A method for realizing pressure sensing based on the pressure response of glass crystals and its applications

Abstract

The present invention discloses a method for realizing pressure sensing based on the pressure response of glass crystals and its application, belonging to the technical field of pressure-sensitive phase change materials. The method includes: (1) heating a crystal material sample to a temperature exceeding the phase change temperature point to make it in a high-temperature plastic crystal phase state; (2) quickly cooling and quenching the sample in the high-temperature plastic crystal phase state to make its temperature lower than the phase change temperature to obtain glass crystals or supercooled plastic crystals; (3) applying an external pressure to the glass crystals (or supercooled plastic crystals) to cause them to undergo a phase change to crystals, and realizing the purpose of pressure sensing according to the changes in their optical and / or electrical properties. This method can be applied to security alarm technology and the preparation of color-changing glass.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive phase change materials, and particularly relates to a method for realizing pressure sensing based on the pressure response of glass crystals and its applications. Background Art

[0002] Crystals and glasses are two common solid substances, which respectively embody the orderliness and disorderliness of solids. A crystal is a structure in which a large number of structural units (molecules, atoms, ions, etc.) are arranged in an orderly manner according to certain rules, forming a long-range ordered lattice, and the orientations of the structural units at the lattice points are all in an ordered state, with typical crystallographic symmetry. While the orientations of the structural units that make up a glass are random, and at the same time, they do not form a long-range ordered lattice and have no definite symmetry. Therefore, when using glass and crystal to describe the properties of substances, they are usually considered to be contrary to each other. However, glass crystals, as a new type of condensed matter, simultaneously possess the characteristics of both crystals and glasses. This is reflected in that the centroids of the structural units that make up such substances maintain lattice symmetry; but the orientations of the structural units at the lattice points are random and do not have symmetry.

[0003] Glass crystals can usually be obtained by quenching plastic crystals, similar to how glass can be obtained by supercooling a molten liquid. The plastic crystals mentioned here are solids with a degree of disorder very close to that of liquids. Compared with crystals, although the centroid positions still maintain a long-range ordered lattice, the orientations of the structural units at the lattice points are completely disordered and in a dynamic rotation state, so they are also called rotationally disordered crystals. Generally, as the temperature decreases, plastic crystals will transform into conventional crystals, and the orientations become ordered, resulting in the breaking of crystal symmetry and the formation of a new crystal structure. Since the proportion of the disordered degrees of freedom of plastic crystals in the total degrees of freedom of the system is close to the limit for maintaining the rigidity of solids, most of the heat stored in the material will be released during the phase change process from plastic crystals to crystals. At the same time, this phase change process is extremely sensitive to pressure. Based on these characteristics, in recent years, the applicant's team has made breakthrough progress in the research on the magnetocaloric effect of plastic crystal materials. In some plastic crystals, the entropy change driven by pressure is as high as several hundred J kg -1 k -1 , providing a very promising solution for the next generation of solid-state refrigeration technology.

[0004] However, when the applicant team studied the electrocaloric effect of certain plastic crystal materials, it was found that the electrocaloric effect has irreversible characteristics. That is, during the heating process, such materials can undergo a transformation from an ordered crystal phase to a plastic crystal phase. However, during the cooling process, even at temperatures far below the phase transition point, no reversible phase transition occurs. As mentioned above, the reason for this result is that when rapidly cooling high-temperature plastic crystals, they will ultimately transform into glassy crystals rather than conventional ordered crystals. When the temperature is between the phase transition temperature (crystal to plastic crystal) and the glass transition temperature, it is in a supercooled plastic crystal phase, and as the temperature decreases, the rotation of the structural units in the supercooled plastic crystal gradually slows down. In addition to the thermal effect, the applicant team found that compared with crystals, glassy crystals and supercooled plastic crystals show significant differences in optical and electrical properties, etc., and have the characteristics of multi-physical response to pressure. Figure 1 Fig. shows a schematic diagram of the phase transition process and physical property changes of a plastic crystal material with a glassy crystal phase.

[0005] Similarly, vanadium dioxide (VO2), as a well-known metal-insulator phase change material, is characterized by drastic changes in electrical conductivity and physical properties such as optical absorption and dielectric properties. Based on these characteristics, researchers have applied VO2 in fields such as optoelectronic switches, storage materials, supercapacitors, and infrared detection. In addition to the metal-to-insulator transition, VO2 is accompanied by a structural phase transition and a large phase transition strain. Therefore, the metal-to-insulator transition can be driven not only by temperature but also by strain, pressure, chemical doping, and intense light or electrostatic fields. These multi-functional characteristics make VO2 an important candidate material for the development of various functional and intelligent response devices. However, at room temperature, the critical pressure field required to drive its phase transition by pressure is too high, severely limiting its further development and application. However, the thermodynamic metastability of glassy crystals and supercooled plastic crystals means that they are still highly sensitive to external pressure. Based on the multi-physical response of glassy crystals / supercooled plastic crystals to small pressures, it is expected to use such materials to achieve a pressure sensor technology and application. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for realizing pressure sensing based on the pressure response of glassy crystals and its application, to realize pressure sensing according to the multi-physical response of glassy crystals / supercooled plastic crystals to small pressures, and to apply it in specific fields.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] A method for realizing pressure sensing based on the pressure response of glassy crystals, the method comprising the following steps:

[0009] (1) Heat up the crystal material sample to a temperature above the phase transition temperature point so that it is in a high-temperature plastic crystal phase state;

[0010] (2) Rapidly cool and quench the sample in the high-temperature plastic crystal phase state so that its temperature is lower than the phase transition temperature to obtain glassy crystals or supercooled plastic crystals; whether it is supercooled plastic crystals or glassy crystals, they appear transparent, have a very high light transmittance for visible light, and also have a very high conductivity;

[0011] (3) When an external pressure is applied to the glassy crystal (or supercooled plastic crystal), it will undergo a phase transition to a crystal, and the crystal appears opaque white, has a low light transmittance, and a small conductivity. Therefore, according to the changes in its optical and / or electrical properties, the response and feedback to the pressure effect can be realized, and the purpose of pressure sensing can be achieved.

[0012] In the above step (1), the crystal material sample is one or more of 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2 (AMP), m-carborane C2B 10 H 12 、1-cyanoadamantane C 11 H 15 N (CAN), adamantanone C 10 H 14 O (AON) and pentachloronitrobenzene C6C l5 NO2 (PCNB); the crystal material sample can be in a plastic crystal phase state after being processed by step (1).

[0013] When the crystal material sample in step (1) is selected as 2-amino-2-methyl-1,3-propanediol (AMP), after being processed by steps (1)-(2), it is in a supercooled plastic crystal state at room temperature, with a transparent color, and the light transmittance for light in the wavelength range of 200 nm - 800 nm reaches more than 95% in this state; this state can be stably stored at room temperature for more than half a year.

[0014] In the above step (3), when a supercooled plastic crystal state of 2-amino-2-methyl-1,3-propanediol (AMP) is pricked, it will rapidly undergo a transformation from a supercooled plastic crystal phase to an ordered crystal; at this time, the color of the ordered crystal appears white and opaque, and the light transmittance for light in the wavelength range of 200 nm - 800 nm drops to less than 10%.

[0015] In the above step (3), the way of applying pressure is to apply isostatic pressure or needle pricking pressure.

[0016] The above method for realizing pressure sensing can be applied to security alarm technology. Specifically: After the crystal material sample is processed through steps (1)-(2), supercooled plastic crystals or glass crystals are obtained and prepared on the outer surface of the protected article. The state of the supercooled plastic crystal phase is transparent and does not affect the external observation of the protected article. Once an article collides with its outer surface, the pressure will induce the supercooled plastic crystal on the surface to transform into an ordered crystal, and at the same time, there will be a huge change in signals such as color, transparency, and / or conductivity, thereby realizing the response to pressure and achieving the function of sensing and alarming through connecting to an alarm system. The protected article is a cultural relic in a cultural relic exhibition cabinet in a museum, or jewelry in a jewelry exhibition cabinet in a shopping mall, etc.

[0017] The above method for realizing pressure sensing can be applied to variable-color glass. Specifically: The crystal material sample is filled in the gap between the double-layer glass, and through a temperature control device integrated around the glass, the crystal material sample is heated and rapidly cooled according to steps (1)-(2) to obtain a supercooled plastic crystal phase. At this time, due to the transparency of the supercooled plastic crystal and high light transmittance (close to 100%), the double-layer glass still remains transparent; when the glass is knocked by an external force and the supercooled plastic crystal is induced by pressure to transform into an ordered crystal phase, at the same time, the color turns into white and opaque, achieving the purpose of color change and light impermeability; at the same time, by using the temperature increase and decrease process of the temperature control device and applying knocking pressure, the double-layer glass can be repeatedly switched between transparent and opaque white.

[0018] The advantages and beneficial effects of the present invention are as follows:

[0019] 1. The present invention will make full use of the characteristics of the plastic crystal material with a glass crystal phase, realize the design and application of a sensor technology by obtaining the supercooled plastic crystal phase at room temperature, and provide a new idea for the development of sensor technology according to the physical property differences between the supercooled plastic crystal and the room-temperature ordered crystal phase.

[0020] 2. The supercooled plastic crystal phase of the plastic crystal material involved in the present invention is sensitive to pressure, and a tiny pressure can induce it to transform into an ordered crystal. Taking 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2 (AMP) as an example, a pressure of 6.7 MPa can also drive its phase change, showing extremely high pressure sensitivity.

[0021] 3. An anti-theft alarm technology method and application can be realized by using the solution of the present invention. By using the plastic crystal material with a glass crystal phase described in the present invention, its supercooled plastic crystal state is obtained and prepared on the outer surface of the protected article. The state of the supercooled plastic crystal phase is transparent and does not affect the external observation of the protected article. Once an article collides with the outer surface of the shell, the pressure will induce the supercooled plastic crystal on the surface to transform into an ordered crystal, and at the same time, there will be a huge change in signals such as color change, transparency change and conductivity, so as to realize the response to pressure and achieve the function of sensing alarm through connecting the alarm system. The protected articles involved herein can be cultural relics in the cultural relic exhibition cabinets in museums, or jewelry and other items in the jewelry exhibition cabinets in shopping malls.

[0022] 4. A design method of a color-changing glass can be realized by the present invention. One implementation is to use the plastic crystal material with a glass crystal phase described in the present invention, fill it in the gap between the double-layer glasses, and heat and rapidly cool the plastic crystal material through the temperature control device integrated around the glasses, so as to obtain the supercooled plastic crystal phase of the plastic crystal material. At this time, due to the transparency of the color of the supercooled plastic crystal and the light transmittance approaching 100%, the glass still remains transparent. When the glass is knocked by an external force, the supercooled plastic crystal is induced by the pressure to transform into an ordered crystal phase, and at the same time, the color changes to white and opaque, achieving the purpose of color change and light impermeability. At the same time, by using the heating and cooling process of the temperature control device and applying the knocking pressure, the double-layer glass can be repeatedly switched between transparent and opaque white. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the phase change process and the change of physical properties of the plastic crystal material with a glass crystal phase;

[0024] Figure 2 It is a heat flow curve of the cooling and heating process of AMP starting from the high-temperature molten state;

[0025] Figure 3 It is an in-situ pressure Raman scattering spectrum of AMP;

[0026] Figure 4 It is the light transmittance of AMP in the optical wavelength range of 200 - 800 nm;

[0027] Figure 5 It is a morphology photo of the supercooled plastic crystal phase of AMP;

[0028] Figure 6 It is a morphology photo of the ordered crystal phase of AMP. DETAILED DESCRIPTION OF THE INVENTION

[0029] To further understand the present invention, the present invention will be described below in conjunction with examples. However, the examples are only for further elaborating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0030] The solution of the present invention is to provide a sensing technology and design method based on the pressure response of glass crystals, including: Step 1, heating a plastic crystal material sample with glass crystals, and the temperature exceeds the phase transition point from the ordered crystal to the plastic crystal phase, so that it is in the high-temperature plastic crystal phase. The heating method includes, but is not limited to, heating with the sample chamber of a microcalorimeter or directly heating the sample with a heating stage.

[0031] Step 2, performing rapid quenching on the high-temperature plastic crystal to obtain glass crystals. The rapid cooling makes the high-temperature disordered state of the plastic crystal phase enter the supercooled state, thus avoiding the complete directional order that usually occurs at low temperatures. When the temperature is below the phase transition temperature (the transition temperature from the ordered crystal to the plastic crystal phase), both the supercooled plastic crystal and the glass crystal appear transparent, have a very high light transmittance to visible light, and also have a very high conductivity. Here, the method of rapid quenching includes, but is not limited to, rapid cooling at a cooling rate of ≥10 K / min or cooling the sample in the high-temperature plastic crystal phase with ice water or liquid nitrogen.

[0032] Step 3, when an external pressure acts on the glass crystal (or supercooled plastic crystal), it will undergo a transformation to an ordered crystal, and the appearance of the ordered crystal is opaque white, with a low light transmittance and a small conductivity. Therefore, according to the huge changes in its optical and electrical properties, the response and feedback to the pressure action can be realized, and the purpose of pressure sensing can be achieved. Here, the way of applying pressure can be applying air pressure to the sample, or knocking, pricking with a needle, etc.

[0033] The pressocaloric material of the present invention is a plastic crystal material with a glass crystal phase, preferably 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2 (AMP), meta-carborane C2B 10 H 12 in the plastic crystal material, 1-cyanoadamantane C 11 H 15 N (CAN), adamantanone C 10 H 14 O (AON), pentachloronitrobenzene C6C l5 NO2 (PCNB), or one or more of them. Among them, 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2 (AMP) is further preferred.

[0034] The applications of the present invention also include a security alarm technology method and application. One implementation is to use the plastic crystal material with a glass crystal phase described in the present invention, obtain its supercooled plastic crystal state, and prepare it on the outer surface of the protected article. The state of the supercooled plastic crystal phase is transparent and does not affect the external observation of the protected article. Once an article collides with the outer surface, the pressure will induce the supercooled plastic crystal on the surface to transform into an ordered crystal, accompanied by significant changes in signals such as color change, transparency change, and conductivity, thereby achieving pressure response and realizing the function of sensing and alarming through connecting an alarm system. The protected articles involved can be cultural relics in the cultural relic exhibition cabinets in museums, or jewelry in the jewelry exhibition cabinets in shopping malls, etc.

[0035] The applications of the present invention also include a design method for a color-changing glass. One implementation is to use the plastic crystal material with a glass crystal phase described in the present invention, fill it in the gap between double-layer glasses, and heat and rapidly cool the plastic crystal material through a temperature control device integrated around the glass, thereby obtaining the supercooled plastic crystal phase of the plastic crystal material. At this time, due to the transparency of the supercooled plastic crystal and a light transmittance close to 100%, the glass still remains transparent. When the glass is knocked by an external force, the supercooled plastic crystal is induced by the pressure to transform into an ordered crystal phase, accompanied by a color change to white opacity, achieving the purpose of color change and light impermeability. At the same time, by using the temperature increase and decrease process of the temperature control device and applying knocking pressure, the double-layer glass can be repeatedly switched between transparent and opaque white.

[0036] Taking 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2 (AMP) as an example, the preferred embodiments of the present invention will be specifically described below.

[0037] Embodiments for the phase change of the AMP plastic crystal material and the acquisition of its supercooled plastic crystal phase and glass crystal phase:

[0038] Put the AMP bulk sample in the low-temperature ordered crystal phase into an atmospheric pressure DSC sample cell, heat it from 425K to 100K at a cooling rate of 10K / minute, and record the heat flow data of the sample, as shown in the cooling curve in Figure 2 . It can be found that for the cooling process of the high-temperature molten liquid state (L) of AMP, AMP shows an exothermic peak at 382K, corresponding to its solidification process. As the temperature continues to decrease, no obvious exothermic peak is seen until a transition from the supercooled plastic crystal (I sc ) to the glass crystal (I g ) occurs at 225K, corresponding to the glass transition temperature (Tg). When the temperature is above Tg, it is in the supercooled plastic crystal state. Finally, when cooled to 100K, no other changes are seen, and it always remains in the glass crystal phase.

[0039] Then, the sample was further heated to 425 K at a heating rate of 10 K / min, and the heat flow data of the sample was recorded, as Figure 2 shown in the heating curve. It can be found that the position at 225 K corresponds to the transformation from the glass crystal to the supercooled plastic crystal. An abnormal exothermic peak appears at 280 K, corresponding to the transformation from the supercooled plastic crystal to the ordered crystal (Ⅱ). Subsequently, an endothermic peak appears at 361 K, corresponding to the transformation from the ordered crystal to the plastic crystal phase (Ⅰ). Finally, another endothermic peak appears at 378 K, corresponding to the melting point of AMP.

[0040] The second embodiment for obtaining the supercooled plastic crystal and the glass crystal phase:

[0041] The AMP powder sample in the ordered crystal phase at room temperature was placed in a glass container and heated by a heating device such as a heating stage. When the temperature exceeds the heating phase transition temperature of AMP (the transition from the low-temperature ordered crystal phase to the high-temperature plastic crystal phase), the high-temperature plastic crystal phase of AMP can be obtained. The AMP in this state was rapidly cooled using ice water or liquid nitrogen, so that its high-temperature disordered state was instantaneously supercooled and frozen, thereby obtaining the glass crystal phase state.

[0042] The phase transition from the supercooled plastic crystal to the ordered crystal of AMP can be driven by pressure:

[0043] The Raman spectra (λ = 532 nm) of AMP in different phases were collected using a Raman device (Horiba Labram HR Evolution). First, the sample was placed in a thermostat. By heating it to the high-temperature plastic crystal phase and then rapidly cooling it to the room temperature environment, the supercooled plastic crystal phase of AMP was obtained, as Figure 3 shown in the supercooled plastic crystal. Pressure was applied to the sample through the pressure application unit of the sample chamber, and its Raman spectrum was monitored, as Figure 3 shown in the ordered crystal. By comparing the results before and after pressurization, it can be found that the phase transition from the supercooled plastic crystal to the ordered crystal can be driven by pressure.

[0044] Changes in the optical properties of AMP:

[0045] First, a layer of AMP sample in the supercooled plastic crystal phase was obtained on a transparent quartz sheet. Its optical photograph is as Figure 4 shown. It can be found that the supercooled plastic crystal appears colorless and transparent. Then, pressure was applied to it using a needle to induce its phase transition to the ordered crystal state. The optical photograph after the phase transition is as Figure 5 shown. It can be found that the color of the sample in this state changes significantly and appears opaque white.

[0046] Furthermore, the transmittance of the supercooled plastic crystal phase and the ordered crystal phase at room temperature was tested. The results are as Figure 6As shown, it can be found that the supercooled state exhibits obvious light filtering characteristics in the wavelength range below 250 nm, and exhibits significant light transmission characteristics when the wavelength is greater than 250 nm, with a light transmittance as high as over 95%. In contrast, the light transmittance of the ordered crystal in the entire spectrum is less than 10%. Therefore, when the AMP undergoes a pressure-driven phase change from the supercooled plastic crystal to the ordered crystal, it is accompanied by a significant decrease in the transmittance.

[0047] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any effective changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. Application of a method for realizing pressure sensing based on the pressure response of glass crystals in security alarm technology, characterized in that: The method for realizing pressure sensing based on the pressure response of a glass crystal includes the following steps: (1) Heat the crystal material sample to a temperature above the phase transition temperature point to make it in a high-temperature plastic crystal phase state; (2) Quench the sample in the high-temperature plastic crystal phase state rapidly to make its temperature lower than the phase transition temperature to obtain a glass crystal or a supercooled plastic crystal; (3) When an external pressure is applied to the glass crystal or the supercooled plastic crystal, it will undergo a phase transition to a crystal. The appearance of the crystal is opaque white, with a low light transmittance and a small conductivity. Therefore, according to the changes in its optical and / or electrical properties, the response and feedback to the pressure action can be realized, and the purpose of pressure sensing can be achieved; After the crystal material sample is processed by steps (1)-(2) to obtain a supercooled plastic crystal or a glass crystal, it is prepared on the outer surface of the protected article. The state of the supercooled plastic crystal phase is transparent and does not affect the observation of the protected article from the outside; once an article collides with the outer surface, the pressure will induce the supercooled plastic crystal on the surface to transform into an ordered crystal, and at the same time, it will be accompanied by changes in color, transparency and / or conductivity signals, so as to realize the response to the pressure and play the role of sensing and alarming through connecting an alarm system.

2. Application of the method for realizing pressure sensing based on the pressure response of glass crystals in security alarm technology according to claim 1, characterized in that: In step (1), the crystal material sample is one or more of 2-amino-2-methyl-1,3-propanediol (CH3)C(CH2)(CH2OH)2, meta-carborane C2B 10 H 12 , 1-cyanoadamantane C 11 H 15 , adamantanone C 10 H 14 O, and pentachloronitrobenzene C6C l5 NO2; after being treated in step (1), the crystal material sample can be in a plastic crystal phase state.

3. Application of the method for realizing pressure sensing based on the pressure response of glass crystals in security alarm technology according to claim 2, characterized in that: When the crystal material sample in step (1) is selected as 2-amino-2-methyl-1,3-propanediol, after being processed by steps (1)-(2), it is in a supercooled plastic crystal state at room temperature and its color is transparent. In this state, the light transmittance for light with a wavelength range of 200 nm - 800 nm is above 95%.

4. Application of the method for realizing pressure sensing based on the pressure response of glass crystals in security alarm technology according to claim 3, characterized in that: In step (3), when the supercooled plastic crystal state of 2-amino-2-methyl-1,3-propanediol is punctured, it will rapidly undergo a phase transition from the supercooled plastic crystal phase to an ordered crystal; at this time, the color of the ordered crystal appears white and opaque, and the light transmittance for light with a wavelength range of 200 nm - 800 nm drops below 10%.

5. Application of the method for realizing pressure sensing based on the pressure response of glass crystals in security alarm technology according to claim 1, characterized in that: In step (3), the way of applying pressure is to apply isostatic pressure or needle-punching pressure.

6. The application according to claim 1, wherein: The protected article is a cultural relic in a cultural relic exhibition cabinet in a museum or a jewelry item in a jewelry exhibition cabinet in a shopping mall.

7. Application of a method for realizing pressure sensing based on the pressure response of glass crystals in color-changing glass, characterized in that: The method for realizing pressure sensing based on the pressure response of a glass crystal includes the following steps: (1) Heat the crystal material sample to a temperature above the phase transition temperature point to make it in a high-temperature plastic crystal phase state; (2) Quench the sample in the high-temperature plastic crystal phase state rapidly to make its temperature lower than the phase transition temperature to obtain a glass crystal or a supercooled plastic crystal; (3) When an external pressure is applied to the glass crystal or the supercooled plastic crystal, it will undergo a phase transition to a crystal. The appearance of the crystal is opaque white, with a low light transmittance and a small conductivity. Therefore, according to the changes in its optical and / or electrical properties, the response and feedback to the pressure action can be realized, and the purpose of pressure sensing can be achieved; Fill the crystal material sample in the gap between the double-layer glasses. Through the temperature control device integrated on the periphery of the glass, heat the crystal material sample according to steps (1)-(2) and rapidly cool it, so as to obtain a supercooled plastic crystal phase. At this time, due to the transparent color of the supercooled plastic crystal and the light transmittance approaching 100%, the double-layer glass still remains transparent; when the glass is tapped by an external force, the supercooled plastic crystal is induced by pressure to transform into an ordered crystal phase, and at the same time, the color turns into white and opaque, achieving the purpose of color change and light impermeability; at the same time, by using the heating and cooling process of the temperature control device and applying tapping pressure, the double-layer glass can be repeatedly switched between transparent and opaque white.

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