JPH10291854A - Polycrystalline mgo vapor depositing material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an MgO film in an almost uniform thickness with little generated splash even by vapor deposition by an electron beam vapor deposition method. SOLUTION: This polycrystalline MgO vapor depositing material is sintered pellets of polycrystalline MgO having >=99.5% purity of MgO and >=97% relative density. The average grain diameter of the pellets is 1-100 μm and the pellets have roundish pores of <=2 μm average inside diameter in the grains. The concns. of Si, Al, Ca, Fe, Cr, V, Ni, Na, K, C and Zr contained as impurities in the pellets are <=150 ppm, <=150 ppm, <=200 ppm, <= 50 ppm, <=10 ppm, <=10 ppm, <=10 ppm, <=20 ppm, <=20 ppm, <=70 ppm and <=150 ppm (expressed in terms of elements), respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polycrystalline M suitable for forming an MgO film of an AC type plasma display panel.
The present invention relates to a gO vapor deposition material and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal (Liquid Crystal Display):
Research and development and commercialization of various flat displays, including LCDs, are remarkable, and their production is increasing rapidly. Recently, color plasma display panels (PDPs) have been actively developed and put into practical use. PDPs are easy to increase in size, are at the shortest distance from large screen wall-mounted televisions for high-definition televisions, and prototypes of 40-inch diagonal PDPs have already been developed. PDPs are classified into an AC type in which a metal electrode is covered with a glass dielectric material in terms of an electrode structure, and a DC type in which a metal electrode is exposed in a discharge space.

At the beginning of the development of the AC type PDP, since the glass dielectric layer was exposed to the discharge space, the glass dielectric layer was directly exposed to the discharge, and the surface of the dielectric layer was changed by ion bombardment, and the discharge starting voltage was lowered. Was rising. For this reason, attempts have been made to use various oxides having high sublimation heat as protective films for the dielectric layer. This protective film plays an important role because it is in direct contact with the discharge gas. That is, the characteristics required for the protective film are a low discharge voltage, resistance to sputtering during discharge, fast discharge responsiveness, and insulation. Materials satisfying these conditions include M
gO is used for the protective film. This protective film made of MgO protects the surface of the dielectric layer from sputtering at the time of discharge, and plays an important role in extending the life of the PDP.

At present, as the above protective film of AC type PDP,
An MgO film formed by an electron beam evaporation method using a crushed single crystal MgO as an evaporation material is known. The MgO film formed by the electron beam evaporation method can be formed at a high speed of 1000 Å / min or more. The crystal orientation of the formed MgO film is such that a film oriented in the (111) plane can be driven at the lowest sustaining voltage, and furthermore, exists in the film (11
1) As the amount of surface increases, the emission ratio of secondary electrons increases,
It is said that the driving voltage also decreases. The single crystal M
The crushed product of gO is obtained by melting MgO clinker having a purity of 98% or more or lightly burned MgO (MgO sintered at 1000 ° C. or less) in an electric arc furnace (arc furnace), that is, into an ingot by electromelting. It is manufactured by taking out a single crystal part from this ingot and crushing it.

[0005]

However, in the conventional electron beam evaporation method using a crushed single-crystal MgO product as an evaporation material, high energy is locally applied to the evaporation material.
There was a problem that the vapor deposition material was scattered (splash) and the vapor deposition efficiency was reduced. In order to prevent the occurrence of this splash, it is considered that increasing the size of the vapor deposition material is effective.
In the case of a single crystal MgO pulverized product, it has been difficult to stably secure particles having a particle size larger than the current particle size of 1 to 5 mm with good yield. In the conventional electron beam evaporation method using a crushed single crystal MgO product as an evaporation material, it is difficult to uniformly form an MgO film on a large-area glass dielectric layer, and there is a problem in film thickness distribution. there were. As a result, when a glass dielectric layer on which an MgO film is formed is incorporated in a PDP, there is a problem that electric characteristics, for example, a discharge starting voltage and a driving voltage are increased or changed.

On the other hand, MgO clinker and lightly burned MgO often use MgCl ₂ obtained from seawater as a raw material, and this MgCl ₂ contains a relatively large amount of Ca, Si, Fe.
And the like, these impurities are contained in the single crystal M
Remains in gO. Further, in the ingot in the production process of the single crystal MgO, the amount of impurities continuously increases from the center of the ingot toward the surface portion. Therefore, the purity of the product varies very easily depending on how the single crystal portion is taken out. As a result, there is a problem that the stability and reliability of the purity of the single crystal MgO are lacking.

In order to solve these problems, a single crystal MgO
Alternatively, a method using polycrystalline MgO may be considered. However, high-density polycrystalline MgO densified by the addition of various sintering aids has a problem that defects are systematically present at crystal grain boundaries, and a problem that the density is lowered when the purity is increased. was there. As a result, MgO was added to the glass dielectric layer by electron beam evaporation using these polycrystalline MgO evaporation materials.
When a film is formed, the amount of orientation of the crystal orientation to the (111) plane is reduced, and the electrical characteristics when this glass dielectric layer is incorporated into a PDP are reduced. Therefore, polycrystalline MgO is used as a vapor deposition material. could not.

It is an object of the present invention to provide a polycrystalline MgO vapor deposition material capable of forming a film at high speed and uniformly without generating a splash even when vapor deposition is performed by an electron beam vapor deposition method, and a method for producing the same. Another object of the present invention is to provide a deposited M
An object of the present invention is to provide a polycrystalline MgO vapor deposition material capable of improving the film characteristics of a gO film and a method for producing the same.

[0009]

The invention according to claim 1 is
Polycrystalline MgO comprising sintered pellets of polycrystalline MgO having a purity of 99.5% or more and a relative density of 97% or more
It is an evaporation material. The polycrystalline MgO according to claim 1
When a MgO film such as an AC-type PDP is formed using a high-purity and high-density polycrystalline MgO vapor-deposited material, a stable film can be formed at a high speed with little splash. In addition, since the film thickness distribution can be improved, M
A gO film can be obtained.

A second aspect of the present invention is the invention according to the first aspect, wherein the average crystal grain size of the sintered compact of polycrystalline MgO is 1 to 100 μm, and It is characterized by having rounded pores having an average inner diameter of 2 μm or less in the grains. In the polycrystalline MgO vapor-deposited material according to the second aspect, since the sintered compact of polycrystalline MgO has a fine crystal structure and can reduce the occurrence of defects at the crystal grain boundaries, the film is formed. The MgO film has excellent film properties.

[0013] The invention according to claim 3 is the invention according to claim 1 or 2, wherein the impurities of Si and Al contained in the sintered compact of polycrystalline MgO each have an element concentration of 150 ppm or less. , Ca impurities have an element concentration of 200 ppm or less, and Fe impurities have an element concentration of 5 ppm or less.
0 ppm or less, impurities of Cr, V and Ni are respectively 10 ppm or less in element concentration, impurities of Na and K are 20 ppm or less in element concentration, and impurities of C are 70 ppm or less in element concentration. Is characterized by an element concentration of 150 ppm or less. In the polycrystalline MgO vapor deposition material according to the third aspect, the impurities contained in the formed MgO film are extremely small, so that the film characteristics of the MgO film are improved.

The invention according to claim 4 has a purity of 99.5%.
A step of mixing a MgO powder having an average particle size of 0.1 to 3 μm, a binder and an organic solvent to prepare a slurry having a concentration of 45 to 75% by weight, and spray-drying the slurry to obtain an average particle size of Obtaining a 50-300 μm granulated powder;
This is a method for producing a polycrystalline MgO vapor deposition material, which includes a step of placing the granulated powder in a predetermined mold and molding at a predetermined pressure, and a step of sintering the molded body at a predetermined temperature. Claim 4
When producing a polycrystalline MgO vapor deposition material by the method described in
A polycrystalline MgO vapor deposition material comprising a sintered pellet of polycrystalline MgO having an MgO purity of 99.5% or more and a relative density of 97% or more can be obtained.

In the method according to the fourth aspect, the granulated powder is uniaxially pressed at a pressure of 750 to 2000 kg / cm ² or the granulated powder is formed at a pressure of 1000 to 3000 kg / cm 2.
It is preferable to perform CIP molding at a pressure of ² , and it is preferable to perform primary sintering of the molded body at a temperature of 1250 to 1350 ° C., and then increase the temperature to perform secondary sintering at a temperature of 1500 to 1650 ° C.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail. The polycrystalline MgO vapor deposition material of the present invention has a sintered polycrystalline MgO pellet having an MgO purity of 99.5% or more, more preferably 99.9% or more, and a relative density of 97% or more, and more preferably 98% or more. Consists of The average grain size of the sintered pellet is 1 to 100 μm, and the sintered pellet has rounded pores having an average inner diameter of 2 μm or less. Here, the reason why the average crystal grain size of the sintered compact is limited to 1 to 100 μm is that the MgO structure can be controlled within this grain size range. The reason why the average inner diameter of the pores in the crystal grains of the sintered pellet is 2 μm or less is that if it exceeds 2 μm, the structure of MgO cannot be controlled.

Impurities (Si, Al, Ca, Fe, Cr, V, Ni, N) contained in the sintered pellet of polycrystalline MgO
It is preferable that the total content of a, K, C and Zr) is 850 ppm or less. The individual content of the above impurities is such that the impurities of Si and Al are each 1 elemental concentration.
50 ppm or less, and the impurity of Ca is 20
0 ppm or less, and the impurity of Fe is 50 p in element concentration.
pm or less, the impurities of Cr, V and Ni are each 10 ppm or less in elemental concentration, the impurities of Na and K are each 20 ppm or less in elemental concentration, and the impurity of C is 70 ppm or less in elemental concentration. Is preferably 150 ppm or less in elemental concentration. If each of the impurities exceeds the above-mentioned value in element concentration, when a glass substrate on which an MgO vapor deposition material is formed by an electron beam vapor deposition method is incorporated into a panel, a variation occurs in the film quality. There is a problem that the voltage becomes high or becomes unstable.

A method of manufacturing the polycrystalline MgO vapor deposition material having the above-described structure will be described. First, M with a purity of 99.5% or more
gO powder, a binder, and an organic solvent are mixed to obtain a concentration of 4
A slurry of 5 to 75% by weight is prepared. The reason why the concentration of the slurry is limited to 45 to 75% by weight is that if it exceeds 75% by weight, the above-mentioned slurry is non-aqueous, so that stable granulation is difficult. This is because a dense MgO sintered body cannot be obtained.
That is, when the slurry concentration is limited to the above range, the viscosity of the slurry becomes 200 to 1000 cps, the granulation of the powder by the spray dryer can be performed stably, and further, the density of the molded body is increased and the dense sintering is performed. Body production becomes possible.

The average particle size of the MgO powder is 0.1 to 3 μm.
It is preferably within the range of m. The reason why the average particle size of the MgO powder is limited to 0.1 to 3 μm is that when the average particle size is less than 0.1 μm, the powder is too fine and agglomerates, so that the handling of the powder becomes poor and a high concentration slurry of 45% by weight or more is prepared. When the thickness exceeds 3 μm,
This is because it is difficult to control the fine structure, and a dense sintered body pellet cannot be obtained. Further, when the average particle size of the MgO powder is limited to the above range, there is also an advantage that a desired sintered body pellet can be obtained without using a sintering aid. It is preferable to use polyethylene glycol or polyvinyl butyral as a binder, and to use ethanol or propanol as an organic solvent. The binder is preferably added in an amount of 0.2 to 2.5% by weight.

The wet mixing of the MgO powder, the binder and the organic solvent, particularly the wet mixing of the MgO powder and the organic solvent as a dispersion medium, is performed by a wet ball mill or a stirring mill. In the case of using a ZrO ₂ ball in a wet ball mill, a large number of ZrO ₂ balls having a diameter of 5 to 10 mm are wet-mixed for 8 to 24 hours, preferably 20 to 24 hours. The reason why the diameter of the ZrO ₂ ball is limited to 5 to 10 mm is that if it is less than 5 mm, the mixing becomes insufficient, and if it exceeds 10 mm, there is a problem that impurities increase. The reason why the mixing time is as long as 24 hours is that generation of impurities is small even when mixing is continued for a long time. On the other hand, when a resin ball containing an iron core is used in a wet ball mill, it is preferable to use a ball having a diameter of 10 to 15 mm.

In a stirring mill, ZrO _{2 having} a diameter of 1 to 3 mm is used.
The mixture is wet-mixed for 0.5 to 1 hour using a ball. Zr
The diameter of the O ₂ ball is limited to 1 to 3 mm.
If the diameter is less than 3 mm, the mixing is insufficient.
This is because if the ratio exceeds the limit, impurities increase. The reason why the mixing time is as short as 1 hour at the maximum is that if the time exceeds 1 hour, not only the mixing of the raw materials but also the work of pulverization is performed, which causes the generation of impurities. .

Next, the above slurry is spray-dried to obtain a granulated powder having an average particle diameter of 50 to 300 μm, preferably 50 to 200 μm, and then the granulated powder is put into a predetermined mold and molded under a predetermined pressure. I do. Here, the average particle size is 50 to 300 μm.
The reason for limiting to m is that if it is less than 50 μm, there is a problem that the moldability is poor, and if it exceeds 300 μm, there is a problem that the molded body density is low and the strength is low. The spray drying is preferably performed using a spray dryer, and the predetermined mold is a uniaxial press device or a cold isostatic pressing device (CIP (CoP
ld Isostatic Press). In the uniaxial pressing device, the granulated powder is 750-2000 kg / cm
² , preferably uniaxial pressure molding at a pressure of 1000 to 1500 kg / cm ² ,
00-3000 kg / cm ² , preferably 1500-2
CIP molding is performed at a pressure of 000 kg / cm ² . The reason for limiting the pressure to the above range is to increase the density of the molded body, prevent deformation after sintering, and eliminate post-processing.

Further, the compact is sintered. Before sintering, it is preferable that the molded body is subjected to a degreasing treatment at a temperature of 350 to 620 ° C. This degreasing treatment is performed in order to prevent color unevenness after sintering of the molded body, and it is preferable to perform the degreasing sufficiently over time. Sintering is performed at a temperature of 1250 to 1350 ° C. for 1 to 5 hours, and thereafter, the temperature is further increased to 1500 to 165
The secondary sintering is performed at a temperature of 0 ° C. for 1 to 10 hours.

When the temperature of the compact is first raised for primary sintering, sintering starts at 1200 ° C., and proceeds considerably at 1350 ° C. By performing primary sintering at this temperature, even if the particle size is large, there is no sintering unevenness (difference in microstructure) between the surface and the inside, and secondary sintering at a temperature of 1500 to 1650 ° C. A sintered body pellet having a density close to 100% is obtained. Although there are few pores in the sintered body pellet, these pores are not in the crystal grain boundaries that affect the properties of the MgO sintered body, but in the crystal grains that hardly affect the properties of the MgO sintered body. Exists. As a result, when the high-purity and high-density MgO sintered pellet of the present invention is formed on a plasma display panel, an MgO film having less splash and excellent film characteristics can be obtained.

In the case of sintering a compact having a large shape, further densification can be achieved by slowing the heating rate during the two-stage sintering to 20 to 30 ° C./hour. Further, in sintering at normal pressure, if the sintering temperature is less than 1500 ° C., it is not possible to sufficiently densify, but the sintering temperature is 1500 ° C.
C. or more, a high-density sintered body can be obtained, so that hot isostatic pressing (HIP)
s) It is not necessary to perform special sintering such as method) or hot pressing.

[0024]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist thereof. <Example 1> First, MgO powder (MJ-3 manufactured by Iwatani Chemical Co., Ltd.)
0, purity 99.9%, average particle size 0.3 μm), polyethylene glycol (Pan manufactured by Sanyo Chemical Co., Ltd.)
EG-200) was added at 1% by weight, and a slurry containing ethanol as a dispersion medium was concentrated at a concentration of 72% by weight (viscosity: 400 cps).
Was prepared. This slurry was then ball milled (diameter 5).
mm ZrO ₂ balls), wet-mixed for 20 hours, and spray-dried with a spray dryer to obtain an average particle size of 80.
A granulated powder of μm was obtained. The spray drying conditions were as follows: the rotation speed of the atomizer (high-speed rotating disk) was set at 10,000 rpm, and the inlet and outlet temperatures of the hot gas were set at 100 ° C. and 60 ° C., respectively. Next, the obtained granulated powder is put into a thin cylindrical container (inner diameter: 155 mm, height: 8 m) of a CIP molding machine.
m) and CIP-molded at 1500 kg / cm ² . Further, the molded body was sintered in two steps, that is, put in an electric furnace (manufactured by Hiroki Co., Ltd.), primary sintered at 1300 ° C. for 2 hours in the air, and then secondary sintered at 1600 ° C. for 2 hours. The rate of temperature rise from primary sintering to secondary sintering was 30 ° C./hour, and the rate of temperature decrease after completion of secondary sintering was 50 ° C./hour. This sintered disk was used as Example 1.

Example 2 A slurry prepared in the same manner as in Example 1 was wet-mixed for 24 hours in a ball mill using the same balls as in Example 1, and then spray-dried with a spray dryer to obtain an average particle diameter of 200 μm. Was obtained. The granulated powder is placed in a uniaxial pressing machine mold (inner diameter 6 mm, depth 3 m).
m) and subjected to uniaxial press molding at 1000 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. This sintered body pellet was used as Example 2. Example 3 A slurry prepared in the same manner as in Example 1 was wet-mixed in a ball mill using the same balls as in Example 1 for 24 hours, and then spray-dried with a spray dryer to form granules having an average particle diameter of 300 μm. A powder was obtained. The granulated powder was filled in a mold of a uniaxial press device (inner diameter: 6 mm, depth: 3 mm), and subjected to uniaxial press molding at 1000 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. This sintered compact was used as Example 3.

Example 4 A slurry prepared in the same manner as in Example 1 was wet-mixed for 24 hours in a ball mill using the same balls as in Example 1, and then spray-dried with a spray dryer to obtain an average particle size of 150 μm. Was obtained. This granulated powder is transferred to a thin cylindrical container (with an inner diameter of 15
5 mm, height 8 mm) and 1500 kg / cm ²
Was CIP molded. Except for the above, it was manufactured in the same manner as in Example 1. The disk of this sintered body was used as Example 4. Example 5 The slurry prepared in the same manner as in Example 1 was wet-mixed for 1 hour in a stirring mill (using ZrO ₂ balls having a diameter of 2 mm), and then spray-dried with a spray dryer to form an average particle diameter of 200 μm. Granular powder was obtained. The granulated powder was filled in a mold of a uniaxial press device (inner diameter: 6 mm, depth: 3 mm), and subjected to uniaxial press molding at 1000 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. This sintered compact pellet was used as Example 5.

Example 6 A slurry prepared in the same manner as in Example 1 was wet-mixed for 1 hour in a stirring mill using the same balls as in Example 5, and then spray-dried with a spray dryer to obtain an average particle size. A granulated powder of 150 μm was obtained. This granulated powder is molded using a uniaxial pressing machine (inner diameter 6 mm, depth 3 mm)
And subjected to uniaxial press molding at 1000 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. Except for the above, it was manufactured in the same manner as in Example 1. This sintered body pellet was used as Example 6. <Example 7> The slurry prepared in the same manner as in Example 1 was wet-mixed for 1 hour with a stirring mill using the same balls as in Example 5, and then spray-dried with a spray dryer to form an average particle diameter of 250 µm. Granular powder was obtained. This granulated powder is
Thin-walled cylindrical container (155 mm inside diameter, 8 m height)
m) and CIP-molded at 1500 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. This sintered disk was used as Example 7. <Example 8> A slurry prepared in the same manner as in Example 1 was wet-mixed for 1 hour in a stirring mill using the same balls as in Example 5, and then spray-dried with a spray dryer to form an average particle diameter of 300 µm. Granular powder was obtained. This granulated powder is
Thin-walled cylindrical container (155 mm inside diameter, 8 m height)
m) and CIP-molded at 1500 kg / cm ² . Except for the above, it was manufactured in the same manner as in Example 1. This sintered disk was used as Example 8.

Comparative Example 1 A slurry prepared in the same manner as in Example 1 was wet-mixed for 48 hours in a ball mill using the same balls as in Example 1, and then spray-dried with a spray dryer to obtain an average particle size of 70 μm. Was obtained. Next, the obtained granulated powder is filled in a thin-walled cylindrical container (inner diameter: 155 mm, height: 8 mm) of a CIP molding apparatus, and 1500 kg /
CIP was performed in cm ² . Further, the molded body was placed in an electric furnace (manufactured by Hirokisha) and sintered at 1650 ° C. in the atmosphere for 3 hours.
This sintered disk was used as Comparative Example 1. <Comparative Example 2> A slurry prepared in the same manner as in Example 1 was wet-mixed in a stirring mill (using a ZrO ₂ ball having a diameter of 3 mm) for 8 hours, and then spray-dried with a spray dryer to form an average particle diameter of 40 µm. Granular powder was obtained. This granulated powder is filled in a mold (inner diameter 6 mm, depth 3 mm) of a uniaxial press machine,
Uniaxial press molding was performed at 1000 kg / cm ² . Sintering was performed in the same manner as in Comparative Example 1. Comparative Example 2
And

Comparative Example 3 The slurry prepared in the same manner as in Example 1 was wet-mixed for 1 hour in a stirring mill (using a ZrO ₂ ball having a diameter of 10 mm), and then spray-dried with a spray dryer to obtain an average particle size. A granulated powder of 100 μm was obtained. This granulated powder is transferred to a thin cylindrical container (inner diameter 1
55mm, height 8mm), 1500kg / cm
CIP molding was carried out at ² . Sintering was performed in the same manner as in Comparative Example 1.
The disc of this sintered body was used as Comparative Example 3. <Comparative Example 4> A slurry prepared in the same manner as in Example 1 was applied to a ball mill (using ZrO ₂ balls having a diameter of 15 mm).
After wet mixing for 8 hours, the mixture was spray-dried with a spray dryer to obtain a granulated powder having an average particle size of 200 μm. The granulated powder is transferred to a thin cylindrical container (155 m inside diameter) of a CIP molding machine.
m, height 8mm) and C at 1500kg / cm ²
IP molded. Sintering was performed in the same manner as in Comparative Example 1. This sintered disk was used as Comparative Example 4. Comparative Example 5 Commercially available single-crystal MgO produced by electrofusion
A crushed product having a purity of 99.3% was used as Comparative Example 5. The diameter of this crushed product was 3 to 5 mm.

<Comparison Test and Evaluation> (a) Relative Density and Breaking Strength Test Purity and relative density of the discs, pellets and crushed products of the sintered bodies obtained in Examples 1 to 8 and Comparative Examples 1 to 5 were determined. Each was measured. Further, the discs of the sintered bodies obtained in Examples 1, 4, 7, 8 and Comparative Examples 1, 3, and 4 were cut out, ground and polished, and 3 mm × according to JIS R1601.
The size of a four-point bending test specimen of 4 mm × 40 mm was determined, and the breaking strength (bending strength) was examined. Table 1 shows the results. The purity was calculated from the analytical value of the impurity, the relative density was measured by the Archimedes method in toluene, and the breaking strength was 3
It was measured by a point bending test. Table 1 shows Examples 1 to 8.
The production conditions of the discs and pellets of the sintered bodies of Comparative Examples 1 to 4, that is, the slurry mixing treatment, the average particle size of the granulated powder, and the sintering conditions of the compact were described.

[0031]

[Table 1]

As is clear from Table 1, in Examples 1 to 8, no impurities were mixed in the manufacturing process, and the purity of the MgO sintered body was 99.9% or more, corresponding to the starting material MgO powder. Yes, the relative density was densified to 99% or more. On the other hand, in Comparative Example 4, although the purity was 99.4%, the dispersion of the raw materials was poor, and the sintered body was deformed. Comparative Examples 1 to
In No. 3, impurities were mixed in the manufacturing process due to improper mixing time and media diameter in a ball mill or a stirring mill.
Further, from Examples 1, 4, 7 and 8, and Comparative Examples 1 to 4, it was found that the two-stage sintering was more preferable than the one-stage sintering with respect to the relative density. That is, Comparative Examples 1 and 3 manufactured by only one sintering
And the bending strength of the test piece of the sintered body of 4 were 290-470M.
Example 1 produced by two-stage sintering,
The bending strength of the test pieces of the sintered bodies 4, 7, and 8 reached 750 to 785 MPa, which was about twice as large as that of the comparative example.

(B) Analysis of impurities Impurities contained in the test piece of the sintered body of Example 4, the test piece of the sintered body of Comparative Example 1, and the crushed single-crystal MgO product of Comparative Example 5 were Atomic absorption and ICP (Inductively Coupled Plasma emission spectroche
mical analysis). Table 2 shows the results.

[0034]

[Table 2]

As is clear from Table 2, while the concentration of the impurities in Example 4 was less than 40 ppm, the concentration of the impurities other than Zr in Comparative Example 1 was 60 ppm or less. Is considerably higher at 11800 ppm
(1.18%). In Comparative Example 5, the impurity Ca
Was extremely high at 5820 ppm. This is because the raw material of Comparative Example 5 contains a large amount of Al, Ca, and Fe, and particularly contains a large amount of Ca.

(C) Characteristic test of formed MgO film and discharge test thereof The sintered pellets of Examples 2, 5 and 6, the sintered pellet of Comparative Example 2, and the single crystal MgO of Comparative Example 5 And 5 pieces of TEG (Test Element Group) substrates were prepared by forming a film of the crushed product on a glass substrate by an electron beam evaporation method. As shown in FIG. 1, a TEG substrate 10 has a thickness of 1 μm and a width of 100 μm on a glass substrate (made of Corning # 7059 glass) 11 having a thickness of 1 mm, and an underlying electrode 12 made of an InSn composite oxide film formed at intervals of 100 μm by photolithography.
And reactive D so as to cover these base electrodes 12.
After forming a glass layer 13 having a thickness of 3 μm by C sputtering, an MgO film 14 having a thickness of 7000 Å was formed by the electron beam evaporation method under the same film forming conditions. The conditions for forming the MgO film were as follows: an acceleration voltage of 15 kV, a deposition pressure of 1 × 10 ⁻² Pa, and a deposition distance of 600 mm.

First, the refractive index and the absorption coefficient of the MgO film were measured. The refractive index and absorption coefficient of the MgO film are He-Ne.
Ellipsometry was performed on the film at one wavelength and two angles of incidence (55 °, 70 °) with a laser (wavelength: 6238 Å), and the value was obtained using analysis software. Next, the above MgO
The firing voltage of the film was measured by the following method. 5 types of T
Ne-5% of the apparatus shown in FIG.
Xe is placed on a heating sample table 16 arranged in a vacuum bell jar 15 of 500 Torr, a base electrode 19 (FIG. 1) is connected to a pulse power source 17, and the TEG substrate 10 is connected to a thermocouple 18.
The power supply voltage was increased while controlling the temperature at a constant value while measuring the above, and the voltage at which discharge was started was measured. The pulse power supply 17 is variable in voltage in the range of 0 to 300 V, and generates a pulse having a frequency of 66 kHz and a pulse width of 10 μsec. Table 3 shows the refractive index, absorption coefficient, and discharge starting voltage of the MgO film.

[0038]

[Table 3]

As is clear from Table 3, Comparative Examples 2 and 5
Had refractive indexes of 1.65 and 1.62,
In Examples 2, 5, and 6, the refractive index was improved to about 1.8.
In Comparative Examples 2 and 5, the absorption coefficient was about 0.01, while in Examples 2, 5, and 6, the absorption coefficient was 0.00.
It improved to 1 or less. In addition, the discharge starting voltage was determined in Examples 2 and 5.
And 6, it was found to be about 10 to 20 V lower than Comparative Examples 2, 3, and 5. Further, the film forming rate of the example was about three times the value of the comparative example. This is because when the electron beam is applied, the single crystal MgO crushed product of Comparative Example 5 has orientation, but the polycrystalline MgO sintered pellet of Example does not have orientation, so that efficient film formation is performed. This is because it became possible.
In addition, when the substrate on which the MgO film was formed using Examples 2, 5, and 6 was incorporated into a PDP, the sputter resistance was good and the driving voltage was lowered.

(D) Film thickness distribution of MgO film The sintered pellet of Example 2, the test piece of Comparative Example 2, and the crushed single crystal MgO of Comparative Example 5 were subjected to electron beam evaporation in the same manner as described above. A film was formed on a glass substrate by a method. This MgO
The film thickness distribution of the film was measured by an ellipsometer of a He-Ne laser (6328A). Table 4 shows the results. In Table 4, the thickness of each part is shown as a ratio to the thickness of the center of the glass substrate. That is, the film thickness at the center of the glass substrate was set to 1.0, and the film thickness of each part was shown by a ratio to this.

[0041]

[Table 4]

As is clear from Table 4, the film thickness of Example 2 and Comparative Examples 2 and 5 both gradually decrease as the distance from the center of the glass substrate increases. It was smaller.

[0043]

As described above, according to the present invention, the polycrystalline MgO vapor-deposited material is formed from sintered pellets of polycrystalline MgO having an MgO purity of 99.5% or more and a relative density of 97% or more. Therefore, this high-purity and high-density polycrystalline MgO
When an MgO film such as an AC type PDP is formed using a vapor deposition material, the film can be formed efficiently with little splash, and an MgO film having a substantially uniform film thickness can be obtained. As a result,
Even when the film area of the MgO film is large, the film can be formed substantially uniformly. For example, when a glass dielectric layer on which an MgO film is formed is incorporated in a PDP, the discharge starting voltage and the driving voltage are reduced. It can be constant, and the electrical characteristics of the PDP can be improved.

If the average crystal grain size of the sintered compact of polycrystalline MgO is 1 to 100 μm and the pores in the sintered pellet are rounded in the crystal grain and have an average inner diameter of 2 μm or less, The sintered pellet of polycrystalline MgO has a fine crystal structure and can reduce the occurrence of defects at the crystal grain boundaries. As a result, the formed MgO film has excellent film properties. In addition, the impurities of Si and Al contained in the sintered pellet of polycrystalline MgO are each 1 element concentration.
Reduce the impurity of Ca to an element concentration of 200
pm or less, Fe impurities at an element concentration of 50 ppm or less, and Cr, V and Ni impurities at an element concentration of 1 ppm or less.
0 ppm or less, Na and K impurities at an element concentration of 20 ppm or less, and C impurity at an element concentration of 70 ppm or less.
If the impurity concentration of Zr is set to 150 ppm or less and the element concentration is set to 150 ppm or less, the impurities contained in the formed MgO film become extremely small, so that the film characteristics of the MgO film are improved.

Further, a slurry having a concentration of 45 to 75% by weight is prepared by mixing MgO powder having a purity of 99.5% or more and an average particle diameter of 0.1 to 3 μm, a binder and an organic solvent,
After the slurry is spray-dried to obtain a granulated powder having an average particle size of 50 to 300 μm, the granulated powder is placed in a predetermined mold, molded at a predetermined pressure, and sintered at a predetermined temperature. Then, the MgO purity is 99.5% or more and the relative density is 9%.
It is possible to obtain a polycrystalline MgO vapor deposition material composed of sintered pellets of polycrystalline MgO of 7% or more.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a TEG substrate having an MgO film formed by a vacuum evaporation method using a polycrystalline MgO evaporation material of the present invention.

FIG. 2 is a configuration diagram of an apparatus for measuring a discharge starting voltage of the TEG substrate shown in FIG.

[Procedure amendment]

[Submission date] May 29, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

<Comparative Test and Evaluation> (a) Purity, relative density and fracture strength test of MgO sintered body Discs, pellets and crushed sintered bodies obtained in Examples 1 to 8 and Comparative Examples 1 to 5 The purity and relative density of the product were measured. Further, the discs of the sintered bodies obtained in Examples 1, 4, 7, 8 and Comparative Examples 1, 3, and 4 were cut out, ground and polished, and 3 mm × according to JIS R1601.
The size of a four-point bending test specimen of 4 mm × 40 mm was determined, and the breaking strength (bending strength) was examined. Table 1 shows the results. The purity was calculated from the analytical value of the impurity, the relative density was measured by the Archimedes method in toluene, and the breaking strength was 3
It was measured by a point bending test. Table 1 shows Examples 1 to 8.
The production conditions of the discs and pellets of the sintered bodies of Comparative Examples 1 to 4, that is, the slurry mixing treatment, the average particle size of the granulated powder, and the sintering conditions of the compact were described.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

First, the refractive index and the absorption coefficient of the MgO film were measured. The refractive index and absorption coefficient of the MgO film are He-Ne.
Ellipsometry was performed on the film at one wavelength and two angles of incidence (55 °, 70 °) with a laser (wavelength: 6238 Å), and the value was obtained using analysis software. Next, the above MgO
The firing voltage of the film was measured by the following method. 5 types of T
Ne-5% of the apparatus shown in FIG.
Xe is placed on a heating sample table 16 placed in a vacuum bell jar 15 of 500 Torr, the base electrode 12 (FIG. 1) is connected to a pulse power source 17, and the TEG substrate 10 is connected to a thermocouple 18.
The power supply voltage was increased while controlling the temperature at a constant value while measuring the above, and the voltage at which discharge was started was measured. The pulse power supply 17 is variable in voltage in the range of 0 to 300 V, and generates a pulse having a frequency of 66 kHz and a pulse width of 10 μsec. Table 3 shows the refractive index, absorption coefficient, and discharge starting voltage of the MgO film. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 27, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

First, the refractive index and the absorption coefficient of the MgO film were measured. The refractive index and absorption coefficient of the MgO film are He-Ne.
Ellipsometry was performed on the film at one wavelength and two angles of incidence (55 °, 70 °) with a laser (wavelength: 6238 Å), and the value was obtained using analysis software. Next, the above MgO
The firing voltage of the film was measured by the following method. 5 types of T
Ne-5% of the apparatus shown in FIG.
Xe is placed on a heating sample table 16 arranged in a vacuum bell jar 15 of 500 Torr, the underlying electrode 12 (FIG. 1) is connected to a pulse power source 17, and the TEG substrate 10 is connected to a thermocouple 18.
The power supply voltage was increased while controlling the temperature at a constant value while measuring the above, and the voltage at which discharge was started was measured. The pulse power supply 17 is variable in voltage in the range of 0 to 300 V, and generates a pulse having a frequency of 66 kHz and a pulse width of 10 μsec. Table 3 shows the refractive index of the MgO film, the absorption coefficient , the discharge starting voltage , the film formation speed, and the presence or absence of splash during film formation .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction contents]

As is clear from Table 3, Comparative Examples 2 and 5
Had refractive indexes of 1.65 and 1.62,
In Examples 2, 5, and 6, the refractive index was improved to about 1.8.
In Comparative Examples 2 and 5, the absorption coefficient was about 0.01, while in Examples 2, 5, and 6, the absorption coefficient was 0.00.
It improved to 1 or less. In addition, the discharge starting voltage was determined in Examples 2 and 5.
And it was found approximately 10~20V lower compared with Comparative Example 2及 beauty 5, 6. Furthermore, the film forming rate of the example is about 3 times that of the comparative example.
A doubled value was obtained. This is when the electron beam hits
Although the single crystal MgO crushed product of Comparative Example 5 has orientation,
This is because the polycrystalline MgO sintered pellet of the example has no orientation, and thus efficient film formation is possible. In addition, when the substrate on which the MgO film was formed using Examples 2, 5, and 6 was incorporated into a PDP, the sputter resistance was good and the driving voltage was lowered.

Claims (7)

[Claims] 1. A polycrystalline MgO vapor deposition material comprising sintered pellets of polycrystalline MgO having an MgO purity of 99.5% or more and a relative density of 97% or more. 2. The sintered pellet of polycrystalline MgO has an average crystal grain size of 1 to 100 μm, and the sintered pellet has rounded pores having an average inner diameter of 2 μm or less. 2. The polycrystalline MgO vapor deposition material according to 1. 3. The Si and Al impurities contained in the polycrystalline MgO sintered compact pellets each have an element concentration of 150%.
ppm or less, and the impurity of Ca is 200 p
pm or less, and the impurity of Fe is 50 ppm in elemental concentration.
The impurities of Cr, V and Ni are each 10 ppm or less in elemental concentration, the impurities of Na and K are each 20 ppm or less in elemental concentration, the impurity of C is 70 ppm or less in elemental concentration, and the content of Zr is 3. The polycrystalline MgO vapor deposition material according to claim 1, wherein the impurity has an element concentration of 150 ppm or less. 4. A composition having a purity of 99.5% or more and an average particle size of 0.5%.
Preparing a slurry having a concentration of 45 to 75% by weight by mixing MgO powder of 1 to 3 μm, a binder, and an organic solvent; and spray-drying the slurry to obtain an average particle size of 50 to 300 μm.
m, a step of placing the granulated powder in a predetermined mold and molding at a predetermined pressure, and a step of sintering the molded body at a predetermined temperature. Manufacturing method. 5. The granulated powder is 750-2000 kg / cm.
5. The polycrystalline Mg according to claim 4, which is formed by uniaxial pressing under a pressure of ^2.
Manufacturing method of O vapor deposition material. 6. A granulated powder of 1000 to 3000 kg / c.
5. The polycrystalline Mg according to claim 4, wherein the CIP is formed at a pressure of m ^2.
Manufacturing method of O vapor deposition material. 7. The method for producing a polycrystalline MgO vapor-deposited material according to claim 4, wherein the molded body is firstly sintered at a temperature of 1250 to 1350 ° C., and then heated and secondarily sintered at a temperature of 1500 to 1650 ° C. .