JPS5923354B2 - Method for producing cerium-activated yttrium orthoaluminate phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a short afterglow ultraviolet phosphor,
In particular, it relates to a method for producing a yttrium orthoaluminate (YAl03) phosphor activated with cerium (Ce).

The luminescence decay time (τl/e) of Ce-activated phosphor is generally l
It is very short, less than 00 nanoseconds, and there is interest in its application to fly fender spot tubes or beam index tubes.

A fly fern spot tube is required to have an emission spectrum covering the entire visible range, and for a beam index tube, the peak wavelength (λmax) of the emission spectrum is 340 to 40.
It is required to be in the range of 0 nm. Commercially available Ce-activated phosphors are P16, P46, P47,
There are four types of P48, and these have the following configuration.

Pl6; Ca2MgSi2O7:Ce, Liλmaxχ
370nmP46; Y3Al5O12:Ceλmaxχ
540P47; Y2SiO5: Ceλmaxχ410n
mP48; P46:P47 mixed at a ratio of 70:30.

Among these, in consideration of τl/e λmax and stability against electron beam impact, P48 is considered promising for use in fly flea spot tubes, and P47 is considered promising for use in beam index tubes.

On the other hand, Y2O3-Al2O3 system has Y2O3:Al2
Y3Al5O12 with O3 of 3:5, YAlO3 with 1:l
and 2:1 Y4Al2O9.

Among these phosphors activated with Ce, Y3Al5012:Ce (P46) is the most widely studied. This is because Y3Al5O12 is the most stable and can be relatively easily obtained as a single phase even by a simple solid phase reaction method. YAlO3:Ce phosphor is manufactured by the Japanese Patent Publication No. 50-298
As shown in the specification of No. 33, it is excellent as a phosphor for flying spot tubes, but according to the same publication, it is stable against electron beam impact, and according to the paper by Weber et al.
In the YAlO3:Ce single crystal grown by the Czyochralski method, τ1/e - 16 ns, λMax≧370 with ultraviolet excitation
nm, and is also promising as a phosphor for beam index tubes.

The present applicant focused on this point and first developed this YAlO3:Ce.
A phosphor with improved luminous intensity was published in Japanese Patent Application Laid-Open No. 51-141.
It has been filed as No. 787. The object of the present invention is to
The purpose of this method is to improve the emission intensity of the O3:Ce phosphor, but the method is completely different from that of JP-A-51-141787.

In the invention of JP-A-51-141787, the Al/(Y+Ce) value, which is the ratio of the number of Al ions contained in the mixture of starting materials to the sum of the numbers of Y ions and Ce ions, is the stoichiometric ratio. It is characterized in that a barium compound such as barium carbonate is further added to this mixture as a reaction accelerator. That is, the emission intensity of the produced phosphor is improved by adding a reaction accelerator. On the other hand, the present invention is characterized in that the Al/(Y+Ce) value in the raw material mixture is reduced from 1 to 0.95 to 0.65, and this mixture is fired at 1100°C to 1400°C. , a reaction accelerator may or may not be added. In other words, the emission intensity of the generated phosphor is improved by Al/(Y+Ce)
is set to 0.95 to 0.65, and the firing temperature is set to 1100 to 14
This is brought about by setting the temperature to 00°C. The concentration range of Ce added as an activator is 0.01 to 0.01 to the molar amount of Y, as in the case of ordinary Ce-activated phosphors.
5 mol% is desirable.

Even if the Ce concentration is outside this range, if the Al/(Y+Ce) value is decreased below 1, an increase in luminescence intensity is observed.
The absolute value of the emission intensity gradually decreases, making it impractical. The present invention will be explained in detail below based on Examples.

Example 1 99.99% with scorching heat loss correction in advance
Yttrium oxide Y2O3, 99.99% aluminum oxide Al2O3, and 99.99% cerium fluoride were weighed in amounts proportional to the following mole numbers.

Y2O3・・・・・・・・・・・・0.495 mol Al2O3・・・・・・・・・0.5y mol C
eF3・・・・・・・・・・・・0.010 mol However, y is 1.00, 0.97, 0.94, 0.91
, 0.88, 0.83, 0.78, 0.73, 0.65
, 0.50 were prepared.

The weighed raw materials were mixed in ethyl alcohol in a wet ball mill for about 20 hours.

The Al/(Y+Ce) value in each mixture is 2×0.5y/(
0.495X2+0.01), so Al/(Y+C
e)=y. After drying each mixture, put it in a platinum crucible,
It was baked at 1400°C for 4 hours. YAlO3, Y3Al5O contained in each product was determined by powder X-ray diffraction.
Changes in the abundance of l2, Y4Al2O, and Y2O3 phases were tracked.

A typical example is shown in Figure 1. YAlO3 is (121), Y3
Al5Ol2 is (420), Y4Al2O9 is (221
) and Y2O3 are plotted against the peak intensity of the diffraction line due to the (222) plane, and each sample was measured under the same conditions.

As is clear from Fig. 1, as y decreases, YAlO3,
Y3Al5Ol2 phase decreases, Y4Al2O9, Y2O
Phase 3 increases. FIG. 2 shows the ultraviolet emission intensity of each product. The measurement was carried out using a demountable electron beam irradiation device, the acceleration voltage of the electron beam was 10K, and the current density was 0.3μ.
A/CrA. The light emitted by electron beam excitation is HOy
The light was received by Hamamatsu TV R666 Photomaru through an aU36O filter. Note that when the emission intensity of the commercially available P47 phosphor is measured using this measurement system, it is 1.

In the figure, when y-1.0, the number of Al ions and Y
This is a case where the sum of the numbers of ions and Ce ions is equal, and this is a YAlO3:Ce phosphor known as a conventional example. As described above, the YAlO3 phase decreases monotonically as y decreases, but as shown in FIG. 2, the ultraviolet emission intensity increases once as y decreases, and then decreases again when y≦0.73. The emission intensity showed a maximum value when y was in the range of 0.91 to 0.73, and the emission intensity increased by about 20% compared to the conventional example of y-1.

This is equivalent to or more than the effect of increasing the luminescence intensity by adding a Ba compound as shown in JP-A-51-141787 by the present applicant. In addition, Y2O3, Y4Al
Since the 2O9 phase is dissolved in dilute nitric acid, by washing the product with dilute nitric acid, the X-ray diffraction peaks of these phases decrease or disappear, but the ultraviolet emission intensity increases, and the emission intensity of the present invention is improved. The increase is Y2O3 or Y4Al
It is clear that this is not related to Ce emission in the 2O9 phase. Example 2 In Example 1, the firing temperature was set to 1100°C.

All other conditions are the same as in Example 1. The measurement results of X-ray diffraction and ultraviolet emission intensity for each product are shown in FIGS. 3 and 4. The amount of YAlO3 phase produced varies when Y is 1 to 0.
It is almost constant up to 7 and shows a decrease when y<0.7,
The ultraviolet emission intensity showed a maximum value at y~0.65, and showed an increase of about 30% compared to the conventional example of y-1, and an increase equal to or higher than that obtained by the addition of a Ba compound by the present applicant.

Example 3 In Example 1, the firing temperature was set to 130°C.

All other conditions are the same as in Example 1. The measurement results of the ultraviolet emission intensity of each product are shown in FIG. As shown in Fig. 5, the ultraviolet emission intensity increases significantly as y decreases, reaching a maximum value when y is 0.83 to 0.73, which is an increase of about 60% compared to the conventional example of y-1. Ta. As is clear from Examples 1 to 3, in y1, the firing temperature was 1100'C to 1
While the ultraviolet emission intensity shows a nearly constant value even when changing at 400'C, it changes considerably at y×1. When Y2O3, Al2O3, and CeF3 are used as starting materials, the most desirable properties are obtained when y is ~0.9 to ~0.7 and the firing temperature is ~1300C. Example 4 Y2O3, YF3, Al2O3 as starting materials
An experiment similar to that in Example 1 was conducted using CeO2.

Y2O3・・・・・・・・・・・・0.485 mole YF3・・・・・・・・・・・・0.020 mole Al2O3・・・・・・・・・...0.5y mol C
eO2・・・・・・・・・・・・0.010 mol However, three types of y-1, 0.88, and 0.78 were prepared,
It was baked at 1300°C for 4 hours. The ultraviolet emission intensity of each product was as shown in FIG. 6, and increased by about 40% when y×1.

Note that in this example, YF3 was not used, and Y2O3, Al2
Even with the combination of O3 and CeO2 alone, an increase in the ultraviolet emission intensity due to a decrease in y was observed, but it was only about 10% at most.
With the use of YF3, the effect becomes more pronounced. Example 5 In Example 4, y-0.78 was fixed, the amount of YF3 used was varied, and the following weights were weighed in proportion to the number of moles.

Y2O3・・・・・・・・・・・・(0.495
-Ix) Molar YF3...
Mol Al2O3・・・・・・・・・0.5×0.
78 mol CeO2・・・・・・・・・・・・0.
010 mol However, x-0, 0.003, 0.010,
．． 0.020, 0.050, . Six types of 0.100 were prepared and fired at 1300°C for 4 hours.

The ultraviolet emission intensity of each product is as shown in FIG.

From this result, the amount of YF3 is 0.010 mol to 0.05 mol.
It has become clear that the range of 0 mol is optimal. Example 6 As a starting material, AlF3 was used instead of YF3 in Example 4.
A similar experiment was conducted using

Y2O3・・・・・・・・・・・・・・・0.495 mol Al2O3・・・・・・・・・(0.5y-0
．． 010) Molar AlF3・・・・・・・・・・・・・・・
・0.020 mol CeO2・・・・・・・・・・・・
...0.010 mol However, two types, y-1 and 0.76, were prepared and fired at 1300°C for 4 hours.

The ultraviolet emission intensity of the product is 7.0 in the conventional example of y1, and y-
At 0.76, it became 9.2, an increase of about 30%. In this case as well, as in Example 4, the use of AlF3 resulted in a remarkable increase in luminescence intensity. Example 7 In Example 4, CeF3 was used instead of CeO2, and y-
A mixture of two types, 1 and y-0.78, was fired at 1300°C.

The ultraviolet emission intensity of the product is 6.8y-0 in the conventional example of y-1.
．． 78 and 10.3, which was almost the same result as in the case of CeO2. As described above, the present invention provides a method for producing a cerium-activated yttrium orthoaluminate phosphor, in which Al/(Y+Ce) in a mixture of starting materials is
The value is less than the stoichiometric value 1 from 0.95 to 0.65
The starting materials are weighed and mixed so that the starting materials are in the range of 1,100°C to 1,400°C, and the mixture is fired at a temperature of 1,100°C to 1,400°C, thereby dramatically improving the luminescence intensity.

[Brief explanation of drawings]

Figures 1 and 3 are at 1400°C and 1100°C, respectively.
YAlO3, Y3Al5Ol2 in the product calcined with
,Y4Al2O,,Y2O3 phase abundance Al/(Y+
Ce) Diagrams showing value-dependent characteristics, Figures 2 and 4 to 7
The figure shows the ultraviolet emission intensity of the phosphor produced according to the present invention.
FIG. 3 is a diagram showing (Y+Ce) value dependence characteristics.

Claims (1)

[Claims] 1 Y_2O_3, Al_2O_3 and CeF_3 or CeO_2 are included in the starting materials, and the ratio of the number of aluminum ions to the sum of the numbers of yttrium ions and cerium ions in the mixture of starting materials Al/(Y+Ce) The starting materials are weighed and mixed so that the value is 0.95 to 0.65 and the molar ratio of cerium to yttrium is 0.01 to 5 mol%, and this mixture is heated at a temperature of 1100°C to 1400°C. A method for producing a cerium-activated yttrium orthoaluminate phosphor, the method comprising firing at a high temperature. 2. The method for producing a cerium-activated yttrium orthoaluminate phosphor according to claim 1, wherein the starting material contains 0.010 to 0.050 mol of YF_3. 3. The method for producing a cerium-activated yttrium ortho aluminate phosphor according to claim 1, characterized in that the starting material contains AlF_3.