High purity metallic strontium

Abstract

A high-purity metallic strontium having a reduced content of Co (cobalt), which is an impurity, is provided by metallic strontium having a Co content of 0.01 wtppm or less.

Description

High-purity metallic strontium

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

[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.

[0004] Japanese Patent Application Laid-Open No. 2015-189996

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

[0006] According to the study by the present inventors, although the high-purity metallic strontium of Patent Document 1 is of high purity, it is a product with an impurity content such that the Co content is less than 0.05 wtppm. And according to the study by the present inventors, when an Sr composite oxide for electronic devices is produced using a high-purity metallic strontium product with such an impurity content, there is a high possibility that a composite oxide such as SrCoO ３ will be simultaneously generated from the impurity Co. This SrCoO ３ is a ferromagnetic substance that behaves metallically and is very undesirable as an impurity in electronic devices. Thus, although the high-purity metallic strontium of Patent Document 1 is of high purity, further reduction of the impurity content, particularly the Co (cobalt) content, is desired.

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

[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 comprises the following (1): (1) Metallic strontium having a Co content of 0.01 wt ppm or less.

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

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

[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, and therefore, the composite oxide SrCoO ３ The generation of SrCoO has been minimized. ３ Strontium 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, 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 more, preferably 99.99 wt% or more, preferably 99.995 wt% or more, and preferably 99.999 wt% or more. 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 wt ppm or less, preferably 0.009 wt ppm or less, preferably 0.008 wt ppm or less, and preferably 0.007 wt ppm or less.

[0017] [Impure 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 given by the values ​​listed below. Unless otherwise specified, each value is given in wt ppm.

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

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

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

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

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

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

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

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

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

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

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

[0029] K content: for example, 1 wt ppm or less, preferably 0.9 wt ppm or less, preferably 0.8 wt ppm or less, preferably 0.7 wt ppm or less, preferably 0.6 wt ppm or less, preferably 0.5 wt ppm or less, preferably 0.41 wt ppm 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 wt ppm or less, preferably 4 wt ppm or less, preferably 3 wt ppm or less, preferably 2.4 wt ppm 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 wt ppm or less, preferably 0.5 wt ppm or less, preferably 0.1 wt ppm or less, preferably less than 0.1 wt ppm;

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

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

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

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

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

[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 wt ppm or less, preferably 75 wt ppm or less, preferably 50 wt ppm or less, preferably less than 50 wt ppm;

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

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

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

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

[0055] Sn content: for example, 7 wt ppm or less, preferably 6 wt ppm or less, preferably 5 wt ppm or less, preferably less than 5 wt ppm;

[0056] Sb content: for example, 7 wt ppm or less, preferably 6 wt ppm or less, preferably 5 wt ppm or less, preferably less than 5 wt ppm;

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

[0058] I. Content: For example, 7 wt ppm or less, preferably 6 wt ppm or less, preferably 5 wt ppm or less, preferably less than 5 wt ppm;

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

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

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

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

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

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

[0065] Sm content: for example, 3 wt ppm or less, preferably 2 wt ppm or less, preferably 1 wt ppm or less, preferably less than 1 wt ppm;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0080] Pt content: for example, 3 wt ppm or less, preferably 2 wt ppm or less, preferably 1 wt ppm or less, preferably less than 1 wt ppm;

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

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

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

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

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

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

[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 Invention] In preferred embodiments, the present invention includes the following: (1) Metallic strontium having a Co content of 0.01 wt ppm or less. (2) Metallic strontium according to (1) having a purity of 99.95 wt% or more.

[0089] (3) Metallic strontium as described in any of (1) to (2), wherein the K content is 1 wt ppm or less. (4) Metallic strontium as described in any of (1) to (3), wherein the B content is 0.05 wt ppm or less.

[0090] (5) Metallic strontium as described in any of (1) to (4), wherein the Sc content is 0.01 wt ppm or less. (6) Metallic strontium as described in any of (1) to (5), wherein the Ni content is 0.05 wt ppm or less.

[0091] (7) Metallic strontium as described in any of (1) to (6), having a V content of 0.01 wt ppm or less. (8) Metallic strontium as described in any of (1) to (7), having a purity of 99.98 wt% or higher. (9) Metallic strontium as described in any of (1) to (7), having 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, and is therefore a composite oxide SrCoO ３ The generation of [unspecified impurities] is minimized, making it particularly excellent as a raw material for electronic devices. Therefore, the present invention also applies to the above-mentioned raw material for electronic devices made of metallic strontium, to the above-mentioned raw material for electronic devices containing metallic strontium, to the above-mentioned method for manufacturing the above-mentioned raw material for electronic devices using metallic strontium, and to the above-mentioned use of metallic strontium for manufacturing the above-mentioned raw material for electronic devices.

[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] High-purity metallic strontium for the examples and comparative examples of the present invention was produced as follows.

[0095] [Raw Materials] As raw materials, 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 an explanatory diagram of the structure of the heating furnace used for sublimation purification. Referring to Figure 1, the process of sublimation purification using this heating 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 heating furnace 3, which has a cylindrical tubular structure, is provided with 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 provided 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 of the inner tube 5 on the 5b side. As a result, a temperature gradient is created on the inner wall of the inner tube 5 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 by the external heater at the heating end: 750°C Temperature holding time for sublimation purification: 6 hours Atmosphere inside the tubular structure: Vacuum maintained at all times (Vacuum level immediately before heating: 6-8 × 10⁻⁶) ―２ Pa) Amount of raw materials used: 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 of the inner tube located inside 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.) that were installed in each part during preliminary heating tests, measuring them 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 GDPM. The results are shown in Tables 1 and 2. Unless otherwise specified, the values ​​are in wt ppm. Values ​​indicated with an inequality sign (<) indicate that the value was below the limit of quantification.

[0103]

[0104]

[0105] Table 2 shows the total value (wt ppm) of impurity elements other than alkaline earth metal elements. Among the impurity elements, values ​​below the limit of quantification were counted as 0 wt ppm and totaled 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] According to one embodiment of the present invention, high-purity metallic strontium is provided. 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-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[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, wherein the purity is 99.95 wt% or higher.

3. The metallic strontium according to any one of claims 1 to 2, wherein the potassium content is 1 wt ppm or less.

4. The metallic strontium according to any one of claims 1 to 2, wherein the B content is 0.05 wt ppm or less.

5. The metallic strontium according to any one of claims 1 to 2, wherein the Sc content is 0.01 wt ppm or less.

6. The metallic strontium according to any one of claims 1 to 2, wherein the Ni content is 0.05 wt ppm or less.

7. The metallic strontium according to any one of claims 1 to 2, wherein the V content is 0.01 wt ppm or less.

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