Ni-doped Cu2S phase change material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of phase change materials, in particular to a Ni-doped Cu2S phase change material and a preparation method and application thereof. The Ni-doped Cu2S phase-change material provided by the invention can generate structural phase change in a temperature interval of 98-102 DEG C, the resistivity of the material after the structural phase change is suddenly increased, and the temperature sensor designed by using the principle can effectively reduce the cost of the traditional temperature sensor. Besides, due to the fact that Ni-doped Cu2S enables a crystal structure to generate weak disorder, carrier concentration of the material can be reduced according to Mott and Anderson theories, resistance of the phase-change material is increased so as to improve heat sensitivity of the Ni-doped Cu2S phase-change material, the Ni-doped Cu2S phase-change material has extremely high sensitivity, and an error between a front phase change point and a rear phase change point does not exceed 1 DEG C; the technical problem that a pure cuprous sulfide phase change material is poor in heat sensitivity is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change materials, and particularly relates to a Ni-doped Cu2S phase change material, a preparation method thereof, and an application thereof. Background Art

[0002] Temperature alarm devices have been widely used in residential life, industrial production, and science and technology military industry. Its principle is to utilize the temperature perception ability of materials, such as resistance, infrared thermal radiation, etc., and convert it into forms such as light and sound for temperature early warning, timely reminding people to discover potential safety hazards.

[0003] Traditional temperature alarm devices mainly use linear temperature sensors, such as PT100. The sensitivity of this type of thermometer and the thermal sensitivity of the temperature alarm device are both poor. To solve the deficiencies of traditional linear temperature sensors, various phase change materials such as copper sulfide phase change materials have emerged on the market. However, for scenarios that require rapid early warning, such as fire monitoring, pure copper sulfide phase change materials still cannot respond quickly. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a Ni-doped Cu2S phase change material, a preparation method thereof, and an application thereof, solving the technical problem of poor thermal sensitivity of pure copper sulfide phase change materials.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a Ni-doped Cu2S phase change material, and the chemical formula of the Ni-doped Cu2S phase change material is Cu 2-x Ni x S, where 0.02 ≤ x ≤ 0.2. The crystal phase transition temperature of the Ni-doped Cu2S phase change material is 98 °C to 102 °C. Before the phase transition, it is monoclinic, and the space group belongs to P21 / c. After the phase transition, it is hexagonal, and the space group belongs to P63 / mmc.

[0006] The present invention provides a preparation method of the above-mentioned Ni-doped Cu2S phase change material, including the following steps: Weigh Cu powder, Ni powder, and S powder as raw materials in a molar ratio of 2 - x : x : 1, mix and grind them evenly. After fixing the shape, under a protective atmosphere, through calcination treatment and annealing treatment, Cu 2-x Ni x S is prepared; where 0.02 ≤ x ≤ 0.2.

[0007] Optionally, the reaction temperature of the calcination treatment is 1000 °C to 1200 °C.

[0008] Optionally, the cooling rate of the annealing treatment is 8 °C / h to 12 °C / h, and the annealing temperature is 500 °C.

[0009] Optionally, the forming pressure of the fixed forming is 6 Mpa to 8 Mpa. In the actual crystal preparation process, if pressing is not carried out, the crystal forming presents as a powdery compound. Although it is the phase of Cu2S after XRD testing, the increase in resistivity, that is, the phase change characteristic, is inhibited. This situation will not occur after pressing forming.

[0010] The present invention provides an application of the above-mentioned Ni-doped Cu2S phase change material in the preparation of a thermistor.

[0011] Optionally, the thermistor includes a Ni-doped Cu2S phase change material and a protective coating that completely coats the Ni-doped Cu2S phase change material.

[0012] The present invention provides an application of the above-mentioned thermistor in the preparation of a temperature sensor.

[0013] Optionally, the temperature sensor includes the above-mentioned thermistor, an alarm device, a protective resistor, a piezoelectric buzzer, and a power source. The protective resistor is connected in parallel with the thermistor to form a temperature measurement device, where the protective resistor plays a role in shunting, and the temperature measurement device is connected in series with the alarm device, the piezoelectric buzzer, and the power source.

[0014] Compared with the prior art, the beneficial effects of the present invention are that the Ni-doped Cu2S phase change material provided by the present invention will undergo a structural phase change in the temperature range of 98 °C to 102 °C. The resistivity of the material after the structural phase change increases sharply. The temperature sensor designed using this principle can effectively reduce the cost of traditional temperature sensors. In addition, since Ni doping in Cu2S will cause weak disorder in the crystal structure, according to the Mott and Anderson theories, the carrier concentration of the material will decrease, increasing the resistance of the phase change material to improve the thermosensitive performance of the Ni-doped Cu2S phase change material, making it have extremely high sensitivity, and the error between the front and back phase change points does not exceed 1 °C, solving the technical problem of poor thermosensitivity of the pure copper sulfide phase change material. Description of the Drawings

[0015] Figure 1 It is the XRD diagram of the Ni-doped Cu2S phase change material prepared in Examples 1 to 3 of the present invention.

[0016] Figure 2 It is the scanning electron microscope diagram of the Ni-doped Cu2S phase change material prepared in Example 2 of the present invention. Among them, a is the scanning electron microscope diagram, and b is the elemental analysis diagram of the area boxed in Figure a.

[0017] Figure 3SEM image of the Ni-doped Cu2S phase change material prepared in Example 3 of the present invention. Among them, a is the SEM image, and b is the elemental analysis diagram of the framed area in Figure a.

[0018] Figure 4 Resistance diagram of the Ni-doped Cu2S phase change material prepared in Examples 1 to 3 of the present invention.

[0019] Figure 5 Schematic structural diagram of a thermistor provided by the present invention.

[0020] Figure 6 Schematic circuit diagram of a temperature sensor provided by the present invention. Detailed implementation manners

[0021] To solve the above technical problems, the present invention provides a Ni-doped Cu2S phase change material, its preparation method and application. Now, the technical solutions and embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0022] The technical solutions adopted by the present invention are as follows: The present invention provides a Ni-doped Cu2S phase change material. The chemical formula of the Ni-doped Cu2S phase change material is Cu 2-x Ni x S, where 0.02 ≤ x ≤ 0.2. The Ni-doped Cu2S phase change material is in the monoclinic system at temperatures below 100 °C, and its space group belongs to P21 / c. After the phase change, it becomes the hexagonal system, and its space group belongs to P63 / mmc.

[0023] The Ni-doped Cu2S phase change material provided by the present invention undergoes a structural phase change at around 100 °C, and the resistivity of the material increases sharply after the structural phase change. The temperature alarm designed using this principle can effectively reduce the cost of traditional temperature sensors. In addition, due to the physical properties of the phase change material itself, it has extremely high sensitivity, and the error between the front and back phase change points does not exceed 1 °C.

[0024] The present invention provides a synthesis method for the Ni-doped Cu2S phase change material used in the above solution, including the following steps: Mix Ni powder, Cu powder, and S powder evenly and then grind them to prepare the reactants. Dope Ni powder into Cu 2-x Ni x S according to the stoichiometric ratio. Place the reactants under a pressure mold and fix them into a 6 mm diameter sheet at 6 Mpa to 8 Mpa.

[0025] Optionally, the above reactants are all made of a mixture of high-purity granular powders.

[0026] Optionally, the sheet formed by shaping the above reactants needs to be placed in a quartz tube sealed with a small amount of argon.

[0027] Optionally, the above-mentioned sealed product needs to be calcined in a muffle furnace at 1000 °C to 1200 °C.

[0028] Optionally, the calcination time is generally controlled within 20 h to 50 h.

[0029] Optionally, after the calcination is completed, the cooling rate is generally controlled at 8 °C / h to 12 °C / h.

[0030] Optionally, the calcination annealing temperature can be selected around 500 °C.

[0031] The present invention will be described in detail below through specific embodiments. The embodiments are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0032] Example 1 This example provides a preparation method of a Ni-doped Cu2S phase change material, including the following steps: Weigh 0.7907 grams of Cu powder with a purity of 99.9%, 0.2019 grams of S powder, and 0.0074 grams of Ni powder.

[0033] Mix the Cu powder, S powder and Ni powder and grind them evenly in a mortar, and then place them in a tablet press mold to fix and form them under a pressure of 6 Mpa to 8 Mpa.

[0034] Put the fixed and formed sample into a corundum crucible, then put it into a quartz tube, evacuate it to a high vacuum mode, add a small amount of argon and seal it.

[0035] Fire at a high temperature of 1100 °C, keep it warm for 30 hours, and then cool it to 500 °C in 80 hours to obtain Cu2S crystals. The chemical formula of the prepared Ni-doped Cu2S phase change material is Cu 1.98 Ni 0.02 S.

[0036] Example 2 The difference compared with Example 1 is that 0.7606 grams of Cu powder with a purity of 99.9%, 0.2024 grams of S powder, and 0.0370 grams of Ni powder are weighed, and the chemical formula of the product is Cu 1.9 Ni 0.1 S.

[0037] Example 3 The difference compared with Example 1 is that 0.7228 grams of Cu powder with a purity of 99.9%, 0.2030 grams of S powder, and 0.0742 grams of Ni powder are weighed, and the chemical formula of the product is Cu 1.8 Ni 0.2 S.

[0038] (1) The Ni-doped Cu2S phase change materials prepared in Examples 1 to 3 were characterized by XRD, and the results are shown in Figure 1 . It can be seen from Figure 1 that the diffraction peaks of the materials conform to the standard peaks of Cu2S. As the Ni content increases, the intensity of some diffraction peaks changes, and at the same time, the diffraction peak angle shifts slightly to the left, indicating that Ni doping in the material replaces a small number of Cu atoms.

[0039] (2) The Ni-doped Cu2S phase change materials prepared in Examples 2 and 3 were characterized by EDX, and the results are shown in Figure 2 and Figure 3 . It can be known from Figure 2 and Figure 3 that the Ni content of the Cu2S phase change material basically conforms to the doping ratio.

[0040] Application Example 1 Based on the chemical formula Cu 1.98 Ni 0.02 S of the Ni-doped Cu2S phase change material in Example 1, a thermistor was prepared, including a Cu 1.98 Ni 0.02 S crystal block, electrodes, leads and a protective coating, as shown in Figure 5 . Among them, 1 is a Cu 1.98 Ni 0.02 S crystal block, 2 is a protective coating, 3a and 3b are electrodes, and 4a and 4b are leads.

[0041] The specific preparation method is as follows: The prepared Cu 1.98 Ni 0.02 S crystal block was used as the temperature sensor main body, and three leads were connected to the material using silver paste. The lead material was 0.08 mm copper wire.

[0042] After the silver paste dried, the copper sulfide single crystal block was encapsulated using black glue as the protective coating. The black glue was Loctite Stycast 2850FT.

[0043] Application Example 2 The difference compared with Application Example 1 is that only the Ni-doped Cu2S phase change material was replaced with Cu 1.9 Ni 0.1 S.

[0044] Application Example 3 The difference compared with Application Example 1 is that only the Ni-doped Cu2S phase change material was replaced with Cu 1.8 Ni 0.2 S.

[0045] (3) Comparing the temperature sensors prepared from the Cu2S phase change materials doped with different Ni contents in Examples 1 to 3, the electrical resistance behavior of the materials is shown in Figure 4 It can be seen that as the doping concentration increases, the thermosensitive properties of the materials gradually change. Among them, the thermosensitive properties of the Ni-doped Cu2S phase change material prepared in Example 3 are better than those of the Ni-doped Cu2S phase change materials prepared in Examples 1 to 2 with lower doping contents, and the degree of resistance transition of the Ni-doped Cu2S phase change materials prepared in Examples 1 to 2 is also weaker than that of the Ni-doped Cu2S phase change material prepared in Example 3.

[0046] Figure 6 A circuit schematic diagram of a temperature sensor is provided. Figure 6 The shown temperature sensor is composed of a thermistor prepared from a Ni-doped high-thermosensitive Cu2S phase change material, a protection resistor, an alarm device, a piezoelectric buzzer, and a power supply. The protection resistor is connected in parallel with the thermistor to form a temperature measurement device, where the protection resistor plays a role in shunting. The temperature measurement device is connected in series with the alarm device, the piezoelectric buzzer, and the power supply. Since the change in temperature will cause the resistivity of the Ni-doped Cu2S phase change material to change, thereby controlling the working state of the circuit to achieve the function of temperature alarm.

[0047] Effect experiment First, a fire simulation is carried out, and the actual simulation is carried out under oil bath conditions.

[0048] When the temperature rises, the resistivity of the material will change. The actual test is carried out using a multimeter. When the temperature is higher than about 100 °C, the resistivity of the material will jump, corresponding to the Figure 4 image in. Among them, the image change of the Ni-doped Cu2S phase change material prepared in Example 3 is the most obvious. The results of repeated tests show that the sudden change in the resistivity of the Ni-doped Cu2S phase change material is near the phase transition point of 100 °C, with excellent accuracy. In addition, due to the reversible phase change of the material during phase change, it can be reused in actual use.

[0049] In the present invention, on the basis of a temperature sensor, the material of a traditional thermistor, such as a PT100 material, is replaced with the Ni-doped Cu2S phase change material provided by the present invention, which has a high response rate and far higher accuracy than that of a general material temperature sensor.

[0050] The above-described are only the preferred embodiments of the present invention, and the above specific embodiments are not limitations to the present invention. Various deformations and modifications can occur within the scope of the technical idea of the present invention. Any retouching, modification, or equivalent replacement made by those of ordinary skill in the art according to the above description shall fall within the scope protected by the present invention.

Claims

1. A Ni-doped Cu2S phase change material, characterized in that, The chemical formula of the Ni-doped Cu2S phase change material is Cu 2-x Ni x S, where 0.02 ≤ x ≤ 0.2; The crystal phase transition temperature of the Ni-doped Cu2S phase change material is 98 °C to 102 °C. Before the phase transition, it is in the monoclinic system with the space group belonging to P21 / c, and after the phase transition, it is in the hexagonal system with the space group belonging to P63 / mmc.

2. A method for preparing the Ni-doped Cu2S phase change material according to claim 1, characterized in that, It includes the following steps: Weigh Cu powder, Ni powder and S powder as raw materials in a ratio of (2 - x):x:1, mix and grind them evenly. After fixing and forming, under a protective atmosphere, through calcination treatment and annealing treatment, Cu 2-x Ni x S is obtained; Among them, 0.02 ≤ x ≤ 0.

2.

3. The preparation method of the Ni-doped Cu2S phase change material according to claim 2, characterized in that, The reaction temperature of the calcination treatment is 1000 °C to 1200 °C.

4. The preparation method of the Ni-doped Cu2S phase change material according to claim 2, characterized in that, The cooling rate of the annealing treatment is 8 °C / h to 12 °C / h, and the annealing temperature is 500 °C.

5. The preparation method of the Ni-doped Cu2S phase change material according to claim 2, wherein, The forming pressure of the fixed forming is 6 Mpa to 8 Mpa.

6. Application of the Ni-doped Cu2S phase change material according to claim 1 in the preparation of a thermistor.

7. The application according to claim 6, characterized in that, The thermistor includes a Ni-doped Cu2S phase change material and a protective coating that completely coats the Ni-doped Cu2S phase change material.

8. Application of the thermistor according to claim 7 in the preparation of a temperature sensor.

9. The application according to claim 8, wherein The temperature sensor includes the thermistor according to claim 7, an alarm device, a protective resistor, a piezoelectric buzzer, and a power supply; The protective resistor is connected in parallel with the thermistor to form a temperature measuring device, where the protective resistor plays a role in shunting, and the temperature measuring device is connected in series with the alarm device, the piezoelectric buzzer, and the power supply.

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