to the active solution prepared in step (1-1) above. The spray solution may preferably be an aqueous solution in which the solvent is water.

The spray solution may have a greater mole fraction of titanium than silicon. Preferably the silicone may have a mole fraction of 2 mol % to 30 mol %. When the molar fraction of silicon is less than 2 mol%, the crystal phase of the parent undergoes a lot of phase change from anatase to rutile during the heat treatment process, thereby reducing luminance or losing luminescence properties. In addition, when the mole fraction of silicon exceeds 30 mol%, the crystallite size of the prepared downconverted phosphor particles decreases, which causes a decrease in luminance of light emission.

In addition, the mole fraction of the silicon may be more preferably 5 mol% to 20 mol%. When the molar fraction of the silicon dopant is 5 mol% to 20 mol%, down-converted phosphor particles having the most excellent luminescence luminance may be realized.

The spray solution may preferably have the largest mole fraction of titanium among metals. Therefore, the prepared down-converted phosphor particles basically have properties of titanium oxide.

The spray solution may preferably contain the active agent and the de-active agent in a molar fraction of 2 to 18 mol% and 2 to 8 mol%, respectively.

If the molar fraction of the active agent in the composition is less than 2 mol%, all of the energy transmitted by the deactivator is not received, so the luminescence brightness of the downconverted phosphor particles is lowered, and the molar fraction of the active agent is excessively higher than 18 mol% When it is high, there is a problem in that the luminance is lowered due to a concentration fading phenomenon due to non-luminescent energy transfer between the activators. In addition, if the molar fraction of the sub-active agent is low, less than 2 mol%, energy cannot be sufficiently transferred to the active agent and the luminance is lowered. There is a problem in that light emission luminance is lowered due to a phenomenon (non-luminous energy is transferred between sub-activators rather than transferred to the activator).

(2) step

The spray solution prepared as described above is a down-conversion phosphor particle composition, and may be prepared as down-conversion phosphor particles by heating and reacting to a predetermined temperature.

The predetermined temperature may be preferably 700 °C to 1,100 °C.

In addition, the step (2) may be preferably performed as a spray pyrolysis process, and in the case of spray pyrolysis, the reaction at normal pressure is possible and the milling process can be omitted. There are possible advantages.

In the case of the spray pyrolysis process, the step (2) includes the steps of (2-1) forming droplets by spraying the spray solution and (2-2) thermally decomposing and drying the droplets to form a precursor powder. This can be done sequentially.

This spray pyrolysis step may be performed using a spray pyrolysis device including a droplet generating unit that generates droplets using an ultrasonic vibrator, a kiln in which thermal decomposition occurs with high-temperature energy, and a collecting unit in which dried particles are collected.

Since the device is maintained at a high temperature in the pyrolysis process, it is preferable to continuously flow the cooling water around the vibrator of the droplet generator, and a flow rate of about 10 L/min to 50 L/min for smooth flow of the droplets generated in the droplet generator air can flow through

(3) step

After collecting the crystallized and dried precursor powder by the reaction of step (2), heat treatment may be performed to prepare downconverted phosphor particles.

The heat treatment may be performed at a temperature of 600 °C to 750 °C. Were heat-treatment temperature is the crystallite (crystallite) is the light emission luminance failure to sufficiently grow during the day is less than 600 ℃, contrast, if the heat treatment temperature exceeds 750 ℃, crystallite is grown to a sufficient size, however, the crystal structure of TiO ₂ is anatase (anatase ), there is a problem in that the rate of change from the rutile phase increases, so that the downconversion fluorescence characteristic decreases. Therefore, it has the most excellent light emission luminance within the above range.

Hereinafter, a down-conversion (DC) phosphor composition obtained according to the manufacturing method of the present invention and a down-conversion (DC) phosphor particle prepared therefrom will be described.

The downconversion phosphor composition according to the present invention includes the spray solution obtained in step (1) of the above production method.

That is, the downconversion phosphor composition according to the present invention may include a parent precursor mixture including titanium and silicon, respectively; and a dopant precursor mixture comprising europium and lithium, respectively. As described above, europium is substituted in the metal cation lattice of the matrix to act as an activator, and lithium acts as a deactivator.

Here, the types, roles and contents of the parent precursor, the activator precursor, the deactivator precursor, and the silicon dopant precursor are the same as those described above, and thus a description thereof will be omitted.

The downconversion phosphor particles according to the present invention are prepared by heating and drying the downconversion phosphor composition, as described above in the manufacturing method.

The downconversion phosphor particles according to the present invention include a compound represented by the following formula (1).

[Formula 1]

(Ti _1-xyz Si _x Eu _y Li _z )O ₂

In Formula 1, 0.02≤x+y+z≤0.5.

Accordingly, in the compound of Formula 1, Ti occupies the largest mole fraction in the cation lattice with a content of 0.5 or more, and thus, the downconversion phosphor particles according to the present invention have TiO ₂ crystal properties as described above.

In addition, in a preferred embodiment of the present invention, Chemical Formula 1 may satisfy at least one of the following conditions 1) to 3).

1) 0.02≤x≤0.3

2) 0.02≤y≤0.18

3) 0.02≤z≤0.08.

The above condition 1) relates to the content of the silicon dopant, and conditions 2) and 3) relate to the contents of the activator and the deactivator, respectively, and the effects thereof are the same as described above, and thus a detailed description thereof will be omitted.

In addition, according to a preferred embodiment of the present invention, the average crystallite size (Dc) of the downconverted phosphor particles may be 4.5 nm to 20 nm. When Dc is smaller than 4.5 nm, the emission luminance may decrease. When the crystallite size exceeds 20 nm, the emission luminance increases, but on the contrary, the emission luminance decreases because the rutile phase increases in the process of increasing the crystallite size. , the downconversion fluorescence property itself may be lost.

The crystallite size Dc may be calculated by the following Relation 1.

[Relational Expression 1]

In Relation 1, k is a Scherrer constant, its value is 0.9, λ is an X-ray wavelength of 0.1542 nm, β _s is a peak width at half maximum (FWHM) in an XRD spectrum, and θ is a central diffraction angle.

In addition, in the downconverted phosphor particles according to the present invention, the %Rutile obtained according to the following relation 2 in the crystal structure may be 15% or less.

[Relational Expression 2]

In Relation 2, A is the area of the peak having the highest point in the region where 2θ is 25.3±0.2˚ among the peaks shown in the XRD pattern of the downconversion phosphor particle, and R is the area of the peak shown in the XRD pattern of the downconversion phosphor particle. The area of the peak having the highest point in the region where 2θ is 27.4±0.2° among the peaks is indicated.

_{This indicates the degree to which the anatase phase of TiO 2} is changed to the rutile phase by heat in the heat treatment step during the manufacturing process of the downconversion phosphor particles, and the greater the %Rutile, the greater the degree of phase change.

When the %Rutile exceeds 15%, the downconversion fluorescence properties of the anatase phase may decrease, so that the luminance may not be sufficient to use the phosphor particles as a security ink.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments so that those skilled in the art can easily carry out the present invention. However, the scope of the present invention is not limited to the following examples, and the present invention may be embodied in various different forms, all of which are included in the scope of the present invention.

[Example]

<Example 1: Preparation of down-conversion phosphor particles>

(1) Preparation of spray solution

Eu ₂ O ₃ (Alfa Aesar, 99.9% _{purity) was selected as the activator precursor, and Li 2} O (Alfa Aesar, 99.9% purity) was selected as the deactivator precursor, and an active solution was prepared by dissolving each with nitric acid.

To prepare an active solution, _{25 g of Eu 2} O ₃ and 5 g of Li ₂ O were put in a 1,000 ml round Erlenmeyer flask _{each containing 50 ml of water (H 2} O), respectively, and then dissolved while slowly adding _{nitric acid (HNO 3 ).} . Distilled water is added little by little in the middle to prevent the heat generated during the melting process. For the amount of nitric acid, 10 times the number of moles compared to the number of moles _{of Eu 2} O ₃ or Li _{2 O was used.} When the oxide was completely dissolved into a transparent aqueous solution, more distilled water was added to make a total of 1,000 g, to prepare a 2.5 wt% Eu activator solution and 0.5 wt% Li subactivator solution.

A spray solution containing 80 mol% Ti, 10 mol% Si, 5 mol% Eu and 5 mol% Li in the parent composition was prepared as follows. To a 500 ml beaker containing 45 ml of 60% aqueous nitric acid solution and 300 ml of water _{, 47.29 g of TiO 2} precursor TTIP (Sigma Aldrich, purity 97%) was slowly added, followed by stirring until it became a clear solution. In another 500 ml beaker, 100 ml of water and 5 ml of nitric acid were put, and 3.95 g of a silicon precursor TEOS (Sigma Aldrich, purity 98%) solution was dissolved. After mixing the aqueous solution of TTIP and TEOS, the active solution was added. At this time, _{the weights of the Eu 2} O ₃ and Li ₂ O active solutions were 70.46 g and 74.79 g, respectively. Then, distilled water was added so that the total solution volume was 1,000 ml. The total concentration of the solution in which the phosphor precursor was dissolved was fixed at 0.2 M.

The prepared downconverted phosphor particles had _{a chemical formula of (Ti 1-xyz} Si _x Eu _y Li _z )O ₂ , where x was 0.1 and y and z were 0.05, respectively.

(2) Spray pyrolysis

The spray solution was subjected to spray pyrolysis using a spray pyrolysis device to obtain a precursor powder.

In a specific method, 200 ml of the spray solution is divided into each so as not to overflow the spray bottle, and air is flowed at a temperature of 900 ° C. at a flow rate of 30 L/min to spray and thermally decompose, thereby recovering the crystallized powder, that is, the precursor powder.

(3) heat treatment step

The obtained precursor powder was heat treated at 700° C. for 3 hours. During the heat treatment, air was flowed at a flow rate of 600 cc/min.

Down-conversion phosphor particles were obtained through heat treatment.

<Comparative Examples 1-1 to 7-3>

Downconversion phosphor particles as shown in Table 1 were prepared in the same manner as in Example 1, except that the mole fraction of Eu was changed and Si and Li were not included.

division (Ti _1-y Eu _y )O ₂ in y Heat treatment temperature (℃) Comparative Example 1-1 0.01 700 Comparative Example 1-2 0.01 600 Comparative Example 1-3 0.01 500 Comparative Example 2-1 0.03 700 Comparative Example 2-2 0.03 600 Comparative Example 2-3 0.03 500 Comparative Example 3-1 0.05 700 Comparative Example 3-2 0.05 600 Comparative Example 3-3 0.05 500 Comparative Example 4-1 0.07 700 Comparative Example 4-2 0.07 600 Comparative Example 4-3 0.07 500 Comparative Example 5-1 0.10 700 Comparative Example 5-2 0.10 600 Comparative Example 5-3 0.10 500 Comparative Example 6-1 0.13 700 Comparative Example 6-2 0.13 600 Comparative Example 6-3 0.13 500 Comparative Example 7-1 0.15 700 Comparative Example 7-2 0.15 600 Comparative Example 7-3 0.15 500

<Experimental Example 1: Evaluation of down-conversion luminescence properties according to Eu mole fraction and heat treatment temperature>

The down-conversion phosphor particles according to Comparative Examples 1-1 to 7-3 were irradiated with 403 nm UV light using a PL measuring device (Perkin Elmer, LS 55, fluorescence spectrometer) to prepare emission spectra. Conditions were performed in biolum mode with Slit 15, scan speed 1,200 nm/s, and the results are shown in FIG. 5 . Also, a graph showing the emission intensity at the wavelength showing the maximum intensity according to the temperature and the mole fraction of Eu is shown in FIG. 6 .

As a result, it can be seen that the emission intensity is excellent when the mole fraction range of 2 to 18 mol% of europium according to the present invention is satisfied as shown in FIG. 5, and referring to FIG. It was confirmed that the emission intensity was significantly reduced in a range outside the mole fraction range of 2 to 18 mol%.

<Comparative Examples 10 to 17>

The downconversion phosphor particles shown in Table 2 below were prepared in the same manner as in Example 1 except that Si was not included, the mole fraction of Eu was changed, and the mole fraction of Li was not included or the mole fraction of Li was changed.

division (Ti _1-y Eu _y Li _z )O ₂ in y (Ti _1-y Eu _y Li _z )O ₂ in z Comparative Example 10 0.01 0.01 Comparative Example 11 0.03 0.03 Comparative Example 12 0.05 0.05 Comparative Example 13 0.10 0.10 Comparative Example 14 0.01 0 Comparative Example 15 0.03 0 Comparative Example 16 0.05 0 Comparative Example 17 0.10 0

<Experimental Example 2: Evaluation of down-conversion emission characteristics according to the mole fraction of Eu and Li and whether or not Li is included>

The down-conversion phosphor particles according to Comparative Examples 10 to 17 were irradiated with 403 nm UV light using a PL measuring device (Perkin Elmer, LS 55, fluorescence spectrometer) to prepare emission spectra. Conditions were performed in biolum mode with Slit 15, scan speed 1,200 nm/s, and the results are shown in FIG. 7a. In addition, a graph showing the emission intensity at the wavelength showing the maximum intensity according to whether Li is included and the mole fraction of Eu is shown in FIG. 7B .

As a result, it can be seen that the emission intensity is excellent when simultaneously satisfying 2 to 18 mol%, which is the mole fraction range of europium, and 2 to 8 mol%, which is the mole fraction range for lithium, according to the present invention, as shown in FIG. 7a, FIG. 7b Referring to , it was confirmed that the emission intensity was excellent when lithium was included and the molar fraction range of europium was 2 to 18 mol%.

<Comparative Example 18>

Downconversion phosphor particles were prepared in the same manner as in Example 1, except that Li was not included.

<Experimental Example 3: Evaluation of down-conversion emission characteristics>

Using a PL measuring device (Perkin Elmer, LS 55, fluorescence spectrometer) to irradiate down-conversion phosphor particles according to Comparative Example 3-1, Comparative Example 18, Comparative Example 12, and Example 1 with 403 nm UV light to prepare an emission spectrum did. Conditions were performed in biolum mode with Slit 15, scan speed 1,200 nm/s, and a graph showing emission intensity at a wavelength showing maximum intensity according to heat treatment temperature is shown in FIG. 8 .

As a result, it was confirmed that Example 1, which satisfies all of the parent body and dopant configuration and heat treatment conditions according to the present invention as shown in FIG. 8, has remarkably excellent emission intensity.

<Comparative Examples 3-1-1, ~ 3-1-5>

The downconversion phosphor particles were prepared by changing the heat treatment temperature to 500°C, 600°C, 800°C, 900°C, and 1000°C, respectively, in the same manner as in Comparative Example 3-1.

<Comparative Examples 18-1 to 18-5>

It was carried out in the same manner as in Comparative Example 18, except that the heat treatment temperature was changed to 500°C, 600°C, 800°C, 900°C, and 1000°C to prepare downconverted phosphor particles.

<Comparative Examples 12-1 to 12-5>

It was carried out in the same manner as in Comparative Example 12, except that the heat treatment temperature was changed to 500°C, 600°C, 800°C, 900°C, and 1000°C to prepare downconverted phosphor particles.

<Examples 1-1 to 1-5>

The downconversion phosphor particles were prepared in the same manner as in Example 1, except that the heat treatment temperature was changed to 500°C, 600°C, 800°C, 900°C, and 1000°C, respectively.

<Experimental Example 4>

Comparative Examples 3-1, 3-1-1 to 3-1-5, Comparative Examples 18, 18-1 to 18-5, Comparative Examples 12, 12-1 to 12-5, Examples 1 and 1-1 to The down-conversion phosphor particles according to 1-5 were checked for crystal phase, crystallite size (Dc) and %Rutile using an X-ray diffractometer (MiniFlex 300/600). The results are shown in FIGS. 9a to 9d, respectively.

Referring to FIG. 9 , it can be seen that the size of crystallites increases significantly from 800° C., but the crystal structure of the rutile phase appears. Therefore, it can be seen that the down-conversion fluorescence properties of the anatase phase are virtually lost when heat-treated at a temperature of 750° C. or higher.

In addition, it was found that when the heat treatment temperature was over 750° C., the pattern of the anatase phase was blurred, and when the heat treatment temperature was 1000° C. or higher, the pattern was different from that of the anatase phase. Therefore, it was found that heat treatment at a temperature of 750° C. or less was desirable, and when the temperature was excessively low, it was evaluated that the crystallite size was too small to exhibit good fluorescence properties.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention can add components within the scope of the same spirit. , changes, deletions, additions, etc. may easily suggest other embodiments, but this will also fall within the scope of the present invention.

Claims (12)

(1) A host precursor mixture containing titanium (Titanium, Ti) and silicon (Si), respectively, and a dopant precursor mixture containing europium (Europium, Eu) and lithium (Lithium, Li), respectively Dissolving in a solvent to prepare a spray solution (spray solution);
(2) heating and reacting the spray solution to a predetermined temperature and drying the spray solution to obtain a precursor powder; and
(3) heat-treating the precursor powder; down-conversion (DC) phosphor particle manufacturing method comprising a. According to claim 1,
The step (2) is a method for producing down-conversion (DC) phosphor particles, characterized in that performed by a spray pyrolysis method. According to claim 1,
A method for producing down-conversion (DC) phosphor particles, characterized in that titanium has a greater molar fraction than silicon in the spray solution. According to claim 1,
In the step (3), a down-conversion (DC) phosphor particle manufacturing method, characterized in that heat treatment at a temperature of 600°C to 750°C. According to claim 1,
In step (1), the mole fraction of silicon is 2 mol% to 30 mol% Down-conversion (DC) phosphor particle manufacturing method, characterized in that. According to claim 1,
The method for producing down-conversion (DC) phosphor particles, characterized in that the spray solution contains the europium and lithium in mole fractions of 2 to 18 mol% and 2 to 8 mol%, respectively. According to claim 1,
The (2) step is a down-conversion (DC) phosphor particle manufacturing method, characterized in that performed at a temperature of 700 ℃ to 1,100 ℃. A downconversion (DC) phosphor composition comprising a parent precursor mixture comprising titanium and silicon, respectively, and a dopant precursor mixture comprising europium and lithium, respectively. 9. The method of claim 8,
A down-conversion (DC) phosphor composition comprising silicon to have a mole fraction of 2 to 30 mol%. It is prepared by reacting the down-conversion (DC) phosphor composition according to claim 8,
Down-conversion (DC) phosphor particles comprising a compound represented by the following formula (1):
[Formula 1]
(Ti _1-xyz Si _x Eu _y Li _z )O ₂
In Formula 1, 0.02≤x+y+z≤0.5. 11. The method of claim 10,
Formula 1 is a down-conversion (DC) phosphor particle, characterized in that it satisfies at least one of the following conditions 1) to 3):
1) 0.02≤x≤0.3
2) 0.02≤y≤0.18
3) 0.02≤z≤0.08. A fluorescent ink comprising the down-conversion (DC) phosphor particles according to claim 10 .

Images