JP2005089496A - Phosphor composition, method for producing the same and fluorescent display apparatus and method for emitting light using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor composition (a fluorescent material) with suppressed lowering of luminescence intensity (luminance) by remaining of impurities and to provide a method for producing the same. <P>SOLUTION: The phosphor composition comprises Ln, R, M and O as principal constituent elements. In the composition, the atomic ratio x=(Ln+R)/M related to the Ln, R and M is 0.850<x<0.999, preferably 0.90≤x≤0.98. The atomic ratio y=R/(Ln+R) related to the Ln and R is 0.001≤y≤0.100. In the phosphor composition, the Ln is one or two or more kinds of elements selected from Y, La and Gd, preferably La and Y. The R is a rare earth element to be a luminescence center, preferably one or two or more kinds of elements selected from Ce, Pr, Eu and Tb. The M is one or two kinds of elements selected from Al and Ga. The phosphor composition is produced by mixing compounds containing the Ln, R and M so as to provide the atomic ratios x and y and firing the resultant mixture. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a phosphor composition with improved light emission intensity (luminance), a method for producing the same, a fluorescent display device using the same, and a light emitting method.

A phosphor (compound) that emits light when irradiated with an electron beam is used as a light emission source in a fluorescent display device such as a fluorescent display (VFD) or a field emission display (FED). In addition, a phosphor that emits light by irradiation with vacuum ultraviolet rays generated by gas discharge is used as a light source in a fluorescent display device such as a plasma display panel (PDP). PDP has been widely spread especially as a large flat panel display.
As a phosphor conventionally used as this type of fluorescent element, for example, a phosphor for red light emission includes (Zn _1-x Cd _x ) S: Ag, Cl (that is, the activator is Ag, Cl, The substance is (Zn _1-x Cd _x ) S. The same shall apply hereinafter).

However, (Zn _1-x Cd _x ) S: Ag, Cl is a sulfide, and when this is used for VFD, the sulfur component decomposed / separated from the base material by the collision of the electron beam etc. is the cathode (cathode). There is a risk that it may adhere to the surface and deteriorate the electron emission characteristics. The decrease in the electron emission characteristics is not preferable because the luminance of the phosphor is decreased and the life of the VFD is shortened. In addition, cadmium is contained in conventional sulfide phosphors, but the use of phosphors containing environmentally undesirable elements such as cadmium has been refrained from increasing environmental problems.
Accordingly, oxide phosphors that can be used in VFDs and the like have been developed instead of sulfide phosphors. In Patent Documents 1 to 6 listed below, various composite oxides (phosphors) are described.

Japanese Patent Publication No. 6-25354 Japanese Patent Publication No.7-113111 JP-A-7-258632 JP-A-8-3549 JP-A-10-140150 JP 2000-21259A

  The composite oxide (phosphor) as described in each of the above publications is obtained by using as a raw material several types of compounds containing any of the atoms (composition atoms) constituting the oxide, and the target composite oxide They are obtained by mixing them according to the elemental composition (component ratio) of (phosphor) and then firing the mixture. However, due to variations in firing conditions, not all of the atoms contained in the used raw material compound became the target composite oxide (that is, not all of the atoms were incorporated into the fired and synthesized phosphor). ), Some of which may form impurities (for example, oxides containing oxygen and other types of atoms; hereinafter referred to as “simple oxides”) and remain (mixed) in the fired composition. In addition, simple oxides can be easily converted into hydroxides by absorbing moisture in the air. When a fired composition containing such impurities (simple oxides and / or hydroxides) is used as a fluorescent material, these remaining impurities are components that do not emit light, which causes a reduction in emission intensity (luminance). .

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a phosphor composition (fluorescent material) in which a decrease in emission intensity (luminance) due to residual impurities is suppressed, and a method for producing the same. It is. Another object of the present invention is to provide a VFD or other fluorescent display device provided with such a phosphor composition (fluorescent material).

  A phosphor composition (fluorescent material) provided to solve the above problems is a phosphor composition having Ln, R, M, and O as main components. Here, Ln is one or two or more elements selected from the group consisting of Y, La and Gd. R is one or more elements selected from rare earth elements that can serve as a luminescent center. M is one or two elements selected from the group consisting of Al and Ga. Here, the atomic ratio x = (Ln + R) / M regarding the Ln, the R, and the M is a number that satisfies 0.850 <x <0.999. Further, the atomic ratio y = R / (Ln + R) regarding the Ln and the R is a number that satisfies 0.001 ≦ y ≦ 0.100.

  The phosphor composition of the present invention (that is, a composition mainly composed of a complex oxide functioning as a phosphor) serves as a luminescent center in the complex oxide composed of the predetermined elements Ln and M. It is a composition prepared by blending various raw material compounds mainly containing a complex oxide (phosphor) doped with R and having an atomic ratio of Ln + R and M within a specific range. In this phosphor composition, the residual (mixture) of impurities that reduce the emission intensity (luminance), that is, the simple oxide (and hydroxide) containing Ln is lower than before, and the phosphor material has high emission intensity (luminance). Can be.

That is, the phosphor composition in which x is set in the above range, in other words, the atomic ratio of Ln and R to M (configuration ratio) x = (Ln + R) / M is 0.850 <x <0.999. Within the range, impurities other than the complex oxide as the main component, which can cause a decrease in emission intensity, that is, impurities including Ln, in particular, residual (mixed) of simple oxides (and hydroxides) are present. Reduced. For this reason, when the phosphor composition of the present invention is excited by ultraviolet rays or electron beams, it is a conventional phosphor composition (fluorescent composition containing a composite oxide as a main component) composed of the same constituent elements, particularly (Ln + R). ) And M can emit light at a high emission intensity (luminance, that is, brightness), which was not conventionally obtained with a phosphor composition having an atomic ratio of about 1.
On the other hand, a phosphor composition in which x is in the range of 0.999 or more is not preferable because the emission intensity is lowered by the increase in the impurity content. In addition, in the phosphor composition in which x is in the range of 0.850 or less, the emission intensity is decreased due to the residual (mixture) of impurities containing M, mainly simple oxides (or hydroxides) containing M, which is preferable. Absent.
In the phosphor composition according to the present invention, since the ratio of (Ln + R) to M is reduced, there are some impurities including M in addition to the composite oxide (phosphor) composed of (Ln + R) and M. A quantity may remain. However, when x is within the above range, the influence is much less than the decrease in emission intensity due to the presence of impurities containing Ln.

  Further, in the phosphor composition according to the present invention, the ratio of doping the element R serving as the emission center is set in the specific range. That is, the phosphor composition in which y is set in the above range, in other words, the atomic ratio of R to Ln + R (configuration ratio) y = R / (Ln + R) is within the range of 0.001 ≦ y ≦ 0.100. If there is, high light emission intensity (luminance) can be obtained. For this reason, when excited by ultraviolet rays or an electron beam, it can emit light at a high emission intensity that has not been obtained in the past with conventional phosphor compositions composed of the same constituent elements (fluorescent compositions containing composite oxide as a main component). . Therefore, clear light emission and color development can be realized.

What is preferable as the phosphor composition of the present invention is such that x is a number satisfying 0.90 ≦ x ≦ 0.98.
A phosphor composition in which x is set in such a range, in other words, the atomic ratio of Ln + R to M (configuration ratio) x = (Ln + R) / M is in the range of 0.90 ≦ x ≦ 0.98. In addition, the residual (mixed) of impurities that cause a decrease in emission intensity, that is, simple oxides (and hydroxides) containing Ln are particularly reduced. For this reason, a particularly high emission intensity can be realized.

The phosphor composition of the present invention is preferably a composition in which R is one or more elements selected from the group consisting of Ce, Pr, Eu and Tb.
By doping any one of Ce, Pr, Eu, and Tb as the element R that constitutes the emission center (acting as an activator), light emission with high emission intensity (luminance) can be realized.

What is preferable as the phosphor composition of the present invention is a composition in which the Ln is one or two elements selected from the group consisting of La and Y.
In particular, residual impurities including La and / or Y, mainly simple oxides (and hydroxides), can reduce the emission intensity relatively large. For this reason, when x is set in the above range, the residual (mixed) of simple oxides (and hydroxides) of La and / or Y can be reduced, and in particular, a decrease in emission intensity (luminance) can be suppressed. . Therefore, it is possible to realize light emission with high light emission efficiency and higher light emission intensity (luminance).

  The present invention also provides a method for producing the fluorescent composition disclosed herein. That is, in the phosphor composition manufacturing method of the present invention, an atomic ratio x = (Ln + R) relating to the Ln, the R, and the M includes a compound containing the Ln, a compound containing the R, and a compound containing the M. ) / M is 0.850 <x <0.999, and the mixing is performed so that the atomic ratio y = R / (Ln + R) regarding Ln and R is 0.001 ≦ y ≦ 0.100. And baking the obtained mixture.

  In the case of manufacturing a phosphor composition (fluorescent material) containing, as a main component, a complex oxide (phosphor) doped with R serving as an emission center in a complex oxide composed of the predetermined elements Ln and M , Various raw material compounds containing these elements are mixed at a blending ratio such that the atomic ratio of Ln + R and M is in the above range. As a result, impurities that lower the emission intensity (luminance), that is, residual (mixture) of simple oxides (and hydroxides) containing Ln are reduced, and the target composite oxide (phosphor) is highly purified. A phosphor composition containing the same can be produced. Therefore, according to the production method of the present invention, a phosphor composition having high emission luminance can be produced as described above.

  Further, in the production method according to the present invention, various raw material compounds containing these elements are mixed in such a mixing ratio that the atomic ratio of R to Rn + R (configuration ratio) y = R / (Ln + R) falls within the specific range. . This makes it possible to produce a phosphor composition that can emit light with high emission intensity when excited by ultraviolet rays or electron beams, as described above.

A preferable manufacturing method according to the present invention is such that x is a number satisfying 0.90 ≦ x ≦ 0.98.
By setting x in such a range, the phosphor composition that realizes high emission intensity by reducing particularly the residual (mixture) of impurities that cause a decrease in emission intensity, that is, simple oxides (and hydroxides) containing Ln. Can be manufactured.

In another preferable production method according to the present invention, R is one or more elements selected from the group consisting of Ce, Pr, Eu and Tb.
A phosphor composition that realizes light emission with high light emission intensity (luminance) by doping (using as an activator) any of Ce, Pr, Eu and Tb as the element R constituting the emission center It can be manufactured easily.

In another preferable production method according to the present invention, Ln is one or two elements selected from the group consisting of La and Y.
When x is set within the above range, the residual (mixture) of simple oxides (and hydroxides) of La and / or Y can be well suppressed, the luminous efficiency is good, and the higher luminous intensity (luminance) is obtained. A phosphor composition that realizes light emission can be manufactured.

As another aspect, the present invention provides a VFD or other fluorescent display device comprising any of the phosphor compositions disclosed herein as a fluorescent material. That is, the fluorescent display device of the present invention typically includes a substrate, an electrode, and a fluorescent material formed in a desired shape, and at least a part of the fluorescent material includes the phosphor disclosed herein. The device in which the composition was used.
The fluorescent display device having this structure (for example, VFD, FED, PDP, various cathode ray tubes (CRT), electroluminescence (EL) elements) emits light with particularly high luminance by using the phosphor composition of the present invention. Can be realized.

Further, according to another aspect of the present invention, in a method for emitting a fluorescent material with a low-energy electron beam or ultraviolet light, any one of the phosphor compositions disclosed herein is used as the fluorescent material. Provide a method.
For example, the phosphor composition of the present invention in which the element R (emission center) is Ce, Pr, and / or Eu in a fluorescent display device (VFD or the like) that emits light by applying a slow electron beam to a fluorescent material. By using it as a fluorescent material, the fluorescent material (specifically, a complex oxide as a main component of the fluorescent material) can be excited by a low-speed electron beam to realize high-luminance light emission.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The phosphor composition disclosed herein is a phosphor composition having Ln, R, M, and O as main constituents (Ln, R, and M are as described above), The atomic ratio (configuration ratio) may be in a predetermined range, and is not limited to a specific compound.

Preferable elements included in the Ln constituting the phosphor composition include yttrium (Y), lanthanum (La), and gadolinium (Gd). Ln may be composed of only one of these, or may be a combination of two or more.
Of these, La, Y, or a combination of La and Y is preferable. Alternatively, a material having a high content of La or Y in Ln is preferable in order to suppress a decrease in light emission efficiency and to realize light emission with a high light emission intensity.

  The element included in the M constituting the phosphor composition is aluminum (Al) and / or gallium (Ga). M may be composed of only one of these, or a combination of these two. In particular, M is preferably Al or has a high Al content from the viewpoint of improving the emission intensity.

  On the other hand, as the element (activator) R constituting the luminescent center, any of the conventionally known rare earth elements that can be luminescent centers can be used. In particular, cerium (Ce), praseodymium (Pr), europium (Eu), and terbium (Tb) are preferable. Among these, Eu capable of realizing high-luminance red light emission, and Pr and Ce capable of realizing green light emission are preferable, and Eu is particularly preferable.

  The phosphor composition disclosed herein typically has x in the above composition, that is, the atomic ratio of Ln + R to M (constituent ratio): (Ln + R) / M is 0.850 <x <0.999. It is a number that satisfies In particular, x is preferably in the range of 0.88 ≦ x ≦ 0.99, and more preferably in the range of 0.90 ≦ x ≦ 0.98.

In particular, when Ln is La, x is in the range of 0.88 ≦ x ≦ 0.98, further in the range of 0.88 ≦ x ≦ 0.95, particularly in the range of 0.90 ≦ x ≦ 0.95. Preferably there is. On the other hand, when Ln is Y, x is preferably in the range of 0.90 ≦ x ≦ 0.98, particularly preferably in the range of 0.95 ≦ x ≦ 0.98.
By including Ln and R with respect to M at such an atomic ratio (configuration ratio), a decrease in emission intensity due to impurities can be reduced, and a phosphor composition with particularly high emission intensity can be obtained.

The phosphor composition disclosed herein typically has y in the above composition, that is, an atomic ratio (component ratio) y of R to Ln + R; R / (Ln + R) is 0.001 ≦ y ≦ 0. It is a number that satisfies 100. In particular, the y is preferably in the range of 0.04 ≦ x ≦ 0.10, and more preferably in the range of 0.06 ≦ x ≦ 0.08.
A phosphor composition having a particularly high light emission luminance can be obtained by doping an element that becomes a light emission center at such an atomic ratio (configuration ratio), particularly Eu or another activator.

As is apparent from the above description, suitable phosphor compositions provided by the present invention include the following.
(1) A phosphor composition having La, R, M, and O as main components.
Here, R and M are as described above, and the atomic ratio x = (La + R) / M with respect to La, R, and M is 0.850 <x <0.999, particularly 0.88 ≦ x ≦ 0.98. The atomic ratio y = R / (La + R) regarding La and R is a number satisfying 0.001 ≦ y ≦ 0.100.

(2) A phosphor composition having Y, R, M, and O as main components.
Here, R and M are as described above, and the atomic ratio x = (Y + R) / M with respect to Y, R and M is 0.850 <x <0.999, particularly 0.90 ≦ x ≦ 0.98. The atomic ratio y = R / (Y + R) regarding Y and R is a number satisfying 0.001 ≦ y ≦ 0.100.

(3) A phosphor composition having Ln, Eu, M, and O as main components.
Here, Ln and M are as described above, and the atomic ratio x = (Ln + Eu) / M regarding Ln, Eu and M is 0.850 <x <0.999, particularly 0.90 ≦ x ≦ 0.98. The atomic ratio y = Eu / (Ln + Eu) for Ln and Eu is a number that satisfies 0.001 ≦ y ≦ 0.100.

(4) A phosphor composition having Ln, R, Al, and O as main components.
Here, Ln and R are as described above, and the atomic ratio x = (Ln + R) / Al regarding Ln, R and Al is 0.850 <x <0.999, particularly 0.90 ≦ x ≦ 0.98. The atomic ratio y = R / (Ln + R) regarding Ln and R is a number satisfying 0.001 ≦ y ≦ 0.100.

Next, a method for producing the phosphor composition of the present invention will be described. The phosphor composition of the present invention can be produced by mixing various raw material compounds (starting materials) and firing at an appropriate temperature, as in the conventional phosphor composition production.
Such a starting material may be any material that decomposes into an oxide during firing, and the raw material compound itself does not necessarily need to be an oxide. Therefore, as starting materials, various hydroxides, carbonates, nitrates, organic acid salts and the like can be used in addition to the original oxides. Thus, in the production method of the present invention, as a raw material compound (preferably in powder form), a compound containing Ln, a compound containing R, and a compound containing M are mixed in the above ratio (of the calcined composition). Mix so as to satisfy the atomic composition ratio. Such mixing may be performed dry by putting each raw material compound in a predetermined vessel (for example, an agate mortar) or wet (for example, mixing by adding acetone in an agate mortar). In addition, since it is the same as that of what was demonstrated in the said phosphor composition about the range of suitable R, Ln, and x selected here, the description is abbreviate | omitted.

  Next, the obtained mixture is preferably fired in a predetermined temperature range in the air or in an oxidizing atmosphere (for example, in an atmosphere containing oxygen at a higher concentration than the air). As a result, the phosphor composition of the present invention is obtained. The firing conditions such as the firing temperature may be the same as in the case of producing a conventional phosphor, and are not particularly limited. However, the firing is preferably performed at a maximum firing temperature of 800 to 1600 ° C., particularly 1000 to 1500 ° C. Is called. The firing time is usually 1 to 50 hours, preferably 10 to 40 hours, particularly 15 to 35 hours, for example, about 20 to 30 hours. In order to obtain a mixed powder having a uniform composition and particle size, pre-baking may be performed before the main baking. Pre-baking is performed at 300 to 1000 ° C., preferably about 500 to 700 ° C. for 1 to 15 hours, preferably about 5 to 10 hours. The temporarily fired powder (temporarily fired powder) is typically pulverized and then fired again.

  Usually, the firing is performed by placing the prepared raw material compound sample in a suitable heat-resistant container for firing such as an alumina crucible and firing at the above temperature. Preferably, baking is performed at a high temperature of about 1200 ° C. to 1400 ° C. for about 20 to 30 hours (preferably 22 to 28 hours). Although not particularly limited, the rate of temperature increase from room temperature to the maximum firing temperature is preferably about 100 to 200 ° C. per hour. After the firing, the product is typically cooled in a furnace to obtain a powdery product (that is, a fired phosphor composition).

  When trying to obtain a phosphor composition having a predetermined shape, the mixed sample is molded into a predetermined shape by various molding means, and then molded into a pellet (for example, uniaxial molding). ) Is preferably fired as described above. Further, when the molded sample is fired, the contact area between the raw material powders is increased as compared with the case where the powder itself is fired, so that the sintering reaction can be promoted.

  The powdery phosphor composition obtained by the above-described firing procedure or the like can be subjected to various secondary processing according to its utilization form as in the case of conventional ceramics. For example, when used as a fluorescent element of a fluorescent display tube (see FIG. 7) as shown in the examples described later, the powdered phosphor composition may be processed into a thin film or plate suitable for the mounting shape. . For example, after processing the phosphor composition of the present invention into a paste using an appropriate vehicle containing an organic binder, the phosphor composition is applied to a glass substrate on which an anode electrode is formed by screen printing, and the organic binder is removed by firing. As a result, an anode substrate coated with the phosphor composition of the present invention can be produced.

The phosphor composition of the present invention can be processed into various forms by performing such secondary processing, and can be used as a fluorescent element for light emission in VFD, FED, CRT and the like. The processing method, processing means, and the like employed may be the same as those used for processing a conventional phosphor composition, and do not particularly characterize the present invention, and thus will not be described in detail.
The present invention will be described in more detail with reference to several examples described below, but the present invention is not intended to be limited to those shown in these examples.

In this example, phosphor compositions having different La contents were produced in a composition comprising a phosphor obtained by doping Eu with a composite oxide having the general formula LaAlO ₃ as a main constituent element. That is, La: Eu: Al = 0.82 to 0.93: 0.06: 1, and the ratio of (La + Eu) / Al was changed from 0.88 to 0.99.
As raw material compounds, powdered La ₂ O ₃ , Al ₂ O ₃ , and EuCl ₃ were weighed out at the blending ratios shown in Table 1, and thoroughly mixed using an alumina mortar. Thereby, in the table, sample No. A total of five types of mixed samples (hereinafter referred to as “raw material powder”) indicated by A1 to A5 were obtained.

  The obtained raw material powder was put in an alumina crucible and fired at 1200 to 1400 ° C. for 24 hours. Subsequently, the obtained baked powder was pulverized in an alumina mortar and then sieved to remove coarse particles. By this series of processing, sample No. The phosphor composition powders were obtained from the raw material powders A1 to A5, respectively.

Next, with respect to each of the obtained powders of the phosphor composition, emission spectra when excited with ultraviolet rays were measured according to the following measurement methods, and the emission intensities were compared.
That is, each phosphor composition powder obtained above was filled in a glass holder of a predetermined size. Next, the glass holder was placed in a sample chamber of a fluorescence spectrophotometer (Hitachi, Ltd. product: F-4500), and an emission spectrum having a wavelength in the range of 300 to 800 nm was measured by irradiating 339 nm ultraviolet rays. FIG. It is a graph which shows the emission spectrum measured about the fluorescent substance composition powder obtained by A3. The numerical value on the horizontal axis in the figure is the wavelength (nm), and the vertical axis indicates the emission intensity (au). At this time, emission spectra were observed at 590 nm (yellowish orange) and 620 nm (red).

In addition, the emission intensity comparison of each sample was performed by using the peak height at the peak position (620 nm) of the emission spectrum as the emission intensity (au) by ultraviolet excitation. 2 is a graph in which the peak height (emission intensity: a.u.) ratio of the emission spectrum is plotted against the (La + Eu) / Al ratio of each phosphor composition (sample Nos. A1 to A5). Here, the peak height of the emission spectrum of the phosphor composition when the (La + Eu) / Al ratio is 0.95 was set to an intensity ratio of 0.8. (Accurately, in Example 2 below, the peak height of the emission spectrum of the phosphor composition when the (Y + Eu) / Al ratio is 0.99 was defined as the intensity ratio 1).
As apparent from FIG. 2, the ratio of (La + Eu) to Al is approximately 0.88 or more and 0.99 or less, particularly 0.88 or more and 0.98 or less, more preferably 0.88 or more. A remarkably high value was observed when it was 0.95 or less, most preferably 0.90 or more and 0.95 or less. Note that the emission intensity is highest when the ratio is 0.95, and decreases as the ratio approaches 1, while it is confirmed that the ratio decreases as the ratio becomes lower than 0.95. It was.

Next, sample no. A3 and No. The XRD profile of the phosphor composition obtained by A5 was measured with an X-ray diffractometer (manufactured by Rigaku Corporation; RAD-B type). Sample No. The XRD profile of the phosphor composition obtained by A3 is shown in FIG. The XRD profile of the phosphor composition obtained by A5 is shown in FIG. In addition, a comparative graph showing the peak position of the XRD profile by LaAlO ₃ and La (OH) ₃ is placed below the above. Comparing FIG. 3 and FIG. 4, the pattern of LaAlO ₃ is recognized in both cases, but the pattern of La (OH) ₃ is hardly recognized in FIG. 3, whereas this pattern is shown in FIG. Is recognized. Therefore, sample no. It can be seen that La (OH) ₃ is generated in the phosphor composition obtained by A5. For this reason, it can be seen that the impurity La (OH) _3, which is a component that does not emit light, is mixed, and the emission intensity is relatively lowered.

In this example, phosphor compositions having different Y contents (component ratios) were produced in a composition containing a phosphor in which Eu was doped in a composite oxide having the general formula: YAlO ₃ . That is, Y: Eu: Al = 0.82 to 0.93: 0.06: 1, and the ratio of (Y + Eu) / Al was changed from 0.88 to 0.99.
A phosphor composition was produced in the same manner as in Example 1 except that powdery Y ₂ O ₃ , Al ₂ O ₃ , and EuCl ₃ were used as raw material compounds at the blending ratios shown in Table 2.

  About each obtained powder of the phosphor composition, the emission spectrum at the time of exciting with an ultraviolet-ray was measured like Example 1, and the emitted light intensity was compared. 5 is a graph in which the peak height (emission intensity: a.u.) ratio of the emission spectrum is plotted against the (Y + Eu) / Al ratio of each phosphor composition (sample Nos. B1 to B5). Here, the peak height of the emission spectrum of the phosphor composition when the (Y + Eu) / Al ratio was 0.99 was defined as an intensity ratio of 1.

  As is clear from FIG. 5, the red emission intensity by ultraviolet excitation is remarkably improved when the ratio of Y + Eu to Al is approximately 0.88 or more and 0.99 or less, particularly 0.90 or more and 0.98 or less. Was recognized. The emission intensity was highest when the ratio was 0.98, and decreased as the ratio approached 1. On the other hand, it was confirmed that the emission intensity decreased as the ratio became lower than 0.98.

In this example, phosphor compositions having different Eu contents (concentrations) were prepared in a composition containing a phosphor obtained by doping Eu into a composite oxide having the general formula LaAlO ₃ . That is, in the general formula (La _1-y Eu _y ) _0.99 AlO ₃ , the value of y (that is, the Eu concentration) was changed from 0.04 to 0.10. Accordingly, the Eu concentration with respect to the sum of La and Eu is 4 mol% to 10 mol%, La: Eu: Al = about 0.95 to 0.89: 0.04 to 0.10: 1, Eu / (La + Eu ) The ratio was varied from 0.04 to 0.10.
A phosphor composition was produced in the same manner as in Example 1 except that powdery La ₂ O ₃ , Al ₂ O ₃ , and EuCl ₃ were used as raw material compounds at the blending ratios shown in Table 3.

  About each obtained powder of the phosphor composition, the emission spectrum at the time of exciting with an ultraviolet-ray was measured like Example 1, and the emitted light intensity was compared. 6 is a graph in which the peak height (emission intensity: a.u.) ratio of the emission spectrum is plotted against the Eu concentration (mol%) of each phosphor composition (sample No. C1 to C4). Here, the peak height of the emission spectrum of the phosphor composition when the Eu concentration was 8 mol% was defined as an intensity ratio of 1.

  As is clear from FIG. 6, the red emission intensity by ultraviolet excitation is when the Eu concentration is 4 mol% or more and 10 mol% or less, further 6 mol% or more and 10 mol% or less, particularly 8 mol% or more and 10 mol% or less. It was found to be expensive. The emission intensity was highest when the Eu concentration was 8 mol%.

In this example, a fluorescent display tube, which is a typical example of a fluorescent display device, was constructed using the phosphor composition obtained in Examples 1 and 2.
An amount of indium oxide powder corresponding to about 12% by mass with respect to the entire phosphor composition powder obtained in each of the above Examples was added and mixed well. Furthermore, an appropriate amount of an appropriate vehicle was added and mixed well to prepare a paste. The prepared paste (hereinafter referred to as “phosphor composition paste”) may be adjusted in viscosity by adding a diluent (solvent) if necessary.
Next, a total of 10 phosphor composition pastes obtained (corresponding to sample Nos. A1 to A5 of Example 1 and sample Nos. B1 to B5 of Example 2 respectively) were used on the graphite anode plate. A fluorescent portion having a predetermined pattern was screen-printed in a thick film. In this way, a fluorescent display tube was constructed by a conventionally known process using the anode plate in which the thick fluorescent portion (hereinafter referred to as “phosphor layer”) corresponding to the fluorescent element was formed. The constructed fluorescent display tube 10 is specifically as follows. FIG. 7 is a perspective view of the fluorescent display tube 10 according to the present embodiment, with a part thereof cut away.

The fluorescent display tube 10 manufactured here is a substrate 12 made of an inferior green material such as glass, ceramics, and cocoons provided with a plurality of phosphor layers 20S, 20D, and 20N as fluorescent elements formed in a predetermined light emission pattern. And a glass spacer 14 formed in a frame shape, a transparent cover glass plate 16, a plurality of anode terminals 18P, a plurality of grid terminals 18G, a cathode 18K, and an auxiliary grid terminal 18SG. Yes.
Thus, the substrate 12, the spacer 14, and the cover / glass plate 16 are sealed with each other to form an airtight container, and a vacuum space surrounded by these members is formed therein. .

On the display surface 19 of the fluorescent display tube 10 covered with the vacuum space of the substrate 12, a plurality of phosphor layers 20S representing “8” character shapes in segments, one phosphor layer 20D representing dot shapes, One phosphor layer 20N or the like that has a “1” character shape is arranged. Each of the phosphor layers 20S, 20D, and 20N is surrounded by the grid electrode 22 and the auxiliary grid electrode 24, respectively.
Of the phosphor layers 20S, 20D, and 20N, the ones predetermined for each display digit are connected to the anode terminals 18P through anode printed wirings 34 (FIG. 9) described later. Has been. Each grid electrode 22 is connected to each grid terminal 18G via a grid wiring 26, and each auxiliary grid electrode 24 is connected to each auxiliary grid terminal 18SG via an auxiliary grid wiring 28.

Further, a pair of filament support frames 30 (only one of which is located on the right side in FIG. 7) provided with the cathode terminals 18K are fixed to both ends of the substrate 12, respectively. 30, a plurality of fine filaments (filaments / cathodes) 32 functioning as a directly heated cathode (cathode) are parallel to the longitudinal direction of the substrate 12 and separated from the display surface 19 of the substrate 12. It is stretched to be at the height position.
The filament 32 is made of, for example, a tungsten wire whose surface is coated with an oxide solid solution of an alkaline earth metal having a relatively low work function such as (Ba, Sr, Ca) O as an electron emission layer. It is.

FIG. 8 and FIG. 9 which is a sectional view taken along line IX-IX of FIG. FIG.
As shown in these drawings, the anode printed wiring 34 connected to the anode terminal 18P is formed on the display surface 19 of the substrate 12 by a thick film screen printing method or a vapor deposition method. On top of that, an insulator layer 38 having a predetermined thickness and appropriately including a through hole 36 penetrating in the thickness direction is fixed. The insulator layer 38 is formed by a thick film screen printing method or the like, and is composed of a low melting point glass and a color pigment.

On the insulator layer 38, a graphite layer 40 having a slightly larger pattern shape similar to the phosphor layer 20S is formed at a position where the graphite layer 40 is electrically connected to the anode printed wiring 34 through the through hole 36. Yes. This graphite layer 40 functions as the anode of the display tube 10.
In the present embodiment, as described above, the phosphor layers 20S, 20D and 20N are formed on the graphite layer (anode plate) 40 by thick printing the phosphor composition paste, and the graphite An acceleration voltage is applied via the layer 40. That is, the phosphor layers 20S, 20D, and 20N that can emit red light.

On the other hand, around the phosphor layer 20 </ b> S, a rib-like wall 44 that is in contact with the outer peripheral edge of the phosphor layer 20 </ b> S is erected in the direction from the top of the graphite layer 40 toward the filament 32. Further, the rib-like wall 44 is surrounded by an auxiliary rib-like wall 46 erected on the green body layer 38. The rib-like wall 44 and the auxiliary rib-like wall 46 are made of a low-melting glass, an inorganic filler such as alumina, etc., and have the same height dimension, and the upper end of each is higher than the phosphor layer 20S. Located on the upper side.
The grid electrode 22 and the auxiliary grid electrode 24 are thick film conductors mainly composed of a particulate conductive material such as particulate graphite, silver, palladium, copper, aluminum, nickel, and the like by a thick film screen printing method. The rib-like wall 44 and the auxiliary rib-like wall 46 are provided at the tops with a predetermined thickness. The grid electrode 22 and the auxiliary grid electrode 24 include a grid wiring 26 formed on the insulator layer 38, an auxiliary grid wiring 28, a grid pad 48 formed continuously therewith, and an auxiliary grid pad 50. Are connected to the grid terminal 18G and the auxiliary grid terminal 18SG, respectively.

  As shown in FIG. 7, an exhaust pipe 52 made of cylindrical glass is provided at the left end portion of the fluorescent display tube 10 according to this embodiment, that is, one end portion in the longitudinal direction. In the manufacturing process of the fluorescent display tube 10, the exhaust pipe 52 is evacuated from the inside after the above-described substrate 12, spacer 14, and cover / glass plate 16 are sealed with glass to form an airtight container. The tip is melted by a gas burner after exhausting.

  When driving the fluorescent display tube 10 configured as described above, an acceleration voltage is sequentially applied to each grid electrode 22 in a state where a predetermined heat current is steadily passed through the filament 32, and a plurality of the voltage is synchronized with each other. An acceleration voltage is applied via the graphite layer 40 to any one of the phosphor layers 20S, 20D, and 20N that should emit light. As a result, the thermoelectrons emitted from the filament 32 are accelerated by the grid electrode 22 to which an acceleration voltage is applied. Thus, when an accelerating voltage force is applied to the phosphor layers 20S, 20D, and 20N surrounded by them, the thermoelectrons collide and the phosphor layers 20S, 20D, and 20N emit light. Here, the grid electrode 22 is a control electrode that controls the arrival of thermoelectrons to the phosphor layers 20S, 20D, and 20N, and the auxiliary grid electrode 24 eliminates the influence of the negative electric field formed by the surrounding grid electrode 22. Thus, the thermoelectrons are directed uniformly toward the phosphor layers 20S, 20D, and 20N. The details of the driving method are not particularly necessary for understanding the phosphor composition disclosed herein, and are omitted because they are well known and common knowledge matters for those skilled in the art.

  Using a total of 10 types of fluorescent display tubes provided with a phosphor layer composed of the phosphor composition powder of the sample of any one of Examples 1 and 2 constructed as described above, a predetermined interval is provided between the cathode and the anode. A voltage was applied, and thermal electrons from the filaments were projected onto the phosphor composition to cause the phosphor composition to emit light. Thus, the luminance of the phosphor composition was measured with a luminance meter (Topcon BM-7) while the phosphor composition was emitting light. In this example, the voltage between the cathode and the anode (excitation voltage) was measured as 26V. As a result, it was confirmed that all phosphor layers can emit light with particularly high luminance (brightness) when excited by a low-speed electron beam (for example, 50 V or less, here 26 V).

It is a graph which shows the emission spectrum by ultraviolet excitation about the fluorescent substance composition manufactured in one Example. It is a graph which shows the relationship between the emitted light intensity by ultraviolet excitation, and (La + Eu) / Al ratio about each fluorescent substance composition manufactured in one Example. It is a graph which shows a XRD profile about the fluorescent substance composition manufactured in one Example. It is a graph which shows a XRD profile about the other fluorescent substance composition manufactured in one Example. It is a graph which shows the relationship between the light emission intensity | strength by ultraviolet excitation, and (Y + Eu) / Al ratio about each fluorescent substance composition manufactured in one Example. It is a graph which shows the relationship between the light emission intensity | strength by ultraviolet excitation, and Eu density | concentration about each fluorescent substance composition manufactured in one Example. It is a perspective view of a partially broken fluorescent display tube in one embodiment. It is a partial top view which shows the fluorescent substance layer vicinity in FIG. It is the IX-IX sectional view taken on the line in FIG.

Explanation of symbols

10. ・ Fluorescent display tube 20S, 20D, 20N ・ ・ Phosphor layer

Claims (10)

Ln (Ln is one or more elements selected from the group consisting of Y, La and Gd) and R (R is one or two or more elements selected from rare earth elements that can be the emission center) Is a phosphor composition comprising, as main components, M (which is an element), M (M is one or two elements selected from the group consisting of Al and Ga), and O,
Here, the atomic ratio x = (Ln + R) / M regarding the Ln, the R, and the M is a number that satisfies 0.850 <x <0.999,
The phosphor composition according to claim 1, wherein the atomic ratio y = R / (Ln + R) relating to Ln and R is a number satisfying 0.001 ≦ y ≦ 0.100.   The phosphor composition according to claim 1, wherein x is a number satisfying 0.90 ≦ x ≦ 0.98.   The phosphor composition according to claim 1 or 2, wherein R is one or more elements selected from the group consisting of Ce, Pr, Eu, and Tb.   The phosphor composition according to claim 1, wherein Ln is one or two elements selected from the group consisting of La and Y. A compound containing Ln (Ln is one or two or more elements selected from the group consisting of Y, La, and Gd) and R (R is a kind selected from rare earth elements that can be the emission center) Or a compound containing M (M is one or two elements selected from the group consisting of Al and Ga).
The atomic ratio x = (Ln + R) / M with respect to Ln, R and M is 0.850 <x <0.999,
Mixing so that the atomic ratio y = R / (Ln + R) for Ln and R is 0.001 ≦ y ≦ 0.100;
Baking the mixture;
A method for producing a phosphor composition, comprising:   The manufacturing method according to claim 5, wherein x is a number satisfying 0.90 ≦ x ≦ 0.98.   The manufacturing method of Claim 5 or 6 whose said R is 1 type, or 2 or more types of elements chosen from the group which consists of Ce, Pr, Eu, and Tb.   The manufacturing method according to any one of claims 5 to 7, wherein Ln is one or two elements selected from the group consisting of La and Y. In a fluorescent display device comprising a substrate, an electrode, and a fluorescent material,
A fluorescent display device, wherein the phosphor composition according to any one of claims 1 to 4 is used for at least a part of the fluorescent material. In a method of emitting a fluorescent material with a low-speed electron beam or ultraviolet rays,
The phosphor composition according to any one of claims 1 to 4 is used as the fluorescent material.

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