JPS5944341B2 - fluorescent material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a portion of the alkaline earth metal of the alkaline earth metal borophosphate phosphor activated with divalent europium is replaced by at least one element selected from cerium and terbium. This relates to a phosphor formed by substitution.

Conventionally, copper-activated strontium magnesium orthophosphate (Srl-x-y
-pBaxCay*mu fluorescer, antimony-activated calcium halophosphate fluorescer, etc. are known.

However, these known phosphors have drawbacks that do not necessarily satisfy them in practical terms. In other words, when the copper-activated strontium or magnesium orthophosphate phosphor is used in low-pressure or high-pressure mercury vapor discharge lamps, the copper activator is oxidized by heat treatment during the lamp manufacturing process, resulting in a significant reduction in luminous output. have. In addition, the antimony-activated calcium halophosphate phosphor has a wide emission band when excited by ultraviolet light, and emits luminous energy in the near-ultraviolet wavelength range, which is almost invisible to the human eye, so it has high luminous efficiency when used in discharge lamps for lighting. It has the disadvantage of being insufficient. However, the inventors of the present invention overcame the drawbacks of the above-mentioned phosphor, and the chemical composition formula (wherein X.y, P.m and n are respectively o≦X≦0.5, 0
≦y≦0.2, 0.001≦p≦0.15, 1.75≦
m≦2.30.0.05≦n≦0.23.

) proposed an alkaline earth metal borophosphate phosphor activated with divalent europium.

(Patent Application No. 52-153473 (Japanese Patent Application No. 54-8519)
(See Publication No. 3)) This phosphor emits a blue-green color with a maximum emission wavelength of 480 to 490 nm when excited by short- and long-wavelength ultraviolet rays, blue visible radiation, or cathode rays, and is suitable for use in low-pressure mercury vapor discharge lamps. When used, it exhibits extremely high luminous efficiency for blue-green luminescence and excellent luminous efficiency maintenance characteristics. FIG. 1 shows the emission spectrum of a divalent europium-activated strontium borophosphate phosphor that conforms to the above chemical composition formula. An object of the present invention is to further improve the light emitting output of the above-mentioned phosphor proposed by the present inventors.

Through subsequent research, the inventors of the present invention have determined that a portion of the alkaline earth metal in the host crystal of the divalent europium-activated alkaline earth metal borophosphate phosphor is at least 1% of the alkaline earth metal selected from cerium and terbium. 254 without almost changing the emission spectrum by substituting with a seed element.
It has been found that the luminescence output by nm ultraviolet excitation can be improved. The phosphor of the present invention has a chemical composition formula (wherein Me represents at least one element selected from cerium and terbium, and X, Y.z.p.m and n are each 0≦ X≦0.5, 0≦y≦0.2, 0.001
≦z≦0.10, 0.001≦p≦0.15, 1.75
≦m≦2.30, 0.05≦n≦0.23.

).

In the phosphor of the present invention, the content of at least one element selected from cerium and terbium varies depending on the type of element, but is selected within the range of about 0.01 to 0.06 in terms of the value of z. This is desirable.

Furthermore, if the value of z exceeds 0.10, the light emission output decreases, so it is necessary to prevent the value of z from exceeding 0.10.
Barium and calcium content Each y is O≦X
It can be within the range of ≦0.5, o≦y≦0.2,
When X exceeds 0.5 and Yb'-0.2, the light emission output decreases, and the position of the maximum light emission peak decreases from about 410 to 430.
As the wavelength range shifts to nm, blue light is emitted, and desirable results cannot be obtained. The values of m and n are 1.75≦X≦2
．． 30,. It is desirable that the values of m and n be within the range of 0.05≦n≦0.23, and in particular, the values of m and n are 1.90≦m≦2.1.
0,. The light emission output reaches its maximum value when it is within the range of 0.14≦n≦0.18. Also, the values of m and n are 1.75≦
Outside the ranges of m≦2.30 and 0.05≦n≦0.23, the light emission output decreases. Europium content p is 0.0
It is preferable that the value of p be within the range of 01≦p≦0.15, especially when the value of p is 0.
When the range is 005≦p≦0.05, a phosphor with the highest luminous output can be obtained. Furthermore, if the value of p is less than 0.001, the absorption of excitation radiation is low and practically effective light emission output cannot be obtained, and if the value of p exceeds 0.15, the quantum efficiency is so low that it cannot be used for practical use. . To synthesize the phosphor of the present invention, CacO3, SrcO3, BaCO3, Ca
HPO4, SrHPO4, BaHPO4, (NH4)2
HP04, H3BO3, CeO2, Tb. O,, EU2
A predetermined amount of compounds such as O3 are mixed, and this mixture is packed in an alumina or silica crucible and fired at a temperature of approximately 1000°C in an electric furnace in a reducing atmosphere such as a mixed gas of nitrogen and hydrogen.
The desired phosphor can be obtained by firing at a temperature of 1250 DEG C. for a certain period of time. Note that the above-mentioned raw material compounds may be salts that change into oxides by heating, and nitrates, oxalates, etc. may also be used. Further, the mixing method may be either dry or wet. The phosphor of the present invention is excited by short-wavelength and long-wavelength ultraviolet rays, blue visible radiation, and is also excited by cathode rays, and emits blue-green light with a highly efficient maximum emission wavelength of 480 to 490 nm, making it a fluorescent lamp. It can be used as a fluorescent lamp for mercury vapor discharge lamps and cathode ray tubes. Hereinafter, the present invention will be explained using examples.

Example 1 The above compounds were weighed and mixed, packed in an alumina or porcelain crucible, and fired at a temperature of 1160°C for 2 hours in an electric furnace in a N2 stream containing 25% H.

Tetravalent cerium was reduced to trivalent cerium during firing.

The phosphor obtained by crushing after cooling emits blue-green light upon excitation with ultraviolet rays or cathode rays. The chemical composition of this phosphor is expressed by the formula, and the luminous output upon excitation with 254 nm ultraviolet light was approximately 4% higher than that of a phosphor containing no cerium.

Example 2 The above compounds were weighed and mixed, packed in an alumina or porcelain crucible, and fired at a temperature of 1150°C for 2 hours in an electric furnace in a N2 stream containing 25% H.

During firing, terbium turned into trivalent terbium. The phosphor obtained by crushing after cooling emits blue-green light upon excitation with ultraviolet rays or cathode rays. The chemical composition of this phosphor is expressed by the following, and the luminous output upon excitation with 254 nm ultraviolet light was approximately 4% higher than that of a phosphor not containing terbium.

Example 3 The above compounds were weighed and mixed, packed in an alumina or porcelain crucible, and fired at a temperature of 1160°C for 2 hours in an electric furnace in a N2 stream containing 25% H.

The phosphor obtained by crushing after cooling emits blue-green light upon excitation with ultraviolet rays or cathode rays. The chemical composition of this phosphor is expressed by the formula below, and the luminescence output upon excitation with 254 nm ultraviolet light was approximately 5% higher than that of a phosphor containing neither cerium nor terbium.

In order to investigate the relationship between the content z of cerium and terbium and the luminous output: , phosphors having the chemical composition formula shown below were manufactured by varying the value of z.

The luminescence output of these phosphors upon excitation with 254 nm ultraviolet light was measured. The measurement results are shown in Figure 2. In the figure, the value of the luminous output is shown as a relative value with the luminous output of the phosphor of z=o not containing cerium or terbium as 100. z
An improvement in light emission output is recognized within a range where the value of is about 0.10 or less. It has been confirmed that substantially the same results as shown in FIG. 2 can be obtained even when cerium and terbium are substituted for a phosphor containing barium or calcium in addition to strontium as an alkaline earth metal.

As explained above, the present invention uses a part of the alkaline earth metal of an alkaline earth metal borophosphate phosphor activated with divalent europium that has a predetermined chemical composition formula and emits blue-green light. It is substituted with at least one element selected from cerium or terbium.

As a result, the luminous output is increased, and its practical value is great.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the emission spectrum of a divalent europium-activated strontium borophosphate phosphor, and FIG. 2 is a diagram showing the relationship between the content z of cerium or terbium and the luminescence output.

Claims (1)

[Claims] 1. Part of the alkaline earth metal of the alkaline earth metal borophosphate phosphor activated with divalent europium is cerium,
A phosphor made by substituting at least one element selected from terbium, whose chemical composition formula is m(Sr_1-x-y
-3/2z-pBaxCMezEupO)・(1-n
)P_2O_5・nB_2O_3 (However, Me in the formula represents at least one element selected from cerium and terbium, and x, y, z, p, m and n are each 0.
≦x≦0.5, 0≦y≦0.20<z≦0.100.0
01≦p≦0.15, 1.75≦m≦2.30.0.0
5≦n≦0.23. ) A phosphor characterized by being represented by: