JP2003106974A - Measuring method for liquid diffusion coefficient - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method for a liquid diffusion coefficient capable of accurately measuring the diffusion coefficient. SOLUTION: The measuring method for the liquid diffusion coefficient is characterized by that it has a process of preparing a diffusion cell with two solution pools connected by a capillary tube, inputting a component to be diffused in the solution pools and diffusing it through the capillary tube, a process of measuring a solution concentration change and a solution weight change of each solution pool caused by diffusion, and a process of determining a diffusion flux J and a concentration gradient dc/dx from measured values, and the diffusion coefficient D is determined on the basis of Fick's first law from the determined diffusion flux J and concentration gradient dc/dx.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid diffusion coefficient measuring method based on a novel algorithm.

[0002]

2. Description of the Related Art Many materials from metals and semiconductors to proteins are produced by crystal growth from a liquid phase.
In order to produce high quality crystals, it is important to control the concentration distribution in the liquid phase, and to do so, it is essential to optimize the growth conditions by numerical calculation. The diffusion coefficient is a very important physical property value in numerical calculation.

However, the conventional diffusion coefficient measuring method is to analyze the solution concentration distribution formed by the diffusion pair experiment based on Fick's second law. However, this method cannot obtain sufficient measurement accuracy. This is because it is extremely difficult not only technically but also in principle to measure the concentration distribution in a solution with high accuracy.There is currently no way to overcome this difficulty, and even if future technological development is anticipated. The conventional method cannot be expected to improve the accuracy any more.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a general industry in which crystal growth is carried out from a liquid phase, particularly a metal / semiconductor industry, and a protein. It is an object of the present invention to provide a measuring method capable of easily acquiring a liquid diffusion coefficient with high accuracy as an indispensable tool for acquiring basic physical property values for crystal preparation in the pharmaceutical industry for crystal preparation.

[0005]

In order to achieve this object, the present invention has the following constitution.

(1) A step of diffusing a predetermined component in a liquid to obtain a diffusion flux J and a concentration gradient dc / dx thereof, and the obtained diffusion flux J and concentration gradient dc / dx,
A method for measuring a liquid diffusion coefficient, which comprises obtaining the diffusion coefficient D based on Fick's first law.

(2) A diffusion cell in which two solution reservoirs are connected by a capillary tube is prepared, and solutions having different concentrations are put in the first and second solution reservoirs, and the components of each solution reservoir are mutually diffused through the capillary tubes. And the step of measuring the change in solution weight and the change in solution concentration caused by diffusion and obtaining the diffusion flux J and the concentration gradient dc / dx from these measured values, and the determined diffusion flux J and the concentration gradient dc. / Dx, a diffusion coefficient D is calculated based on Fick's first law.

(3) A diffusion cell in which two solution reservoirs are connected by a capillary tube is prepared, solutions having different concentrations are put in the first and second solution reservoirs, and the solution concentration is kept constant in the first solution reservoir. Put the solute replenishing crystal to hold the solution in the solution, diffuse the components of each solution reservoir through the capillary tube, and measure the change in the solution weight and the change in the solution concentration caused by the diffusion. Flux J and concentration gradient dc / d
The step of obtaining x, the obtained diffusion flux J and the concentration gradient dc /
dx and the diffusion coefficient D based on Fick's first law
A method for measuring a liquid diffusion coefficient, which comprises:

In summary, the present invention measures the time variation of the concentration in a solution by using the in-situ method for measuring the concentration of the solution in the diffusion experiment, which has been difficult until now, and also provides a novel diffusion coefficient deriving algorithm. It is used to enable the measurement of the liquid diffusion coefficient. Further, according to the present invention, it has the following structural features that are not available in the conventional method.

Measuring the diffusive flux. -Perform analysis based on Fick's first law. The method of the present invention has the following effects. -In this method, measurement accuracy depends on in-situ measurement technology. This is extremely easy as compared with the improvement in accuracy of the conventional concentration distribution measuring method. -It is possible to acquire the mutual diffusion coefficient, the intrinsic diffusion coefficient, and the self diffusion coefficient at the same time. -The in-situ measurement method and the material of the diffusion cell can be freely designed depending on the material to be measured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an experiment is conducted using a special diffusion cell. The diffusion cell is composed of two solution reservoir parts and a capillary part connecting them. As shown in FIG. 1A, when the solution and solute replenishing crystal S are put into the first solution reservoir 10, the solution component diffuses through the capillary tube 20 and the capillary tube 20 as shown in FIG. 1B. As a result, the solution concentration and weight of the respective solution reservoirs 10 and 30 change. The flux J and the concentration gradient dc / dx are obtained by measuring the weight change and the concentration change of the solution concentration of the second solution reservoir 30, and the diffusion coefficient is calculated from these values based on Fick's first law shown in the following equation. Find D. (C)
Indicates that both solutions have the same concentration and the diffusion is completed. In the figure, C1 is the concentration of the solution in the first solution reservoir,
C2 represents the concentration in the second solution reservoir, and t represents time.

[0012]

[Formula 1]

Here, it is based on the assumption that the solution in each of the solution reservoirs 10 and 30 is homogeneous and the diffusion in the capillary tube 20 is stationary. The cell in the figure and the in-situ measurement technique can be freely designed according to the material to be measured, and the present invention does not depend on these measurement methods and cell material.

The present invention requires a flux, which is peculiar to the present invention. Also, the measurement accuracy of the diffusion coefficient
The same or better than the conventional method has been obtained. Further, since the accuracy of the measured value according to the present invention depends only on the in-situ measurement technique, further improvement in accuracy can be expected if only the in-situ measurement technique is improved in the future. This is the greatest advantage over the conventional method.

Further, as shown in FIG. 4, the diffusion coefficient can be measured without inserting the solute supplementing crystal S.
That is, the solution for measuring the diffusion coefficient is put in each of the first solution reservoir 10 and the second solution reservoir 30. At this time, different solution concentrations are used for the respective solution reservoirs. Then,
As shown in (b), the solution component diffuses through the capillary tube 20. As a result, the solution concentration and weight of the respective solution reservoirs 10 and 30 change. The flux J and the concentration gradient dc / dx are obtained by measuring the weight change and the concentration change of the solution concentration of the second solution reservoir 30, and the diffusion coefficient is calculated from these values based on Fick's first law shown in the above equation. Find D.

[0016]

EXAMPLES The diffusion coefficient of GaZn was measured using the apparatus shown in FIG. A fluorescent X-ray analysis method is used for the in-situ measurement method, and a dedicated graphite cell is used for the diffusion cell.

The results are shown in FIG. (A) shows a diffusion flux J, and (b) shows an example of actual measurement of the concentration gradient dc / dx in the capillary. The horizontal axis represents the measurement time, and the vertical axis represents each value. The diffusion coefficient D is obtained by dividing the flux by the value of the concentration gradient.

In order to confirm the accuracy of the diffusion coefficient measured in the examples, the concentration change in the solution reservoir was obtained by numerical calculation and compared with the experimental value. This is shown in FIG. It can be seen that the calculation result using the value of the diffusion coefficient obtained in the figure shows good agreement with the experimental value.

Also, when the apparatus of FIG. 4 is used, a good agreement with the experimental value was similarly found.

The present inventor is not limited to GaZn, and
The usefulness of the present invention was confirmed by measuring the mutual diffusion coefficient, the intrinsic diffusion coefficient and the self diffusion coefficient of the aGe binary solution.

[0021]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, in the industries in which crystal growth is carried out from a liquid phase, particularly in the metal / semiconductor industry and the pharmaceutical industry for producing protein crystals,
As a tool indispensable for acquiring basic physical property values for crystal production, it is possible to provide a measuring method that can easily and accurately acquire a liquid diffusion coefficient.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of diffusion coefficient measurement, where (a) shows a state at the beginning of the experiment, (b) shows a state in the middle of diffusion, and (c) shows a state where both solutions have the same concentration and the diffusion is completed. .

FIG. 2 shows the results of an example in which the diffusion coefficient of GaZn was measured, (a) is a diagram showing the time course of diffusion flux, and (b) is a diagram.
FIG. 4 is a diagram showing an example of actual measurement of concentration gradient in a capillary tube.

FIG. 3 is a diagram in which a change in concentration of a solution reservoir is obtained by numerical calculation and is compared with an experimental value.

FIG. 4 is a schematic explanatory view of diffusion coefficient measurement different from FIG.
(A) is the initial state of the experiment, (b) is in the process of diffusion,
(C) shows a state where both solutions have the same concentration and the diffusion is completed.

[Explanation of symbols]

10. ． ． First solution reservoir 20. ． ． Capillaries 30. ． ． Second solution reservoir S. ． ． ． Solute supply crystal

Continued front page    (72) Inventor Kazuo Nakajima             1-35-6 Momijigaoka, Yamato-cho, Kurokawa-gun, Miyagi Prefecture

Claims (3)

[Claims] 1. A process of diffusing a predetermined component in a liquid to obtain a diffusion flux J and a concentration gradient dc / dx thereof, and a diffusion flux J and a concentration gradient dc / dx thus determined, A method for measuring a liquid diffusion coefficient, which comprises obtaining the diffusion coefficient D based on the first law. 2. A diffusion cell in which two solution reservoirs are connected by a capillary tube is prepared, and solutions having different concentrations are put into the first and second solution reservoirs, and the components of each solution reservoir are mutually diffused through the capillary tube. The steps, the step of measuring the change in the solution weight and the change in the solution concentration caused by diffusion, and obtaining the diffusion flux J and the concentration gradient dc / dx from these measured values, and the obtained diffusion flux J and the concentration gradient dc / A method for measuring a liquid diffusion coefficient, which comprises obtaining a diffusion coefficient D from dx based on Fick's first law. 3. A diffusion cell in which two solution reservoirs are connected by a capillary tube is prepared, solutions having different concentrations are respectively placed in the first and second solution reservoirs, and the solution concentration is kept constant in the first solution reservoir. Put a solute replenishing crystal for holding and diffuse the components of each solution reservoir mutually through a capillary tube, and measure the change in solution weight and the change in solution concentration caused by diffusion, and measure the diffusion flow from these measured values. A step of obtaining the bundle J and the concentration gradient dc / dx, and a diffusion coefficient D obtained based on Fick's first law from the obtained diffusion flow flux J and the concentration gradient dc / dx. Measuring method.