JPS62167260A - Luminescent sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a luminescent sintered body that emits light under ultraviolet rays, X-rays, or electron beams.

[Technical background of the invention and its problems]

Nitride sintered bodies are being used as high-temperature component materials and semiconductor substrates due to their large mechanical strength and high thermal conductivity. For these sintered bodies, it is desired to non-destructively inspect variations in properties between firing lots and among the sintered bodies. This calibration plays an important role in improving reliability.

Conventionally, various methods have been tried as non-destructive testing. For example, by using X-ray imaging, it is possible to detect voids and foreign objects in a sintered body. Further, ultrasonic inspection can detect defects in density and on the order of several tens of micrometers. However, these methods require an apparatus for imaging the defect image, and the inspection apparatus is expensive and large. Furthermore, detection of minute defects is difficult.

Fluorescent dye penetrant flaw detection is simple and effective for inspecting a large number of products, but is limited to the detection of relatively large geometric flaws on one surface. Moreover, with either method, it is not easy to detect essential variations in the sintered body, such as chemical composition distribution and crystal structure distribution.

In semiconductors and oxide single crystals, attempts have been made to associate lattice defects with cathodoluminescence or photoluminescence. This method utilizes the fact that lattice defects in a uniform material serve as emission centers, and is an excellent method for detecting microscopic defects. However, it is difficult to apply this method to ordinary nitride sintered bodies as a simple and highly accurate defect detection method. This is because when a normal sintered body is exposed to ultraviolet rays, xmh, or electron beams, it does not emit light, or even if it does emit light, the intensity is weak. Another reason is that the light emission of nitride sintered bodies has not been well studied, so it is not possible to determine the type of defect or composition from a single light emission.

[Purpose of the invention]

The object of the present invention is to provide a nitride sintered body suitable for non-destructive testing using light emission.

[Summary of the invention]

This invention was made by focusing on the fact that a nitride sintered body usually contains an oxide phase caused by a sintering aid in addition to the nitride phase, which is the main component. That is, this was achieved by incorporating a trace amount of a luminescent element into these oxide phases.

The sintering aid is added to the main component raw material in order to densify the main VC sintered body. This is a substance that is added in an amount of 1 to 15 wt.

In the case of aluminum nitride, a compound powder that turns into yttrium oxide or calcium oxide at high temperatures is used as an auxiliary agent, which becomes a liquid phase during the high-temperature sintering process and promotes sintering due to the presence of VC between the main component nitride particles. In addition, it is said to improve properties such as heat conduction by incorporating impurities in the main components such as oxygen.

After sintering, the auxiliary agent exists as a solid solution or subphase between the main particles. In case of aluminum nitride sintered body and yttrium oxide auxiliary agent, it is expressed by the chemical composition of subphase y2o3 x A1203, and depending on the auxiliary content, Y3AlsO1z (
x=-), YAIOa(x=1), Y4A1
It becomes a crystal such as 20g (x=1/2).

In this invention, when the sintering aid powder is added to the nitride raw material powder, at the same time, 0.001 to 50% cerium is added to the cationic element constituting the aid.

A compound containing at least one element of praseodymium, neodymium, and bismuth is added. For addition, these elements can be added to the auxiliary by pre-containing these elements in the auxiliary by means such as coprecipitation, or by adding compound powder or liquid containing these elements to the auxiliary. The lower limit of the amount of the impurity element added was determined from the limit at which the emission intensity becomes stronger than in the case of no addition. If the impurity element compound is added in an amount exceeding the main limit value, concentration quenching occurs and the emission intensity becomes weak, which is not suitable for the purpose of the present invention.

Moreover, in this case, there is a possibility that the purpose of the auxiliary agent to promote sintering and improve the properties of the sintered body may be impaired.

Next, a method for manufacturing an AM sintered body according to the present invention will be briefly explained.

Add an appropriate amount of a luminescent element to the powder and at least one kind of rare earth compound or alkaline earth compound as a sintering aid to the mass A, or add a rare earth compound or alkaline earth containing a luminescent element by means such as coprecipitation in advance. After adding at least one type of compound, the mixture is mixed using a ball mill or the like. For sintering, a pressureless sintering method, a hot press sintering method, etc. are used. In the case of the pressureless sintering method, a binder is added to the mixed powder, and the mixed powder is mixed, granulated, and sized, and then molded. As the molding method, mold press isostatic pressing, sheet molding, etc. are adopted. Subsequently, the molded body is heated, for example, in a N2 gas stream to remove the binder, and then pressureless sintering is performed. On the other hand, when using the hot press sintering method, the mixed powder may be directly hot pressed.

In these processes, whether by the pressureless sintering method or the hot press sintering method, the sintering degree is 1600 to 2.
000℃, and in practical terms l 700'O~1800
℃ range.

〔Effect of the invention〕

When the sintered body of the present invention is placed under an excitation source consisting of ultraviolet rays, X-rays, or electron beams, it emits light. ) The distribution of luminescence intensity in the i8 housing can be easily observed visually. This distribution is often non-uniform even when the sintered body has a uniform body color distribution over the entire surface. The distribution of luminescence intensity is thought to be due to the content distribution of luminescent elements in the sintered body, the content distribution of subphase products generated in the sintered body, or the distribution of chemical species of subphase organisms. Therefore, from this distribution, the chemical composition of the sintered body and the uniformity of its amount can be easily determined.

On the other hand, it is well known that luminescent elements located within the crystal lattice of different chemical species exhibit different luminescent colors. For example, Y3AA contains cerium impurities! so 12 exhibits yellow emission under ultraviolet light, whereas YAlO3 exhibits ultraviolet emission. In the case of oxides containing europium or chromium impurities, the emission color varies greatly depending on the chemical species, with the former being red to orange and the latter deep red. Species can be identified. Therefore, the chemical species of the subphase generated in the sintered body can be estimated from the emission color.

As described above, by using the sintered body of the present invention, the uniformity of the chemical composition and amount in the sintered body and the species of subphase products can be easily investigated by observing luminescence. In the case of ultraviolet excitation, the light source may be, for example, a commercially available fluorescent inspection lamp (FI-31L type) manufactured by Tokyo Kogaku Kikai Co., Ltd., and luminescence can be visually observed in the air. This is simpler than other non-destructive testing methods.

Roughly weak luminescence can be detected visually, and can be detected using a tube-sensitive detection method. Furthermore, since the emission spectrum generally changes sensitively depending on the intracrystalline environment in which the element serving as the emission center is located, it is also possible to detect the chemical composition and crystal structure with high precision. Using these techniques, it is also possible to obtain information that cannot be obtained using conventional non-destructive testing methods. For example, by comparing a secondary electron image and a cathodoluminescence image under a scanning electron microscope, it is possible to obtain the crystallinity of a subphase product between main component particles with high sensitivity and precision.

Next, the method for manufacturing the A/N fi aggregate of the present invention will be briefly explained. First, a suitable amount of at least one kind of rare earth compound or alkaline earth compound as a sintering aid and a luminescent element are added to the AfN powder, or a rare earth compound or alkaline earth compound containing a luminescent element is added by means such as coprecipitation in advance. After adding at least one compound, the mixture is mixed using a ball mill or the like.

For sintering, a pressureless sintering method, a hot press sintering method, etc. are used. When using the pressureless sintering method, a binder is added to the mixed powder, kneaded, granulated, and sized, and then shaped. As the molding method, shed press, isostatic press, sheet molding, etc. are adopted. Subsequently, the molded body is heated, for example, in a N2 gas stream to remove the binder, and then pressureless sintering is performed. On the other hand, when using the hot press sintering method, the mixed powder may be directly hot pressed.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

Example I M■ powder with 3% by weight of Y2O3 powder and Tb4O7
A raw material was prepared by adding 0.030% of the mixture and mixing with powdered sand in a ball mill. Subsequently, 7% paraffin was added to this raw material and granulated, followed by press molding at a pressure of 500 kg/ad to obtain a green compact of 30×30×8 size.

Subsequently, this green compact was heated to 700°C in a nitrogen atmosphere to remove paraffin.

Next, it was placed in a carbon container and placed in a nitrogen gas atmosphere.
An Am sintered body was produced by pressureless sintering at 1800°C for 2 hours.

When the obtained sintered body was irradiated with ultraviolet light (Ci length: 365 nm), the sintered body uniformly emitted green fluorescence.

The sintered body also emitted similar fluorescence when irradiated with an electron beam at an accelerating voltage of xoKV and a current density of lμA/d.

Also, X-ray [! ll! When the constituent phases of the sintered body were investigated, it was found that they were AM and Y3Also 12.

Example 2 A raw material was prepared by adding 1% by weight of Y2O3 powder and 0.01% by weight of Cr2O3 to the same A powder as in Example 1, and performing pulverization and double polymerization in a ball mill. Subsequently, this raw material was press-molded at a pressure of 500 mm to 9 mm to form a green compact with a diameter of 12 mm and a thickness of 10 mm. Next, the green compact was placed in a carbon mold and heated at 1750° in a nitrogen gas atmosphere.
An AM sintered body was manufactured by hot press sintering at C for 1 hour under a pressure of 100 to 9 m.

When the obtained sintered body was irradiated with ultraviolet light (wavelength: 365 μm), the sintered body uniformly emitted pale orange fluorescence. When the constituent phases were identified by X-ray diffraction, they were A-image and YaAlso 12, as in Example-1.

Examples 3 to 15 Sintering aids and luminescent compounds as shown in Table 1 were added to the same AIN powder as in Example 1, and each sintering process was carried out as described in Example 1. I got a body.

The fluorescent color of the sintered body by ultraviolet irradiation or electron beam irradiation and the constituent phases by X-ray diffraction are shown in Table 11c.

Example-16 10% by weight of Y2O3 was added to the A/N powder used in Example-1.
A sintered body was obtained in the same manner as in Example-1 by adding 30.005% by weight of Crp and 0.05% by weight of CeO2.

When the sintered body was irradiated with ultraviolet light (365 nm), the center of the sintered body emitted yellow light, and the periphery of the sintered body emitted light orange.

When this sintered body was cut in half and the cross section was observed,
It was found that sub-constituent phases other than MN were clearly distributed more in the center than in the periphery.

Example 17 1% by weight of Tb4O7 based on Y2O3 and Y2O3 was dissolved in concentrated nitric acid, and an aqueous Schellic acid solution was added thereto to obtain an oxalate coprecipitation of yttrium and terbium.

Subsequently, this oxalate coprecipitate was washed with water, dried, and then decomposed and calcined in the air at 1000° C. for 2 hours to obtain yttrium oxide containing terbium ((Y,Tb)zo3). Next, the above (Y,
1% by weight of Tb)203 was added and a sintered body was obtained in the same manner as described in Example-1.

When the obtained sintered body was irradiated with ultraviolet light, the sintered body uniformly emitted green fluorescence. Similar fluorescence was also emitted by electron beam irradiation. Further, when the constituent phases of the sintered body were examined by X-ray diffraction, they were found to be AIN and Y3Al5O12.

As described above, by using the nitride sintered body of the present invention, non-destructive inspection of composition and content variations of the sintered body can be easily performed. On the other hand, it is also possible to consider applications other than non-destructive testing by utilizing the luminescence property. For example, in the case of silicon nitride sintered bodies, it is possible to add luminescence to the original properties of being lightweight and having high strength at high temperatures, so scintillators that can be used at high temperatures can be made. Furthermore, the translucent aluminum nitride sintered body can be applied to a laser oscillation material with high thermal conductivity. (Hereafter in white) Table
-1 Example-3Ca■3 1wt% Pigeon■3 0.01
wt% 1800℃・2 hours 14Ba■3 1
MnCO30.01wt% 1800'OIy5sr
■31MoQ) 31J, 01wt%1800#1
6YF3 3-% CeO20,001vrt% 17
00 #1 7 La2O31Cr2O3
0.03wt% 1800 11 8 Gd
z03' Eu2O30.03wt%
1800 11 9 Lu2O3'
Tb4O70.03wt% 1800 11 1
0 LaF3' Tb4O70,03
wt% 1750 #' 11 CaF2
' Ga2O30.03wt% 175
0 tl 12 BaF2'
guzos o, o3 wt% 1750
1t13SrF21&n2030.03wt%1750
z' 14 8CzO310wt% Tb40?
Does not emit 0.1 wt% 1900 Green color A/N, CaOφ2 human body 3 emits rx I Green color A! ! N+
BaO'6A1203 does not emit green color
~N, unknown phase yellow yellow keN+Y3)J
! 5012 Red -) -INtL Lie 3 Red Red 1 (Jd Pus3 Green Green 'L□3 Green Green ' LaAt!03 Blue -Term, CaO"2AIE3 Back color -1Bao・6 people 12o3 Orange Color I Unknown phase line color
I5C203,lF! 1m Yellow Yellow Warehouse, Y3Al5O121”Ca() 2 people 120
3

Claims (4)

[Claims] (1) A luminescent sintered body made of an aluminum nitride sintered body characterized by containing an element that becomes a luminescent center under ultraviolet rays, X-rays, or electron beams. (2) The luminescent sintered body according to claim 1, wherein the luminescent center is in a sub-constituent phase other than aluminum nitride. (3) Additives are SC, La, Y, Gd, Lu and C
A compound of at least one of a, Ba, and Sr, and a compound of an element serving as a luminescent center including Ce, Pr, and Nd.
, Sm, Eu, Tb, Er, Tm, Ho, Cr, Mn,
The light-emitting sintered body according to claim 2, characterized in that at least one member from the group of compounds of Ga, Pb, and Bi is added in an amount of 0.001 to 10 atomic % based on the additive. (4) Luminescent sintering according to claim 3, characterized in that a mixed powder in which the total amount of additives is 0.01 to 15% by weight in terms of elements is sintered at 1600 to 2000°C. body.