JPH08325565A - Zinc sulfide phosphor - Google Patents

Abstract

PURPOSE: To obtain a high-luminance phosphor capable of attaining sufficiently high luminance without the aid of high-density electron beam irradiation. CONSTITUTION: This phoshor is a zinc sulfide phosphor represented by the composition formula (Zn1-x Cdx ) S:Cu, Cl (0<=(x)<=0.1; the concentrations of the activators, Cu and Cl are each 500ppm or less), wherein, in relation to zinc defect concentration ([VZn ], a molar concentration, the concentrations indicated hereafter by [ ] are all molar concentrations) defined by the formula: [Cl concentration - Cu concentrations] × 1/2, the half/value width of<67> Zn signal (Δν1/2 (Zn)) determined by static NMR is plotted, and in relation to zinc defect concentration ([VZn <s> T]) defined as half of the Cl concentration of a (Zn1-x Cdx )S:Cl phosphor as the standard, the half-value width of<67> Zn signal (Δν1/2 (Zn)) determined by static NMR is plotted, the relationship; Δν1/2 (Zn)>Δν1/2 (Zn)<s> T+10Hz is satisfied at the point where [VZn ]=[VZn <s> T].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc sulfide phosphor, and more particularly to a zinc sulfide phosphor used in a cathode ray tube for a color television, which exhibits high brightness characteristics when excited by an electron beam.

[0002]

2. Description of the Related Art Phosphors containing zinc sulfide as a main component show bright fluorescence and have high practical value. C as an activator for ZnS
ZnS: Cu, Cl to which u and Cl are added has the highest utility value as a green phosphor and is used in televisions, displays, cathode ray tubes for measuring instruments, and the like.

In recent years, high-definition televisions such as high-definition televisions have become widespread, but in order to express the screen of such high-definition televisions with high precision and high brightness, a high-density electron beam is placed in the cathode ray tube. It is being incident.

However, when the current density is increased with the sulfide phosphor, the luminous efficiency of the phosphor is lowered. For this reason, it has been put to practical use by shifting the focus of the electron beam spot to widen the spot diameter and suppressing the decrease in light emission efficiency due to the increase in current density. However, the brightness is not sufficient for a high-density screen, and it is still insufficient. No highly precise and bright zinc sulfide phosphor has been proposed.

[0005]

[Problems to be Solved by the Invention] Under these circumstances,
There was a need for zinc sulfide phosphors with higher brightness characteristics at low current densities. The present invention provides a zinc sulfide phosphor that maintains high-definition and high-luminance brightness on a television or cathode ray tube of a display and a measuring instrument without increasing the intensity of an incident electron beam.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted a study on the lattice defects of the crystal and the distribution state of Cu element and Cl element added as activator elements in order to achieve the above object, and as a result, The inventors have found that a zinc sulfide phosphor having NMR (nuclear magnetic resonance) characteristics has high brightness characteristics, and have reached the present invention.

The present invention provides a compositional formula (Zn _1-X Cd _x ) S:
A zinc sulfide phosphor represented by Cu and Cl (wherein x is 0 ≦ x ≦ 0.1, and the concentrations of the activators Cu and Cl are 500 ppm or less, respectively), [Cl concentration-Cu Density] × _1/2, the half-value width (Δν _1/2 (Zn)) of the ⁶⁷ Zn signal by static NMR is plotted against the zinc defect concentration ([V _Zn ]), which serves as the standard (Z
n _1-X Cd _x ) S: Cl The zinc defect concentration ([V _Zn ^ST ]) defined as 1/2 of the Cl concentration of the phosphor and the full width at half maximum of the ⁶⁷ Zn signal by static NMR (Δν _1/2 (Z
n) ^ST ) when plotted, at the point of [V _Zn ] = [V _Zn ^ST ], Δν _1/2 (Zn)> Δν _1/2 (Zn) ^ST +10 Hz
And a zinc sulfide phosphor. Here, all the concentrations shown in [] are molar concentrations.

The phosphor of the present invention is (Zn _1-X Cd _x ).
It has a composition formula represented by S: Cu, Cl. When x is 0.1 (molar composition) or less, it can be favorably used as a green phosphor. Cu and / or activator elements
Alternatively, Cl is 500 ppm or less, respectively. The preferable content of Cu is 40 to 500 ppm, and particularly 40 to 3
It is 50 ppm, and the preferable content of Cl is 20 to 5
00 ppm, especially 20 to 300 ppm.

Although the emission mechanism of the phosphor has not been sufficiently clarified, in the case of ZnS: Cu, Cl, the emission mechanism is presumed as follows. The activator element Cl ⁻ solid-dissolved in ZnS replaces S ²⁻ to form a donor level, while Cu ⁺ replaces Zn ²⁺ to form an acceptor level. Electrons that enter the phosphor in this state and reach the conduction band from the charge band move to the donor level, and emit fluorescence corresponding to the energy difference between the donor level and the acceptor level.

Cu ⁺ substituted with Zn ²⁺ and Cl ⁻ substituted with S ²⁻ have charges of −1 and +1 respectively, and the charges are mutually compensated. Since Cl ⁻ has a charge of +1, Zn ²⁺ becomes a hole having a charge of −2 and the charge is compensated. That is, charge compensation is performed with two Cl ⁻ and one zinc defect (V _zn ). The zinc defect concentration ([V _zn ]) is represented by [V _zn ] = [Cl concentration-Cu concentration] × 1/2.

The present inventors have conducted various studies on the above-mentioned zinc defect concentration [V _zn ] and the relation between the relative distribution of Cu ⁺ and Cl ⁻ and the brightness of the phosphor, and as a result, C
The distribution state of u ⁺ and Cl ⁻ is reflected in the line width of the ⁶⁷ Zn signal around 380 ppm by static NMR, that is, the line width is wide (the full width at half maximum is large).
It was found that the brightness was higher.

The present invention uses 38 by static NMR.
The line width of the ⁶⁷ Zn signal near 0 ppm is _linearly proportional to the V _Zn concentration, and when the V _zn concentration is constant, this
^This is based on the fact that the larger the line width of the ⁶⁷ Zn signal, the higher the brightness that can be achieved. Although the scientific elucidation of this has not been done so far, the broadening of the line width of the ⁶⁷ Zn signal peak near 380 ppm is caused by the paramagnetic relaxation of electrons or holes incorporated in zinc defects. It is considered that this reflects the difference in the distribution of V _{Zn in} the ZnS crystal and the state of bonding and substitution of Zn, S, Cu and Cl.

The line width broadening of the ⁶⁷ Zn signal at around 380 ppm by static NMR is represented by the half-value width (Δν _1/2 (Zn)) of the signal peak, and the resonance frequency of 18.
8 MHz, pulse width 5 μsec (30 ° pulse), waiting time 2.5 sec, integration time is usually 1000 to 2000
It is obtained by measuring the number of times. From the linear shape of the signal, the linear width is obtained by separating the linear shape using a Gaussian function by a conventional method. The half-value width is plotted on the vertical axis, and the V _Zn concentration is plotted on the horizontal axis.

Next, a standard line is created. First, Zn
Prepare S: Cl standard. After thoroughly mixing zinc sulfide and sodium chloride corresponding to each concentration, the mixture is filled in a cylindrical tube container made of quartz and baked at 950 ° C. in a hydrogen sulfide gas stream for 3 hours. The fired product obtained is thoroughly washed with pure water, dried at 120 ° C., and sieved to obtain a ZnS: Cl standard substance.

Using the same standard material as above, a ⁶⁷ Zn signal near 380 ppm was obtained by static NMR, and the half-value width (Δν _1/2 (Zn) ^ST ) was determined. Similarly to the above, the half width is plotted on the vertical axis and the V _Zn concentration is plotted on the horizontal axis.

The phosphor of the present invention can be preferably produced, for example, by the following method. Mix the raw material zinc sulfide and sodium chloride to the desired composition and mix in a hydrogen sulfide gas stream at 950 ° C.
Bake for hours. The fired product obtained is washed with water and dried at 120 ° C. In addition, even in the case of such a step or other manufacturing method, it is possible to prepare a calibration curve using a standard substance in advance and monitor the half width of the obtained phosphor to adjust the amount of activator and each treatment condition. It can also be manufactured.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. ^{The full} width at half maximum of the ⁸⁹ Y signal (Δν _1/2 (Zn), Δν _1/2 (Zn) ^ST ) was measured by mounting a static probe on a solid state NMR apparatus MSL-300 manufactured by Bruker.

The measurement conditions are as follows.

[0019]

[Table 1] Probe: Static probe Resonance frequency: 18.8 MHz Pulse sequence: Single pulse Pulse width: 5 μsec (30 ° pulse) Wait time: 2.5 sec

Below, the Cu, Cl and impurity concentrations of the respective samples were measured by the Seiko SPS-1200A ICP apparatus (inductively coupled high frequency plasma emission spectrometer) and Rigaku3.
Quantification was performed using a 370 X-ray fluorescence system. In addition, the measurement of the brightness of the phosphor is performed by using an electron beam excitation device (TOPCON ABT
-32).

(Preparation of Standard Material) Raw material zinc sulfide and sodium chloride were thoroughly mixed in a dry manner so as to have the composition shown in Table 1 below, and the mixture was filled in a cylindrical tube container made of quartz and 950 ° C. in a hydrogen sulfide gas stream. It was baked for 3 hours. The fired product obtained was thoroughly washed with pure water, dried at 120 ° C., and sieved to obtain a chlorine-activated zinc sulfide standard substance. As a result of powder X-ray diffraction, all were zinc sulfide single layers. In addition, the amount of Zn / Cl in the ICP apparatus was in agreement with the charged amount within the range of experimental error.

[0022]

[Table 2]

(Preparation of ⁶⁷ Zn Standard Line) With respect to the standard substances of Reference Examples 1 to 6, the full width at half maximum of the ⁶⁷ Zn signal (Δν _1/2 (Zn) ^ST ) was measured by static NMR. The measurement was carried out by mounting a static probe on a solid state NMR apparatus MSL-300 manufactured by Bruker.

⁶⁷ Zn signal full width at half maximum Δν _1/2 (Zn)
^ST is shown in Table 1 together with the zinc defect concentration [V _Zn ^ST ] and the Cl concentration [Cl]. Based on this, the vertical axis shows ⁶⁷ Zn.
FIG. 2 shows a standard line obtained by plotting the half-value width Δν _1/2 (Zn) ^ST of the signal as the zinc defect concentration [V _Zn ^ST ] on the horizontal axis and plotting the relationship to make it linear.

(Examples 1 to 5) (Comparative Example 1) The raw material zinc sulfide, sodium chloride and copper nitrate were sufficiently mixed in a dry manner so as to have the composition shown in Table 2 below, and the mixture was filled in a cylindrical tube container made of quartz. Then, it was fired in a hydrogen sulfide gas stream at 950 ° C. for 3 hours. The obtained fired product was thoroughly washed with pure water, dried at 120 ° C., and sieved to obtain a ZnS: Cu, Cl phosphor. When these phosphors were excited by electron beams or ultraviolet rays, all of them glowed green.

This was analyzed by static NMR to obtain ⁶⁷ Zn
The full width at half maximum of the signal (Δν _1/2 (Zn)) was measured. The NMR chart of Example 3 is shown in FIG. Then, the brightness was measured, and the results are shown in Table 3.

[0027]

[Table 3]

[0028]

[Table 4]

The full width at half maximum of ⁶⁷ Zn signal in Table 3 Δν _1/2 (
⁶⁷ Zn) is plotted on the ordinate and zinc defect concentration [V _Zn ] is plotted on the abscissa, and the relationship is plotted to show the relationship with the standard line of FIG.

As is apparent from FIG. 1, those of the examples of the present invention having excellent relative luminance have a half width value higher than the standard line.

[0031]

EFFECTS OF THE INVENTION The phosphor of the present invention has a high brightness and can achieve a sufficiently high brightness regardless of high-density electron beam irradiation.

[Brief description of drawings]

FIG. 1 is a full width at half maximum Δν of ⁶⁷ Zn signal of the phosphor of the present invention.
_The figure which shows the relationship of _1/2 (Zn) and zinc defect density [ _VZn ], and a standard line.

[Fig. 2]⁶⁷Full width at half maximum of Zn signal Δν
_1/2(Zn)^STAnd zinc defect concentration [V_Zn ^ST] Relationship
Diagram of standard line.

3 is an NMR chart of the zinc sulfide phosphor of Example 3. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuji Adachi 1060 Narita, Odawara-shi, Kanagawa Kasei Optonix Co., Ltd. Odawara Plant (72) Inventor, Hase Ko, 1060 Narita, Odawara-shi, Kanagawa Odawara Plant Within

Claims (1)

[Claims] 1. A composition formula (Zn _1-X Cd _x ) S: Cu, C
l (where x is 0 ≦ x ≦ 0.1, and activators Cu, C
The concentration of 1 is 500 ppm or less. ), Which is a zinc sulfide phosphor represented by [Cl concentration−Cu concentration] × 1
Zinc defect concentration ([V _Zn ], molar concentration,
The concentrations shown in [] below are all molar concentrations. ) FWHM of ⁶⁷ Zn signal by a static NMR a _{(Δν 1/2 (Zn)} ) plotted against, the standard (Zn
_The zinc defect concentration ([V _Zn ^ST ]) defined as 1/2 of the Cl concentration of the _1-X Cd _x ) S: Cl phosphor and the full width at half maximum of the ⁶⁷ Zn signal by static NMR (Δν _1/2 (Z
n) ^ST ) when plotted, at the point of [V _Zn ] = [V _Zn ^ST ], Δν _1/2 (Zn)> Δν _1/2 (Zn) ^ST +10 Hz
And a zinc sulfide phosphor.