JPH04122837A - Analyzing method of copper in superconductor - Google Patents

Abstract

PURPOSE:To improve a quality control and a process control of a superconductor by determining copper quantity in the suprconductor with high sensitivity by an ICP method and by making definite the relation between the composition and the characteristics of the copper in the superconductor. CONSTITUTION:The title method is an analyzing method of copper in a superconductor by a high-frequency inductively coupled plasma emission method. A hydrochloric acid and a nitric acid are added to the superconductor and the superconductor is decomposed by heating and then cooled down. Next, europium is added as a standard substance to a mixed solution of a filtered liquid obtained by filtering a decomposition solution thus obtained and of a washed liquid obtained by washing a precipitate by the hydrochloric acid, then the solution is made to be of a prescribed volume by the hydrochloric acid. The solution thus prepared is used as a sample solution and the intensity of emission is measured by using the high-frequency inductively coupled plasma emission method, so as to analyze the copper in the superconductor. According to this constitution, the relation between the composition and the characteristics of the copper in the superconductor is made definite and also a quality control and a process control of the superconductor are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention is directed to a high frequency inductively coupled plasma luminescence method (hereinafter referred to as IC).
This invention relates to a method for analyzing copper in superconductors using the P method.

B0 Summary of the Invention The present invention involves adding hydrochloric acid and nitric acid to a superconductor, decomposing the superconductor by heating, cooling it, and then washing the filtrate and precipitate obtained by filtering the decomposed solution with hydrochloric acid. Europium (hereinafter referred to as EU) is added as a standard substance to the mixture with the washing solution obtained by the method, and the volume is made up to a certain level with hydrochloric acid.The luminescence intensity is measured using the high-frequency inductively coupled plasma luminescence method as a sample solution. As a result, copper in superconductors can be quantified with high sensitivity, making it possible to clarify the relationship between the composition and properties of copper in superconductors, and to improve quality control and process control of superconductors. .

C0 Conventional technology Research and development of superconducting materials has progressed rapidly in recent years, and is being actively carried out in various places using materials centered on rare earth elements.Recently, 5b-Bi-5r-Ca-Cu ceramics are also being worked on. ing.

The most important factor determining the quality of this superconductor is the composition of raw materials.

That is, superconducting properties are greatly affected by the combination and formulation of raw materials.

Therefore, in order to more clearly and quantitatively understand the relationships among the raw materials of superconductors, it is essential to establish a method for analyzing trace amounts of copper.

D0 Problems to be Solved by the Invention The present invention was devised by paying attention to such problems, and provides an ICP method for quantifying copper in superconductors with high sensitivity.

20 Means and Effects for Solving the Problems That is, the present invention is obtained by adding hydrochloric acid and nitric acid to a superconductor, decomposing the superconductor by heating, cooling it, and then filtering this decomposed solution. EU was added as a standard substance to a mixture of filtering and washing solution obtained by washing the precipitate with hydrochloric acid, and the amount was made up to a certain amount with hydrochloric acid. This was used as a sample solution and the luminescence intensity was measured using a high-frequency inductively coupled plasma luminescence method. The solution is to measure it.

The present invention will be explained in more detail below.

First, when carrying out the method according to the present invention, a superconductor as a sample is thoroughly decomposed.

This decomposition is carried out using hydrochloric acid and nitric acid.

Further, in order to perform the analysis method according to the present invention with higher precision, it is preferable to measure the amounts of hydrochloric acid and nitric acid using a whole pipette.

The superconductor sample was prepared using a conical beaker.
Decompose by heating.

Next, after cooling the above-mentioned decomposed product, it is treated with a slippery paper or the like, and the mouthpiece is placed in a volumetric flask or the like. Further, in order to obtain the copper content remaining in the opening paper, the precipitate is thoroughly washed with MCI, and the resulting washing liquid is similarly placed in a volumetric flask or the like. Further, the resulting oral solution and the washing liquid are thoroughly mixed and used as a sample solution in a method for quantitatively analyzing copper in a superconductor using the ICP method.

The superconductor that can be used in the method of the present invention may be any superconductor as long as it contains copper as a raw material, preferably a 5b-Bi-8r-Ca-Cu superconductor.

By the way, yttrium and E are usually used as internal standard substances.
Rare earth elements such as U and strontium are generally used, but the analytical method according to the present invention may also aim to quantify strontium together with copper in superelectric ceramics, and strontium is usually contained in ceramics. Furthermore, since y-Ba-Cu ceramic contains yttrium, EU is used as an internal standard substance.

By the way, the causes of variations in the ICP method include the expansion and contraction of the diffraction grating due to temperature changes in the measurement chamber, which causes the wavelength to shift, causing variations in measured values, and the cause in which the amount of sample sucked changes due to the viscosity of the sample, causing variations in measured values. There is. The internal standard method is a method for correcting the latter variation. That is, a certain amount of a standard substance (EU is used in the present invention) is added to the sample solution, the ratio of the luminescence intensity of the analyte and the standard substance is determined, and the change in the amount of sample sucked is corrected.

Add hydrochloric acid to the sample solution containing the above reagents to make a constant volume, and use it as an analysis sample.

Note that it is preferable to use purified water obtained by further distilling ion-exchanged water twice.

F. Examples Hereinafter, a detailed explanation of the method for quantitatively analyzing copper in a superconductor by the ICP method according to the present invention will be explained based on examples.

1. Analyzer and Reagents 1.1 Analyzer and Measurement Conditions The ICP emission spectrometer used was a Shimadzu model ICAP-1000. The measurement conditions are shown in Table 1.

Table 1 Measurement Conditions 1.2 Reagents Sb, Bi, Sr, Ca, Cu, and EU stock solutions were 11000 pp solutions for atomic absorption measurement manufactured by Wako Pure Chemical Industries, Ltd., respectively. Moreover, HCI and HNO used for toxic metal analysis manufactured by Wako Pure Chemical Industries, Ltd. were similarly used.

2. Sample decomposition and preparation method First, 0.2g of 5b-Bi-5r-Ca-Cu based superconducting ceramics was collected in a conical beaker and diluted with hydrochloric acid (1+
1) 30ml and nitric acid (1+1)lQmA' were added and thermally decomposed.

Next, after cooling, it was filtered using No. 5C filter paper, and the obtained filtered wave was filtered at 100 ml! 'Received in volumetric flask.

Furthermore, the filter paper was thoroughly washed with HCI (1+5), and the obtained washing liquid and filtered water were mixed and made constant with HCJ (1+5).

Take 10 mA' from this solution and give 20 mA of MCI (111)! Add 1.0m9 of EU and 100mA with water.
'Keep it constant and use this as the sample for analysis.

The water used was purified water obtained by distilling ion-exchanged water twice. Note that the reason for keeping the capacity constant with HCI (1+5) is to prevent precipitation of sb, which is a coexisting substance.

3. Experiments and results 3.1 Selection of analysis line In order to select the most suitable wavelength for copper analysis, analysis lines were qualitatively selected using individual solutions and reagents of each element that makes up the superconductor. . The results are shown in FIGS. 1 to 3.

That is, the concentration of each element in the test solution prepared in 2 above was 40 ppm for Ca and 200 ppm for Sb.

Typical emission lines of copper, 324.754, 327.396° 224.
A profile at 700 nm was measured.

The results are shown in FIGS. 1, 2, and 3, respectively. From this result, the spectra of the coexisting substances at all three wavelengths all pass on the baseline, and it is predicted that there is no interference with copper, and therefore, any wavelength can be used as an analysis line. Here, the wavelength with the highest detection sensitivity is 324.75.
4 nm was adopted as the analytical line.

3.2 Sensitivity (HV) selection Sensitivity (HV) refers to the high voltage applied to the photomultiplier.
There is an optimal HV depending on the concentration. Therefore, the copper concentration is 60
EV selection was performed using a ppm solution. The results are shown in FIGS. 4 to 6. From Figure 6, the emission intensity of HV40 is saturated (100), so here we use 30 as HV.
It was adopted.

3.3 Selection of internal standard substance and its wavelength Rare earths such as EU and Y, and Sr are generally used as internal standard substances. However, since Sr is included as a component in this ceramic, it cannot be used as an internal standard substance. Also,
EU and Y can be used as internal standard substances, but Y-
Since it is included as a component in Ba-Cu ceramics, it cannot be used in Y-Ba-Cu ceramics.

Furthermore, from the viewpoint of ease of analysis, it is preferable to unify internal standard substances. Therefore, Y-Ba-Cu.

EU, which is not contained in 5b-B i-3r-Ca-Cu ceramics, was selected as an internal standard substance. EU
In order to select the analytical line of
381,996,412,974°420.505nm
) profile was measured qualitatively. The results are shown in FIGS. 7 to 9. These figures show that all three wavelengths have only EU spectra, and all coexisting substances are on the baseline, and no interference with EU is observed.

Therefore, any wavelength can be used as an analytical line, but
Here, a wavelength of 381.966 nm with high detection sensitivity was employed as the analysis line.

3.4 Accuracy of calibration curve The concentration of copper in the test solution prepared by decomposition by the method shown in 2 above is approximately 30 ppm. Therefore, the copper concentration is 0 to 60p.
The accuracy of the calibration curve was confirmed in the pm range. The result is the first
Shown in Figure 0. From this figure, it can be seen that the calibration curve almost passes through the origin, and the correlation coefficient is 0.999' and the standard deviation is 0.14 ppm, indicating very good accuracy.

3.5 Effects of Hydrochloric Acid and Nitric Acid Hydrochloric acid and nitric acid were added stepwise to a solution with a copper concentration of 40 ppm, and their effects were quantitatively investigated. The results are shown in FIG. Nitric acid had no effect within the allowable range shown by the broken line. On the other hand, as the amount of hydrochloric acid added increased, the measured value of copper decreased. This is because the coexistence of hydrochloric acid increased the viscosity of the sample solution, decreased the amount of sample sucked in, and decreased the luminescence intensity.

Therefore, it was decided to suppress the effect by making the acid concentration in the test solution and the solution for creating the calibration curve the same.

3.6 Effects of Coexisting Elements Sb, Bi, Sr, Ca, and EU were each added stepwise to a copper concentration of 40 ppm, and the effects of these coexisting elements were quantitatively investigated.

The results are shown in FIGS. 12 to 16. The presence or absence of these effects was determined within ±2% of the copper recovery rate, and the allowable range is indicated by a broken line in the figure. From this, it was found that none of the elements had any effect within the allowable range shown by the broken line.

3.7 Effect of decomposition reagent on internal standard EU Hydrochloric acid and nitric acid were added stepwise to an EU solution with a concentration of 10 ppm, and the effect was quantitatively investigated. The results are shown in FIG. Nitric acid had no effect within the allowable range shown by the broken line.

On the other hand, as the amount of hydrochloric acid added increased, the measured value of EU decreased. This is because the coexistence of hydrochloric acid increased the viscosity of the sample, resulting in a decrease in the amount of sample sucked in and a decrease in the luminescence intensity.

Therefore, the acid concentration in the test solution and the standard solution for creating the calibration curve were made the same to suppress the influence.

3.8 Effect of coexisting elements on internal standard EU In order to quantitatively investigate the effect of coexisting elements on EU,
Sb and Bi in a solution with a U concentration of 10 ppm.

Sr, Ca, and Cu were each added stepwise, and the influence of each element on EU was quantitatively investigated.

The results are shown in FIGS. 18 to 22. All elements were within the allowable range indicated by the broken line, and had no effect on EU.

3.9 Verification of analytical accuracy using synthetic solutions In order to verify the analytical accuracy under the conditions studied above, six synthetic solutions were prepared. As a result, the recovery rate of strontium was 102.0
%, coefficient of variation is 0.60% and measured value X = 30.6pp
For practical purposes, a sufficiently satisfactory accuracy was obtained.

Table 2 shows the composition of the synthetic solution. The measurement results are shown in Table 3.

1) Composition of synthetic solution Table 2 Composition of synthetic solution Measurement results of synthetic solution Table 3 shows the measurement results of the synthetic solution.

Table 3 Measurement Results of Synthetic Solutions 3.10 Verification of Analytical Accuracy Using Actual Samples As a result of measuring the copper concentration in five samples with different synthesis conditions, results were obtained that were in good agreement with the amount added. Table 4 shows the measurement results.

Table 4 Measurement Result 4, Discussion From the above results, 5b-B by ICP method according to the present invention
As a result of studying quantitative analysis methods for i-S r-Ca-Cu based superconducting ceramics, the following findings were obtained.

(1) Decomposition of sample 0.2 g of sample was easily dissolved in a mixed acid of 30 mJ of hydrochloric acid (1+1) and 10 ml of nitric acid (1+1).

(2) Effect of decomposition reagent 2 ml of nitric acid (1+1) had no effect within the tolerance range of ±2%, but hydrochloric acid (1+1) showed negative interference. This is because the coexistence of hydrochloric acid increased the viscosity of the sample solution, decreased the amount of sample sucked in, and decreased the luminescence intensity. Therefore, the acid concentration in the test solution and the standard solution for creating the calibration curve were made the same to suppress the influence.

(3) Influence of coexisting elements Bi, Sr, Sb, Cu, EU (internal standard substance) is ±
There was no effect within the tolerance range of 2%.

(4) Adoption of internal standard method and internal standard material ICAP-10
The 00II type has a function that allows control of fluctuations in the spectroscopic chamber, but does not allow control of the light emitting section (fluctuations in the amount of sample sucked in, modification of light emission, etc.).

Therefore, an internal standard method was adopted as the measurement method to reduce the influence of fluctuations in the light emitting part. The internal standard substance is E.
It was set as U. This is because it is an element that is not often contained in the raw materials used and can also be used in Y-Ba-Cu based superconducting ceramics.

(5) The following measurement method was used with a focus on ensuring accuracy. That is, wavelength calibration - wavelength set (wavelength set of internal standard substance) - calibration curve creation - measurement (10 samples, one standard sample at the end).

(6) Analysis accuracy From the measurement results of 6 synthetic solutions, the coefficient of variation Cv is 0.60
%, and the recovery rate was 102.0%, which is an accuracy that is sufficiently satisfactory for practical use.

(7) Calibration curve solution Sb and Bi because there was no influence of coexisting elements.

A mixed calibration curve solution of Sr, Ca, and Cu was prepared.

Effects of the G0 Invention According to the ICP method according to the present invention, copper in a superconductor can be quantified with high sensitivity, which not only clarifies the relationship between the composition and properties of copper in a superconductor but also It makes it possible to improve quality control and process control.

[Brief explanation of drawings]

Figures 1 to 3 are graphs showing the emission spectrum of copper, Figures 4 to 6 are graphs showing sensitivity (HV) selection, and Figure 7 is a graph showing the selection of sensitivity (HV).
Figures 9 to 9 are graphs showing the profile of coexisting substances with EU, Figure 10 is a graph showing the copper calibration curve, Figure 11 is a graph showing the influence of hydrochloric acid (HC7) and nitric acid (HNOs), and Figure 9 is a graph showing the profile of coexisting substances with EU. Figures 12 to 16 are graphs showing the results of qualitative analysis of copper in each coexisting substance, Figure 17 is a graph showing the influence of the decomposition reagent on the internal standard EU, and Figures 18 to 22.
The figure is a graph showing the influence of coexisting elements on the internal standard EU. Figure 1 Profile of wavelength 324.754 nm Figure 2 Profile u of wavelength 327.396 nm 0.5 mg: ■ /Loo Weight Eu-o, 5 mg: Su/100 m1 Figure 3 Profile u of wavelength 224.700 nm → Wavelength (nm> /100m1 Figure 4 HV: 20 Figure 5 HV230 Sample name: Cu-6mg/100+J Sample name: Cu 6mg/100mJ Figure 6 HV: 40 → Wavelength (nm) Sample name: Cu-6mg /100m! Fig. 7 Eu ; Spectrum of 381.966 nm Fig. 8 Eu : Spectrum of 412.974 nm / 100 m1 7100 m1 Fig. 9 Eu ; Spectrum of 420.505 nm u → Wavelength (nm) Fig. 10 Calibration curve of Cu Elements :Cu Wavelength: 324.754nm Calibration curve: Linear equation Linear equation: (Content) -AIX (Intensity) +
A. A1=0.12096301 Ao=-0,00923607 →Content (mg/100m1) Fig. 11 Influence of decomposition reagent Fig. 12 Influence of Bi Bi (ppm> Fig. 13 Influence of Sr Fig. 14 Influence of Ca No. 15 Fig. 16 Influence of Eu Fig. 17 Influence of decomposition reagent HCI+1+-1) 30 (ml) Fig. 18 Influence of sb Sb (ppm> Fig. 19 Influence of B1 Fig. 20 Influence of Sr Sr (ppm )

Claims (1)

[Claims] (1) Washing liquid obtained by adding hydrochloric acid and nitric acid to a superconductor, decomposing the superconductor by heating, cooling it, then filtering the decomposed solution and washing the precipitate with hydrochloric acid. This method is characterized by adding europium as a standard substance to a mixed solution of copper, making it to a certain volume with hydrochloric acid, and using this as a sample solution to measure the emission intensity using a high-frequency inductively coupled plasma emission method. Analysis method.