JPS63218255A - Method for producing supercooling state by pressure jump - Google Patents

Abstract

PURPOSE:To instantaneously lead the state to a uniform supper cooling state, by exerting a hydrostatic pressure on a substance through a pressure medium, and instantaneously changing the hydrostatic pressure to impart a state exceeding the phase transition point in the temp.-pressure state diagram to the substance. CONSTITUTION:A hydrostatic pressure is exerted on the substance 6 in a high- pressure cell 5 through the pressure medium 11, then the hydrostatic pressure is instantaneously changed by controlling a hydraulic compressor 4 to impart a state exceeding the phase transition point in the temp.-pressure state diagram to the substance 6, and the substance is supercooled. Namely, the state can be jumped and moved from a certain point to another point in the state diagram in an extremely short time by instantaneously changing the water pressure exerted on the substance from the outside, and the substance can be supercooled.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for generating a supercooled state due to a pressure jump, and in particular, the present invention relates to a method for generating a supercooled state due to a pressure jump. We will discuss how to generate a supercooled state by pressure jump to obtain a supercooled state that is essential for the study of the supercooled state.

[Conventional technology]

Supercooled states are achieved by rapidly changing the temperature when studying the dynamics of temporary phase transitions, or more specifically, the crystallization process of materials. (Solid State Communications, 1, 1487.198
2) [Problems to be solved by the invention] The above-mentioned conventional method of changing temperature has a finite size, so a temperature distribution occurs inside the material.
It is not possible to obtain a uniform supercooled state. For this reason, there is a drawback that it is difficult to distinguish whether the physical properties of a true supercooled state are being measured or whether the fluctuations in physical properties due to the temperature distribution inside the substance are simply being measured. Furthermore, the sample
It is surrounded by other materials such as sample containers and has a finite heat capacity. Furthermore, since the sample itself has heat capacity, it takes a finite amount of time to obtain a uniform desired temperature even if the temperature changes rapidly, making it unsuitable as a method for tracking rapidly changing phenomena. be.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method of generating a supercooled state by pressure jump, which instantly achieves a uniform supercooled state.

[Means for solving problems]

The method of generating a supercooled state by pressure jump according to the present invention is as follows:
Means for applying hydrostatic pressure to a substance via a pressure medium and instantaneously changing the hydrostatic pressure to bring the substance into a state exceeding the phase transition point in a temperature versus pressure phase diagram and bringing it into a supercooled state. It is composed of:

[Effect]

While heat requires a finite amount of time to transfer through a material, hydrostatic pressure is applied to the material immediately and uniformly. Utilizing this fact, the temperature TO and pressure P of the substance to be sampled can be determined in advance.
o is set near the phase transition point in the temperature vs. pressure state diagram, and then rapid pressurization or depressurization is performed to obtain the temperature To and the pressure P.

If this pressure is such that P crosses the phase transition point in the temperature versus pressure phase diagram, the substance placed under this pressure P will be in a uniform supercooled state.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a cross-sectional view showing a partial block diagram of an embodiment of the present invention. In FIG. 1, a hydraulic compressor 1 is a pressurizing device on the primary side, and oil 1 as a compressed pressure medium
1 is fed into a pressure intensifier 3 through a high-pressure metal pipe 2. The increased pressure is applied to the pressure medium oil 11 and sent into the high pressure cell 5 through the high pressure metal pipe 2. A sample 6 is sealed in the high pressure cell 5, and the pressure of the oil 11 pressurized by the pressure intensifier 3 becomes the pressure directly applied to the sample 6. The entire high-pressure cell 5 has a structure that can be heated by a heater 4, and the temperature of the sample 6 can be made variable. The temperature of the sample 6 is measured with a thermocouple 7. Pressurization and depressurization of the sample 6 can be easily performed by controlling the hydraulic compressor 1. FIG. 2 is a general temperature versus pressure phase diagram of a substance. Phases (I) and (n) correspond, for example, to a liquid phase and a homogeneous phase, respectively.

(a) shows the direction of change when a variable cooling state is obtained by changing the temperature, and (b) shows the direction of change when obtaining a variable cooling state by changing the pressure. FIG. 3 is a diagram showing the temporal change characteristics of temperature versus temperature when the temperature of a substance is changed. Time t. The temperature TO starts to change at tl, and the desired temperature T is reached at tl. This is a process corresponding to (a) in FIG. FIG. 4 is a graph showing the time change characteristic of the pressure pair when the pressure of the substance is changed. 1. It can be seen that the desired pressure P can be achieved in a short time by changing the pressure P. This is a process corresponding to (b) in FIG.

As shown in Fig. 2, the temperature and pressure of the sample are set to Po and To near the phase transition points in the temperature vs. pressure phase diagram, respectively, and the temperature change is changed to the temperature change shown in Fig. 3 to cause the rapid change shown in Fig. 4. By bringing about a phase transition in the sample by applying a certain pressure, it is possible to realize a supercooled state due to a so-called pressure jump, which rapidly leads the sample to uniform supercooled states P and T. Second
In the illustrated example, this pressure jump is caused by increased pressure, but it goes without saying that the phase transition state may also be achieved by reduced pressure.

〔Effect of the invention〕

As explained above, according to the present invention, by instantaneously changing the water pressure applied to a substance from the outside, it is possible to jump and move from one point to another point on a phase diagram in a very short time, and to avoid overshooting. This method has the effect of realizing a method of generating a supercooled state by pressure jump, which can bring the substance into a cooled state and keep the substance under uniform pressure and temperature conditions.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a partial block diagram of an embodiment of the present invention, Fig. 2 is a general temperature versus pressure state diagram of a substance, and Fig. 3 is a temperature versus time diagram when the temperature of the substance is changed. Fig. 4 is a pressure vs. time change characteristic diagram when the pressure of a substance is changed. DESCRIPTION OF SYMBOLS 1... Hydraulic compressor, 2... Metal pipe for high pressure, 3... Pressure intensifier, 4... Rator, 5... High pressure cell, 6... Sample, 7... Thermocouple, 11 ···oil.
′・′Representative: Susumu Uchihara, patent attorney.

Claims (1)

[Claims] It is characterized by applying hydrostatic pressure to a substance via a pressure medium and instantaneously changing the hydrostatic pressure, thereby bringing the substance into a state exceeding the phase transition point in a temperature vs. pressure phase diagram and leading it to a supercooled state. A method for generating supercooling by pressure jump, comprising means for: