METHOD OF PRODUCING HIGH BULK DENSITY MOLYBDENUM OXYCHLORIDE

Abstract

Provided is a method of producing a high purity molybdenum oxychloride by including means of sublimating and reaggregating a raw material molybdenum oxychloride in a reduced-pressure atmosphere, or means of retaining a gaseous raw material molybdenum oxychloride, which was synthesized in a vapor phase, in a certain temperature range, and thereby growing crystals to obtain a higher purity molybdenum oxychloride having a high bulk density and high hygroscopicity resistance.

Claims

1. A method of producing a molybdenum oxychloride comprising the steps of heating a raw material molybdenum oxychloride, which is a crystal powder, at a temperature range of 70 C. or higher and 150 C. or less in a reduced-pressure atmosphere, sublimating a molybdenum oxychloride from the raw material, and cooling/reaggregating a product thereof to obtain molybdenum oxychloride having a bulk density that is higher than that of the raw material.

2. The method of producing a molybdenum oxychloride according to claim 1, wherein the reduced-pressure atmosphere is an atmosphere of a pressure of 1 kPa or more and 20 kPa or less.

3. A method of producing a molybdenum oxychloride comprising the steps of retaining a gaseous raw material molybdenum oxychloride, which was synthesized based on a reaction of a molybdenum oxide powder and chlorine gas at 700 C. or higher in a vapor phase, at a temperature range of 40 C. or higher and 120 C. or less in an atmospheric pressure, growing crystals of molybdenum oxychloride from the raw material, and obtaining a molybdenum oxychloride having a bulk density that is higher than that of the raw material.

4. The method of producing a molybdenum oxychloride according to claim 3, wherein the molybdenum oxychloride is one among molybdenum dichloride dioxide (MoO.sub.2Cl.sub.2), molybdenum trichloride oxide (MoOCl.sub.3) or molybdenum tetrachloride oxide (MoOCl.sub.4).

5. The method of producing a molybdenum oxychloride according to claim 4, further comprising the step of synthesizing the raw material molybdenum oxychloride based on a reaction of a molybdenum dioxide (MoO.sub.2) powder or a molybdenum trioxide (MoO.sub.3) powder and chlorine gas (Cl.sub.2) at 700 C. or higher.

6. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 5, wherein a bulk density of the molybdenum oxychloride is 0.5 g/cm.sup.3 or more.

7. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 6, wherein a purity of the molybdenum oxychloride is 99.999 wt % (5N) or higher.

8. The method of producing a molybdenum oxychloride according to claim 3, further comprising the step of synthesizing the raw material molybdenum oxychloride based on a reaction of a molybdenum dioxide (MoO.sub.2) powder or a molybdenum trioxide (MoO.sub.3) powder and chlorine gas (Cl.sub.2) at 700 C. or higher.

9. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 3, wherein a bulk density of the molybdenum oxychloride is 0.5 g/cm.sup.3 or more.

10. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 3, wherein a purity of the molybdenum oxychloride is 99.999 wt % (5N) or higher.

11. The method of producing a molybdenum oxychloride according to claim 2, wherein the molybdenum oxychloride is one among molybdenum dichloride dioxide (MoO.sub.2Cl.sub.2), molybdenum trichloride oxide (MoOCl.sub.3) or molybdenum tetrachloride oxide (MoOCl.sub.4).

12. The method of producing a molybdenum oxychloride according to claim 11, further comprising the step of synthesizing the raw material molybdenum oxychloride based on a reaction of a molybdenum dioxide (MoO.sub.2) powder or a molybdenum trioxide (MoO.sub.3) powder and chlorine gas (Cl.sub.2) at 700 C. or higher.

13. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 12, wherein a bulk density of the molybdenum oxychloride is 0.5 g/cm.sup.3 or more.

14. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 13, wherein a purity of the molybdenum oxychloride is 99.999 wt % (5N) or higher.

15. The method of producing a molybdenum oxychloride according to claim 1, wherein the molybdenum oxychloride is one among molybdenum dichloride dioxide (MoO.sub.2Cl.sub.2), molybdenum trichloride oxide (MoOCl.sub.3) or molybdenum tetrachloride oxide (MoOCl.sub.4).

16. The method of producing a molybdenum oxychloride according to claim 1, further comprising the step of synthesizing the raw material molybdenum oxychloride based on a reaction of a molybdenum dioxide (MoO.sub.2) powder or a molybdenum trioxide (MoO.sub.3) powder and chlorine gas (Cl.sub.2) at 700 C. or higher.

17. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 1, wherein a bulk density of the molybdenum oxychloride is 0.5 g/cm.sup.3 or more.

18. The method of producing a molybdenum oxychloride having a bulk density that is higher than that of the raw material according to claim 1, wherein a purity of the molybdenum oxychloride is 99.999 wt % (5N) or higher.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is diagram showing an example of the device configuration for synthesizing a molybdenum oxychloride.

[0032] FIG. 2 is a diagram showing an example of the device configuration for sublimating/reaggregating a molybdenum oxychloride.

[0033] FIG. 3 is a diagram showing the appearance of the molybdenum oxychloride of Comparative Example 1.

[0034] FIG. 4 is a diagram showing the appearance of the molybdenum oxychloride of Example 1.

[0035] FIG. 5 is a diagram showing the appearance of the molybdenum oxychloride of Example 2.

[0036] FIG. 6 is a diagram showing the appearance of the molybdenum oxychloride of Example 3.

DESCRIPTION OF EMBODIMENTS

[0037] The present invention is, as the essential technical means, a method of producing a molybdenum oxychloride including the steps of sublimating a raw material molybdenum oxychloride by heating it in a reduced-pressure atmosphere, and cooling the sublimated vapor phase state molybdenum oxychloride for once again aggregating/solidifying the molybdenum oxychloride. The advantages of the present invention based on its operation and effect can be enjoyed by using a crystal powder having a low bulk density as the raw material molybdenum oxychloride. As this kind of raw material crystal powder having a low bulk density, listed may those having a bulk density of 0.1 g/cm.sup.3 or less, 0.8 g/cm.sup.3 or less, and even 0.5 g/cm.sup.3 or less.

[0038] The heating temperature upon subjecting the raw material molybdenum oxychloride to reduced-pressure sublimation may be set to a range of 70 C. to 150 C. Since the temperature in which the raw material molybdenum oxychloride becomes sublimated will change depending on the ambient pressure during sublimation, the sublimation temperature is preferably set and adjusted according to the ambient pressure. In order to maintain the proper sublimated state according to the ambient pressure, the sublimation temperature may be preferably set to 85 C. or higher, 95 C. or higher, or even 105 C. or higher in certain cases. Similarly, in order to maintain the proper sublimated state according to the ambient pressure, the sublimation temperature may be preferably set to 140 C. or less, 130 C. or less, or even 120 C. or less in certain cases.

[0039] The molybdenum oxychloride that is sublimated and became a vapor phase state is cooled, once again becomes a solid phase state, and then becomes aggregated. Here, preferably, the molybdenum oxychloride in a vapor phase state is aggregated/solidified upon being transferred to a position that is separated by a predetermined distance from the sublimation position where the raw material molybdenum oxychloride is held and heated. The temperature at the position of cooling and subsequently aggregating/solidifying the molybdenum oxychloride may be set to a temperature that is roughly 20 C. lower than the sublimation temperature, or even lower. As an example of a specific device configuration for realizing this kind of sublimation/reaggregation, a configuration of using a reaction tube having a temperature gradient in which the temperature gradually decreases as it becomes separated from the container for holding and heating the raw material molybdenum oxychloride may be used, but the configuration is not limited thereto.

[0040] As the molybdenum oxychloride to which the method of the present invention can be applied, there are the following depending on the difference in valence of molybdenum; namely, molybdenum dichloride dioxide (VI) (MoO.sub.2Cl.sub.2), molybdenum trichloride oxide (V) (MoOCl.sub.3), and molybdenum tetrachloride oxide (VI) (MoOCl.sub.4). Among the above, the method of the present invention can be preferably applied to MoO.sub.2Cl.sub.2 which has a high utility value as a raw material of CVD or ALD and as a catalyst for chemical reactions.

[0041] While the sublimation/reaggregation of the molybdenum oxychloride in the method of the present invention is performed in a reduced-pressure atmosphere, the ambient pressure can be set to a pressure in a range of 1 kPa or more and 20 kPa or less. The proper pressure is set and adjusted within the foregoing pressure range according to the sublimation temperature and the reaggregation temperature. When the ambient pressure is less than 1 kPa, the sublimation/aggregation temperature will decrease and it may be difficult to control the sublimation rate, the aggregated molybdenum oxychloride may not exhibit sufficiently high density, and a sudden winding of the raw material molybdenum oxychloride tends to occur during the heating process.

[0042] Moreover, when the ambient pressure exceeds 20 kPa, the sublimation temperature will increase and the energy cost required for the heating process will also increase, and it may become difficult to control the proper sublimation/aggregation conditions due to the sublimation rate becoming too fast or the reaction tube becoming clogged. In light of the above, the ambient pressure during the sublimation/reaggregation of the present invention may be set to 3 kPa or more, and 4 kPa or more, and be set to 10 kPa or less, and 7 kPa or less.

[0043] There is no particular limitation in the method of producing the raw material molybdenum oxychloride used in the present invention so as long as the attainment of a higher bulk density can be expected based on the operation and effect of the present invention. However, as a step of synthesizing the raw material molybdenum oxychloride in which the foregoing operation and effect, particularly the operation of effect of attaining a higher bulk density, can be exhibited, the step of chloridating molybdenum dioxide (MoO.sub.2) or molybdenum trioxide (MoO.sub.3) with a chlorine gas (Cl.sub.2) may be included in the method of the present invention. The molybdenum oxychloride obtained by chloridating MoO.sub.2 or MoO.sub.3 with a Cl.sub.2gas becomes a fluffy floccose crystal powder with an extremely low bulk density, but the bulk density can be considerably increased by applying the method of the present invention.

[0044] For example, the synthesis of molybdenum oxychloride by chloridating MoO.sub.3 with a Cl.sub.2 gas is performed by causing the Cl.sub.2 gas to flow, at a predetermined flow rate, to the MoO.sub.3 powder which has been heated to a reaction temperature, and causing the vapor phase molybdenum oxychloride generated from the reaction of the MoO.sub.3 powder and the Cl.sub.2 gas to become reprecipitated in a solid phase. The heating temperature of MoO.sub.3 during the reaction is preferably set to 700 C. or higher. The vapor phase molybdenum oxychloride generated based on the foregoing reaction becomes reprecipitated in a solid phase as a result of being cooled. As an example of a specific device configuration for realizing this kind of reactive precipitation, a configuration of using a reaction tube having a temperature gradient in which the temperature gradually decreases as it becomes separated from the position of holding and heating MoO.sub.3 and capable of continuously flowing the reaction gas may be used, but the configuration is not limited thereto.

[0045] When synthesizing the molybdenum oxychloride based on the foregoing reaction, since a fluffy floccose crystal powder having a low bulk density will become precipitated in a huge volume at the precipitated part, a large-capacity crystal precipitation container is preferably mounted. Since the molybdenum oxychloride in a precipitated state is extremely inconvenient to handle as is, the crystals in the container may be stirred using a stirring rod or a stirrer to reduce and compress the volume of the crystals. Here, the operation is preferably performed in an inert gas atmosphere of dried (dew-point minus 60 C. or less) nitrogen or rare gas.

[0046] Here, in synthesizing the molybdenum oxychloride, the bulk density of the precipitated solid phase molybdenum oxychloride can also be increased by growing the crystals while holding the vapor phase molybdenum oxychloride, which is generated based on the reaction of the MoO.sub.3 powder and the Cl.sub.2 gas, at a predetermined temperature range in an atmospheric pressure. The holding temperature is set to 40 C. or higher, and preferably 45 C. or higher. When the holding temperature is less than 40 C., a floccose crystal powder having a low bulk density will be produced. Meanwhile, when heated to 120 C. or higher, the molybdenum oxychloride will be sublimated again and cannot be recovered and, therefore, the holding temperature is set to 120 C. or less, and preferably 100 C. or less.

[0047] Accordingly, a molybdenum oxychloride crystal powder having a low bulk density can be collected as a molybdenum oxychloride having a bulk density of 0.5 g/cm.sup.3 or more by applying the sublimation/reaggregation of the present invention, or applying solid precipitation in a proper temperature range. By properly controlling the sublimation/reaggregation conditions, the molybdenum oxychloride collected after undergoing reaggregation will have a bulk density of 1.0 g/cm.sup.3 or more, and even 1.2 g/cm.sup.3 or more.

[0048] Moreover, the method of the present invention can reduce the content of impurities contained in the molybdenum oxychloride collected after undergoing reaggregation in comparison to that of the raw material as one effect of the sublimation/reaggregation process, and the produced molybdenum oxychloride will have a purity of 99.999 wt % (5N) or higher. Note that the purity of the molybdenum oxychloride in the present invention is defined as a value obtained by analyzing the elements that are anticipated as being contained as impurities in the molybdenum oxychloride, and subtracting the total content of elements that appeared in a content above the detection limit from 100 wt %.

[0049] Here, the impurity elements anticipated in the present invention are Be, Mg, Al, K, Ga, Ge, As, Sr, Ba, W, Ti, U, Ag, Na, Co, Fe, In, Mn, Ni, Pb, Zn, Cu, Cr, TI, Li, Th, Sc, Se, Hf, Ta, and Bi, and, among the above, K is analyzed based on the atomic absorption spectrometry (AAS) method, and elements other than K are analyzed based on the inductively coupled plasma mass spectrometry (ICP-MS) method. The content of the detection limit used in the analysis of the present invention is 0.5 wtppm for Ni and Se, and 0.1 wtppm for the other elements indicated above. Note that the impurity elements of a content that is less than the measurement limit are deemed not to be substantially contained upon calculating the purity.

[0050] As described above, the molybdenum oxychloride obtained by applying the sublimation/reaggregation of the present invention is collected via predetermined means. Here, the collection of the molybdenum oxychloride is also preferably performed in an inert gas atmosphere. Since the bulk density of the collected molybdenum oxychloride has improved drastically from the state of the raw material, it can be stored and transported easily, and the hygroscopicity resistance is also improved during the preservation thereof. In addition to the improvement in the hygroscopicity resistance during the preservation of the molybdenum oxychloride, because the purity is also improved from the state of the raw material due to the sublimation/reaggregation process, the present invention can be suitably applied to uses requiring high purity products such as for a raw material of CVD or ALD or for a catalyst for chemical reactions.

EXAMPLES

[0051] The present invention is now specifically explained based on the Examples and Comparative Examples. The following descriptions of the Examples and Comparative Examples are merely specific examples for facilitating the understanding of the technical contents of the present invention, and the technical scope of the present invention is not limited in any way by these specific examples.

[0052] <Manufacturing Apparatus>

[0053] Foremost, in performing the method of the present invention, a molybdenum oxychloride was synthesized by chloridating MoO.sub.2 or MoO.sub.3 with a Cl.sub.2 gas. FIG. 1 is a diagram showing an example of the configuration of the device 100 for synthesizing a molybdenum oxychloride. A MoO.sub.2 or MoO.sub.3 raw material 101 is placed on a raw material holding container 102, and this is placed inside a quartz reactor vessel 103. The outer periphery of the part of the reactor vessel where the raw material is placed can be heated with a raw material heating device 104, and temperature control is thereby enabled. A gas inlet port 105 is provided to one end of the reactor vessel, and a gas pipe 106 connected thereto is branched midway and leads to an introductory part of Cl.sub.2 to become the reaction gas for synthesizing a molybdenum oxychloride, and an introductory part of inert gas such as N.sub.2 to become the carrier gas. A valve or flow rate control device may be provided to the path of the gas pipe as needed.

[0054] A collection container 107 where the synthesized molybdenum oxychloride is precipitated and accumulated is connected to the other end of the reactor vessel 103. While the example of FIG. 1 adopts a configuration of using an L-shaped quartz tube as the reactor vessel and connecting it to the upper part of the collection container, there is no limitation in the shape or material of the reactor vessel or its mode of connection to the collection container, and may be changed as needed.

[0055] While the synthesized molybdenum oxychloride 110 based on a reaction is precipitated and accumulated inside the collection container, here, when the container is less than 40 C., the obtained molybdenum oxychloride becomes floccose with a low bulk density, and the volume tends to become enormous. Thus, when giving consideration to the collection of the obtained molybdenum oxychloride or work efficiency of the synthesizing process, it is preferable to use a large collection container with wide opening. Meanwhile, by maintaining the container to be within a range of 40 C. to 120 C., it is possible to precipitate molybdenum oxychloride crystals having a high bulk density.

[0056] Connected to the collection container are an exhaust pipe 108 which discharges unreacted chlorine or sublimatory chloride and leads to a detoxifying device which renders these substances harmless, and a vacuum pipe 109 which leads to a vacuum pump for adjusting the pressure inside the device.

[0057] FIG. 2 is a diagram showing an example of the device configuration for sublimating and reaggregating a molybdenum oxychloride and used in performing the method of the present invention. The configuration of FIG. 2(a) includes a raw material holding container 201, a molybdenum oxychloride raw material 202 is placed therein, and the raw material is heated with the raw material heating device 203. Moreover, the inside of the raw material holding container 201 is exhausted with a vacuum pumping unit 206 connected via a liquid-nitrogen trap 205 to achieve a reduced-pressure atmosphere of a predetermined pressure. A reaggregation/precipitation unit 204 is mounted at the upper part within the raw material holding container, and a liquid or gas coolant is caused to flow therein to achieve a predetermined cooling temperature. The raw material heated to a predetermined sublimation temperature under a predetermined pressure is vaporized based on sublimation, re-cooled with the reaggregation/precipitation unit at the upper part thereof, and becomes solidified and precipitated on the surface thereof.

[0058] The configuration of FIG. 2(b) is a modification of the configuration of the reaggregation/precipitation unit, which is configured as a reaction tube 210 that is separated to the outside from within the raw material holding container. A temperature control mechanism 211 having a coolant circulation mechanism and/or a heating mechanism may also be placed outside the reaction tube. Moreover, the reaction tube may be connected to the upper part of the raw material holding container, and the inside thereof may be observed via the view port 212 from the upper part thereof. The inside of the raw material holding container and the reaction tube is exhausted with the vacuum pumping unit 206 connected via the liquid-nitrogen trap 205 to achieve a reduced-pressure atmosphere of a predetermined pressure. In the example of FIG. 2(b), while an exhaust device is connected to one end of a T-shaped branched pipe connected to the upper part of the reaction tube, there is no limitation to this configuration, and the configuration for connecting the exhaust device may be changed as needed.

[0059] Even in the configuration of FIG. 2(b), while the raw material heated within the raw material holding container becomes vaporized based on sublimation, it will reach the reaction tube which was cooled to a predetermined temperature, then be re-cooled, and become solidified and precipitated within the reaction tube. The configuration of FIG. 2(a) is advantageous in terms that the device configuration is simple and production can be performed easily, and the configuration of FIG. 2(b) is advantageous in that it is suitable for mass production by adjusting the capacity of the reaction tube and high-purity products can be obtained. The synthesizing apparatus and sublimation device described above are examples of the device configuration that may be used, and it goes without saying that devices configured by modifying the foregoing configuration or devices having a different configuration may also be applied so as long as the purpose of this invention can be achieved.

[0060] <Production Example>

Comparative Example 1

[0061] Comparative Example 1 is an example in which sublimation and reaggregation are not performed in a reduced-pressure atmosphere, which is the essential means in the present invention; that is, an example of only performing the synthesis of a molybdenum oxychloride. Here, MoO.sub.3 and a Cl.sub.2 gas were reacted to synthesize MoO.sub.2Cl.sub.2 by using the device having the configuration shown in FIG. 1.

[0062] A high purity MoO.sub.3 (purity: 4N) powder in an amount of 61.5 g was placed in a holding container made of quartz, and this was disposed at the end of an L-shaped reaction tube made of quartz. While supplying a nitrogen gas as a carrier gas into the reaction tube, and MoO.sub.3 was gradually heated with an electric furnace and the heating temperature of MoO.sub.3 was retained upon reaching 720 C. When a Cl.sub.2 gas was supplied into the reaction tube in this state at a flow rate of 30 mL/minute, MoO.sub.3 and Cl.sub.2 were reacted, the generated MoO.sub.2Cl.sub.2 in a vapor phase state was transported from the reaction tube to the collection container, and the MoO.sub.2Cl.sub.2 cooled within the collection container became precipitated in a solid phase state.

[0063] Nevertheless, the MoO.sub.2Cl.sub.2 precipitated within the collection container, as shown in FIG. 3, was in the form of floccose crystals having a fluffy appearance and an extremely low bulk density, and while a 4 L collection container was connected to the reactor vessel in this example, because the entire reactor vessel was filled with the foregoing floccose precipitate, the supply of chlorine was stopped at such point in time and the synthesis of the MoO.sub.2Cl.sub.2 was ended. The precipitated MoO.sub.2Cl.sub.2 was cooled with a nitrogen flow, and the MoO.sub.2Cl.sub.2 was thereafter collected in a nitrogen atmosphere. At the time of this collection, the MoO.sub.2Cl.sub.2 in a precipitated state was foremost stirred with a stirring rod to reduce the volume within the collection container and thereafter transferred to a storage container, and was further stirred within the storage container using a stirrer to further reduce the volume. The obtained MoO.sub.2Cl.sub.2 had a bulk density of 0.05 g/cm.sup.3, and a purity of 4N. The MoO.sub.2Cl.sub.2 yield amount was 51 g, and the yield rate was 60%.

Example 1

[0064] By using the MoO.sub.2Cl.sub.2 obtained in Comparative Example 1 as the raw material, the method of the present invention, including sublimation/reaggregation, was applied in a reduced-pressure atmosphere. Here, the device having the configuration of FIG. 2(b) was used to perform the sublimation/reaggregation of the MoO.sub.2Cl.sub.2. The MoO.sub.2Cl.sub.2 as the raw material was held in a raw material holding container of a sublimation device, and this was connected to one end of a reaction tube made of glass. The inside of the sublimation device was depressurized by being exhausted from the side while maintaining the other end of the reaction tube in a state where the inside of the tube can be observed from the upper part. In Example 1, the pressure inside the device was set to 1 kPa. In this state, the MoO.sub.2Cl.sub.2 in the raw material holding container was gradually heated, and held at a heating temperature of 95 C. in which the raw material can be stably sublimated. When this state is maintained, the MoO.sub.2Cl.sub.2, which was transferred and reaggregated after being sublimated, was accumulated at the upper part of the reaction tube. The temperature of the reaggregated part was 75 C. Finally, the MoO.sub.2Cl.sub.2 accumulated in the reaction tube was cooled and thereafter collected. FIG. 4 shows the appearance of the MoO.sub.2Cl.sub.2 obtained in Example 1. The MoO.sub.2Cl.sub.2 obtained in Example 1 had a bulk density of 1.0 g/cm.sup.3, and a purity of 5N5.

Example 2

[0065] The pressure inside the device was set to 5 kPa, and the raw material MoO.sub.2Cl.sub.2 was subject to sublimation/reaggregation in the same manner as Example 1. In Example 2, the temperature that the raw material MoO.sub.2Cl.sub.2 can be stably sublimated was 117 C., and the heating temperature of the raw material MoO.sub.2Cl.sub.2 was held at this temperature. Here, the temperature of the reaggregated part was 97 C. In this state, the sublimation/reaggregation of the MoO.sub.2Cl.sub.2 was performed until the sublimated sediment no longer increased based on visual observation while adjusting the position in the reaction tube where the reaggregated MoO.sub.2Cl.sub.2 is accumulated. Finally, when the MoO.sub.2Cl.sub.2 accumulated in the reaction tube was cooled and thereafter collected, it became separated from the inner wall of the reaction tube with relatively weak force, and could be easily recovered. FIG. 5 shows the appearance of the MoO.sub.2Cl.sub.2 obtained in Example 2. The MoO.sub.2Cl.sub.2 obtained in Example 2 had a bulk density of 1.1 g/cm.sup.3, and a purity of 5N5. Only blue floccose residue was observed in the raw material holding container.

Example 3

[0066] The pressure inside the device was set to 20 kPa, and the raw material MoO.sub.2Cl.sub.2 was subject to sublimation/reaggregation in the same manner as Example 1. In Example 3, the temperature that the raw material MoO.sub.2Cl.sub.2 can be stably sublimated was 135 C., and the heating temperature of the raw material MoO.sub.2Cl.sub.2 was held at this temperature. Here, the temperature of the reaggregated part was 115 C. In this state, the sublimation/reaggregation of the MoO.sub.2Cl.sub.2 was performed until the sublimated sediment no longer increased based on visual observation while adjusting the position in the reaction tube where the reaggregated MoO.sub.2Cl.sub.2 is accumulated. Finally, when the MoO.sub.2Cl.sub.2 accumulated in the reaction tube was cooled and thereafter collected, the sediment tended to become hard and affixed to the inner wall of the reaction tube, and much effort was required for collecting the MoO.sub.2Cl.sub.2 in comparison to Examples 1 and 2. FIG. 6 shows the appearance of the MoO.sub.2Cl.sub.2 obtained in Example 3. The MoO.sub.2Cl.sub.2 obtained in Example 3 had a bulk density of 1.2 g/cm.sup.3, and a purity of 5N5. In addition to blue floccose residue, non-sublimated MoO.sub.2Cl.sub.2 also remained in the raw material holding container.

Comparative Example 2

[0067] The pressure inside the device was set to an atmospheric pressure (101.3 kPa), and the raw material MoO.sub.2Cl.sub.2 was subject to sublimation/reaggregation in the same manner as Example 1. In Comparative Example 2, the temperature that the raw material MoO.sub.2Cl.sub.2 can be stably sublimated was 200 C., and the heating temperature of the raw material MoO.sub.2Cl.sub.2 was held at this temperature. Here, the temperature of the reaggregated part was 185 C. In this state, the sublimation/reaggregation of the MoO.sub.2Cl.sub.2 was performed until the sublimated sediment no longer increased based on visual observation while adjusting the position in the reaction tube where the reaggregated MoO.sub.2Cl.sub.2 is accumulated. Finally, when the MoO.sub.2Cl.sub.2 accumulated in the reaction tube was cooled and thereafter collected. The MoO.sub.2Cl.sub.2 obtained in Comparative Example 2 had a bulk density of 0.8 g/cm.sup.3, and a purity of 5N. In order to recover the MoO.sub.2Cl.sub.2 as a solid, it is necessary to sufficiently lower the temperature of the gaseous sublimate, and consequently the device needs to be enlarged (longer than the entire length of 210 in FIG. 2), and there is a problem in that the amount of the product that can be recovered will decrease. There is also a problem in that the gaseous sublimate, which was not sufficiently cooled, becomes precipitated at the reaction tube discharge part, and clogs the reaction tube discharge part.

Example 4

[0068] Example 4 is an example in which sublimation and reaggregation are not performed in a reduced-pressure atmosphere, which is one means in the present invention, in the same manner as Comparative Example 1; that is, an example of only performing the synthesis of molybdenum oxychloride. A major difference in comparison to Comparative Example 1 is that the temperature of the part where chloride is precipitated, solidified and recovered was held in a range of 40 C. to 120 C., and the density of the recovery was increased by growing the crystals at the precipitated part.

[0069] A high purity MoO.sub.3 (purity: 4N) powder in an amount of 63.2 g was placed in a holding container made of quartz, and this was disposed at the end of an L-shaped reaction tube made of quartz. While supplying a nitrogen gas as a carrier gas into the reaction tube, and the MoO.sub.3 was gradually heated with an electric furnace and the heating temperature of the MoO.sub.3 was retained upon reaching 720 C. When a Cl.sub.2 gas was supplied into the reaction tube in this state at a flow rate of 30 mL/minute, the MoO.sub.3 and Cl.sub.2 were reacted, the generated MoO.sub.2Cl.sub.2 in a vapor phase state was transported from the reaction tube to the collection container, and the MoO.sub.2Cl.sub.2 became precipitated as thick crystals within the collection container maintained at 100 C. with a heater. The reaction could be advanced to the end without the floccular precipitate filling the container and clogging the pipe as in Comparative Example 1. The obtained MoO.sub.2Cl.sub.2 had a bulk density of 1.2 g/cm.sup.3, and a purity of 5N. The MoO.sub.2Cl.sub.2 yield amount was 65 g, and the yield rate was 74.5%. This is assumed to be because a large amount of chloride was discharged to the outside in gaseous form, without becoming solidified, due to the high temperature of the recovery part.

Example 5

[0070] Example 5 is the same as Example 4 other than the charge-in quantity being set to 61.1 g, and only the temperature of the recovery part being lowered to 50 C. to precipitate the MoO.sub.2Cl.sub.2. The obtained MoO.sub.2Cl.sub.2 had a bulk density of 0.6 g/cm.sup.3, and a purity of 5N. Because the temperature of the recovery part was lowered, it is assumed that the crystals bonded together slowly and could not be grown, and became an aggregate of small crystals. The MoO.sub.2Cl.sub.2 yield amount was 72 g, and the yield rate was 85.3%. This is assumed to be because the amount of crystal precipitation at the recovery part was greater in comparison to Example 4.

[0071] The foregoing results are summarized in Table 1. Based on these results, it was confirmed that both the bulk density and purity of the MoO.sub.2Cl.sub.2 collected after undergoing sublimation/reaggregation had improved in a reduced-pressure atmosphere under any of the conditions of Examples 1 to 3 in comparison to the state of the raw material. When the ambient pressure is near 20 kPa, the sublimation rate is fast since the sublimation temperature becomes high, and clogging tends to occur even near the raw material, and it becomes difficult to stably control the sublimation/reaggregation. In the sublimation/reaggregation under an atmospheric pressure, while the purity will improve, the bulk density will decrease, and the exhaust pipe tends to become clogged with gaseous sublimate, and the device needs to be enlarged and production also becomes difficult. Accordingly, the ambient pressure is preferably set to a range of 1 to 10 kPa, preferably near 5 kPa, in order to stably control the sublimation/reaggregation of the MoO.sub.2Cl.sub.2.

[0072] Moreover, in directly recovering chloride without performing reduced-pressure sublimation, a highly dense solid can be recovered by properly controlling the temperature of the chloride recovery part, and, while the purity will decrease slightly in comparison to the case of performing reduced-pressure sublimation, there is no major problems in terms of use with the quality being 5N.

TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 1 Example 2 Example 3 Example 2 Example 4 Example 5 Sublimation/Reaggregation None Observed Observed Observed Observed None None Chloridation temperature ( C.) 720 720 720 720 720 720 720 Chloride recovery part 25 25 25 25 25 100 50 temperature ( C.) Sublimation atmospheric 1 5 20 101.3 (atmospheric pressure (kPa) pressure) Sublimation temperature ( C.) 95 117 135 200 Sublimate recovery part 64 71 75 100 temperature ( C.) Clogging of reaction tube None None None Observed discharge part Bulk density (g/cm.sup.3) 0.05 1.0 1.1 1.2 0.8 1.2 0.6 Purity 4N 5N5 5N5 5N5 5N5 5N 5N

INDUSTRIAL APPLICABILITY

[0073] The present invention can achieve a higher bulk density of molybdenum oxychloride, which has a low bulk density and synthesized with a conventional synthesizing method, thereby increase the hygroscopicity resistance, and reduce impurities to achieve a higher purity. Thus, the present invention can offer considerable technical contribution to industries and technical areas such as the semiconductor industry, electronic device production, functional material fabrication, and organic/inorganic chemical industry which forms thin films or synthesizes compounds by using a molybdenum oxychloride as a raw material or a catalyst of CVD or ALD.

DESCRIPTION OF REFERENCE NUMERALS

[0074] 100 synthesizing apparatus

[0075] 101 MoO.sub.3 raw material

[0076] 102 raw material holding container

[0077] 103 reactor vessel

[0078] 104 raw material heating device

[0079] 105 gas inlet

[0080] 106 gas pipe

[0081] 107 collection container

[0082] 108 exhaust pipe

[0083] 109 vacuum pipe

[0084] 110 synthesized molybdenum oxychloride

[0085] 201 raw material holding container

[0086] 202 molybdenum oxychloride raw material

[0087] 203 raw material heating device

[0088] 204 reaggregation/precipitation unit

[0089] 205 liquid-nitrogen trap

[0090] 206 vacuum pumping unit

[0091] 207 cooling water (aspiration)

[0092] 208 cooling water (discharge)

[0093] 210 reaction tube

[0094] 211 temperature control mechanism

[0095] 212 view port