JPS6112785A - Red light emitting fluorescent substance - Google Patents

Abstract

PURPOSE:An economical red light emitting fluorescent substance, consisting of a red light emitting specific trivalent Eu-activated yttrium oxide based fluorescent substance, and having a small particle diameter and high brightness. CONSTITUTION:A red light emitting fluorescent substance expressed by the formula (x is 0<x<=0.05; y is 0.01<=y<=0.3; A is In or Sc), and obtained by dissolving Y2O3, Eu2O3, In2O3 and Sc2O3 in a nitric acid solution, adding oxalic acid to the resultant solution to give coprecipitates of oxalates, washing the coprecipitates with water, filtering the coprecipitates, drying the resultant filter cake, placing the dried cake in a quartz crucible or alumina crucible, primarily firing the cake at 800-1,000 deg.C in the air for 1-2hr, cooling the substance, secondarily firing the cooled substance at 1,200-1,400 deg.C in the air for 1-5hr, cooling and filtering the resultant composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improved trivalent europium-activated IJ oxide based red-emitting phosphor.

[Technical background of the invention and its problems 3 The trivalent europium-activated yttrium oxide phosphor is
It is widely used for wavelength range fluorescent lamps and single-bulb fluorescent lamps.

Conventionally, as a method for improving the brightness of a trivalent europium-activated yttrium oxide phosphor, for example, Japanese Patent Application Laid-Open No. 56-9
There have been improvements in the firing method as seen in No. 9276 and Japanese Unexamined Patent Publication No. 55-161882. However, these methods have the drawback that the particle size of the phosphor increases, and when applied to a fluorescent lamp, the amount of adhesion increases, resulting in high costs.

[Purpose of the invention]

The present invention was made to solve the above-mentioned drawbacks, and an object of the present invention is to provide an improved trivalent europium-activated yttrium oxide red-emitting phosphor having a small particle size and high brightness.

[Summary of the invention]

Specifically, the red-emitting phosphor of the present invention is characterized in that a part of the yttrium in the conventional trivalent europium-activated yttrium oxide is replaced with at least one of In and Sc, and is represented by the following formula (Y+ -x- yAxEuy)t(1
(In the formula, x and y are respectively 0<x<0.05 and 0.0
1 <, y = 0.3, and A represents at least one of In and Sc. ) has the composition shown.

Here, X represents the amount of at least one of In and 8c mixed in the phosphor, and is set to satisfy the relationship Q<x<0.05. In the phosphor of the present invention, I
When n and Sc are blended, the brightness of the resulting phosphor when irradiated with ultraviolet rays is improved. However, if the index X exceeds 0.05, the luminous efficiency will decrease.

Furthermore, the index y is an index representing the amount of Eu blended in the phosphor, and is set to satisfy the relationship 0.01≦Y<0.3. When the index y is less than 0.01, the luminance of the obtained phosphor is extremely low;
Even if the amount exceeds 100%, no significant improvement in the brightness of the resulting phosphor is observed, and it is not economically advantageous since it only involves adding unnecessarily expensive Eu.

The phosphor of the present invention is prepared in the following manner.

i.e. yttrium oxide, europium oxide.

A predetermined amount of indium oxide and scandium oxide is dissolved in a nitric acid solution, and a predetermined amount of oxalic acid is added to obtain coprecipitation of the oxalate salt of the above composition.

After that, the obtained oxalate coprecipitate was washed with water.

Filtered and dried, placed in a quartz crucible or aluminum crucible, and subjected to primary firing for 1 to 2 hours at a relatively low temperature of 800 to 1000°C in the air, and after cooling, heated to 1200 to 1400°C in the air. the second for 1 to 5 hours at a temperature of
Perform firing. The resulting composition is cooled and sieved to obtain the phosphor of the present invention.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on examples.

Using the raw materials shown in the Examples table, various phosphors having different amounts of In and Sc were prepared as follows.

Table 1 These raw material compositions are added little by little to a nitric acid solution at 70 to 80°C and dissolved. Next, a predetermined amount of oxalic acid is added to obtain coprecipitation of oxalate of the above composition.

Thereafter, the obtained oxalate is washed with water until its coprecipitated pH becomes about 1PH7, filtered, dried, placed in a quartz crucible, and calcined in the atmosphere at 900° C. for 2 hours. After the obtained fired product was cooled and separated, it was placed again in a quartz crucible and fired in the atmosphere at 1350° C. for 3 hours, cooled and sieved to obtain a phosphor sample of an example.

The crystal types of these various samples were examined by powder X-ray diffraction and were found to be the same as Y-03 (ASTM Card 25-1200).

The relative brightness and particle size of these various samples were measured, and the results are shown in Table 2. (The numbers in Table 2 are
It corresponds to the number in the table. ) Figure 1 also shows indium oxide (curve 1) which combines the relative brightness of these various samples.
) and the number of moles of scandium oxide (curve 2).

The specifications for each of the above measurement items are as follows.

Relative brightness: Various samples with sample numbers 1 to 15 are irradiated with 254 nm ultraviolet rays, and the brightness of each sample at this time is the same wavelength ultraviolet irradiation of the sample (number 16, index X = Q) that does not contain indium oxide or scandium oxide. This is a relative value when the luminance at that time is set to 100, and this represents the magnitude of luminance and luminous efficiency.

Particle size: The particle size of various samples of sample numbers 1 to 16 was measured by the Blaine method.

Table 2 Also, FIG. 2 shows the emission spectrum when the phosphor of the present invention was irradiated with 254 nm ultraviolet rays.

[Effects of the Invention] As is clear from the results shown in FIGS. 1 and 2, the phosphor of the present invention has higher brightness and smaller particles than the conventionally known trivalent europium-activated yttrium oxide phosphor. It turned out to be a red-emitting phosphor with a smaller or similar diameter.

[Brief explanation of drawings]

FIG. 1 shows the relative brightness of a phosphor of the present invention. This is a diagram showing the relationship between the number of moles (index X) of indium oxide and scandium oxide to be blended, and FIG. 2 is an emission spectrum diagram of the phosphor of the present invention when irradiated with ultraviolet light of 254 nm. Agent: Patent Attorney Noriyuki Chika (and 1 other person) No. 1
Figure 0 2 4 4 8 fDX<
xto station

Claims (1)

[Claims] The following formula, (Y_1_−_x_−_yA_xEu_y)_
2O_3 (where x and y are respectively 0<x<0.05
, 0.01≦y≦0.3, and A is at least one of In and Sc).