Application of nickel phosphide with high sound velocity and low thermal conductivity

Abstract

The invention provides an application of a nickel phosphide material with both high sound velocity and low thermal conductivity, the material is a NiP2 single crystal, can be applied to the fields of thermal management, sound wave transmission and the like, and can be used as a substrate of a surface acoustic wave (SAW) element. The sound velocity of the NiP2 single crystal reaches up to 5763 m / s, and the NiP2 single crystal is a good acoustic conductor; meanwhile, the material has very low thermal conductivity, namely 9.7 W / mK, which is 1-2 orders of magnitude lower than that of a material with the same sound velocity, so that the material is a good thermal management material. Therefore, the invention provides the nickel phosphide with high sound velocity and low thermal conductivity, and the nickel phosphide has great research value and potential application to thermal management in the acoustic field.

Description

Technical Field

[0001] The invention relates to the field of material science, and in particular to a nickel phosphide material with high sound velocity and low thermal conductivity and application thereof. Background Art

[0002] The relationship between thermal conductivity and phonon propagation velocity has always attracted much attention in the field of materials. Single crystals have nearly ideal crystal structures, high-quality physical phases, and anisotropic properties, so they have great potential in the fields of semiconductor devices, radio frequency devices, and optical devices. In particular, single crystals with anisotropy have excellent properties along specific orientations. For example, layered materials have extremely low thermal conductivity, high-efficiency electrical transport, and excellent acoustic conductivity along the surface, which plays an important role in the preparation of devices with special properties. Heat transfer is an inherent thermophysical property of materials, among which low thermal conductivity plays an important role in the application of materials, such as thermal management of microelectronic devices, thermal insulation materials, and improvement of thermoelectric conversion efficiency in thermoelectric materials. The high sound velocity characteristic also enables the material to play an important role in phonon conduction or acoustic devices, such as SAW (Surface Acoustic Wave) devices for wireless communications, which need to conduct sound waves through the material to filter wireless signals in a specific frequency band. Therefore, the material is required to have an extremely high sound velocity to improve the response efficiency. ZnO and LiNbO are usually selected. 3 and diamond films as substrates, however, although these materials have high sound velocities, their thermal conductivity is also high, making it difficult to manage heat. Therefore, materials that have both high sound velocities and low thermal conductivity are of great research significance, especially in areas where precise control of sound wave transmission is required. However, materials with high sound velocities are often accompanied by higher thermal conductivity, which makes it impossible to effectively suppress heat conduction in some thermal management applications. For example, in microelectronic devices, thermoelectric devices, and thermal insulation systems in high-temperature environments, a material that has both high sound velocities and low thermal conductivity is needed to ensure good thermal shielding performance.

[0003] The thermal conductivity of most materials is positively correlated with their phonon velocity, and low thermal conductivity often corresponds to a lower average phonon velocity. Due to the existence of one or more scattering mechanisms such as phonon scattering, phonon disorder scattering, and phonon defect scattering in these materials, most materials have low thermal conductivity and very low sound velocity, which greatly limits the widespread application of these materials. Therefore, it is urgent to propose a material that has both high sound velocity and low thermal conductivity, which provides a new research direction for the application of a new generation of efficient thermal management devices and thermal shielding materials. Summary of the invention

[0004] The present invention aims to provide an application of a novel nickel phosphide material, which has significant application potential in the fields of thermal management, thermal shielding and phonon conduction.

[0005] The technical solution of the present invention is:

[0006] The invention discloses an application of nickel phosphide as a sound wave transmission material.

[0007] The invention discloses an application of nickel phosphide as a SAW element substrate.

[0008] Furthermore, the nickel phosphide is NiP 2 Single crystal material, sound velocity is 5104~5763m / s, thermal conductivity is 9.7W / m K.

[0009] The NiP 2 The preparation method of single crystal material is as follows: take NiP 2 Polycrystalline and tin are placed in a container and heated in a high-temperature furnace for reaction, then cooled, kept warm, separated into solid and liquid, and the solid is washed with dilute hydrochloric acid and dried to obtain NiP. 2 Single crystal.

[0010] Furthermore, the diameter of the container is 34-42 mm, preferably 38-40 mm; the heating reaction is at a temperature of 1000-1080°C, and the insulation time is 40-50 hours; the cooling process is at a cooling rate of 2-3°C / h; the insulation process is at a temperature of 500-550°C, and the insulation time is 1-2 hours; the mass concentration of the dilute hydrochloric acid is 6-15%, and the cleaning time is 2-5 hours.

[0011] Furthermore, the thermal conductivity of the material is low, and NiP 2 The thermal conductivity of the single crystal is 9.7 W / m K. As the temperature decreases, the thermal conductivity gradually increases, and when the temperature is below 50 K, the thermal conductivity suddenly decreases.

[0012] Furthermore, the sound velocity can be obtained by the following three methods. The first method is based on first principle calculation, and NiP is obtained by calculation. 2 The average phonon velocity of the crystal is 5233m / s; the second is based on the detection of energy dispersion of lattice vibration, which is tested using a large scientific device inelastic neutron scattering spectrometer, using the energy exchange between neutrons and phonons to record the relationship between the energy dispersion of phonons and the wave vector, and the average phonon velocity is obtained by calculating the dispersion slope of the Brillouin center. In this invention, the NiP 2 Neutron detection was used in the crystal, and the detected data was the dispersion curve of the single crystal. The average phonon velocity was calculated to be 5104m / s. The third method was to compare the thermal data fitting and test the NiP using the Heat capacity option in the comprehensive physical property test system (PPMS, designed by QD). 2The specific heat data of the crystal is fitted with the Debye model, and the average phonon velocity obtained is 5763m / s. The sound velocities obtained by the above methods all indicate that the material has an extremely high average phonon velocity. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram and a physical picture of a necked quartz tube;

[0014] Figure 2 NiP grown for containers of different diameters 2 Crystals;

[0015] Figure 3 For NiP 2 X-ray diffraction results of single crystals;

[0016] Figure 4 NiP is obtained based on first principles 2 The phonon spectrum and the total average sound velocity;

[0017] Figure 5 For NiP based on neutron testing 2 The phonon spectrum and the average sound velocity at the Brillouin center;

[0018] Figure 6 NiP calculated based on specific heat test 2 The speed of sound;

[0019] Figure 7 For NiP 2 Thermal conductivity curve of single crystal;

[0020] Figure 8 Schematic diagram of the SAW component structure. DETAILED DESCRIPTION

[0021] The present invention is further explained below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] Preparation of NiP 2 Single crystal

[0024] Preparation of NiP 2 The method for single crystal is the co-solvent method, and the reaction raw material is NiP 2 Polycrystalline and solvent, the solvent is metal tin, here NiP 2 Polycrystalline and metallic tin were purchased from the market, the brand is Macklin, the purity is 99%, NiP 2 The polycrystalline is a powder with a particle size of 50μm, and the metal tin is a particle with a particle size of 1-4mm. 2To reduce the resistance of crystal growth along the (100) crystal plane, quartz tubes with diameters of Φ32mm, Φ34mm, Φ36mm, Φ38mm, Φ40mm, Φ42mm and Φ44mm were prepared, and the tube mouths of the quartz tubes were heat treated. At a distance of 60-80mm from the bottom of the tube, specifically 70mm, the tube mouths were necked at high temperature, and the neck diameter was Φ6-10mm, specifically 8mm, and the length of the neck section was 40-80mm, specifically 50mm. Figure 1 As shown. Take 1.1129gNiP 2 The polycrystal and 18.8877 g of metallic tin were placed in the 7 quartz tubes described above, evacuated, and then sealed to a vacuum degree of 10 -4 Pa. Put the sealed quartz tube into the muffle furnace, first heat it up to 1080℃, the heating rate is 100℃ / h, keep it at 1080℃ for 48h, then cool it down at a cooling rate of 2℃ / h. After cooling to 500℃, keep it for 1h, turn the quartz tube upside down, and use gravity to make the liquid metal tin flow away. 2 The single crystal is bound to the bottom wall of the quartz tube, so the NiP 2 The single crystal and liquid metal tin are separated. After the quartz tube cools down to room temperature, the quartz tube is smashed and the NiP is taken out. 2 The single crystal was immersed in 8% dilute hydrochloric acid for 3 hours and then dried in a vacuum oven at 100°C. Figure 2 As shown, for NiP 2 The single crystal was characterized on a smartlab small XRD diffractometer, and the obtained diffraction spectrum is as follows Figure 3 As shown, Figure 3 The diffraction pattern only shows the NiP prepared in the Φ32mm quartz tube 2 The results of single crystal are the same as those of other crystals and will not be repeated here. 2 The single crystal grows along the (100) crystal plane. The single crystal diffraction peak is steep and the half-height width is small, indicating that the quality of the single crystal is very good. When the container diameter is Φ32mm, the crystal size is 3mm×13mm×1mm; when the container diameter is Φ34mm, the crystal size is 8mm×10mm×1mm; when the container diameter is Φ36mm, the crystal size is 9mm×14mm×0.5mm; when the container diameter is Φ38mm, the crystal size is 13mm×20mm×0.4mm; the results of the container diameters of Φ40mm and Φ42mm are similar to those of Φ38mm. When the container diameter is Φ44mm, the liquid level is too low due to insufficient raw materials, and the crystal cannot grow.

[0025] Example 2

[0026] The single crystal prepared above was taken to test the phonon velocity and thermal conductivity. The size of the tested crystal was 1 mm×1 mm×8 mm (the tested crystal was cut from the crystal prepared in a Φ34 mm quartz tube).

[0027] (1) Phonon velocity test

[0028] The speed of sound is obtained through theoretical calculation, neutron test and specific heat test.

[0029] The theoretical calculation method is based on first-principles calculation to calculate NiP 2 The relationship between the lattice vibration and the wave vector in a crystal is also called the phonon dispersion curve, such as Figure 4 As shown, the energy of the phonon is shown on the ordinate, the wave vector of the phonon is shown on the abscissa, and the three lines at the bottom are acoustic phonon dispersion curves, one longitudinal wave phonon dispersion and two transverse wave phonon dispersions. All the previous ones are optical phonon dispersions. Acoustic phonons are the carriers of heat and sound. The slope of acoustic phonon dispersion is the average sound velocity of phonons. Figure 4 The average sound speeds of longitudinal and transverse acoustic phonons are calculated, ν LA =6597m / s, ν TA1 =2558m / s and ν TA2 =2060m / s, average speed of sound ν m =2900m / s; Calculate the average sound velocity in all wave vector directions to get the total average sound velocity of 5233m / s. The total average sound velocity of the crystal determines the macroscopic ability of the crystal material to transmit sound waves.

[0030] The neutron test was conducted at the Australian Science and Technology Organisation (ANSTO). It was based on the detection of energy dispersion of lattice vibrations. The test was conducted using the large scientific facility inelastic neutron scattering spectrometer. The energy exchange between neutrons and phonons was used to record the relationship between the energy dispersion and wave vector of phonons. The average phonon velocity was obtained by calculating the dispersion slope of the Brillouin center, such as Figure 5 As shown, the average phonon velocity is calculated to be 5104 m / s.

[0031] The specific heat test is carried out by fitting comparative heat data and testing NiP using the Heat capacity option in a comprehensive physical property test system (PPMS, designed by QD). 2 The specific heat data of the crystal are fitted by the Debye model, and the average phonon velocity is 5763m / s, as shown in Figure 6 shown.

[0032] The sound velocity results obtained by the above three methods are very close, indicating that NiP 2 Single crystals have a higher sound velocity.

[0033] (2) Thermal conductivity test

[0034] The comprehensive physical property test system (PPMS) designed by QD was used for testing, the thermal transport option (TTO) was selected for testing, the four-wire method was used for wiring, and the continuous test mode was used. Figure 7 NiP shown 2 The thermal conductivity of a single crystal varies with temperature. From the figure, we can conclude that NiP 2 The thermal conductivity of a single crystal is 9.7 W / m K.

[0035] Compared with materials with similar sound speeds such as GaP (sound speed: 4110 m / s; thermal conductivity: 77 W / m K), ZnO (sound speed: 6080 m / s; thermal conductivity: 60 W / m K), Si (sound speed: 6419 m / s; thermal conductivity: 156 W / m K), AlN (sound speed: 6980 m / s; thermal conductivity: 319 W / m K), etc., NiP 2 Single crystal has high sound velocity and lower thermal conductivity. 2 Single crystals can be used in SAW (Surface Acoustic Wave) components for sound conduction and thermal management.

[0036] like Figure 8 As shown, NiP 2 Schematic diagram of crystal used in the conduction of acoustic waves and thermal management of SAW components. SAW components are used in the field of wireless communications. Radio signals are converted into surface acoustic waves through interdigital transducers. The surface acoustic waves are conducted through the crystal substrate and then converted into radio signals through the interdigital transducer at the other end. The radio signals are filtered by using the principle that the transmission speed of ultrasonic waves is lower than the propagation speed of radio. NiP 2 The crystal can be used as the crystal substrate of the SAW element to conduct surface acoustic waves, while shielding the heat flow generated by the operation of the motherboard and maintaining the thermal stability of the substrate.

[0037] NiP of the present invention 2 Single crystal materials have two advantages: (1) High acoustic velocity is the key to the conduction of surface acoustic waves on the substrate of SAW components. 2 The material has a specific speed and can be used to filter radio in a specific band; (2) NiP 2 Single crystal materials also have the property of low thermal conductivity, which prevents the heat generated by the device from being transferred to the SAW element substrate, thereby maintaining the temperature stability of the SAW element during operation. Materials with different sound velocities have different shielding capabilities for different radio bands, so the discovery of high sound velocity and low thermal conductivity materials is of great significance to the development of thermal management in the field of wireless communications.

[0038] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. Application of nickel phosphide as an acoustic wave transmission material.

2. Application of nickel phosphide as SAW element substrate.

3. The use according to claim 1 or 2, characterized in that: The nickel phosphide is a NiP2 single crystal material with a high orientation (100) crystal plane.

4. The use according to claim 3, characterized in that: The sound velocity of the NiP2 single crystal material is 5104-5763 m / s, and the thermal conductivity is 9.7 W / m K.

5. The use according to claim 3, characterized in that: The preparation method of the NiP2 single crystal material is: taking NiP2 polycrystal and tin in a container, heating and reacting in a high-temperature furnace, then cooling, heat preservation, solid-liquid separation, washing the solid with dilute hydrochloric acid, and drying to obtain the NiP2 single crystal.

6. The use according to claim 5, characterized in that: The diameter of the container is 34 to 42 mm, preferably 38 to 40 mm; the temperature of the heating reaction is 1000 to 1080°C, and the insulation time is 40 to 50 hours; the cooling process has a cooling rate of 2 to 3°C / h; the insulation process has a temperature of 500 to 550°C, and the insulation time is 1 to 2 hours; the mass concentration of the dilute hydrochloric acid is 6 to 15%, and the cleaning time is 2 to 5 hours.

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