JPS59193983A - Fluorescent substance of silicate of rare earth element - Google Patents

Abstract

PURPOSE:A green emission fluorescent substance producing high luminance with extremely small power output, consisting of a specific fluorescent substance of a silicate of rare earth element activated with terbium. CONSTITUTION:The desired fluorescent substance of a silicate of rare earth element activated with terbium shown by the formula (Ln is Y, Ca, Gd, or Ru; Ln' is Dy, or Pr; p, 2, r, x, and y are in the following relationship 0.50<=p/r<= 1.25, 0<=q/r<=0.20, 0.001<=x<=0.3, 1X10<-6=y<=1X10<-3>). The fluorescent substance is obtained by packing a raw material mixture for the fluorescent substance into a heat-resistant container such as alumina crucible, quartz crucible, etc., calcining it in neutral or reducing atmosphere usually at 1,200-1,500 deg.C once or twice.

Description

[Detailed description of the invention]

The present invention relates to rare earth silicate phosphors, and more particularly to terbium-activated rare earth silicate phosphors that exhibit high brightness green light emission. In recent years, as devices that utilize the light emission of phosphors, such as display devices such as cathode ray tubes and lighting devices such as discharge lamps, have become more and more widely used, it has become easier to further improve their brightness depending on the application. There is. For this reason, for example, cathode ray tubes used in projection televisions use electron beams with high current density to excite the phosphors, and high-pressure mercury vapor discharge lamps use ultraviolet rays with high energy density to excite the phosphors. , therefore a large output is required. By the way, the brightness of a phosphor generally improves as the excitation energy increases, but its characteristics (gamma characteristics) differ from phosphor to phosphor. Therefore, it is believed that the phosphor used in high-energy excitation as described above has good energy conversion efficiency especially in high-energy excitation. In particular, green-emitting phosphors emit light that occupies the main part of the human visual field, so it is of great technical significance to improve its gamma characteristics and obtain good brightness with high-energy excitation. . Although various green-emitting phosphors are known, terbium-activated yttrium silicate phosphors are preferably used for high-energy excitation because of their good gamma characteristics. However, the absolute value of brightness of this phosphor is still not sufficient. In view of the above-mentioned prior art, the present invention provides an improved green light-emitting phosphor that has good gamma characteristics, emits light with sufficient brightness through high-energy excitation, and can therefore produce high brightness with as little output as possible. That is, the present invention provides a phosphor for rare earth silicic acid represented by the compositional formula %. Here, Lnu is yttrium, lanthanum, gadolinium, or lutetium, or two or more thereof, and L1
2 is dysprosium or/and praseodymium. Also, 0.50≦p/r≦1.25.0≦q/r≦0.2
0.0.001≦X≦03 and 1 cutting O≦y≦] cutting O. The phosphor of the present invention having the composition as described above is manufactured as follows. First, the raw materials for the phosphor are:) yttrium oxide (Y2O0, lanthanum oxide (La
20s") - a first group of compounds whose oxidation consists of trinium (Gd20ρ and lutetium oxide (Lu203),
and Y2O3, La2O3, Gd2O3 easily at high temperature.
or at least one compound selected from the second compound group consisting of trinium compounds and lutetium compounds, such as yttrium compounds, lanthanum compounds, and lanthanum compounds that can be converted into Lu2O3;
At least one compound selected from the group of compounds consisting of silicon compounds that can be changed to 02, terbium oxide (Tb407) and i? At least one compound selected from the group of compounds consisting of terbium compounds that can be easily converted to Tb4O7 in 4 lagoons, iv)
A first group of compounds consisting of dysprosium oxide (Dy205) and praseodymium oxide (P r 6011 ), and easily Dy2O3 or P r 601 at high temperatures.
1] fL and v) Fi
Barium J2ide (Bad) and BaO easily with high i islands
31 from the compound group consisting of barium compounds that fall in love with
71
．． -ru. The above phosphor raw materials are stoichiometrically p(Lnl-
x-yTbxLn'y)203・qBaO・rSiO2
[However, Ln is at least one of yttrium, lanthanum, gadolinium, and lutetium, and Ln
'u at least one glaze of nisonuprosium and praseodymium, p%q. r, x and y are 0.50≦p/r≦1, 25.0≦q/
r≦0.20.0.001≦X≦03, and 1×river≦y
≦1×10] The mixed phase is weighed out and mixed thoroughly. It may be carried out in a dry manner using a mixing ball mill, a mixer mill, a mortar, etc., or it may be carried out in a wet manner in the form of a paste using water, alcohol, a weak acid aqueous solution, etc. as a medium. In addition, in the production of phosphors, for the purpose of improving the luminance brightness, powder characteristics, etc. of phosphors that are generally affected,
A fluxing agent is often added to the phosphor raw material mixture, but in the production of the phosphor of the present invention, ammonium fluoride (NH
4F), a-type ammonium fluoride (NH4F-HP), potassium fluoride (KF), lithium chloride (LiC4λ sodium fluoride (NaF), magnesium fluoride (MgF)
2), barium fluoride (BaF2), zinc fluoride (Zn
Emission brightness can be improved by adding and mixing appropriate amounts of F2), aluminum fluoride (AtF3), ammonium chloride (NH4C/=), etc. to the phosphor raw material mixture as a flux. Next, mix the above phosphor raw material mixture with aluminum and quartz. Fill it in a heat-resistant container such as , etc., and perform baking. Firing is performed in air, in a neutral atmosphere such as an argon atmosphere, an elemental gas atmosphere, or a nitrogen gas atmosphere containing a small amount of hydrogen.
1200-1500 in a reducing atmosphere such as a carbon atmosphere
It is carried out once or twice or more at a temperature of preferably 1250 to 1450°C. In this case, in order to ensure that the valence of terbium, which acts as an activator, is trivalent, at least the final firing (or the firing if only one firing) is performed in a neutral atmosphere or in a reducing atmosphere. Preferably, it is carried out in an atmosphere. The firing time varies depending on the temperature of the phosphor raw material mixture filled in the thermal container, the firing temperature employed, etc., but in general, the above firing time (15 minutes to 5 hours is appropriate in the mK range). The phosphor of the present invention is obtained by pulverizing, washing, drying, and sieving the obtained fired product according to operations generally employed in the production of isofluorescent phosphors. FIG. 1 is a graph showing the luminance characteristics of the phosphor of the invention. FIG. Yes, track 6: jr A shows the phosphor of the present invention, and curve B shows the phosphor (comparative example) in which y in the compositional formula of the phosphor of the present invention is 0.Thereby, dysprosium or/and praseodymium are added. It can be seen that the luminance is improved by this. Fig. 2 is a graph showing a typical example of the change in relative luminance when changing one axis of y in the compositional formula of the phosphor of the present invention. It can be seen that when the value of y is 1×l0-6 or more, the effect of improving luminance is remarkable.However,
In the compositional formula of the phosphor of the present invention, if the value of y is larger than 1×]0, a luminescence nuctor specific to dysprosium or praseodymium will appear and the luminescent color will deteriorate; therefore, in the present invention, the upper limit of y in one direction is 1 And this 1
The color of the emitted light does not change after F. FIG. 3 is a graph showing the gamma characteristics of the phosphor of the present invention when the accelerating voltage is 25 kV, where curve A is the phosphor of the present invention and curve B is the phosphor ( Comparative example). This shows that the phosphor of the present invention has sufficiently high luminance when excited at high current density. Note that the dysprosium and/or praseodymium in the phosphor of the present invention is used to sensitize the emission of terbium, and may be used in a trace amount. Further, the phosphor of the present invention containing BaO has more preferable light emission characteristics because BaO has the effect of assisting light emission. The present invention will be explained below with reference to Examples. Example j Yttrium (Y2O2) 203.3
．． 9

[Terbium dioxide (Tb 40.)
37.4 & silicon dioxide (Sin2)
60.1gK dysprosium (Dy203)
0.04. ! 9 Barium nitrate [Ba(NOx)2)
52.3 g of the above phosphor raw materials were sufficiently mixed to become homogeneous, and the 14-gold mixture was filled into an alumina crucible, covered with a lid, and fired at a temperature of 1450° C. for 4 hours. After firing, the resulting fired product was loosened, washed with water, dried, and then hung in a cylinder. In this way, the present invention (YO, 8999
TbO,lDy0.00o1)z05'5102'0.
2BaO phosphor was added to 1(). The emission color of this phosphor under electron beam excitation is yellow-green (x=0335. y=0), which is the same as the emission color of a conventional phosphor made in exactly the same way except for the star containing Dy2O3'f: .587), and the luminance was 8% higher than that of the conventional phosphor. Example 11 Yuba Yttrium (Y2O3) 2o3.
3. ! i' Terbium oxide (Tb40.)
37.47j Silicon dioxide (Sin2)
60. ],! Noraseodymium 9 oxide (Pr60.,)
0.039 Ammonium chloride (NH2Cl)
] 3.9,? The above phosphor raw materials and flux
The method of the present invention (Y
O,8999Tb0,I PrO,0001)203
- Obtained 5io2 phosphor. The emission color of this phosphor is Pr601. under electron beam excitation. It exhibits yellow-green luminescence (x = 0.336, y = 0.587), which is the same as the luminescence color of a conventional phosphor manufactured in exactly the same way except for two things that do not contain Also, y4 degrees was 9% higher. Example 3 Yttrium oxide (Y2O2207.9g Terbium oxide (Tb40.) 29.9g Silicon dioxide
(Sin2) 60. ]g Dysglosium oxide (Dy203) o, o4g Noriu sulfate A
(Ba5O4) 11.7 g (YO,9199TbO,08Dy0.0001) of the present invention was prepared in the same manner as [flJ] except that the above phosphor raw material was used.
A 203'S'02''0.05 BaO phosphor was obtained.The luminescent color of this phosphor was different from that of Dy2O3 under electron beam excitation.
The outside of the vehicle, which does not contain
=Q, 587), and the brightness was 8.0 cm higher than that of the conventional fluorescent lamp itself. Example 4 Yttrium oxide (Y2O2) 203.3 & terbium oxide (Tb 40.) 37.4,
! i+silicon dioxide (Sin2) 60
．． 1g dinuprosium chloride (DyC73.6H20)
0.08g Parium nitrate A [Ba(No,)3
: ] 2e+, 2g The (YO, 8999T) of the present invention was prepared in the same manner as in Example 1 except that the above phosphor raw material was used.
bO,I Dy0.0001)203・5i02'0.
1 BaO phosphor was obtained. Under electron beam excitation, the emission color of this phosphor is yellow-green (x=0.335- y= 0.587), and the luminance was 6% higher than that of the conventional phosphor. Example 5 Yttrium oxide (Y2O2) 203.4g
Terbium oxide (Tb40.) 37.49
Silicon dioxide (Sin, ) 60.19
Zolaceodi oxide A (PrO) 0.039
11 Dinuprosium oxide (Dy O) 0.04g3 Ammonium chloride (NH4C7) 13.8
(YO, 8998TbO, I
DyO,0001Pr0.0001) 20g・5IO2
A phosphor was obtained. The emission color of this phosphor under electron beam excitation is P r 6011 and Dy20. It emits yellow-green light (x = 0.336, y = 0.588), which is the same as that of a conventional phosphor manufactured in exactly the same way except that it does not contain was 10 yen more expensive. It's rough.

Claims (1)

[Claims] (1) The composition formula is p (Lnl-X-, TbXLn/y)203-q B
a0ar 5in2 [However, Ln is at least one of yttrium, lanthanum, gadolinium, and lutetium, Ln' is at least one of dinuglossium and praseodymium, and p, q, r,! and y is 0.50
≦p/r≦1.25.0≦q/r≦0,20.0.00
1≦X≦0.3 and 1×10 ≦y≦lXl0. A rare earth silicate phosphor represented by: