JP2008069201A - Light-emitting material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a light-emitting material having electrical conduction property and to provide a method for producing the same. <P>SOLUTION: The light-emitting material having electrical conduction property is produced by adding Pr (praseodymium) as a light-emitting center ion to a matrix of titanate represented by a composition formula Ca<SB>4</SB>Ti<SB>3</SB>O<SB>10</SB>and firing the mixture in a reducing atmosphere. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is suitable for application to a display device such as an FED (Field Emission Display) that uses an electron beam (low speed electron beam) with a low acceleration voltage of about 1 [kV] or less as an excitation source, and a method for manufacturing the same. About.

Conventionally, titanate An _{n + 1} Ti _n O _{3n + 1} having a Ruddlesden-Popper type layered structure similar to a perovskite type structure as a crystal structure (A is Ca or Sr, n is 1, 2 or ∞) SrTiO ₃ , Sr ₂ TiO ₄ , Sr ₃ Ti ₂ O ₇ , and Ca ₃ Ti ₂ O ₇ doped with rare earth element Pr have been reported to show visible light emission (non-patent literature). 1). Among these, it is known that Pr doped with Sr ₃ Ti ₂ O ₇ and Ca ₃ Ti ₂ O ₇ emit relatively strong red light.
Japanese Journal of Applied Physics, 44,1B, 2005, pp761-764)

  However, since the above-described phosphor material is manufactured by firing in an air atmosphere, it has an insulator characteristic. Therefore, when the above-described fluorescent material is excited by a low-speed electron beam used in FED or the like, charging occurs on the surface of the fluorescent material, and subsequent electrons cannot enter the phosphor film, and good light emission cannot be expected. Also, under low-energy electron beam excitation, the penetration length of electrons cannot be gained, so that the antistatic treatment (metal back) implemented in CRT or the like cannot be performed. From such a background, in order to obtain good light emission characteristics by a low-speed electron beam, it is an urgent need to provide a fluorescent material having electrical conductivity.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a light-emitting material having electrical conductivity and a method for manufacturing the same.

As a result of intensive research, the inventors of the present invention have added Pr (praseodymium) as a luminescent center ion to a titanate base represented by the composition formula Ca ₄ Ti ₃ O ₁₀ , and reduced atmosphere. It was found that a light-emitting material having electrical conductivity can be produced by firing at 1.

  According to the luminescent material and the method for producing the same of the present invention, a luminescent material having electrical conductivity can be provided. In addition, when the light emitting material according to the present invention is applied to a display device, the reliability of the display device can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described.

[Example 1]
In Example 1, first, CaCO ₃ powder, TiO ₂ powder, and Pr ₆ O ₁₁ powder were weighed at a molar ratio of 3.99: 3: 0.0016, and isopropyl alcohol was used as the solvent in a cylindrical shape. In a plastic pot. Next, after rotating and rotating and mixing the plastic pot for 1 minute, the slurry in the plastic pot is dispersed with an ultrasonic homogenizer for 1 minute and the plastic pot is rotated and rotated and rotated again for 1 minute to obtain a mixed slurry. It was. Next, the obtained mixed slurry was dried in a nitrogen stream at 110 [° C.] to obtain a raw material powder of Example 1. Next, the raw material powder is uniaxially pressed at a pressure of 200 [kgf / cm ₂ ] to produce a disk-shaped molded body having a diameter of about 50 [mm] and a thickness of about 5 [mm]. After CIP molding, the phosphor material of Example 1 was obtained by storing in a firing graphite sheath and firing. In addition, the normal pressure carbon furnace was utilized for baking processing, and it cooled, after hold | maintaining for 1 hour with the baking temperature of 1500 [degreeC]. Moreover, 0.15 [MPa] nitrogen gas or argon gas was introduce | transduced into the baking atmosphere from the room temperature state.

[Comparative Example 1]
Comparative Example 1 is an example except that SrCO ₃ powder was used instead of CaCO ₃ powder, and SrCO ₃ powder, TiO ₂ powder, and Pr ₆ O ₁₁ powder were weighed in a molar ratio of 2.99: 2: 0.0016. The fluorescent material of Comparative Example 1 was obtained by performing the same treatment as in Example 1.

[Comparative Example 2]
In Comparative Example 2, the same treatment as in Example 1 was carried out except that CaCO ₃ powder, TiO ₂ powder, and Pr ₆ O ₁₁ powder were weighed at a molar ratio of 0.99: 1: 0.0016, thereby giving a comparative example. Two fluorescent materials were obtained.

[Comparative Example 3]
In Comparative Example 3, SrCO ₃ powder and Eu ₂ O ₃ powder were used instead of CaCO ₃ powder and Pr ₆ O ₁₁ powder, and the molar ratio of SrCO ₃ powder, TiO ₂ powder, and Eu ₂ O ₃ powder was 2.99: 2: A fluorescent material of Comparative Example 3 was obtained by performing the same treatment as in Example 1 except that it was weighed at 0.0016.

[Electric conductivity]
The electrical conductivity of each of the fluorescent materials of Example 1 and Comparative Examples 1 to 3 was measured in the air at room temperature by a method according to JIS C2141. The shape of the test piece is 35 mm × 1 [mm], and each electrode has a main electrode diameter of 10 [mm], a guard electrode inner diameter of 20 [mm], a guard electrode outer diameter of 30 [mm], and an applied electrode diameter of 30 [mm]. Was formed of silver. The applied voltage was 100 [V / mm], the current at 1 minute after voltage application was read, and the electrical conductivity was calculated. The results are shown in Tables 1 and 2 below. As is clear from Tables 1 and 2, it was found that the electrical conductivity of the fluorescent material of Example 1 was significantly greater than that of Comparative Examples 1 to 3.

[Evaluation of crystal phase]
The crystal phases of the fluorescent materials of the above examples and comparative examples were changed to a rotating counter cathode type X-ray diffractometer manufactured by Rigaku Corporation (measurement conditions: CuKα radiation source, 35 [kV], 20 [mA], 2θ = 10 70 °). As an example, FIG. 1 shows an X-ray diffraction profile obtained from the fluorescent material of Example 1, and Tables 1 and 2 show the identification results of the fluorescent materials of other Examples and Comparative Examples. As a result of identification, it was confirmed that the fluorescent material of Example 1 was formed only from Ca ₄ Ti ₃ O ₁₀ , and the fluorescent materials of Comparative Examples 1 to 3 were also single phase.

[Luminescence intensity]
The light emission characteristics of the fluorescent materials of the above examples and comparative examples were measured using a spectrofluorophotometer FP-6300 manufactured by JASCO Corporation. Specifically, a fluorescent material was filled in a dedicated holder, irradiated with excitation light in an arbitrary ultraviolet wavelength region, and a fluorescence (PhotoLuminescence: PL) spectrum was measured. The excitation spectrum at the peak wavelength of the obtained PL spectrum was measured in the wavelength range of 220 to 400 [nm]. Further, the PL spectrum was measured in the wavelength range of 400 to 700 [nm] by irradiating the peak wavelength of the excitation spectrum, and the PL spectrum at the excitation wavelength giving the maximum intensity was obtained. 2 shows the PL spectrum at the maximum excitation wavelength obtained from the fluorescent material of Example 1, FIG. 3 shows the PL spectrum at the maximum excitation wavelength obtained from the fluorescent material of Comparative Examples 1 to 3, and Tables 1 and 2 show the results. The maximum peak wavelength in PL spectrum obtained from the fluorescent material of Example 1 and Comparative Examples 1-3 is shown. As is clear from FIG. 2, it was confirmed that the fluorescent material of Example 1 emitted red light having a peak wavelength of 611 [nm]. Moreover, it was confirmed that the fluorescent materials of Comparative Examples 1 to 3 have emission peaks within a wavelength range of 570 [nm] or more and 650 [nm] or less.

  As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

The X-ray-diffraction profile of the luminescent material of Example 1 is shown. The photoexcitation emission spectrum of the luminescent material of Example 1 is shown. The photoexcitation emission spectrum of the luminescent material of Comparative Examples 1-3 is shown.

Claims (3)

A light-emitting material whose crystal structure is a Rudolsden-hopper type layered structure and which is represented by a composition formula Ca _4-x Pr _x Ti ₃ O ₁₀ (0.0001 ≦ x ≦ 0.1). The luminescent material according to claim 1, wherein the luminescent material has an electric conductivity of 10 ₋₁₂ [S / cm] or more. A method for producing a luminescent material, comprising a step of firing CaCO ₃ powder, TiO ₂ powder, and Pr ₆ O ₁₁ powder in a reducing atmosphere.

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