Low α ray bismuth oxide

Abstract

To provide bismuth oxide with reduced α radiation dose.SOLUTION: A bismuth oxide powder has an α radiation dose of 0.002 cph / cm2 or less and a bismuth oxide purity of 99.99 wt.% or more.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to low-alpha bismuth oxide. [Background technology]

[0002] Bismuth oxide is used in electronic components such as varistors and ceramic capacitors, as well as in magnetic materials such as ferrite, and already occupies an important position as an electronic material.

[0003] In recent years, the effects of alpha rays have come to the fore as a cause of software errors in semiconductor circuits. As a result, there is a growing demand to reduce the generation of alpha rays from all parts of semiconductor materials.

[0004] Patent Document 1 discloses metallic bismuth with reduced alpha radiation dose and a method for producing the same, but does not disclose bismuth oxide with reduced alpha radiation dose and a method for producing the same.

[0005] Bismuth oxide and a method for producing the same are disclosed in Patent Documents 2 to 5. However, Patent Documents 2 to 5 do not disclose bismuth oxide with a reduced alpha dose or a method for producing the same. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6271642 [Patent Document 2] Patent No. 5120663 [Patent Document 3] Patent No. 3928023 [Patent Document 4] Patent No. 4619428 [Patent Document 5] Patent No. 4185197 Summary of the Invention [Problem to be solved by the invention]

[0007] Thus, there is a growing demand for reducing the generation of alpha rays from every part of semiconductor materials.

[0008] Therefore, an object of the present invention is to provide bismuth oxide with reduced alpha radiation dose. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above object can be achieved by the following method, and have arrived at the present invention.

[0010] The present invention includes the following (1). (1) Alpha radiation dose is 0.002cph / cm 2 is as follows: Bismuth oxide powder having a purity of 99.99 wt% or more. [Effects of the Invention]

[0011] The present invention provides bismuth oxide with reduced alpha radiation. The bismuth oxide of the present invention has reduced alpha radiation, which minimizes the generation of alpha radiation, which is avoided as a cause of software errors in semiconductor circuits, and can be widely used as a semiconductor material. [Brief explanation of the drawings]

[0012] [Figure 1A] FIG. 1A is a chart showing the results of XRD measurement of the bismuth oxide powder of Sample 1 (roasted at 700° C.) obtained in Example 1. [Figure 1B] FIG. 1B is a chart showing the results of XRD measurement of the bismuth oxide powder of Sample 2 (roasted at 500° C.) obtained in Example 1. [Figure 1C] FIG. 1C is a chart showing the results of XRD measurement of the bismuth oxide powder of Sample 3 (roasted at 720° C.) obtained in Example 1. [Figure 1D]FIG. 1D is a chart showing the results of XRD measurement of the bismuth oxide powder of Sample 4 (roasted at 680° C.) obtained in Example 1. [Figure 2A] FIG. 2A is a photograph of the appearance of the dissolved bismuth oxide of Sample 1 (0 minutes after addition) added to an aqueous methanesulfonic acid solution. [Figure 2B] FIG. 2B is a photograph of the appearance of the dissolved bismuth oxide of Sample 1 (5 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 2C] FIG. 2C is a photograph of the appearance of the dissolved bismuth oxide of Sample 1 (10 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 2D] FIG. 2D is a photograph of the appearance of the dissolved bismuth oxide of Sample 1 (15 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 2E] FIG. 2E is a photograph of the appearance of the dissolved bismuth oxide of Sample 1 (20 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 3A] FIG. 3A is a photograph of the appearance of the dissolved bismuth oxide of Sample 2 (0 minutes after addition) added to an aqueous methanesulfonic acid solution. [Figure 3B] FIG. 3B is a photograph of the appearance of the dissolved bismuth oxide of Sample 2 (5 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 3C] FIG. 3C is a photograph of the appearance of the dissolved bismuth oxide of Sample 2 (10 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 3D] FIG. 3D is a photograph of the appearance of the dissolved bismuth oxide of Sample 2 (15 minutes after being added) in an aqueous methanesulfonic acid solution. [Figure 3E] FIG. 3E is a photograph of the appearance of the dissolved bismuth oxide of Sample 2 (20 minutes after being added) in an aqueous methanesulfonic acid solution. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below by way of examples, but the present invention is not limited to the specific examples described below.

[0014] [Bismuth oxide powder] The present invention uses a α-ray dose of 0.002 cph / cm 2 The bismuth oxide powder has a purity of 99.99 wt% or more.

[0015] [α dose] In a preferred embodiment, the alpha dose of the bismuth oxide powder of the present invention is, for example, 0.002 cph / cm 2 Less than or equal to 0.0015 cph / cm 2 Less than or equal to 0.0014 cph / cm 2 Less than or equal to 0.0013 cph / cm 2 Less than or equal to 0.0012 cph / cm 2 Less than or equal to 0.0011 cph / cm 2 Less than or equal to 0.001 cph / cm 2 The value of the alpha dose can be measured by the means described later in the Examples.

[0016] [purity] In a preferred embodiment, the purity of the bismuth oxide powder of the present invention can be, for example, 99.99 wt% or more, preferably 99.995 wt% or more, and preferably 99.996 wt% or more. The purity of the bismuth oxide powder can be calculated by the method described later in the Examples.

[0017] [Specific surface area] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.1 to 1.0 m 2 / g, preferably 0.1 to 0.9 m 2 / g, preferably 0.1 to 0.8 m 2 / g, preferably 0.1 to 0.7m 2 / g, preferably 0.1 to 0.6 m 2 / g, preferably 0.1 to 0.5m2 / g, preferably 0.1 to 0.4 m 2 / g, preferably 0.1 to 0.3 m 2 / g, preferably 0.1 to 0.25 m 2 / g, preferably 0.1 to 0.24 m 2 / g, preferably 0.1 to 0.23 m 2 / g, preferably 0.1 to 0.22 m 2 The specific surface area of ​​the bismuth oxide powder can be measured by the method described later in the Examples.

[0018] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.1 to 0.21 m 2 / g range, 0.1~0.20m 2 / g range, 0.1~0.19m 2 / g range, 0.1~0.18m 2 / g range, 0.1~0.17m 2 / g.

[0019] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.1 to 0.16 m 2 / g range, 0.1~0.15m 2 / g range, 0.1~0.14m 2 / g.

[0020] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.11 to 1.0 m 2 / g, preferably 0.11 to 0.9m 2 / g, preferably 0.11 to 0.8m 2 / g, preferably 0.11 to 0.7m 2 / g, preferably 0.11 to 0.6m 2 / g, preferably 0.11 to 0.5m 2 / g, preferably 0.11 to 0.4 m 2 / g, preferably 0.11 to 0.3 m 2 / g, preferably 0.11 to 0.25 m 2 / g, preferably 0.11 to 0.24 m 2 / g, preferably 0.11 to 0.23 m 2 / g, preferably 0.11 to 0.22 m 2 / g.

[0021] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.11 to 0.21 m 2 / g range, 0.11~0.20m 2 / g range, 0.11~0.19m 2 / g range, 0.11~0.18m 2 / g range, 0.11~0.17m 2 / g.

[0022] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.11 to 0.16 m 2 / g range, 0.11~0.15m 2 / g range, 0.11~0.14m 2 / g.

[0023] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.12 to 1.0 m 2 / g, preferably 0.12 to 0.9 m 2 / g, preferably 0.12 to 0.8 m 2 / g, preferably 0.12 to 0.7m 2 / g, preferably 0.12 to 0.6 m 2 / g, preferably 0.12 to 0.5m 2 / g, preferably 0.12 to 0.4 m 2 / g, preferably 0.12 to 0.3 m 2 / g, preferably 0.12 to 0.25 m 2 / g, preferably 0.12 to 0.24 m 2 / g, preferably 0.12 to 0.23 m 2 / g, preferably 0.12 to 0.22 m 2 / g.

[0024] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.12 to 0.21 m 2 / g range, 0.12~0.20m 2 / g range, 0.12~0.19m 2 / g range, 0.12~0.18m 2 / g range, 0.12~0.17m 2 / g.

[0025] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.12 to 0.16 m 2 / g range, 0.12~0.15m 2 / g range, 0.12~0.14m 2 / g.

[0026] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.13 to 1.0 m 2 / g, preferably 0.13 to 0.9 m 2 / g, preferably 0.13 to 0.8m 2 / g, preferably 0.13 to 0.7m 2 / g, preferably 0.13 to 0.6m 2 / g, preferably 0.13 to 0.5m 2 / g, preferably 0.13 to 0.4 m 2 / g, preferably 0.13 to 0.3 m 2 / g, preferably 0.13 to 0.25 m 2 / g, preferably 0.13 to 0.24 m 2 / g, preferably 0.13 to 0.23 m 2 / g, preferably 0.13 to 0.22 m 2 / g.

[0027] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.13 to 0.21 m 2 / g range, 0.13~0.20m 2 / g range, 0.13~0.19m 2 / g range, 0.13~0.18m 2 / g range, 0.13~0.17m 2 / g.

[0028] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.13 to 0.16 m 2 / g range, 0.13~0.15m 2 / g range, 0.13~0.14m 2 / g.

[0029] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.15 to 1.0 m 2 / g, preferably 0.15 to 0.9 m 2 / g, preferably 0.15 to 0.8 m 2 / g, preferably 0.15 to 0.7m 2 / g, preferably 0.15 to 0.6 m 2 / g, preferably 0.15 to 0.5m 2 / g, preferably 0.15 to 0.4 m 2 / g, preferably 0.15 to 0.3 m 2 / g, preferably 0.15 to 0.25 m 2 / g, preferably 0.15 to 0.24 m 2 / g, preferably 0.15 to 0.23 m 2 / g, preferably 0.15 to 0.22 m 2 / g.

[0030] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.15 to 0.21 m 2 / g range, 0.15~0.20m 2 / g range, 0.15~0.19m2 / g range, 0.15~0.18m 2 / g.

[0031] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.16 to 1.0 m 2 / g, preferably 0.16 to 0.9 m 2 / g, preferably 0.16 to 0.8 m 2 / g, preferably 0.16 to 0.7m 2 / g, preferably 0.16 to 0.6m 2 / g, preferably 0.16 to 0.5m 2 / g, preferably 0.16 to 0.4 m 2 / g, preferably 0.16 to 0.3 m 2 / g, preferably 0.16 to 0.25 m 2 / g, preferably 0.16 to 0.24 m 2 / g, preferably 0.16 to 0.23 m 2 / g, preferably 0.16 to 0.22 m 2 / g.

[0032] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.16 to 0.21 m 2 / g range, 0.16~0.20m 2 / g range, 0.16~0.19m 2 / g range, 0.16~0.18m 2 / g.

[0033] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.17 to 1.0 m 2 / g, preferably 0.17 to 0.9 m 2 / g, preferably 0.17 to 0.8 m 2 / g, preferably 0.17 to 0.7m 2 / g, preferably 0.17 to 0.6 m 2 / g, preferably 0.17 to 0.5m 2 / g, preferably 0.17 to 0.4 m 2 / g, preferably 0.17 to 0.3 m 2 / g, preferably 0.17 to 0.25 m 2 / g, preferably 0.17 to 0.24 m 2 / g, preferably 0.17 to 0.23 m 2 / g, preferably 0.17 to 0.22 m 2 / g.

[0034] Alternatively, in a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.17 to 0.21 m 2 / g range, 0.17~0.20m 2 / g range, 0.17~0.19m 2 / g range, 0.17~0.18m 2 / g.

[0035] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.19 to 1.0 m 2 / g, preferably 0.19 to 0.9m 2 / g, preferably 0.19 to 0.8 m 2 / g, preferably 0.19 to 0.7m 2 / g, preferably 0.19 to 0.6m 2 / g, preferably 0.19 to 0.5m 2 / g, preferably 0.19 to 0.4 m 2 / g, preferably 0.19 to 0.3 m 2 / g, preferably 0.19 to 0.25 m 2 / g, preferably 0.19 to 0.24 m 2 / g, preferably 0.19 to 0.23 m 2 / g, preferably 0.19 to 0.22 m 2 / g.

[0036] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.20 to 1.0 m 2 / g, preferably 0.20 to 0.9 m 2 / g, preferably 0.20 to 0.8m 2 / g, preferably 0.20 to 0.7m 2 / g, preferably 0.20 to 0.6 m 2 / g, preferably 0.20 to 0.5m 2 / g, preferably 0.20 to 0.4 m 2 / g, preferably 0.20 to 0.3 m 2 / g, preferably 0.20 to 0.25 m 2 / g, preferably 0.20 to 0.24 m 2 / g, preferably 0.20 to 0.23 m 2 / g, preferably 0.20 to 0.22 m 2 / g.

[0037] In a preferred embodiment, the specific surface area of ​​the bismuth oxide powder of the present invention is, for example, 0.21 to 1.0 m 2 / g, preferably 0.21 to 0.9 m 2 / g, preferably 0.21 to 0.8m 2 / g, preferably 0.21 to 0.7m 2 / g, preferably 0.21 to 0.6m 2 / g, preferably 0.21 to 0.5m 2 / g, preferably 0.21 to 0.4 m 2 / g, preferably 0.21 to 0.3 m 2 / g, preferably 0.21 to 0.25m 2 / g, preferably 0.21 to 0.24 m 2 / g, preferably 0.21 to 0.23 m 2 / g, preferably 0.21 to 0.22 m 2 / g.

[0038] [Bulk density] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 2.5 to 6.0 g / cm 3 in the range of 2.5 to 5.5 g / cm3 in the range of 2.5 to 5.0 g / cm 3 in the range of 2.5 to 4.9 g / cm 3 in the range of 2.5 to 4.8 g / cm 3 The bulk density of the bismuth oxide powder can be measured by the method described later in the Examples.

[0039] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 2.5 to 4.6 g / cm 3 range, 2.5~4.5g / cm 3 range, 2.5~4.4g / cm 3 range, 2.5~4.3g / cm 3 range, 2.5~4.2g / cm 3 range, 2.5~4.1g / cm 3 range, 2.5~4.0g / cm 3 range, 2.5~3.9g / cm 3 range, 2.5~3.8g / cm 3 The range can be:

[0040] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 2.5 to 3.7 g / cm 3 range, 2.5~3.6g / cm 3 range, 2.5~3.5g / cm 3 The range can be:

[0041] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.0 to 6.0 g / cm 3 in the range of 3.0 to 5.5 g / cm 3 in the range of 3.0 to 5.0 g / cm 3 in the range of 3.0 to 4.9 g / cm 3 in the range of 3.0 to 4.8 g / cm 3 The range can be:

[0042] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.0 to 4.6 g / cm 3 range, 3.0~4.5g / cm 3 range, 3.0~4.4g / cm 3 range, 3.0~4.3g / cm 3 range, 3.0~4.2g / cm 3 range, 3.0~4.1g / cm 3 range, 3.0~4.0g / cm 3 range, 3.0~3.9g / cm 3 range, 3.0~3.8g / cm 3 The range can be:

[0043] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.0 to 3.7 g / cm 3 range, 3.0~3.6g / cm 3 range, 3.0~3.5g / cm 3 The range can be:

[0044] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.1 to 6.0 g / cm 3 in the range of 3.1 to 5.5 g / cm 3 in the range of 3.1 to 5.0 g / cm 3 in the range of 3.1 to 4.9 g / cm 3 in the range of 3.1 to 4.8 g / cm 3 The range can be:

[0045] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.1 to 4.6 g / cm 3 range, 3.1~4.5g / cm 3 range, 3.1~4.4g / cm 3 range, 3.1~4.3g / cm 3 range, 3.1~4.2g / cm 3 range, 3.1~4.1g / cm 3 range, 3.1~4.0g / cm 3range, 3.1~3.9g / cm 3 range, 3.1~3.8g / cm 3 The range can be:

[0046] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.1 to 3.7 g / cm 3 range, 3.1~3.6g / cm 3 range, 3.1~3.5g / cm 3 The range can be:

[0047] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.2 to 6.0 g / cm 3 in the range of 3.2 to 5.5 g / cm 3 in the range of 3.2 to 5.0 g / cm 3 in the range of 3.2 to 4.9 g / cm 3 in the range of 3.2 to 4.8 g / cm 3 The range can be:

[0048] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.2 to 4.6 g / cm 3 range, 3.2~4.5g / cm 3 range, 3.2~4.4g / cm 3 range, 3.2~4.3g / cm 3 range, 3.2~4.2g / cm 3 range, 3.2~4.1g / cm 3 range, 3.2~4.0g / cm 3 range, 3.2~3.9g / cm 3 range, 3.2~3.8g / cm 3 The range can be:

[0049] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.2 to 3.7 g / cm 3 range, 3.2~3.6g / cm 3 range, 3.2~3.5g / cm 3 The range can be:

[0050] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.3 to 6.0 g / cm 3 in the range of 3.3 to 5.5 g / cm 3 in the range of 3.3 to 5.0 g / cm 3 in the range of 3.3 to 4.9 g / cm 3 in the range of 3.3 to 4.8 g / cm 3 The range can be:

[0051] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.3 to 4.6 g / cm 3 range, 3.3~4.5g / cm 3 range, 3.3~4.4g / cm 3 range, 3.3~4.3g / cm 3 range, 3.3~4.2g / cm 3 range, 3.3~4.1g / cm 3 range, 3.3~4.0g / cm 3 range, 3.3~3.9g / cm 3 range, 3.3~3.8g / cm 3 The range can be:

[0052] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.3 to 3.7 g / cm 3 range, 3.3~3.6g / cm 3 range, 3.3~3.5g / cm 3 The range can be:

[0053] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.4 to 6.0 g / cm 3 in the range of 3.4 to 5.5 g / cm 3 in the range of 3.4 to 5.0 g / cm 3 in the range of 3.4 to 4.9 g / cm 3 in the range of 3.4 to 4.8 g / cm 3 The range can be:

[0054] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.4 to 4.6 g / cm 3 range, 3.4~4.5g / cm 3 range, 3.4~4.4g / cm 3 range, 3.4~4.3g / cm 3 range, 3.4~4.2g / cm 3 range, 3.4~4.1g / cm 3 range, 3.4~4.0g / cm 3 range, 3.4~3.9g / cm 3 range, 3.4~3.8g / cm 3 The range can be:

[0055] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.4 to 3.7 g / cm 3 range, 3.4~3.6g / cm 3 range, 3.4~3.5g / cm 3 The range can be:

[0056] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.5 to 6.0 g / cm 3 in the range of 3.5 to 5.5 g / cm 3 in the range of 3.5 to 5.0 g / cm 3 in the range of 3.5 to 4.9 g / cm 3 in the range of 3.5 to 4.8 g / cm 3 The range can be:

[0057] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.5 to 4.6 g / cm 3 range, 3.5~4.5g / cm 3 range, 3.5~4.4g / cm 3 range, 3.5~4.3g / cm 3 range, 3.5~4.2g / cm 3 range, 3.5~4.1g / cm 3range, 3.5~4.0g / cm 3 range, 3.5~3.9g / cm 3 range, 3.5~3.8g / cm 3 The range can be:

[0058] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.5 to 3.7 g / cm 3 range, 3.5~3.6g / cm 3 The range can be:

[0059] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.7 to 6.0 g / cm 3 in the range of 3.7 to 5.5 g / cm 3 in the range of 3.7 to 5.0 g / cm 3 in the range of 3.7 to 4.9 g / cm 3 in the range of 3.7 to 4.8 g / cm 3 The range can be:

[0060] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.7 to 4.6 g / cm 3 range, 3.7~4.5g / cm 3 range, 3.7~4.4g / cm 3 range, 3.7~4.3g / cm 3 range, 3.7~4.2g / cm 3 range, 3.7~4.1g / cm 3 range, 3.7~4.0g / cm 3 range, 3.7~3.9g / cm 3 range, 3.7~3.8g / cm 3 The range can be:

[0061] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.8 to 6.0 g / cm 3 in the range of 3.8 to 5.5 g / cm 3 in the range of 3.8 to 5.0 g / cm 3in the range of 3.8 to 4.9 g / cm 3 in the range of 3.8 to 4.8 g / cm 3 The range can be:

[0062] Alternatively, in a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 3.8 to 4.6 g / cm 3 range, 3.8~4.5g / cm 3 range, 3.8~4.4g / cm 3 range, 3.8~4.3g / cm 3 range, 3.8~4.2g / cm 3 range, 3.8~4.1g / cm 3 range, 3.8~4.0g / cm 3 range, 3.8~3.9g / cm 3 The range can be:

[0063] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 4.0 to 6.0 g / cm 3 in the range of 4.0 to 5.5 g / cm 3 in the range of 4.0 to 5.0 g / cm 3 in the range of 4.0 to 4.9 g / cm 3 in the range of 4.0 to 4.8 g / cm 3 The range can be:

[0064] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 4.5 to 6.0 g / cm 3 in the range of 4.5 to 5.5 g / cm 3 in the range of 4.5 to 5.0 g / cm 3 in the range of 4.5 to 4.9 g / cm 3 in the range of 4.5 to 4.8 g / cm 3 The range can be:

[0065] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 4.6 to 6.0 g / cm 3 in the range of 4.6 to 5.5 g / cm3 in the range of 4.6 to 5.0 g / cm 3 in the range of 4.6 to 4.9 g / cm 3 in the range of 4.6 to 4.8 g / cm 3 The range can be:

[0066] In a preferred embodiment, the bulk density of the bismuth oxide powder of the present invention is, for example, 4.7 to 6.0 g / cm 3 in the range of 4.7 to 5.5 g / cm 3 in the range of 4.7 to 5.0 g / cm 3 in the range of 4.7 to 4.9 g / cm 3 in the range of 4.7 to 4.8 g / cm 3 The range can be:

[0067] [Average particle size D50] In a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 30 μm, preferably 11 to 30 μm, preferably 12 to 30 μm, preferably 13 to 30 μm, preferably 14 to 30 μm, preferably 15 to 30 μm, or preferably 16 to 30 μm. The average particle size D50 of the bismuth oxide powder can be measured by the means described later in the Examples.

[0068] In a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 29 μm, preferably in the range of 11 to 29 μm, preferably in the range of 12 to 29 μm, preferably in the range of 13 to 29 μm, preferably in the range of 14 to 29 μm, preferably in the range of 15 to 29 μm, or preferably in the range of 16 to 29 μm.

[0069] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 25 μm, preferably in the range of 11 to 25 μm, preferably in the range of 12 to 25 μm, preferably in the range of 13 to 25 μm, preferably in the range of 14 to 25 μm, preferably in the range of 15 to 25 μm, or preferably in the range of 16 to 25 μm.

[0070] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 20 μm, preferably in the range of 11 to 20 μm, preferably in the range of 12 to 20 μm, preferably in the range of 13 to 20 μm, preferably in the range of 14 to 20 μm, preferably in the range of 15 to 20 μm, or preferably in the range of 16 to 20 μm.

[0071] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 19 μm, preferably in the range of 11 to 19 μm, preferably in the range of 12 to 19 μm, preferably in the range of 13 to 19 μm, preferably in the range of 14 to 19 μm, preferably in the range of 15 to 19 μm, or preferably in the range of 16 to 19 μm.

[0072] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 18 μm, preferably in the range of 11 to 18 μm, preferably in the range of 12 to 18 μm, preferably in the range of 13 to 18 μm, preferably in the range of 14 to 18 μm, preferably in the range of 15 to 18 μm, or preferably in the range of 16 to 18 μm.

[0073] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 10 to 17 μm, preferably in the range of 11 to 17 μm, preferably in the range of 12 to 17 μm, preferably in the range of 13 to 17 μm, preferably in the range of 14 to 17 μm, preferably in the range of 15 to 17 μm, or preferably in the range of 16 to 17 μm.

[0074] In a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 20 to 30 μm, preferably 25 to 30 μm, preferably 26 to 30 μm, preferably 27 to 30 μm, or preferably 28 to 30 μm.

[0075] Alternatively, in a preferred embodiment, the average particle size D50 of the bismuth oxide powder of the present invention can be, for example, in the range of 20 to 29 μm, preferably in the range of 25 to 29 μm, preferably in the range of 26 to 29 μm, preferably in the range of 27 to 29 μm, or preferably in the range of 28 to 29 μm.

[0076] [Average particle size D10] In a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be, for example, in the range of 4 to 10 μm, preferably in the range of 4 to 9 μm, and more preferably in the range of 4 to 8 μm. The average particle size D10 of the bismuth oxide powder can be measured by the means described later in the Examples.

[0077] Alternatively, in a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be set, for example, in the range of 4 to 7 μm, preferably in the range of 4 to 6 μm, and more preferably in the range of 4 to 5 μm.

[0078] In a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be set, for example, in the range of 5 to 10 μm, preferably in the range of 5 to 9 μm, and more preferably in the range of 5 to 8 μm.

[0079] Alternatively, in a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be set, for example, in the range of 5 to 7 μm, preferably in the range of 5 to 6 μm.

[0080] In a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be set, for example, in the range of 6 to 10 μm, preferably in the range of 6 to 9 μm, and more preferably in the range of 6 to 8 μm.

[0081] In a preferred embodiment, the average particle size D10 of the bismuth oxide powder of the present invention can be set, for example, in the range of 7 to 10 μm, preferably in the range of 7 to 9 μm, and more preferably in the range of 7 to 8 μm.

[0082] [Average particle size D90] In a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be, for example, in the range of 100 to 150 μm, preferably in the range of 100 to 140 μm, and more preferably in the range of 100 to 135 μm. The average particle size D90 of the bismuth oxide powder can be measured by the means described later in the Examples.

[0083] Alternatively, in a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be set in the range of, for example, 100 to 130 μm.

[0084] In a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be, for example, in the range of 110 to 150 μm, preferably in the range of 110 to 140 μm, and more preferably in the range of 110 to 135 μm.

[0085] Alternatively, in a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be set in the range of, for example, 110 to 130 μm.

[0086] In a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be, for example, in the range of 120 to 150 μm, preferably in the range of 120 to 140 μm, and more preferably in the range of 120 to 135 μm.

[0087] Alternatively, in a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be set in the range of, for example, 120 to 130 μm.

[0088] In a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be, for example, in the range of 125 to 150 μm, preferably in the range of 125 to 140 μm, and more preferably in the range of 125 to 135 μm.

[0089] Alternatively, in a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be set in the range of, for example, 125 to 130 μm.

[0090] In a preferred embodiment, the average particle size D90 of the bismuth oxide powder of the present invention can be, for example, in the range of 130 to 150 μm, preferably in the range of 130 to 140 μm, and more preferably in the range of 130 to 135 μm.

[0091] [Particle size distribution] In a preferred embodiment, the bismuth oxide powder of the present invention has a particle size distribution that satisfies the following formula: ("Average particle diameter D90" - "Average particle diameter D10") / "Average particle diameter D50" The value obtained by this can be set, for example, in the range of 4.0 to 10.0, preferably in the range of 4.0 to 9.0, and more preferably in the range of 4.0 to 8.0.

[0092] Alternatively, in a preferred embodiment, the bismuth oxide powder of the present invention can have a value obtained by the above formula as an index representing the sharpness of the particle size distribution, for example, in the range of 4.0 to 7.0, 4.0 to 6.0, or 4.0 to 5.0.

[0093] In a preferred embodiment, the bismuth oxide powder of the present invention can have a value obtained by the above formula as an index representing the sharpness of the particle size distribution in the range of, for example, 5.0 to 10.0, preferably 5.0 to 9.0, and more preferably 5.0 to 8.0.

[0094] In a preferred embodiment, the bismuth oxide powder of the present invention can have a value obtained by the above formula as an index representing the sharpness of the particle size distribution in the range of, for example, 6.0 to 10.0, preferably 6.0 to 9.0, and more preferably 6.0 to 8.0.

[0095] In a preferred embodiment, the bismuth oxide powder of the present invention can have a value obtained by the above formula as an index representing the sharpness of the particle size distribution in the range of, for example, 7.0 to 10.0, preferably 7.0 to 9.0, and more preferably 7.0 to 8.0.

[0096] [Solubility of bismuth oxide powder] In a preferred embodiment, the bismuth oxide powder of the present invention is a bismuth oxide powder that exhibits excellent solubility in the solubility test described later in the Examples.

[0097] In a preferred embodiment, the bismuth oxide powder of the present invention can have, for example, a turbidity of 0 to 5 and a chromaticity of 0 to 5, preferably a turbidity of 0 to 4 and a chromaticity of 0 to 4, preferably a turbidity of 0 to 3 and a chromaticity of 0 to 3, preferably a turbidity of 0 to 2 and a chromaticity of 0 to 2, preferably a turbidity of 0 to 1 and a chromaticity of 0 to 1, and preferably a turbidity of 0 and a chromaticity of 0. The turbidity and chromaticity can be measured by the means described later in the Examples.

[0098] [Impurity content of bismuth oxide powder] In a preferred embodiment, the impurity content of the bismuth oxide powder can be set to the following ranges for each element. Unless otherwise specified, the following values ​​are in wt ppm. The impurity content of each of these elements can be measured by the means described below in the Examples.

[0099] Li: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Be: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; B: For example, 0.5 wtppm or less, preferably 0.47 wtppm or less; F: for example, 0.1 wtppm or less, preferably 0.07 wtppm or less; Na: for example, 5 wtppm or less, preferably 1 wtppm or less, preferably 0.2 wtppm or less, preferably 0.13 wtppm or less; Mg: for example, 0.05 wtppm or less, preferably 0.02 wtppm or less, preferably 0.016 wtppm or less; Al: for example, 1.0 wtppm or less, preferably 0.5 wtppm or less, preferably 0.45 wtppm or less; Si: for example, 15 wtppm or less, preferably 13 wtppm or less; P: for example, 0.05 wtppm or less, preferably 0.032 wtppm or less; S: for example, 3 wtppm or less, preferably 1 wtppm or less, preferably 0.5 wtppm or less, preferably 0.49 wtppm or less; Cl: for example, 12 wtppm or less, preferably 10 wtppm or less, preferably 9 wtppm or less, preferably 8.7 wtppm or less; K: for example, 0.05 wtppm or less, preferably less than 0.05 wtppm; Ca: for example, 0.5 wtppm or less, preferably 0.2 wtppm or less, preferably 0.11 wtppm or less; Sc: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0100] Ti: for example, 0.5 wtppm or less, preferably 0.46 wtppm or less; V: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Cr: for example, 0.01 wtppm or less, preferably 0.006 wtppm or less; Mn: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; Fe: for example, 0.5 wtppm or less, preferably 0.2 wtppm or less, preferably 0.10 wtppm or less; Co: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Ni: for example, 0.1 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm; Cu: for example, 1.0 wtppm or less, preferably 0.5 wtppm or less, preferably less than 0.5 wtppm; Zn: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm; Ga: for example, 0.5 wtppm or less, preferably 0.34 wtppm or less; Ge: for example, 0.05 wtppm or less, preferably less than 0.05 wtppm; As: for example, 0.05 wtppm or less, preferably less than 0.05 wtppm; Se: for example, 0.1 wtppm or less, preferably less than 0.1 wtppm; Br: for example, 0.05 wtppm or less, preferably 0.04 wtppm or less;

[0101] Rb: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Sr: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Y: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Zr: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Nb: for example, 0.5 wtppm or less, preferably less than 0.5 wtppm; Mo: for example, 0.5 wtppm or less, preferably less than 0.5 wtppm; Ru: for example, 0.05 wtppm or less, preferably 0.010 wtppm or less; Rh: for example, 0.01 wtppm or less, preferably 0.008 wtppm or less; Pd: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; Ag: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less; Cd: for example, 0.1 wtppm or less, preferably 0.07 wtppm or less; Sn: for example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2.6 wtppm or less; Sb: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; Te: for example, 0.7 wtppm or less, preferably 0.66 wtppm or less;

[0102] I: For example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Cs: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Ba: for example, 0.05 wtppm or less, preferably 0.034 wtppm or less; La: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Ce: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Pr: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Nd: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Sm: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Eu: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Gd: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Tb: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Dy: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Ho: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Er: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0103] Tm: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Yb: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Lu: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Hf: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; W: for example, 2 wtppm or less, preferably less than 2 wtppm; Re: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Os: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; Ir: for example, 0.05 wtppm or less, preferably 0.03 wtppm or less; Pt: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; Hg: for example, 0.05 wtppm or less, preferably less than 0.05 wtppm; Tl: for example, 0.01 wtppm or less, preferably less than 0.01 wtppm; Pb: for example, 0.05 wtppm or less, preferably less than 0.05 wtppm; Th: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm; U: for example, 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0104] [Bismuth oxide powder, Bi2O3 single phase] In a preferred embodiment, the bismuth oxide powder of the present invention can be a bismuth oxide powder that is determined to be a Bi2O3 single phase by XRD measurement. The determination of a Bi2O3 single phase by XRD measurement can be made by the means described later in the Examples. That is, as in the XRD measurement test described later, when all peaks of a sample coincide with those of Bi2O3, and no peaks at 10 to 15° or near 30° specific to Bi5O7NO3 are observed, it is determined that a Bi2O3 single phase has been formed.

[0105] [Preferred embodiment] In preferred embodiments, the present invention includes the following (1) embodiments: (1) Alpha radiation dose is 0.002cph / cm 2 is as follows: Bismuth oxide powder having a purity of 99.99 wt% or more. (2) Specific surface area: 0.1 to 1.0 m 2 / g (1). (3) Bulk density: 2.5 to 6.0 g / cm 3 The bismuth oxide powder according to (1), wherein the bismuth oxide powder has a viscosity of 1000 MPa or less. (4) The bismuth oxide powder according to (1), having a D50 in the range of 10 to 30 μm. (5) The bismuth oxide powder according to (1), having a Na content of 5 wtppm or less. (6) The bismuth oxide powder according to (1), wherein the value of ("average particle diameter D90" - "average particle diameter D10") / "average particle diameter D50" is in the range of 4.0 to 10.0. (7) The bismuth oxide powder according to (1), wherein 5.0 g of the bismuth oxide powder is added to 500 ml of a 200 g / L aqueous methanesulfonic acid solution and stirred, and 10 minutes later, the turbidity is 0 to 5 and the color is 0 to 5.

[0106] In a preferred embodiment, the present invention can be embodied as a combination of the above embodiment (1) with one, two, three, four, five, or six of the above embodiments (2), (3), (4), (5), (6), and (7). In this case, the specific items described in the above embodiments (1) to (7) can be limited to the numerical ranges described above in this specification. [Example]

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0108] [Example 1: Production of bismuth oxide powder] [Example 1] The raw material is metallic bismuth (purity 99.99%, alpha dose 0.000043cph / cm 2 ) was prepared.

[0109] This metallic bismuth was dissolved in 8.4 mol / L concentrated nitric acid, and the solution was diluted with pure water to a Bi concentration of 100 g / L to obtain a metallic bismuth nitric acid solution.

[0110] To the metallic bismuth nitrate solution, 12 mol / L of ammonia water was added at a rate of 1 ml / s until the pH of the solution reached 8.5 or higher.

[0111] A slurry was produced by adding aqueous ammonia to a metallic bismuth nitrate solution, which was then repulped and washed, and subjected to solid-liquid separation by suction filtration.

[0112] The precipitate obtained by solid-liquid separation was dried overnight at 70°C to obtain a dried precipitate.

[0113] The obtained dried precipitate was roasted at 700°C for 2 hours under atmospheric pressure to obtain bismuth oxide powder (Sample 1).

[0114] [Comparative Example 1] The dried precipitate obtained in the same manner as in Example 1 was roasted at 500°C for 2 hours under atmospheric pressure to obtain bismuth oxide powder (sample 2).

[0115] [Example 2] The dried precipitate obtained in the same manner as in Example 1 was roasted at 720°C for 2 hours under atmospheric pressure to obtain bismuth oxide powder (sample 3).

[0116] [Example 3] The dried precipitate obtained in the same manner as in Example 1 was roasted at 680°C for 2 hours under atmospheric pressure to obtain bismuth oxide powder (sample 4).

[0117] [Example 2: Analysis of bismuth oxide powder] [D10, D50, D90] The bismuth oxide powders (Sample 1, Sample 2, Sample 3, and Sample 4) obtained in Example 1 were measured by laser diffraction and scattering methods using a particle size analyzer (Microtrac, Model MT3300EXII). The obtained particle size values ​​D10, D50, and D90 are summarized in Table 1.

[0118] [Table 1]

[0119] [BET specific surface area] The BET specific surface areas of the bismuth oxide powders (Samples 1, 2, 3, and 4) obtained in Example 1 were measured using a specific surface area measuring device (Quantachrome, Model No. Monosorb MS-21). The obtained specific surface area values ​​are summarized in Table 1.

[0120] [Bulk density] The bulk density of the bismuth oxide powders (Sample 1, Sample 2, Sample 3, and Sample 4) obtained in Example 1 was measured. The bulk density was measured by placing 1 ml of each sample in a 5 ml measuring cylinder. The obtained bulk density values ​​are summarized in Table 1.

[0121] [XRD measurement] XRD measurement was performed on the bismuth oxide powders (samples 1, 2, 3 and 4) obtained in Example 1. The conditions for the XRD measurement are summarized in Table 2 below.

[0122] [Table 2]

[0123] The obtained XRD measurement results are shown in Figures 1A, 1B, 1C, and 1D. Figure 1A is a chart showing the XRD measurement results of bismuth oxide powder of Sample 1 (roasted at 700°C) obtained in Example 1. Figure 1B is a chart showing the XRD measurement results of bismuth oxide powder of Sample 2 (roasted at 500°C) obtained in Example 1. Figure 1C is a chart showing the XRD measurement results of bismuth oxide powder of Sample 3 (roasted at 720°C) obtained in Example 1. Figure 1D is a chart showing the XRD measurement results of bismuth oxide powder of Sample 4 (roasted at 680°C) obtained in Example 1. For comparison, in each chart, charts of Bi2O3 and Bi5O7NO3 are shown alongside the charts of the sample measurement results. In Figures 1A, 1B, 1C, and 1D, the top charts are for Sample 1, Sample 2, Sample 3, and Sample 4, respectively, the middle chart is for Bi5O7NO3, and the bottom chart is for Bi2O3.

[0124] As shown in Figure 1A, all peaks in Sample 1 matched those of Bi2O3, indicating that a single Bi2O3 phase had formed. The peaks at 10-15° and near 30°, which are characteristic of Bi5O7NO3, were not observed in Sample 1.

[0125] On the other hand, as shown in Figure 1B, many of the peaks in sample 2 match those of Bi5O7NO3, indicating the presence of a considerable amount of Bi5O7NO3. Bi2O3 peaks are also observed near 25° and 45°, indicating the presence of Bi2O3.

[0126] As shown in Figures 1C and 1D, all peaks in Samples 3 and 4 coincided with those of Bi2O3, just like Sample 1, indicating that a single Bi2O3 phase had formed. In Samples 3 and 4, the peaks at 10 to 15° and the peak around 30° that are specific to Bi5O7NO3 were not observed.

[0127] [Example 3: Dissolution test] The bismuth oxide powders (samples 1 and 2) obtained in Example 1 were subjected to a dissolution test to examine their solubility.

[0128] 500 ml of a 200 g / L methanesulfonic acid aqueous solution was prepared in a beaker. A 64 mm stirring bar was placed in the beaker and the mixture was stirred at 360 rpm.

[0129] 5.0 g of bismuth oxide of Sample 1 or Sample 2 was added to the methanesulfonic acid aqueous solution in the beaker, and stirring was continued.

[0130] The dissolution state of bismuth oxide added to the methanesulfonic acid solution was observed, and a portion of the solution was taken out at regular intervals and measured with a digital turbidity meter (manufacturer: Kyoritsu Chemical Research Institute, product name: (model) DTC-4DG).

[0131] The turbidity meter was used to measure under the following conditions: Turbidity measurement wavelength: 860nm Color measurement wavelength: 390nm

[0132] The results obtained are summarized in Table 3.

[0133] [Table 3]

[0134] Photographs of the appearance of the dissolved bismuth oxide of Sample 1 added to an aqueous methanesulfonic acid solution are shown in Figure 2A (0 minutes after addition), Figure 2B (5 minutes after addition), Figure 2C (10 minutes after addition), Figure 2D (15 minutes after addition), and Figure 2E (20 minutes after addition), respectively.

[0135] As shown in Figures 2A to 2E, in the case of bismuth oxide sample 1, the solution was cloudy immediately after addition (0 minutes), but after 5 minutes it had become a slightly white, transparent solution, and after 10 minutes it had become a colorless, transparent solution.

[0136] Photographs of the appearance of the dissolution of bismuth oxide from Sample 2 added to an aqueous methanesulfonic acid solution are shown in Figure 3A (0 minutes after addition), Figure 3B (5 minutes after addition), Figure 3C (10 minutes after addition), Figure 3D (15 minutes after addition), and Figure 3E (20 minutes after addition), respectively.

[0137] As shown in Figures 3A to 3E, in the case of bismuth oxide sample 2, the solution was a cloudy yellow mixture of white and yellow immediately after addition (0 minutes), remained a similar cloudy yellow solution even after 5 minutes, became a slightly cloudy yellow solution after 10 minutes, became a transparent, light yellow solution after 15 minutes, and became a colorless, transparent solution after 20 minutes.

[0138] The reason for the large difference in solubility between Sample 1 and Sample 2 in the dissolution test of Example 3 is unclear, but the inventors believe that the difference in properties shown in the results of the analysis of the bismuth oxide powder of Example 2 caused this difference in solubility.

[0139] [Example 4: Alpha dose measurement] The bismuth oxide powder (sample 1) obtained in Example 1 was subjected to alpha dosimetry. Because measurement is difficult using the oxide powder as is, bismuth oxide powder (Sample 1) was reduced to metallic Bi by heating at 450°C for 5 hours under a hydrogen atmosphere at atmospheric pressure with a hydrogen flow rate of 0.5 L / min. The resulting metallic Bi was then cast into a graphite mold to form a plate (28 cm x 31 cm, approximately 2.5 mm thick). After pickling with 3 mol / L dilute nitric acid at room temperature, the α-ray dose was measured using a Model-1950 manufactured by Alpha Sciences Inc. The gas used in this instrument was 90% argon and 10% methane, with a gas flow rate of 250 mL / min. The measurement time was 104 hours for both the background and the sample. The first 4 hours of the measurement time were used to purge the measurement chamber, and the period from 5 hours to 104 hours was used to measure the data. Since the measuring device emits a small amount of alpha rays (background (BG) alpha rays), the value obtained by subtracting the background alpha ray count from the measurement data for the alpha ray count was evaluated as the alpha ray count of metallic bismuth. The results obtained are shown in Table 4 below.

[0140] [Table 4]

[0141] As shown in Table 4, the metallic bismuth obtained by reducing the bismuth oxide of Sample 1 had an extremely reduced alpha dose. In other words, the alpha dose of the bismuth oxide powder (Sample 1) was estimated to be at least 0.002 cph or less.

[0142] [Example 5: Impurity measurement] The impurity content of the bismuth oxide powder (Sample 1) obtained in Example 1 was measured by GD-MS. The GD-MS measurement was carried out under the following conditions: Device name: Astrum (manufactured by Nu Instruments) Discharge current: 2.0mA Discharge voltage: 1.0 kV Discharge time: Approximately 1 hour Discharge gas: Ar

[0143] The results are shown in the following Tables 5-1 to 5-3. In Tables 5-1 to 5-3, unless otherwise specified, the impurity contents are in wtppm. In the tables, an inequality sign (<) indicates that the value was below the specified lower limit of quantitation.

[0144] [Table 5-1]

[0145] [Table 5-2]

[0146] [Table 5-3]

[0147] When the impurity content measured above was less than the lower limit of quantification, it was counted as the lower limit and the total was calculated to be 31.99 wtppm.

[0148] From this impurity content of 31.99 wtppm, the purity of the bismuth oxide powder of Sample 1 was calculated to be 99.9968 wt%. [Industrial Applicability]

[0149] According to the present invention, it is possible to provide bismuth oxide with a reduced alpha dose. The present invention is an industrially useful invention.

Claims

1. Alpha radiation dose is 0.002 cph / cm ２ is as follows: Bismuth oxide powder having a purity of 99.99 wt% or more.

2. Specific surface area: 0.1 to 1.0 m ２ 2. The bismuth oxide powder of claim 1, wherein the bismuth oxide powder has a ZnO content in the range of 0.1 wt. / g.

3. Bulk density: 2.5 to 6.0 g / cm ３ 2. The bismuth oxide powder according to claim 1, wherein the bismuth oxide powder has a viscosity in the range of 1000:1 or 1000:

2.

4. 2. The bismuth oxide powder according to claim 1, wherein D50 is in the range of 10 to 30 μm.

5. 2. The bismuth oxide powder according to claim 1, wherein the Na content is 5 wtppm or less.

6. 2. The bismuth oxide powder according to claim 1, wherein the value of ("average particle size D90" - "average particle size D10") / "average particle size D50" is in the range of 4.0 to 10.

0.

7. 2. The bismuth oxide powder according to claim 1, wherein 5.0 g of the bismuth oxide powder is added to 500 ml of a 200 g / L aqueous methanesulfonic acid solution and stirred, and 10 minutes later, the turbidity is 0 to 5 and the color is 0 to 5.

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