WO2019087814A1

WO2019087814A1 - Fluorescent body

Info

Publication number: WO2019087814A1
Application number: PCT/JP2018/038964
Authority: WO
Inventors: 大長　久芳
Original assignee: 株式会社小糸製作所
Priority date: 2017-11-02
Filing date: 2018-10-19
Publication date: 2019-05-09
Also published as: JPWO2019087814A1

Abstract

This fluorescent body is a fluorescent body which comprises a single phase and has a perovskite crystal structure having a light-emitting site represented by ABX3 (A, B are cations, and X is an anion), and in which a light-emitting element is located at a B site that is the body center of the perovskite crystal structure. The fluorescent body has: a light-emitting site ABX3; and a light-emitting site (AA')BX3 in which a part of the cation A of the light-emitting site ABX3 is substituted with a cation A' having a smaller ionic radius than the cation A.

Description

Phosphor

The present invention relates to a phosphor.

In recent years, white light emitting diodes (LEDs) have become widespread as alternative light sources for phosphors and incandescent bulbs. Also in such a white LED, high color rendering property close to natural light is required as in the conventional light source. At present, mainstream white LEDs are generally a combination of a blue light emitting semiconductor light emitting element and a yellow phosphor.

However, it is difficult to realize high color rendering because pseudo white obtained by combining blue light and yellow light is insufficient in red component. Therefore, a phosphor having MgAl ₂ Si ₄ O ₆ N ₄ as a main phase having a very wide emission wavelength range ranging from the blue wavelength range to the red wavelength range has been devised (see Patent Document 1).

JP 2008-50462 A

The above-described phosphor is added with a plurality of elements (eg, Eu ²⁺ and Mn ²⁺ ) as activators. Therefore, when this phosphor is irradiated with ultraviolet light, the light is absorbed by Eu ²⁺ to emit blue-green light with a wavelength of 450 to 520 nm, and Mn ²⁺ absorbs a part of the energy of excited Eu ²⁺ Emits orange-red light with a wavelength of 590 to 660 nm. As a result, light of two colors emitted from one kind of phosphor is added to obtain white light.

On the other hand, while the emission lifetime of Eu ²⁺ as an activator is about 1 μs, the emission lifetime of Mn ²⁺ is about 1 ms, so the luminance saturation of Mn ²⁺ occurs with the increase of the excitation light density, and the emission color Sometimes shifts blue.

The present invention has been made in view of these circumstances, and an object thereof is to provide a novel phosphor.

In order to solve the above problems, the phosphor according to an embodiment of the present invention has a perovskite crystal structure in which a light emitting site is represented by ABX ₃ (A and B are cations and X is an anion), and a body of the perovskite crystal structure A single-phase phosphor in which the light emitting element is located at the central B site, and a part of the cation A of the light emission site ABX ₃ and the light emission site ABX ₃ has a smaller ion radius than the cation A. And a luminescent site (AA ') BX ₃ substituted with

According to this aspect, a plurality of light emissions with different peak wavelengths can be realized.

The ionic radius I _A of the cation located at the A site of the perovskite crystal structure is 15% or more larger than the ionic radius I _{B of the} cation located at the B site.

The cation A may be K ⁺ and the cation A ′ may be Na ⁺ or Li ⁺ .

The cation B may be one or more cations selected from the group consisting of Eu ²⁺ , Ce ³⁺ , Sm ²⁺ and Yb ²⁺ . This facilitates 4f-5d transition.

Another aspect of the present invention is also a phosphor. This phosphor has a perovskite crystal structure in which the light emission site is represented by ABX3 (A and B are cations and X is an anion), and the light emitting element is located at the B site which is the body center of the perovskite crystal structure A phosphor consisting of phases, the emission spectrum having a first peak in the violet to green wavelength range and a second peak in the yellow to red wavelength range.

According to this aspect, white light can be realized by light of a plurality of colors emitted by one kind of phosphor.

Arbitrary combinations of the above-described components, conversions of the expression of the present invention among manufacturing methods, devices such as lamps and lights, light emitting modules, light sources and the like are also effective as aspects of the present invention.

According to the present invention, novel phosphors can be provided.

It is a figure for demonstrating the mechanism of excitation and light emission according to the state of a crystal | crystallization. It is a figure which shows an example of the excitation spectrum and emission spectrum of general red fluorescent substance which make a nitride the base. It is a schematic diagram for demonstrating a Stokes shift. It is a schematic diagram which shows coordination coordinates. It is a figure which shows a perovskite crystal structure. FIG. 6 (a) is a view schematically showing a six-coordinate BX ₆ octahedron, and FIG. 6 (b) is a view for explaining the energy state of the 5d orbital in six-coordinate. It is the figure which showed typically the breadth of the divided | segmented track | orbit. It is a figure which shows the X-ray-diffraction pattern of the fluorescent substance which concerns on a reference example. It is a figure which shows the result of the resonance spectrum measured without decoupling. It is a figure which shows the result of the resonance spectrum which canceled and measured the interaction of PF. It is a figure which shows the result of ³¹ P { ¹⁹ F} CP-CPMAS measurement. It is a schematic diagram which shows the crystal structure of the fluorescent substance which concerns on this Embodiment. It is a figure for demonstrating the crystal structure which a luminescent site has. It is the schematic diagram which looked at the crystal structure of the fluorescent substance shown in FIG. 12 from another direction. It is a figure which shows the light emission site of the perovskite crystal structure which concerns on this Embodiment. It is the schematic diagram which looked at the unit cell of the fluorescent substance which concerns on this Embodiment from an a-axis. It is the schematic diagram which looked at the unit cell of the fluorescent substance which concerns on this Embodiment from b axis. It is the schematic diagram which looked at the unit cell of the fluorescent substance which concerns on this Embodiment from c axis. It is a figure which shows the excitation spectrum and emission spectrum of fluorescent substance which concern on a reference example. It is a figure which shows the temperature characteristic of fluorescent substance light emission which concerns on a reference example. It is a schematic diagram illustrating the spread of the electron cloud in the octahedral _EuO 4 _{F 2.} It is a figure which shows the emission spectrum at the time of irradiating the ultraviolet-ray of high energy to the fluorescent substance which concerns on a reference example. It is a figure which shows the diffuse reflection spectrum of the fluorescent substance which concerns on a reference example. FIG. 24A is a perspective view schematically showing the light emitting site (AA ′) BX ₃ , and FIG. 24B is a side view schematically showing the light emitting site (AA ′) BX ₃ . FIG. 2 is a view showing an X-ray diffraction pattern of a phosphor according to Example 1; FIG. 2 is a view showing an excitation spectrum and an emission spectrum of a phosphor according to Example 1. FIG. 6 is a view showing an X-ray diffraction pattern of a phosphor according to Example 2. FIG. 6 is a diagram showing an excitation spectrum and an emission spectrum of a phosphor according to Example 2. FIG. 29 (a) schematically shows an energy diagram in which only potassium ion is coordinated to A site, and FIG. 29 (b) shows only potassium ion and sodium ion (lithium ion) coordinated to A site FIG. 6 schematically shows an energy diagram of FIG.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and duplicating descriptions will be omitted as appropriate. In addition, the embodiments do not limit the invention and are merely examples, and all the features and combinations thereof described in the embodiments are not necessarily essential to the invention.

The phosphor according to the present embodiment is a phosphor that is efficiently excited and emits light with ultraviolet light or short wavelength visible light. Specifically, it shows strong excitation with near-ultraviolet light or short-wavelength visible light of 420 nm or less, and the second emission spectrum has a first peak in the violet to green wavelength range and a second peak in the yellow to red wavelength range. And a peak of In addition, the phosphor according to the present embodiment realizes light emission by doping a host crystal of a halo oxide with an activator such as Eu ²⁺ ion.

The phosphor according to the present embodiment is a phosphor that emits light in a wavelength range of at least yellow to red, which has a large Stokes shift (approximately 0.8 to 1.2 eV). Therefore, it is difficult to absorb visible light emitted from other phosphors such as blue, green and yellow. The Stokes shift refers to the energy difference between the excitation end wavelength and the peak wavelength of the emission spectrum. Here, the excitation end wavelength indicates a wavelength at which the decrease in excitation intensity on the long wavelength side in the excitation spectrum starts to decrease sharply.

First, the process of achieving the present invention will be described. A phosphor corresponding to light of a semiconductor light emitting device having a high excitation light density requires a fast excitation-emission cycle (short emission life). For that purpose, 4f-5d allowable transition which can make transition while maintaining the electron spin state is preferable.

The elements capable of 4f-5d transition include rare earth elements of Eu ²⁺ , Ce ³⁺ , Sm ²⁺ , Yb ^{2+ and} the like. The outer shell orbit of those rare earth elements is 6s, and the inner shell has a 4f orbit. In the 4f-5d transition, an electron in the 4f orbital forms an excited state by transitioning to the 5d orbital located in the outer shell. At this time, the larger the spread of the electron cloud in the 5d orbit, the lower the energy level of this orbit, and the higher the transition probability. That is, to efficiently absorb the light of the semiconductor light emitting element, it is necessary to lower the energy level of the 5d orbit. To that end, it is desirable to increase the crystal field splitting of the luminescent site.

FIG. 1 is a diagram for explaining the mechanism of excitation and light emission depending on the state of the crystal. Excitation with low energy requires complex (or distorted low symmetry) light emitting site structure or covalent bonding.

For example, the 4f-5d transition with free ions requires an energy of 4.0 eV or more. In that case, no transition occurs in the light of the semiconductor light emitting element that emits near ultraviolet light having a wavelength of about 380 to 450 nm or visible light with a short wavelength. Therefore, to lower the 4f-5d transition energy, it is effective to dope the crystal and coordinate anions around rare earth ions. The 5d orbital is reduced in energy by two actions (center of gravity shift E _c , crystal field splitting E _cfs ) by coordination of anions.

The center-of-gravity shift E _c is the coordination of the anion to the rare earth element (cation), and due to the influence of the surrounding negative charge, the energy of all the 5 d orbitals is reduced. The effect is small when the anion to be coordinated is ionically bound and increases as the covalentity increases.

In the case of ionic bonding, valence electrons contributing to bonding are distributed on the anion side. Electrons excited in the 5d orbital have large electrical repulsion with anions of negative charge, and the spread of the electron cloud in the 5d orbital (reduction of transition energy level) becomes limited.

In the case of covalent bonding, the valence electrons contributing to the binding are shared by the anion and the cation. The negative charge of the covalent anion is less than the negative charge of the ionic bond. Therefore, the electrostatic repulsion of the electrons excited in the 5d orbital is reduced, and the electron cloud in the 5d orbital spreads widely, resulting in an effective decrease in transition energy. In other words, it can be understood that it is important to increase the covalent bond in order to increase the center-of-gravity shift.

The crystal field splitting E _cfs is that the degeneracy of five 5d orbitals is resolved by the steric structure in which the anion is coordinated to the rare earth element (cation), and the energy level (orbital level) of the 5d orbital is split. The 5d orbital that spreads in the direction in which the occupancy density of the anion is low (the direction in which the anion is not present) has small electrostatic repulsion with the anion, and the electron cloud of the 5d orbital tends to spread (the energy level becomes low). On the other hand, in the direction in which the occupancy density of the anions is high (the direction in which the anions are coordinated), the electrostatic repulsion becomes large and the energy level becomes high. Light emission occurs at the transition from the energy level to the ground state after the nonradiative transition from the high energy level 5d orbit to the low energy level 5d orbit. Therefore, a specific transition (emission color) occurs from one emission site, and the emission color of the 4f-5d transition phosphor is often monochromatic. In addition, a distorted ligand field is required to largely split the degeneracy of the 5d orbital.

FIG. 2 is a diagram showing an example of an excitation spectrum and an emission spectrum of a general red phosphor based on nitride. A red phosphor that has become widespread in recent years is a phosphor based on nitrides such as CaAlSiN ₃ : Eu and Ca ₂ Si ₅ N ₈ : Eu. Since these phosphors increase the barycentric shift by enhancing the covalent bonding property, as shown in FIG. 2, the excitation band (excitation spectrum) is extended to the long wavelength side, and only the light in the ultraviolet region is It also absorbs blue, green and yellow visible light.

FIG. 3 is a schematic view for explaining the Stokes shift. Stokes shift is caused by relaxation of the crystal structure in the excited state. When the fluorophore is excited from the ground state 4f to the excited state 5d, the excited electron orbitals approach the coordinating anion. At this time, due to electrostatic repulsion, positions of light (small atomic weight) anions are shifted as compared to cations (rare earth elements). However, because there are other cations originally present around the anion, it will move to the equilibrium position. Such an anion transfer makes the crystal structure of the excited state different from that of the ground state. After the crystal structure change (relaxation 1) in this excited state occurs, the state returns to the ground state, and light emission occurs accordingly.

As shown in FIG. 3, the light emitting element which is a cation is excited from the ground state to be in the excited state, and emits light after the crystal structure change (relaxation) in the excited state. At this time, the energy state changes. This change is generally expressed in coordination coordinates. FIG. 4 is a schematic view showing coordination coordinates. The ordinate of the coordination coordinate indicates the energy level of the valence electron of the light emitting element, and the abscissa indicates the displacement between the light emitting element and the anion at which the energy level decreases most in the ground state of the crystal.

At the moment when 4f electrons of the light emitting element absorb the excitation light, the energy level rises and becomes an excited state. In the excited state, relaxation occurs to eliminate electrostatic repulsion with the coordination anion, and the energy level drops to the equilibrium state. Since the issuance starts from that point, a transition of energy smaller than the excitation energy, a long wavelength shift, occurs. At this time, it is phonon oscillation that must be taken into consideration. The greater the displacement, the greater the phonon vibration. In that case, the energy level of the system rises. In addition, when the temperature rises and becomes equal to the vibration level of the ground state due to phonon vibration in the excited state, non-radiative transition occurs. In general, when the Stokes shift becomes large, there is a concern that the temperature characteristic is lowered.

The present inventors have considered the possibility of a phosphor having a new crystal structure that increases the Stokes shift, based on the above findings and considerations.

The excitation / emission of the phosphor is caused by electron orbital transition in the luminescent center element. Therefore, as a phosphor in a high luminance light source such as a white LED, a light emitting element (for example, Eu ²⁺ or Ce ³⁺ ) having 4f-5d transition with high transition speed is desirable. In the excitation of the 4f-5d transition, electrons in the 4f orbital in the inner shell of the 6s orbital absorb excitation energy and transition to the 5d orbital spreading in the outer shell of the 6s orbital. Light emission occurs from the 5d orbit back to the 4f orbit. Therefore, in order to show a large Stokes shift, it is important that the spread of the 5d orbit in the excited state is large. The spread of the 5d orbital is determined by the crystal structure around the light emitting element. Therefore, the inventors of the present invention have devised a crystal structure that increases the spread of the 5d orbital.

First, attention was focused on the perovskite crystal structure as one of the crystal structures of the phosphor according to the present embodiment. FIG. 5 is a view showing a perovskite crystal structure.

The perovskite crystal represented by the composition formula ABX ₃ ideally has a cubic system unit cell, metal A at each vertex (A site) of the cubic crystal, and metal B at the body center site (B site) However, the anion X is arrange | positioned at each face-centered site (X site) of a cubic crystal. In addition, six anions X are coordinated to the metal B to form a BX ₆ octahedron. In addition, in the light emitting site according to the present embodiment, a light emitting element having a 4f-5d transition is located at the B site. As described above, the phosphor according to the present embodiment is a novel phosphor having a perovskite crystal structure as the light emitting site.

The anion X forming the BX ₆ octahedron may be composed of two or more types of anions. Specifically, one of the anions X is oxygen. Another type of anion X is halogen. Among the halogens, fluorine is particularly preferred. In another form, another anion X other than oxygen may be nitrogen.

The A site according to the present embodiment is occupied by a monovalent or divalent cation having a large ionic radius. The ionic radius I _A of the cation located at the A site is larger than the ionic radius I _B of the light emitting element located at the B site. In addition, the ion radius I _A may be 10% or more larger than the ion radius I _B , and preferably 15% or more. The cation occupying the A site may be a monovalent cation, a divalent cation, or both. The phosphor according to the present embodiment configured in this way can be excited at low energy, and the Stokes shift is also large.

FIG. 6 (a) is a view schematically showing a six-coordinate BX ₆ octahedron, and FIG. 6 (b) is a view for explaining the energy state of the 5d orbital in six-coordinate. In the mechanism of low energy excitation, it is preferable to have a mixed ligand (multiple ligands) that reduces the symmetry of the aforementioned six-coordinated BX ₆ octahedron. The general perovskite structure is represented by ABO ₃ , and six oxygen ions are coordinated to the B site. Therefore, the B site has strong ionic bondability, high symmetry, and less distortion of the ligand field. Therefore, excitation is difficult with small energy such as light of the wavelength (380 to 450 nm) of a semiconductor light emitting element used for a white LED.

Therefore, in the phosphor according to the present embodiment, two or more types of anions X are coordinated to the B site of the light emitting site to make the electron density involved in the binding of BX ₆ octahedron nonuniform. As a result, crystal field splitting becomes large, and the excitation band falls to the energy level excited by light emission (low energy) of the semiconductor light emitting device used for the white LED. Degeneracy of this time 5d orbit, since spread to avoid electrostatic repulsion between the anions X in the axial direction, the energy level of t _{2 g} orbit than e _g orbitals decreases. Among the t _2g orbitals, the energy level in the d _xz and d _yz directions is low, where the density of anions X is low.

FIG. 7 is a view schematically showing the spread of the split orbit. As shown in FIG. 7, the split d _xz and d _yz orbitals spread in the direction of the A site located at each vertex of the cubic crystal. The cation at the A site is charged to a positive charge. Electrons in d _xz and d _yz orbitals that have spread from the B site are attracted to the A site (the cation at the A site is not attracted by electrostatic attraction because the ion radius is large and the mass is large).

The energy level of the d _xz and d _yz orbits decreases in the excited state because the electron cloud in the d _xz and d _yz orbits is greatly spread by electrostatic attraction. Therefore, the Stokes shift becomes large. The relaxation of the normal excited state is considered to occur as the coordination position of the anion is changed by the electrostatic repulsive force of the 5 d electron and the anion, and the structure of the ligand field is largely changed. On the other hand, since the crystal structure of the present invention spreads the 5d orbital by the electrostatic attraction of 5d electrons and cations, the structural change of the ligand field is small. This is because the atomic weight of the cation is large and heavy, so it is difficult to move. Therefore, the phosphor according to the present embodiment exhibits stable temperature characteristics despite the large Stokes shift.

A first phosphor (for example, a red phosphor) according to the present embodiment and a second phosphor (for example, a blue phosphor, a green phosphor, a yellow fluorescence) emitting fluorescence of a color different from that of the first phosphor A light emitting module provided with a body, an orange phosphor and the like, and a semiconductor light emitting element that emits light for exciting the first phosphor and the second phosphor exhibits the following effects.

First, since the absorption of the first phosphor according to the present embodiment is scarcely in the wavelength range longer than the emission wavelength of the semiconductor light emitting device, the color is mixed when mixed with the second phosphor of another emission color. It becomes difficult to cause a gap. Second, the first phosphor according to the present embodiment does not cause relaxation of the excited state due to the movement of anions, so there is little change in the crystal structure due to excitation, and the temperature characteristics are large despite the large Stokes shift. It becomes good.

(Reference example)
First, a perovskite crystal structure, which is a basic structure of the phosphor according to the present embodiment, will be described using a reference example. In the phosphor according to the reference example, the elements constituting the crystal structure ABX ₃ of the light-emitting site, the cation A is ^{K +,} cations B is ^{Eu 2+,} anion X is ^{O 2-} and F ^- a. In addition to Eu ²⁺ , Ce ³⁺ , Sm ²⁺ , Yb ²⁺ or the like may be added as cation B. This facilitates 4f-5d transition. Further, a cation M constituting tetrahedral MO ₄ which connects the perovskite structures of the light emitting site is P ⁵⁺ . M may be a trivalent to pentavalent metal element.

The phosphor according to the reference example is manufactured by the following method. First, KF, K ₂ CO ₃ powder is dried at 150 ° C. for 2 hours. Then, in a glove box filled with dry N ₂ , KF, K ₂ CO ₃ , CaHPO ₄ , (NH ₃ ) ₂ HPO ₄ , and Eu ₂ O ₃ have a stoichiometric ratio of 1.000: 0.500: 0. The mixture was precisely weighed to a ratio of 990: 0.010: 0.0050 (mol), and ground and mixed in an alumina mortar to obtain a raw material mixed powder. The raw material mixed powder was placed in an alumina crucible and fired at 1000 ° C. for 6 hours to obtain a fired powder. The atmosphere at the time of firing is a mixed gas atmosphere of N ₂ / H ₂ = 95/5. Then, the obtained fired powder was washed with pure water to obtain a phosphor according to a reference example.

[X-ray diffraction pattern]
Next, X-ray diffraction measurement will be described. First, using a powder X-ray diffractometer (RINT Ultima III: manufactured by Rigaku), using powder X-ray tube emitting Kα rays of Cu, powder X-ray powder under conditions of sampling width 0.01 ° and scan speed 0.05 ° / min. Diffraction measurements were made. FIG. 8 is a view showing an X-ray diffraction pattern of a phosphor according to a reference example.

As shown in FIG. 8, at least a part of the crystal contained in the phosphor according to the reference example has a diffraction angle 2θ of 31.0 ° to 33.0 in an X-ray diffraction pattern using a Kα characteristic X-ray of Cu. When the first diffraction peak P1, the second diffraction peak P2 and the third diffraction peak P3 exist in the range of °, and the diffraction intensity of the highest first diffraction peak P1 is 100, the second diffraction peak P2 and The diffraction intensity of the third diffraction peak P3 is 30 to 50. Further, it has a fourth diffraction peak P4 whose diffraction intensity is 15 to 25 in the range of the diffraction angle 2θ of 27.0 ° to 29.0 °. Further, the fifth diffraction peak P5 having a diffraction intensity of 15 to 25 is in the range of the diffraction angle 2θ of 41.0 ° to 43.0 °. In addition, the sixth diffraction peak P6 having a diffraction intensity of 10 to 15 is provided in the range of the diffraction angle 2θ of 29.0 ° to 31.0 °. In addition, the seventh diffraction peak P7 having a diffraction intensity of 10 to 15 is provided in the range of the diffraction angle 2θ of 36.0 ° to 39.0 °. Further, the eighth diffraction peak P8 having a diffraction intensity of 5 to 10 is provided in the range of the diffraction angle 2θ of 13.0 ° to 15.0 °.

In addition, with respect to the powder sample of the phosphor according to the reference example, the crystal system of the phosphor according to the present embodiment, the brabe based on the data processing software (Rapid Auto: manufactured by Rigaku) from the X-ray diffraction pattern obtained by The lattices, space groups, and lattice constants were determined as follows.
Crystal system: Monoclinic Brave lattice: Simple lattice space group: P2 ₁ / m
Lattice constant:
a = 7.3161 (4) Å
b = 5.8560 (6) Å
c = 12.6434 (1) Å
α = γ = 90 °
β = 90.3200 °
V = 541.673782 Å ³

Thereafter, atomic coordinates were determined using crystal structure analysis software. As a result of the above analysis, it was found that the above-mentioned crystal is a crystal of a novel structure not registered in ICDD (International Center for Diffraction Date), which is an X-ray diffraction database widely used for X-ray diffraction.

The phosphor of the reference example contains oxygen and fluorine in the anion. Oxygen and fluorine are elements adjacent to each other in the periodic table, and it is difficult to specify the occupied position only from the data of X-ray diffraction.

Then, in order to grasp the occupied position of F, solid-state NMR measurement of the sample concerning a reference example was performed. In solid-state NMR, the coupling state of an element having a spin quantum number of 1/2 can be grasped, and the coupling relation between ¹⁹ F and ³¹ P can be investigated. The measurement was performed using JNM-ECZ500R (manufactured by JEOL Ltd.) with a magnetic field strength of 11.7 T (500 MHz). About 50 μL of the sample was packed in a 3.2 mm measuring probe and measured at room temperature (about 23 ° C.).

First, DD-MAS (Dipolar Decoupling-Magic Angle Spinning) measurement of ³¹ P was performed. FIG. 9 is a diagram showing the results of resonance spectra measured without decoupling. As shown in FIG. 9, resonance spectra were confirmed at 0.64 ppm and 0.76 ppm. Next, a radio wave (470.6 MHz) corresponding to a gyromagnetic ratio of ¹⁹ F was irradiated to cancel the interaction of PF and to perform decoupling measurement. FIG. 10 is a diagram showing the result of the resonance spectrum in which the interaction of PF is eliminated and the decoupling measurement is performed. As shown in FIG. 10, the resonance spectrum changed to one broad signal. This result indicates that F interferes with the atomic vibration of P in some way, but it has not reached the judgment of the presence or absence of coupling.

Next, ³¹ P { ¹⁹ F} CP-CPMAS (Cross Polarization-Magic Angle Spinning) measurement was performed. The contact time was measured at 50 to 20000 μs in a variable manner. FIG. 11 is a diagram showing the results of ³¹ P { ¹⁹ F} CP-CPMAS measurement. As shown in FIG. 11, the maximum value of the signal intensity did not appear even if the contact time was extended to 20000 μs, and the signal intensity monotonously increased with the passage of the contact time. From this, it is understood that although fluorine is in the vicinity of phosphorus, fluorine and phosphorus are not directly bonded.

Phosphorus tends to have a tetragonal coordination structure. From the results of the solid state NMR described above, it was determined that four oxygens were coordinated to phosphorus. Therefore, in structural analysis conducted on the basis of X-ray diffraction data of the reference example, structural analysis was performed on the assumption that the crystal is present in the form of (PO ₄ ) ^3- .

The relationship between each element and atomic coordinates is shown in Table 1.

The results of crystal structure analysis are shown in FIG. FIG. 12 is a schematic view showing a crystal structure of the phosphor according to the present embodiment. The occupied position of the light emitting element Eu ²⁺ is the Ca site (see Table 1). The crystal structure shown in FIG. 12 shows the case of viewing from the b-axis direction.

FIG. 13 is a diagram for explaining the crystal structure of the light emitting site. The Eu ²⁺ site has an octahedral structure in which six anions are coordinated. The breakdown of the anion is 4 oxygen ions and 2 fluorine ions. The structure of the octahedron EuO ₄ F ₂ is a cis structure in which two fluorine ions are adjacent to each other.

The fluorine ions of the octahedron EuO ₄ F ₂ are linearly arranged in the b-axis direction of the present crystal, and connect the octahedron EuO ₄ F _{2 to} each other in such a manner that the apexes of the octahedron EuO ₄ F ₂ are shared. As a result, the octahedron EuO ₄ F ₂ is connected zigzag in the b-axis direction centering on the fluorine ion (see FIG. 14). Each oxygen ion of octahedral EuO ₄ F ₂ shares a vertex with the PO ₄ tetrahedron.

FIG. 14 is a schematic view of the crystal structure of the phosphor shown in FIG. 12 as viewed from another direction. As shown in FIG. 14, when the crystal is viewed from the direction ([303] or [-303] direction) in which the c-axis is rotated 30 ° about the b-axis, the fluoride ion and the PO ₄ tetrahedron form octahedron EuO. ₄ F ₂ are arranged in a staggered pattern. The potassium ions line up to fill the houndstooth of octahedral EuO ₄ F ₂ . Has a perovskite structure represented by a composition formula ABX ₃ and attention is paid to the relationship between potassium ions and octahedral _EuO 4 _{F 2.}

FIG. 15 is a view showing a light emitting site of the perovskite crystal structure according to the present embodiment. As shown in FIG. 15, eight potassium ions are located at the top of the cubic lattice (A site). Oxygen ions and fluoride ions as anions of octahedral EuO ₄ F ₂ are located at the face center of the cubic lattice formed by potassium. And europium (or calcium) ion is located in the body center of cubic lattice (B site). Considering the case where all A sites are occupied only by potassium ions, the ion radius of 1.55 Å of potassium ions (K ⁺ ) occupying A sites is the ion radius 1 of europium ions (Eu ²⁺ ) occupying B sites. 32% larger than .17 Å.

The electron density of cis octahedron EuO ₄ F ₂ centering on divalent europium ion is biased to the fluorine side with high electronegativity. Because of this, the symmetry of the octahedral electron distribution is broken, and the degeneracy of the 5d orbital of the divalent europium ion is solved. As a result, valence electrons in the inner shell 4f orbit of divalent europium _tend to transition to the d _xz or d _yz orbit of the 5 d orbit even at low energy. The direction of the d _xz or d _yz orbitals is the vertex direction of the cubic lattice constituting the perovskite structure. The position is occupied by the cation K ⁺ having a large ion radius. As a result, electrostatic attraction is generated between the electron cloud of the 5 d electron (d _xz or d _yz orbit) of Eu ²⁺ and the cation K ⁺ . At this time, the mass of the K ⁺ ions is large and it is difficult to move, so the spread of the d _xz or d _yz orbital electron cloud is large. As a result, the probability of the presence of electrons in the d _xz or d _yz orbitals increases, and the energy level decreases, thus exhibiting a large Stokes shift.

[Unit cell]
The unit cell of the crystal structure shown in FIG. 12 and FIG. 14 is shown below. FIG. 16 is a schematic view of the unit cell of the phosphor according to the present embodiment as viewed from the a-axis. FIG. 17 is a schematic view of a unit cell of the phosphor according to the present embodiment as viewed from the b axis. FIG. 18 is a schematic view of a unit cell of the phosphor according to the present embodiment as viewed from the c-axis. The unit cell contains atoms of the coordinates shown in Table 1. The a axis corresponds to coordinates (x, 0, 0), the b axis corresponds to (0, y, 0), and the c axis corresponds to (0, 0, z).

[Excitation spectrum and emission spectrum]
FIG. 19 is a diagram showing an excitation spectrum and an emission spectrum of a phosphor according to a reference example. The measurement of the excitation light emission spectrum was performed at room temperature using a multi-channel optical spectrometer (PMA C5966-31 (manufactured by Hamamatsu Photonics)). The emission spectrum was measured at 400 nm excitation. The excitation spectrum was measured by matching the monitor wavelength to the emission peak wavelength at 400 nm excitation.

As shown in FIG. 19, the excitation spectrum L1 of the phosphor according to the reference example has a peak wavelength λ1 in the range of 330 to 420 nm, more specifically in the range of 350 to 390 nm. The excitation end wavelength λe is about 420 nm, and the energy of the wavelength is 2.938 eV. On the other hand, the emission spectrum L2 of excitation light having a peak wavelength of 400 nm has a peak wavelength λ2 of 658 nm, a half width of 152 nm, and an energy of the peak wavelength λ2 of 1.884 eV. Therefore, the Stokes shift is 1.054 eV. The chromaticity coordinates (cx, cy) of the light emitted from this phosphor are (0.613, 0.384).

The powder sample obtained in the reference example was subjected to compositional analysis using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography. As a result, it was revealed that the composition ratio of the phosphor according to the reference example was KF · Ca _0.99 KPO ₄ : Eu ²⁺ _0.01 .

FIG. 20 is a diagram showing temperature characteristics of phosphor light emission according to a reference example. FIG. 17 shows the relative intensity of each temperature normalized with the emission intensity at 30 ° C. excited with light having a wavelength of 400 nm as 100%. Even though the maintenance rate of emission intensity at 150 ° C. was 90% or more at 30 ° C., and although the Stokes shift was large, good temperature characteristics could be confirmed.

[Light emission by short wavelength excitation]
The inventors of the present invention have found that the light emission site of the perovskite structure of the reference example shifts to a bluish green color upon excitation with high energy (short wavelength).

As described above, the anion for the emission center Eu of the phosphor according to the reference example has a cis octahedral structure of EuO ₄ F ₂ . In other words, anions are positioned in each crystal axis direction (see FIG. 6A). For example, when excited the phosphor according to the reference example in lower energy of about 3.10 eV (400 nm), lower the energy level of _{t 2 g} orbit due to the crystal field splitting of the 5d orbital and 5d orbital in this direction spreads.

On the other hand, when excited with a high energy of 4.13 eV (300 nm), an electron cloud of 5 d orbital spreads in an orbital e _g with high energy level due to crystal field splitting of 5 d orbital, that is, an axial direction in which an anion exists. FIG. 21 is a schematic view showing the spread of electron clouds in octahedron EuO ₄ F ₂ . The electrostatic attraction of the cation at the top of the perovskite cube does not act on the axially extended 5d orbital. Instead, electrostatic repulsion (repulsion) with the anion in the axial direction acts. Therefore, the spread of the 5d trajectory is suppressed, and the light emission shifts to the light on the short wavelength side. FIG. 22 is a view showing an emission spectrum in the case where the phosphor according to the reference example is irradiated with ultraviolet light of high energy. As shown in FIG. 22, in the phosphor according to the reference example, blue-green emission with a peak wavelength λ2 of the emission spectrum of 476 nm could be confirmed.

Next, as evidence that one light emitting element emits light of two colors, the diffuse reflection spectrum of the phosphor according to the reference example was measured. FIG. 23 is a view showing a diffuse reflection spectrum of the phosphor according to the reference example. As indicated by line L1 in FIG. 23, it can be seen that most of the light of 420 nm or less is absorbed. The excitation spectrum L2 for red light emission (monitor wavelength 622 nm) and the excitation spectrum L3 for blue-green light emission (monitor wavelength 476 nm) are superimposed on this. From this, the excitation band of red light emission is at 330 to 420 nm, and the excitation band of blue-green light emission can be confirmed at around 250 to 320 nm. This indicates that one emission center changes the emission color due to the difference in excitation wavelength.

As described above, the phosphor according to the reference example of the present embodiment emits red light with light of the first wavelength (for example, near-ultraviolet light or short-wavelength visible light with a peak wavelength of 380 to 450 nm) Light of a second wavelength (for example, 200-350 nm forbidden ultraviolet light) having a shorter wavelength than light of a wavelength emits light with a color shorter than red (for example, blue to green at a wavelength of 450 nm to 550 nm).

Example 1
As a result of the inventors of the present invention performing further studies based on the above findings, it has been realized that a phosphor of a single phase emitting plural colors of light (a plurality of lights having different peak wavelengths) is realized by the phosphor of the following configuration. . Specifically, the light emitting element is located in a body-centered become B site of the perovskite crystal structure (cubic), a phosphor composed of a single phase, and the light-emitting site ABX _3, the light-emitting site ABX ₃ cation A Is a phosphor having a luminescent site (AA ') BX ₃ substituted by a cation A' having a smaller ionic radius than the cation A.

As described above, there are two or more types of cations (cation A and cation A '), which constitute the A site serving as each vertex of the perovskite crystal structure. In addition, 95% to 99% of the cations constituting the A site may be occupied by ions larger by 15% or more than the ion radius of the cation B of the B site. In addition, 1 to 5% of the cations constituting the A site may be occupied by ions having an ion radius equal to or smaller than that of the cation B of the B site.

In the light-emitting site ABX _3, because the larger the cation A than the ionic radius of the cation B in all the A-site is occupied, the anion X which is located on the surface center of the perovskite structure is sandwiched four cations A of the A site It is fixed in shape. Therefore, since electrostatic repulsion 5d orbital and anions is large, when excited the phosphor with a low energy, lower the energy level of t _{2 g} orbit due to the crystal field splitting of the 5d orbital, the electron cloud of the 5d orbital T2g direction spread.

The d _xz and d _yz orbitals split in the T2g direction are attracted to the cation A of the A site located at each vertex of the cubic crystal, and the electron cloud is widely spread by electrostatic attraction, so the energy levels of the d _xz and d _yz orbitals Decreases. As a result, it emits light of long wavelength (yellow to red).

On the other hand, the light emission site (AA ′) BX ₃ has a different light emission form. FIG. 24A is a perspective view schematically showing the light emitting site (AA ′) BX ₃ , and FIG. 24B is a side view schematically showing the light emitting site (AA ′) BX ₃ . In the light emitting site (AA ′) BX ₃ , since a part of the A site is occupied by the cation A ′ having a smaller ion radius than the cation A, a gap is generated around the anion X located in the face center of the perovskite structure An anion X can move (see FIG. 24B). Therefore, allows energy relaxation, 5d orbital spreads E _g direction.

The 5d orbital spread in E _g direction, the electrostatic attraction of the cation in the vertex positions of the perovskite cube does not act. Instead, electrostatic repulsion (repulsion) with the anion X in the axial direction acts. At this time, the anion X can move to the side of the cation A ′ having a smaller ion radius occupied at the A site, and the electrostatic repulsion can be relaxed. As a result, it emits short wavelength (purple to green) light from the 5d orbit suppressed by electrostatic repulsion.

Next, the phosphor according to Example 1 will be specifically described. In the phosphor according to Embodiment 1, the elements constituting the crystal structure AA'BX ₃ of emission sites, + cation A is ^K (0.975), + cation A 'is ^Na (0.025), cationic B eu ^2+, anion X is ^{O 2-} and F ^- a. Further, a cation M constituting tetrahedral MO ₄ which connects the perovskite structures of the light emitting site is P ⁵⁺ .

The phosphor according to Example 1 is manufactured by the following method. First, KF, NaF, and K ₂ CO ₃ powder are dried at 150 ° C. for 2 hours. And, in a glove box filled with dry N ₂ , KF, K ₂ CO ₃ , NaF, CaHPO ₄ , (NH ₃ ) ₂ HPO ₄ , Eu ₂ O ₃ at a stoichiometric ratio of 0.950: 0.500: The mixture was precisely weighed to a ratio of 0.050: 0.960: 0.040: 0.020 (mol), and ground and mixed in an alumina mortar to obtain a raw material mixed powder. Thereafter, the same processing as in the reference example was performed to obtain a phosphor according to example 1. The powder sample obtained in Example 1 was subjected to composition analysis in the same manner as in the reference example. As a result, it was revealed that the compositional ratio of the phosphor according to Example 1 was (K _1.95 , Na _0.05 ) Ca _0.96 PO ₄ F: Eu 2 ⁺ _0.04 .

FIG. 25 is a diagram showing an X-ray diffraction pattern of the phosphor according to Example 1. The measurement was performed using a device similar to Reference Example 1, with a sampling width of 0.02 °, and a scan speed of 2.0 ° / min.

The obtained powder X-ray diffraction profile shows the same diffraction pattern as the phosphor of the reference example (K ₂ Ca (PO ₄ ) F: Eu ²⁺ ), and Rietveld analysis using the same crystal as a model, Rw 6 It converges to less than%, It turned out that it is crystal structure (Crystal system: monoclinic crystal, Bravais lattice: simple lattice, space group: P2 ₁ / m) of the crystal structure of the same system. In the following, the description overlapping with the reference example is appropriately omitted.

The phosphor according to Example 1 has the same crystal structure (see FIGS. 12 to 18) as the phosphor according to the reference example from the measurement results described above, and a part of the A site is occupied by sodium ions. Are the main differences.

Alkali ions (potassium ions, sodium ions) are arranged to fill in a zigzag grid of octahedral EuO ₄ F ₂ . It has a perovskite structure represented by a composition formula (AA ') BX ₃ and attention is paid to the relationship between the alkali ions and octahedral _EuO 4 _{F 2.}

As shown in FIG. 15, eight alkali ions are located at the top of the cubic lattice (A site). Oxygen ions and fluorine ions as anions of octahedral EuO ₄ F ₂ are located at the face center of the cubic lattice composed of potassium or sodium. And europium (or calcium) ion is located in the body center of cubic lattice (B site). Of the alkali ions occupying the A site, the ion radius of 1.59 Å of potassium ion (K ⁺ ) is 32% larger than the ion radius of 1.17 Å of the europium ion (Eu ²⁺ ) occupying the B site. On the other hand, the ion radius of 1.32 Å of sodium ion (Na ⁺ ) occupying A site is relatively close to the ion radius 1.17 of europium ion (Eu ²⁺ ) occupying B site.

For example, when all eight A sites of the perovskite structure are occupied by potassium ions, valence electrons in the inner shell 4f orbital of divalent europium transition to d _xz or d _yz orbital of 5 d orbital even at low energy. It becomes easy to do. The direction of the d _xz or d _yz orbitals is the vertex direction of the cubic lattice constituting the perovskite structure. The position is occupied by the cation K ⁺ having a large ion radius. As a result, electrostatic attraction is generated between the electron cloud of the 5 d electron (d _xz or d _yz orbit) of Eu ²⁺ and the cation K ⁺ . At this time, the mass of the K ⁺ ions is large and it is difficult to move, so the spread of the d _xz or d _yz orbital electron cloud is large. As a result, the probability of the presence of electrons in the d _xz or d _yz orbitals is increased, and the energy level is reduced, thus emitting red light.

On the other hand, when the eight certain A site of the perovskite structure is occupied also sodium ions as well as potassium ions, the valence electrons in the inner shell 4f orbit of divalent europium, by the excitation light irradiation, E _g direction of 5d orbital A transition is possible (in the direction of the axis: the direction of d _x ^2- _y ² or d _z ² trajectory). This is because when a small cation occupies a part of the A site, a gap is formed around the anion of the face center, and energy relaxation occurs due to the movement of the anion. The electrostatic attraction of the cation at the top of the perovskite cube does not act on the axially extended 5d orbital. Instead, electrostatic repulsion (repulsion) with the anion in the axial direction acts. Therefore, the spread of the 5d trajectory is suppressed, the emission wavelength shifts to the short wavelength side, and bluish green emission can be confirmed.

FIG. 26 is a diagram showing an excitation spectrum and an emission spectrum of the phosphor according to Example 1. The measurement of the excitation light emission spectrum was performed at room temperature using a multi-channel optical spectrometer (PMA C5966-31 (manufactured by Hamamatsu Photonics)). The emission spectrum L2 was measured at 400 nm excitation. The excitation spectra L1 and L1 'were measured by matching the monitor wavelength to the emission peak wavelength (655 nm and 493 nm) at 400 nm excitation.

As shown in FIG. 26, the emission spectrum L2 of the phosphor according to Example 1 was white light in which blue green light having a peak wavelength λ2 ′ of 493 nm and red light having a peak wavelength λ2 of 655 nm were mixed. Thus, the fluorescent substance which concerns on Example 1 can implement | achieve white light by the light of the several color which 1 type of fluorescent substance which consists of single phase emits. Here, “single phase” means that the material has a component (composition) that is uniform, and the basic crystal structure (perovskite structure in this embodiment) can also be said to be one type of substance. Other interpretations can be made without departing from the spirit of the present invention.

The excitation spectrum L1 '(measured in accordance with the emission peak wavelength 493 nm) of the phosphor according to Example 1 has a peak wavelength λ1' in the range of 300 to 420 nm, more specifically in the range of 300 to 350 nm. The excitation spectrum L1 (measured to match the emission peak wavelength of 655 nm) has a peak wavelength λ1 in the range of 300 to 420 nm, more specifically in the range of 350 to 400 nm. The chromaticity coordinates (cx, cy) of the light emitted from this phosphor are (0.434, 0.386).

The profile of the excitation spectrum L1 is almost the same as that of the reference example in which all of the A sites are occupied by potassium ions. On the other hand, the excitation spectrum L1 'shows a peak at around 300 nm and extends to around 400 nm showing red emission. Therefore, in emission spectrum L2 by excitation light including light with a wavelength of 400 nm, two emission peaks of blue-green emission and red emission are shown.

(Example 2)
Next, the phosphor according to Example 2 will be specifically described. The description of the same configuration as that of the first embodiment will be appropriately omitted. In the phosphor according to the second embodiment, the elements constituting the crystal structure AA'BX ₃ of emission sites, + cation A is ^K (of 0.99), + cation A 'is ^Li (0.01), cationic B eu ^2+, anion X is ^{O 2-} and F ^- a. Further, a cation M constituting tetrahedral MO ₄ which connects the perovskite structures of the light emitting site is P ⁵⁺ .

The phosphor according to Example 2 is manufactured by the following method. First, KF, LiF, K ₂ CO ₃ powder is dried at 150 ° C. for 2 hours. And, in a glove box filled with dry N ₂ , KF, K ₂ CO ₃ , LiF, CaHPO ₄ , (NH ₃ ) ₂ HPO ₄ , and Eu ₂ O ₃ have a stoichiometric ratio of 0.98: 0.50: The mixture was precisely weighed to have a ratio of 0.020: 0.960: 0.040: 0.020 (mol), and ground and mixed in an alumina mortar to obtain a raw material mixed powder. Thereafter, the same processing as in the reference example was performed to obtain a phosphor according to example 2. The powder sample obtained in Example 2 was subjected to composition analysis in the same manner as in the reference example. As a result, the composition ratio of the phosphor according to the second _{_{_{_{embodiment, (K 1.98, Li 0.02)}}}} Ca 0.96 PO 4 F: revealed a _{Eu 2+ 0.04.}

FIG. 27 is a diagram showing an X-ray diffraction pattern of the phosphor according to Example 2. The measurement was performed using a device similar to Reference Example 1, with a sampling width of 0.02 °, and a scan speed of 2.0 ° / min. The obtained powder X-ray diffraction profile showed a diffraction pattern similar to that of the phosphor of Example 1. In the following, description overlapping with the first embodiment will be omitted as appropriate.

The phosphor according to Example 2 has the same crystal structure (see FIGS. 12 to 18) as the phosphor according to Example 1 from the above measurement results, and a part of the A site is occupied by lithium ions. Is the main difference.

Alkali ions (potassium ions, lithium ions) are arranged to fill in a zigzag grid of octahedral EuO ₄ F ₂ . It has a perovskite structure represented by a composition formula (AA ') BX ₃ and attention is paid to the relationship between the alkali ions and octahedral _EuO 4 _{F 2.}

Eight alkali ions are located at the apex of the cubic lattice (A site). Oxygen ions and fluoride ions as anions of octahedral EuO ₄ F ₂ are located at the face center of the cubic lattice composed of potassium or lithium. And europium (or calcium) ion is located in the body center of cubic lattice (B site). Of the alkali ions occupying the A site, the ion radius of 1.59 Å of potassium ion (K ⁺ ) is 32% larger than the ion radius of 1.17 Å of the europium ion (Eu ²⁺ ) occupying the B site. On the other hand, the ion radius of 0.92 Å of the lithium ion (Li ⁺ ) occupying the A site is smaller than the ion radius 1.17 of the europium ion (Eu ²⁺ ) occupying the B site.

The phosphor according to Example 2 having such a structure exhibits similar emission characteristics to Example 1 by the same emission mechanism as that of Example 1.

FIG. 28 is a diagram showing an excitation spectrum and an emission spectrum of a phosphor according to Example 2. The measurement of the excitation emission spectrum is the same as in Example 1. The excitation spectra L1 and L1 'were measured by matching the monitor wavelength to the emission peak wavelength (662 nm and 495 nm) at 400 nm excitation.

As shown in FIG. 28, the emission spectrum L2 of the phosphor according to Example 2 was white light in which blue green light having a peak wavelength λ2 ′ of 495 nm and red light having a peak wavelength λ2 of 662 nm were mixed. Thus, the fluorescent substance which concerns on Example 2 can implement | achieve white light by the light of the several color which 1 type of fluorescent substance which consists of single phases emits.

The excitation spectrum L1 '(measured to match the emission peak wavelength of 495 nm) of the phosphor according to Example 2 has a peak wavelength λ1' in the range of 300 to 420 nm, more specifically in the range of 300 to 350 nm. The excitation spectrum L1 (measured to match the emission peak wavelength 662 nm) has a peak wavelength λ1 in the range of 300 to 420 nm, more specifically in the range of 350 to 400 nm. The chromaticity coordinates (cx, cy) of the light emitted from this phosphor are (0.424, 0.369).

(Selectivity of cation A 'and cation B in luminescent site (AA') BX ₃ )
The ionic radius (10 coordination) of monovalent metal ions is 1.59 Å for potassium ions, 1.32 Å for sodium ions, and 0.92 Å for lithium ions. The ionic radius (six coordination) of the divalent metal ion is 1.00 Å for calcium ions and 1.17 Å for europium ions.

As mentioned above, the ionic radius of the europium ion is larger than the ionic radius of the calcium ion. Therefore, when the B site is occupied by europium ions, distortion occurs in the crystal lattice. Therefore, the distortion can be alleviated by replacing part of the potassium ions at the A site with sodium ions or lithium ions having an ion radius smaller than the ion radius of the potassium ions. Therefore, in order to minimize the total energy of the crystal and obtain a stable structure, Eu and Na (Li) tend to be doped at the same light emitting site in a pairwise manner.

In each of the above-described embodiments, since the doping amount is Eu> Na (Li), the light emitting site where all the A sites constituting the perovskite are occupied by K, and the A site are occupied by the potassium ions and sodium ions Luminescent sites are generated. Fig. 29 (a) schematically shows an energy diagram in which only potassium ions are occupied at the A site, and Fig. 29 (b) shows energy in which only potassium ions and sodium ions (lithium ions) are occupied at the A site. It is the figure which showed the diagram typically.

By the excitation and light emission process shown in FIGS. 29A and 29B, white light emission can be realized by mixing light of a plurality of colors having different peak wavelengths in the phosphor having a single crystal structure.

As mentioned above, although the present invention was explained with reference to the above-mentioned embodiment and each example, the present invention is not limited to the above-mentioned embodiment and each example, but the embodiment and each example The present invention also includes those in which the configurations are appropriately combined or substituted. Further, it is also possible to appropriately rearrange the combination and order of processing in the embodiment and each embodiment based on the knowledge of the person skilled in the art, and add various modifications such as design changes to the embodiment and each embodiment. However, an embodiment in which such a modification is added can be included in the scope of the present invention.

The present invention can be used for phosphors used in lighting devices and the like.

Claims

A single-phase fluorescence that has a perovskite crystal structure in which the light emission site is represented by ABX 3 (A and B are cations and X is an anion) and the light emitting element is located at the B site that is the body center of the perovskite crystal structure Being a body
The light emitting site ABX 3 and the light emitting site (AA ′) BX 3 in which a part of the cation A of the light emitting site ABX 3 is substituted with a cation A ′ smaller in ion radius than the cation A Phosphor.
The phosphor according to claim 1, characterized in that the ion radius I A of the cation located at the A site of the perovskite crystal structure is 15% or more larger than the ion radius I B of the cation located at the B site.
The phosphor according to claim 1 or 2, wherein the cation A is K + and the cation A 'is Na + or Li + .
The phosphor according to any one of claims 1 to 3, wherein the cation B is at least one cation selected from the group consisting of Eu 2+ , Ce 3+ , Sm 2+ and Yb 2+. .
A single-phase fluorescence that has a perovskite crystal structure in which the light emission site is represented by ABX 3 (A and B are cations and X is an anion) and the light emitting element is located at the B site that is the body center of the perovskite crystal structure Being a body
A phosphor having an emission spectrum having a first peak in the violet to green wavelength range and a second peak in the yellow to red wavelength range.