JPH078983B2 - Fluorescent body - Google Patents

Description

The present invention relates to a terbium-activated phosphor that emits light in the green to blue region.

[Conventional technology]

As is well known, fluorescent substances based on rare earth oxysulfides are widely used for X-ray intensifying screens, X-ray fluorescent plates, etc. due to their large amount of X-ray absorption and high luminous efficiency. .
However, Gd ₂ O based on rare earth oxysulfaide
₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, Y ₂ O ₂ S: Tb and other phosphors for X-ray intensifying screens are more comparable to the CaWO ₄ phosphors that have been used conventionally. Then, the luminous efficiency is high, but the afterglow is long, and reduction of the afterglow has been desired.

Regarding the afterglow improvement of a phosphor based on a rare earth oxysulfide, it is known that the afterglow is reduced by adding a small amount (5 × 10 ^-7 mol or more) of cerium (Japanese Patent Publication No. 59- 38280 publication).

[Object of the Invention]

As a result of intensive studies by the present inventors to obtain a phosphor having high emission intensity and short afterglow, a trace amount of neodymium and / or a cerium-containing terbium-activated rare earth oxysulfide-based phosphor is obtained. The inventors have found that by incorporating scandium, the afterglow can be significantly shortened without impairing the emission intensity, and the present invention has been completed.

[Structure of Invention]

That is, the gist of the present invention, (1-w-x) R 2 O 2 S · wTb 2 O 2 S · xCe 2 O 2 S 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol of Nd ₂ O is added to the phosphor represented by
It exists in a phosphor containing ₂ S and / or Sc ₂ O ₂ S.

Hereinafter, the present invention will be described in detail.

The phosphor was cerium-containing terbium with active rare earth oxy sulfates eyed the substrate in the present invention, the formula (1-w-x) R 2 O 2 S · wTb 2 O 2 S · xCe 2 O 2 S It is a fluorescent substance represented by. Especially x is 1 × 10 ^-8 ≦ x ≦ 5
From the viewpoint of emission intensity, it is preferable to set the range of ^{x10 -6} , more preferably ^{1x10 -8} ≤x≤3x10 ^-7 .

Nd contained in the cerium-containing terbium-activated phosphor
₂ O ₂ S and / or Sc ₂ O ₂ S is 1 × 10 ⁻⁸ to 1 mol per 1 mol of the phosphor.
It is 1 × 10 ⁻⁴ mol, preferably 1 × 10 ^{−8 to} 5 × 10 ⁻⁶ mol. If it is too much, the emission intensity may be reduced. On the contrary, if it is too small, the effect of the present invention cannot be expected.

Further, the phosphor of the present invention is the above-mentioned Nd ₂ O ₂ S and / or Sc.
_In addition to ₂ O ₂ S, metals other than rare earths, such as Cu, Ag, Au, Be, M
g, Ca, Sr, Ba, Zn, Cd, Hg, Ti, Ge, Sn, Pb, V, Nb, Ta, Cr, Mo, W, S
You may contain e, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt etc. Of the above, divalent or tetravalent metals, specifically
Ti is preferred.

The amount to be present is 50 ppm or less, preferably 10 ppm or less with respect to the entire phosphor.

The elemental analysis in the phosphor of the present invention can be carried out by various known methods. For example, a very small amount of cerium or the like can be measured by spark source mass spectrometry.

The present phosphor can be easily manufactured by a conventional method for manufacturing a rare earth oxysulfide-based phosphor. For example, sulfur is blended with an oxide composed of a part or all of metals other than the R element of the above general formula, terbium, cerium, scandium, neodymium, and rare earths, finely pulverized, and each raw material is uniformly mixed and fired. It can be easily obtained. At this time, as a flux, an alkali metal polysulfide (Na ₂ Sx
Etc.), sodium carbonate, potassium carbonate, etc. may be added.

Further, in order to make the mixing of terbium, cerium, scandium and the like, which are added in a trace amount, more uniform, the raw materials may be dissolved in mineral acid and coprecipitated with a suitable precipitant, and then thermally decomposed to form an oxide. Alternatively, instead of the rare earth oxide, a compound that can easily be converted into an oxide by thermal decomposition, for example, a compound such as a carbonate or an oxalate and sulfur or the like may be mixed and uniformly mixed and baked.

After firing, the sintered body is cooled, excess sulfur, alkali metal polysulfide and the like are removed by washing with water and the like, and dried to obtain a phosphor powder.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1, Comparative Examples 1 and 2 and Reference Examples 1 to 3 220 g of cadolinium oxide was dissolved in 670 ml of 18% by weight hydrochloric acid, and a hydrochloric acid solution containing 5% by weight in terms of oxide of terbium oxide (Tb ₄ O ₂ ). 22.7 ml, 1.0 mg / oxide equivalent of cerium oxide (Ce
O ₂ ) -containing hydrochloric acid solution 10.5 ml and oxide conversion 1.0 mg /
Add 10.3 ml of neodymium oxide solution of
Diluted to.

While stirring the above solution, 60 ° C., 28 wt% oxalic acid solution 1.1
Was added in 3 minutes, and stirring was carried out for 10 minutes after the addition. The generated oxalate was washed by decantation until the pH became 4.5, and the oxalate was removed. The precipitate was heated and decomposed at 1000 ° C. for 1 hour to obtain an oxide.

200 g of the rare earth oxide obtained by the above method, 50 g of potassium carbonate,
50g of sodium carbonate, 8g of lithium phosphate and 60g of sulfur are mixed well and calcined in an alumina crucible at 1250 ° C for 2 hours and 30 minutes. After the calcining, the sintered body is cooled and immersed in water.
Rinse with water until 10 and then with 5% hydrochloric acid, then wash
It was washed with water until the pH became 4, and dried at 120 ° C. to obtain a phosphor represented by the following formula.

0.995Gd ₂ O ₂ S ・ 0.005Tb ₂ O ₂ S ・ 5 × 10 ^-8 Ce ₂ O ₂ S ・ 5 × 10 ^-8
Nd ₂ O ₂ S emission intensity was measured by applying a tube voltage of 60% to the phosphor powder described above.
X-rays were irradiated at kvp, a tube current of 1 mA, and an irradiation distance of 1 m, and the luminescence amount was measured with a luminance meter.

X-ray afterglow is measured by fluorescent powder with tube voltage of 65 kvp and tube current of 3 m.
A, X-ray is irradiated for 1 minute at an irradiation distance of 60 cm, and immediately after the irradiation is stopped, an X-ray film (GRENEX RXO- made by Fuji Photo Film Co., Ltd.)
H (trademark) was brought into close contact and left for 30 minutes for development.

The blackness of the film produced by the afterglow is measured by an automatic densitometer manufactured by Malumi Co., and the input light to the film is calculated from the measured blackness and the photographic characteristics of the X-ray film used. The afterglow value was used.

Ultraviolet afterglow measurement is performed by irradiating the phosphor powder with ultraviolet rays of 365 nm for 3 minutes, and 3 seconds after the irradiation is stopped, X-ray film (GRENEX RXO-H manufactured by Fuji Photo Film Co., Ltd.) is brought into close contact with it and left to develop for 30 minutes. I went. The measurement was performed in the same manner as the X-ray afterglow.

The measurement results are shown in Table 1.

In addition, for comparison, as a conventional example, a phosphor containing neither neodymium nor cerium (Comparative Example 1) and a phosphor containing no neodymium added in an amount of 5 × 10 ⁻⁷ mol of cerium (Comparative Example 2) were used. Table 1 also shows the optical properties and the fluorescent properties of the phosphors in which the amounts of cerium shown in the table were added without addition of neodymium as Reference Examples 1 to 3.

Examples 2 to 14 Cadolinium oxide, terbium oxide, cerium oxide, neodymium oxide, and scandium oxide were mixed in appropriate amounts to produce a phosphor in the same manner as in Example 1, and the formula 0.995Gd ₂ O ₂ S.0.005Tb ₂ O ₂ B ・ xCe ₂ O ₂ S ・ yNd ₂ O ₂ S ・ zSc ₂ O ₂
I got the S phosphor.

Table 1 shows the fluorescent characteristics and the values of x, y, z of the above fluorescent body.

Examples 15 to 18 Gadolinium oxide, terbium oxide, cerium oxide, neodymium oxide and titanium were mixed in appropriate amounts to produce a phosphor in the same manner as in Example 1, and the formula 0.995Gd ₂ O ₂ S.0.005Tb ₂ O _{2 was produced.} S ・ xCe ₂ O ₂ S ・ 2 × 10 ^-7 Nd ₂ O ₂ S
* Obtained a vTi phosphor.

The fluorescent characteristics of this phosphor are shown in Table 2.

[Effects of the Invention] Compared with the case where only the same amount of cerium is added, the phosphor of the present invention has a similar emission intensity and a significantly short afterglow, and thus has a large industrial value.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumiya Ishikawa, Inventor, Fumaya Ishida, Kitakyushu City, Fukuoka Prefecture 2447 Fujita, Hachimansai Ward, Kurosaki Plant, Mitsubishi Kasei (72) Inventor Toshinori Tanaka Fujita, Hachimansai Ward, Kitakyushu, Fukuoka Prefecture Address 1 at 2447 Mitsubishi Chemical Industries Kurosaki Plant

Claims (5)

[Claims] [Claim 1] (1-w-x) R 2 O 2 S · wTb 2 O 2 S · XCe 2 O 2 S A phosphor obtained by containing 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol of Nd ₂ O ₂ S and / or Sc ₂ O ₂ S in 1 mol of the phosphor represented by. 2. The phosphor according to claim 1, wherein the phosphor contains 50 ppm or less of a metal other than a rare earth element. 3. The phosphor according to claim 1, wherein x is 1 × 10 ⁻⁸ ≦ x ≦ 5 × 10 ⁻⁶ . 4. The phosphor according to claim 1, wherein x is 1 × 10 ⁻⁸ ≦ x ≦ 3 × 10 ⁻⁷ . 5. The fluorescent substance according to claim 3, wherein Ti is contained as a metal in an amount of 50 ppm or less.