JP3548799B2 - Method for producing spinel-type germanium nitride powder - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for mass-producing high-pressure phase spinel-type germanium nitride powder, which has not been known at all, and more specifically, transforms low-pressure phase germanium nitride into cubic spinel-type germanium nitride using various conventionally known impact compression methods. The present invention relates to a method for producing spinel-type germanium nitride by a so-called impact pressurization method.
[0002]
[Prior art]
As a method for producing spinel-type germanium nitride, low-pressure phase germanium is subjected to a solid pressure method of 12 GPa or more by a diamond anvil cell or a press at a high temperature and high pressure of 1000 to 1200 ° C., or 14 GPa or more of Ge and a nitrogen fluid to 1700. Synthetic methods for reacting at a temperature of at least ℃ are known.
[0003]
[Problems to be solved by the invention]
The conventional method of producing spinel-type germanium nitride can produce at most 100 milligrams of sample at a time on an experimental scale. In addition, a step such as pulverization was required to obtain a fine powder.
[0004]
[Means for Solving the Problems]
The present inventor has conducted intensive studies to solve the above problems, and as a result, mixed an appropriate amount of metal powder with low-pressure phase germanium nitride powder, pressed and molded to an appropriate density, and applied an appropriate pressure and temperature to the molded body. If the impact compression is applied for a short period of time over a certain degree, it can be converted into a high-pressure phase spinel-type germanium nitride fine powder in high yield and produced in large quantities without changing the composition of the initial germanium nitride powder. Was.
[0005]
That is, the present invention provides a method for synthesizing spinel-type germanium nitride in a high-pressure phase by pressurizing low-pressure phase germanium nitride (α-Ge ₃ N ₄ , β-Ge ₃ N ₄ , or amorphous Ge ₃ N ₄ ) by a shock wave. A spinel-type germanium nitride powder characterized in that a pressed compact of a mixture of a low-pressure phase powder and a metal powder is placed in a metal container and subjected to instantaneous pressurization by a shock wave having a pressure of 20 GPa or more and a pressurization time of 5 microseconds or less. It is a manufacturing method.
[0006]
Further, the present invention is a method for producing a spinel-type germanium nitride powder, wherein the metal powder mixed with the low-pressure phase powder described above is a copper powder.
Further, the present invention is a method for producing a spinel-type germanium nitride powder, characterized in that the mixing ratio of the low-pressure phase powder and the copper powder is 99 to 50% by weight of copper.
Further, the present invention provides a spinel-type germanium nitride, wherein the density of the pressed compact of the mixture of the low-pressure phase powder and the copper powder described above is 8.9 g / cm ³ to 4.5 g / cm ^3. This is a method for producing powder.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention specifies the initial state of the sample and the conditions of the impact environment when synthesizing the spinel-type germanium nitride using the high-temperature and high-pressure state generated by instantaneous impact compression. In the initial state of the sample, the selection of the starting material, the presence or absence of a mixture with a metal such as copper powder, the apparent density of the compact, the distribution of voids in the compact, and the like are important. The amount of the voids is defined by the density of the pressed compact, and the distribution is defined by the particle size and shape of the metal powder.
[0008]
The starting material germanium nitride powder is preferably a fine powder having good crystallinity, and the particle size is preferably 10 μm or less. Both α-type and β-type may be used. Further, a small amount of unreacted Ge may be contained. In the case of amorphous germanium nitride, a powder containing no hydrogen or the like is preferable.
[0009]
Mixing with a metal such as copper powder is necessary to make the impact conditions uniform and to increase the impact pressure. For that purpose, the particle size of the metal powder is desirably 50 microns or less. At this time, the type of metal is most preferably copper, which is a metal that does not react with germanium nitride. The particle shape of the copper powder or the like is preferably spherical because the density of the press-formed body is increased. It is important that the metal used as the container be sufficiently protected from destruction from a shock wave and not react with the sample, and copper is used.
[0010]
The apparent density of the pressed body is important for controlling the impact temperature, and sufficiently increases the reaction rate. In addition, the apparent density must be lower than the temperature at which germanium nitride does not decompose or melt. To about 95% is appropriate. This value also depends on the mixing ratio with the copper powder, and may be decreased when the amount of copper is large, and must be increased when the amount of copper is small. The density is from 8.9 g / cm ³ to 4.5 g / cm ³ . Preferably, the compact is a mixture of 10 to 15% by weight of germanium nitride and 90 to 85% by weight of copper powder, and has a density of 7.5 g / cm ³ to 6.5 g / cm ³ . Moreover, it is desirable that the distribution of voids in the compact is as uniform as possible.
[0011]
The condition of the impact environment requires a pressure of 20 GPa or more. When the pressure is increased to 60 GPa or more, it becomes difficult to collect the sample when the pressure is released. The temperature is desirably 1000 ° C or more and 2000 ° C or less. As long as such impact conditions are realized, the method of impact treatment is not limited. That is, a shock wave that can be realized by collision of a high-speed flying object may be used, or a method of processing using a commercially available explosive, a so-called cylindrical method, may be used. The impact pressure is calculated by the impedance matching method by measuring the velocity of the flying object immediately before the collision. The impact temperature is calculated assuming that the impact temperature of a large amount of copper powder and that of the sample are in thermal equilibrium.
[0012]
FIG. 1 illustrates the relationship between the generation of a shock wave and a shock-treated sample for carrying out the method of the present invention. Specifically, the sample (2) is placed in a collection container (3) for protecting the sample from shock wave destruction, pressed from behind the sample with a screw lid (4), and then embedded in a large circular container (1). , Target.
On the other hand, in order to generate a shock wave by a collision of a high-speed flying object (8), acceleration is performed by a gunpowder. In order to increase the impact pressure, the flying object has a metal flying plate (7) in front of the servo (6).
[0013]
【Example】
Example 1
The apparent density of a sample of a pressed body of a mixture of germanium nitride and copper powder was adjusted by increasing or decreasing the forming pressure. A sample container made of a mixture of 10% by weight of α-germanium nitride and 90% by weight of β-germanium nitride mixed powder and 90% by weight of copper powder with an apparent density of 7.56 g / cm ³ (porosity of 10%). And a flying plate were used to collide a copper plate at a speed of 1.87 km / sec to perform an impact treatment of about 44 GPa.
[0014]
The recovered sample was taken out of the sample container, the copper powder was removed by acid treatment, and the obtained germanium nitride was identified by X-ray powder diffraction. FIG. 2 shows the obtained diffraction pattern. In FIG. 2, 1 is a low-pressure phase germanium nitride as a starting material, symbol a is a peak of α-type Ge ₃ N _{4 in} the raw material, Ge is impurity Ge in the raw material, and all unmarked peaks are β-type Ge ₃ N ₄ . Corresponding. 2 is the product after the impact treatment of about 36 GPa, 3 is the product after the impact treatment of about 44 GPa, the symbol c is the peak of spinel type Ge ₃ N ₄ , and the number in () indicates the diffraction index. As shown by 3 in FIG. 2, it was found that almost 100% of cubic spinel-type germanium nitride was present.
[0015]
Example 2
In the same manner as in Example 1, a copper plate was made to collide with a sample having an apparent density of 6.03 g / cm ³ (porosity 28%) using the same mixed powder at a speed of 1.59 Km / sec and subjected to impact treatment at about 36 GPa. Was. The recovered sample was taken out of the sample container, the copper powder was removed by acid treatment, and the obtained germanium nitride was identified by X-ray powder diffraction. The obtained diffraction pattern, as indicated by 2 in FIG. 2, revealed that the starting material was a mixed product of low-pressure phase germanium nitride and cubic spinel-type germanium nitride.
[0016]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to mass-produce spinel-type germanium nitride having a high conversion rate and a high pressure phase from a low-pressure phase germanium nitride in one impact treatment.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration example of an apparatus for the present invention.
FIG. 2 is an X-ray powder diffraction pattern of an impact recovery sample.

Claims (4)

In a method of compressing low-pressure phase germanium nitride (α-Ge ₃ N ₄ , β-Ge ₃ N ₄ , or amorphous Ge ₃ N ₄ ) by a shock wave to synthesize spinel-type germanium of a high-pressure phase, a low-pressure phase powder and a metal powder are used. A pressure-molded article of the mixture of the above and a metal container, and instantaneously pressurized by a shock wave having a pressure of 20 GPa or more and a pressurization time of 5 microseconds or less, a method for producing spinel-type germanium nitride powder. The method for producing a spinel-type germanium nitride powder according to claim 1, wherein the metal powder mixed with the low-pressure phase powder is copper powder. The method for producing a spinel-type germanium nitride powder according to claim 2, wherein the mixing ratio of the low-pressure phase powder and the copper powder is 99% by weight to 50% by weight of copper. 4. The spinel mold according to claim 2, wherein the density of the press-formed body of the mixture of the low-pressure phase powder and the copper powder is 8.9 g / cm ³ to 4.5 g / cm ^{3. 5.} Manufacturing method of germanium nitride powder.

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