High-purity metallic strontium

Abstract

This invention provides high-purity metallic strontium in which the content of the impurity Co (cobalt) has been reduced. [Solution] Metallic strontium with a Co content of 0.01 wt ppm or less.

Description

Technical Field

[0001] The present invention relates to high-purity metallic strontium.

Background Art

[0002] With the advancement of electronic device products, there has been an increasing demand for higher purity of high-purity metals used as raw materials. In ceramic capacitor products, high-purity metallic strontium is used.

[0003] Patent Document 1 discloses a method for producing high-purity metallic strontium and the high-purity metallic strontium obtained thereby.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 discloses that for the obtained high-purity metallic strontium, the content of Co as an impurity was less than 0.05 wtppm.

[0006] According to the inventors' research, although the high-purity metallic strontium in Patent Document 1 is of high purity, it is a product with an impurity content of less than 0.05 wt ppm of Co. Furthermore, according to the inventors' research, when a Sr composite oxide for electronic devices is produced using a high-purity metallic strontium product with this level of impurity content, there is a high possibility that a composite oxide called SrCoO3 will be simultaneously produced from the impurity Co. This SrCoO3 is a ferromagnetic material that behaves metallicly and is highly undesirable as an impurity in electronic devices. Thus, although the high-purity metallic strontium in Patent Document 1 is of high purity, further reduction of impurity content, especially a reduction in the Co (cobalt) content, is desirable.

[0007] Therefore, an object of the present invention is to provide high-purity metallic strontium in which the content of the impurity Co (cobalt) is reduced. [Means for solving the problem]

[0008] The inventors, through diligent research and development, have achieved the production of high-purity metallic strontium, as described below, and have arrived at the present invention.

[0009] Therefore, the present invention includes (1) the following: (1) Metallic strontium with a Co content of 0.01 wt ppm or less. [Effects of the Invention]

[0010] This invention provides high-purity metallic strontium with a reduced content of the impurity Co (cobalt). [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an explanatory diagram of the structure of the heating furnace used for sublimation purification. [Figure 2]Figure 2 is a graph showing the results of a heating test to determine the temperature of each part inside the inner tube located within the cylindrical tubular structure of the heating furnace used for sublimation purification. [Modes for carrying out the invention]

[0012] The present invention will be described in detail below with reference to specific embodiments. The present invention is not limited to the specific embodiments disclosed below.

[0013] [High-purity metallic strontium] This invention relates to metallic strontium having a Co content of 0.01 wt ppm or less.

[0014] The high-purity metallic strontium of the present invention has a reduced Co content, which minimizes the formation of the composite oxide SrCoO3. SrCoO3 is a ferromagnetic material that behaves metallically and is a highly undesirable impurity in electronic devices. Therefore, the high-purity metallic strontium of the present invention is particularly excellent as a raw material for electronic devices.

[0015] [purity] In a preferred embodiment, the purity of the high-purity metallic strontium of the present invention can be, for example, 99.95 wt% or more, preferably 99.96 wt% or more, preferably 99.97 wt% or more, preferably 99.98 wt% or more, or preferably 99.99 wt% or more, or preferably 99.981 wt% or more, preferably 99.982 wt% or more, preferably 99.983 wt% or more, preferably 99.984 wt% or more, preferably 99.985 wt% or more, preferably 99.986 wt% or more, preferably 99.987 wt% or more, or preferably 99.9871 wt% or more, preferably 99.98715 wt% or more, or preferably 99.98716 wt% or more. Alternatively, in a preferred embodiment, the purity of the high-purity metallic strontium of the present invention can be, for example, 99.95 wt% or higher, preferably 99.99 wt% or higher, preferably 99.995 wt% or higher, and preferably 99.999 wt% or higher. The purity of the high-purity metallic strontium can be calculated by the means described later in the examples.

[0016] [Co content] In a preferred embodiment, the Co content (cobalt content) of the high-purity metallic strontium of the present invention can be, for example, 0.01 wtppm or less, preferably 0.009 wtppm or less, preferably 0.008 wtppm or less, and preferably 0.007 wtppm or less.

[0017] [Impurity element content] In a preferred embodiment, the high-purity metallic strontium of the present invention may contain the following impurity elements, each of which is expressed in wtppm unless otherwise specified.

[0018] Li content: for example, 0.03 wtppm or less, preferably 0.02 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0019] Be content: for example, 0.03 wtppm or less, preferably 0.02 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0020] B content: for example, 0.05 wtppm or less, preferably 0.04 wtppm or less, preferably 0.03 wtppm or less;

[0021] F content: for example, 150 wtppm or less, preferably 120 wtppm or less, preferably 90 wtppm or less, preferably 52 wtppm or less;

[0022] Na content: for example, 3.0 wtppm or less, preferably 2.0 wtppm or less, preferably 1 wtppm or less, preferably 0.93 wtppm or less;

[0023] Mg content: for example, 40 wtppm or less, preferably 30 wtppm or less, preferably 20 wtppm or less, preferably 12 wtppm or less;

[0024] Al content: for example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2.1 wtppm or less;

[0025] Si content: for example, 100 wtppm or less, preferably 50 wtppm or less, preferably 30 wtppm or less, preferably 29 wtppm or less;

[0026] P content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably 0.8 wtppm or less;

[0027] S content: for example, 50 wtppm or less, preferably 40 wtppm or less, preferably 30 wtppm or less, preferably 28 wtppm or less;

[0028] Cl content: for example, 20 wtppm or less, preferably 15 wtppm or less, preferably 10 wtppm or less, preferably 8.9 wtppm or less;

[0029] K content: for example, 1 wtppm or less, preferably 0.9 wtppm or less, preferably 0.8 wtppm or less, preferably 0.7 wtppm or less, preferably 0.6 wtppm or less, preferably 0.5 wtppm or less, preferably 0.41 wtppm or less;

[0030] Sc content: for example, 0.01 wtppm or less, preferably 0.009 wtppm or less, preferably 0.008 wtppm or less, preferably 0.007 wtppm or less, preferably 0.006 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0031] Ti content: for example, 5 wtppm or less, preferably 4 wtppm or less, preferably 3 wtppm or less, preferably 2.4 wtppm or less;

[0032] V content: for example, 0.01 wtppm or less, preferably 0.009 wtppm or less, preferably 0.008 wtppm or less, preferably 0.007 wtppm or less, preferably 0.006 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0033] Cr content: for example, 1 wtppm or less, preferably 0.5 wtppm or less, preferably 0.1 wtppm or less, preferably less than 0.1 wtppm;

[0034] Mn content: for example, 4 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1.8 wtppm or less;

[0035] Fe content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably 0.63 wtppm or less;

[0036] Co content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.007 wtppm or less;

[0037] Ni content: for example, 0.05 wtppm or less, preferably 0.04 wtppm or less, preferably 0.03 wtppm or less, preferably 0.02 wtppm or less;

[0038] Cu content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0039] Zn content: for example, 4 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1.3 wtppm or less;

[0040] Ga content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0041] Ge content: for example, 1 wtppm or less, preferably 0.5 wtppm or less, preferably 0.1 wtppm or less, preferably less than 0.1 wtppm;

[0042] As content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0043] Se content: for example, 2 wtppm or less, preferably 1 wtppm or less, preferably 0.5 wtppm or less, preferably less than 0.5 wtppm;

[0044] Br content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0045] Rb content: for example, 2 wtppm or less, preferably 1 wtppm or less, preferably 0.5 wtppm or less, preferably less than 0.5 wtppm;

[0046] Y content: for example, 7 wtppm or less, preferably 6 wtppm or less, preferably 5 wtppm or less, preferably less than 5 wtppm;

[0047] Zr content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0048] Nb content: for example, 2 wtppm or less, preferably 1 wtppm or less, preferably 0.5 wtppm or less, preferably less than 0.5 wtppm;

[0049] Mo content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0050] Ru content: for example, 100 wtppm or less, preferably 75 wtppm or less, preferably 50 wtppm or less, preferably less than 50 wtppm;

[0051] Rh content: for example, 700 wtppm or less, preferably 600 wtppm or less, preferably 500 wtppm or less, preferably less than 500 wtppm;

[0052] Pd content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0053] Ag content: for example, 200 wtppm or less, preferably 150 wtppm or less, preferably 100 wtppm or less, preferably less than 100 wtppm;

[0054] Cd content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0055] Sn content: For example, 7 wtppm or less, preferably 6 wtppm or less, preferably 5 wtppm or less, preferably less than 5 wtppm;

[0056] Sb content: For example, 7 wtppm or less, preferably 6 wtppm or less, preferably 5 wtppm or less, preferably less than 5 wtppm;

[0057] Te content: for example, 2 wtppm or less, preferably 1 wtppm or less, preferably 0.5 wtppm or less, preferably less than 0.5 wtppm;

[0058] I content: for example, 7 wtppm or less, preferably 6 wtppm or less, preferably 5 wtppm or less, preferably less than 5 wtppm;

[0059] Cs content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0060] Ba content: for example, 600 wtppm or less, preferably 500 wtppm or less, preferably 400 wtppm or less, preferably 310 wtppm or less;

[0061] La content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0062] Ce content: for example, 0.02 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0063] Pr content: for example, 0.02 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0064] Nd content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0065] Sm content: For example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0066] EU content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0067] Gd content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0068] Tb content: for example, 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0069] Dy content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0070] Ho content: for example, 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0071] Er content: for example, 0.04 wtppm or less, preferably 0.03 wtppm or less, preferably 0.02 wtppm or less;

[0072] Tm content: for example, 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0073] Yb content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0074] Lu content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0075] Hf content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0076] W content: for example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0077] Re content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0078] Os content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0079] Ir content: for example, 1 wtppm or less, preferably 0.5 wtppm or less, preferably 0.1 wtppm or less, preferably 0.07 wtppm or less;

[0080] Pt content: For example, 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0081] Hg content: for example, 1 wtppm or less, preferably 0.5 wtppm or less, preferably 0.1 wtppm or less, preferably less than 0.1 wtppm;

[0082] Tl content: for example, 0.2 wtppm or less, preferably 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably less than 0.05 wtppm;

[0083] Pb content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0084] Bi content: for example, 0.1 wtppm or less, preferably 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably less than 0.01 wtppm;

[0085] Th content: for example, 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm;

[0086] U content: For example, 0.05 wtppm or less, preferably 0.01 wtppm or less, preferably 0.005 wtppm or less, preferably less than 0.005 wtppm.

[0087] [Production of high-purity metallic strontium] In a preferred embodiment, the high-purity metallic strontium of the present invention can be produced by means described later in the examples.

[0088] [Preferred embodiments of the present invention] In preferred embodiments, the present invention includes (1) and the following: (1) Metallic strontium with a Co content of 0.01 wt ppm or less. (2) Metallic strontium as described in (1), with a purity of 99.95 wt% or higher.

[0089] (3) Metallic strontium as described in (1), having a K content of 1 wt ppm or less. (4) (1) The metallic strontium described above, having a B content of 0.05 wt ppm or less.

[0090] (5) (1) The metallic strontium described above, having an Sc content of 0.01 wt ppm or less. (6) (1) The metallic strontium described above, having a Ni content of 0.05 wt ppm or less.

[0091] (7) (1) The metallic strontium described above, having a V content of 0.01 wt ppm or less. (8) (1) Metallic strontium with a purity of 99.98 wt% or higher. (9) (1) Metallic strontium with a purity of 99.987 wt% or higher.

[0092] In a preferred embodiment, the high-purity metallic strontium of the present invention has a reduced Co content, thereby minimizing the formation of the complex oxide SrCoO3, making it particularly excellent as a raw material for electronic devices. Therefore, the present invention also relates to a raw material for electronic devices consisting of the above-mentioned metallic strontium, a raw material for electronic devices containing the above-mentioned metallic strontium, a method for manufacturing a raw material for electronic devices using the above-mentioned metallic strontium, and the use of the above-mentioned metallic strontium for the manufacture of a raw material for electronic devices. [Examples]

[0093] The present invention will be described in detail below with reference to examples. The present invention is not limited to the examples illustrated below.

[0094] [Example 1] The high-purity metallic strontium of the examples and comparative examples of the present invention was produced as follows.

[0095] [Raw materials] As a raw material, we prepared metallic strontium with a purity of 99.5% or higher, manufactured by Furuuchi Chemical.

[0096] [Heating furnace used for sublimation purification] Figure 1 shows a diagram illustrating the structure of the heating furnace used for sublimation purification. Referring to Figure 1, the sublimation purification process using this furnace will be explained below.

[0097] The heating furnace 3 has a cylindrical tubular structure and is designed to heat the inside while maintaining vacuum suction. As shown in the figure, for structural and operational convenience, the cylindrical tubular heating furnace 3 has an inner tube 5 inside, and the deposition of Sr metal gas occurs inside this inner tube 5. The raw material 9 is placed at one end of the inner tube 5 on the 5a side, and while maintaining a vacuum suction state, the raw material 9 can be sublimated by heating with external heaters (7a, 7b). The flow of metal gas (13a, 13b) generated when the raw material 9 sublimes due to heating by the heaters (7a, 7b) diffuses inside the inner tube 5 located inside the vacuum-suctioned cylindrical tubular structure, and diffuses to reach areas far from the heating points by the heaters (7a, 7b). Heating by the heaters (7a, 7b) is performed at one end of the inner tube 5 on the 5a side, which is located inside the cylindrical tubular structure, but not at the other end on the 5b side. As a result, a temperature gradient is created on the inner wall of the inner tube 5, which is located inside the cylindrical tubular structure, from the heated end to the unheated end. Thereupon, the metal gas generated by sublimation is deposited at a location (deposition site) according to the properties of the metal within the temperature gradient from the heated end to the unheated end, forming deposited materials (11a, 11b). Arrow 15 indicates the flow of vacuum suction inside the heating furnace 3.

[0098] [Sublimation purification] Sublimation purification was performed using the heating furnace described in Figure 1 under the following conditions. Maximum set temperature using the external heater at the heating end: 750℃ Temperature holding time for sublimation purification: 6 hours Atmosphere inside the tubular structure: Constantly under vacuum (Vacuum level immediately before heating starts: 6-8 x 10) ―2 Pa) Ingredient preparation amount: 102g

[0099] As described above, after 6 hours, the material was allowed to cool naturally for 3 hours, and the deposited material in the 565°C to 582°C portion inside the inner tube of the cylindrical tubular structure was collected and designated as Sample 1.

[0100] The temperature of each part inside the inner tube of the cylindrical tubular structure was measured by removing the Refathermo (common thermal history sensor, manufactured by JFCC) and Thermoproof (manufactured by Nichiyu Giken Kogyo Co., Ltd.) installed in each part during preliminary heating tests, measuring the temperature with a micrometer, and observing the discoloration of the seals. The temperature was then calculated from a graph plotting these values. The tolerance for these temperature values ​​was +10 to -10°C. The graph used for the calculation is shown in Figure 2. Distance was expressed as a relative value, with the center of the heater set to 0 and the end of the inner tube 5 set to 1.

[0101] Furthermore, in the same manner as the recovery of Sample 1, the deposited material deposited in the 599-616°C portion of the inner tube located inside the cylindrical tubular structure was recovered and designated as Sample 2, and the deposited material deposited in the 582-599°C portion was recovered and designated as Sample 3.

[0102] [analysis] Samples 1, 2, and 3 obtained in Example 1 were analyzed by GDMS. The results are shown in Tables 1 and 2. Unless otherwise specified, values ​​are in wtppm. Values ​​indicated with an inequality sign (<) indicate that the value was below the limit of quantification.

[0103] [Table 1]

[0104] [Table 2]

[0105] Table 2 shows the total value (wtppm) of impurity elements other than alkaline earth metal elements. Among the impurity elements, values ​​below the limit of quantification were counted as 0 wtppm to calculate the total value. This total value of impurity elements was subtracted from 100 wt% to calculate the purity of Sample 1 as 99.98716 wt%.

[0106] Similarly, based on measurements performed separately, the purity of sample 2 was calculated to be 99.96747 wt%, and the purity of sample 3 was calculated to be 99.97045 wt%.

[0107] [Potential contribution to SDGs] One embodiment of the present invention provides high-purity metallic strontium. Since high precision of materials and components is important for the development of IoT and AI technologies, one embodiment of the present invention has the potential to contribute to the development of IoT and AI technologies. For this reason, one embodiment of the present invention has the potential to contribute to Goal 9 of the United Nations Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation." [Industrial applicability]

[0108] This invention provides high-purity metallic strontium in which the content of the impurity Co (cobalt) has been reduced. This invention is industrially useful.

Claims

1. Metallic strontium with a CO content of 0.01 wt ppm or less.

2. The metallic strontium according to claim 1, having a purity of 99.95 wt% or higher.

3. The metallic strontium according to claim 1, wherein the potassium content is 1 wt ppm or less.

4. The metallic strontium according to claim 1, wherein the B content is 0.05 wt ppm or less.

5. The metallic strontium according to claim 1, wherein the Sc content is 0.01 wt ppm or less.

6. The metallic strontium according to claim 1, wherein the Ni content is 0.05 wt ppm or less.

7. The metallic strontium according to claim 1, wherein the V content is 0.01 wt ppm or less.

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