阅读说明：本技术 一种三方晶系的RhO2晶体及其制备方法和应用 (RhO of trigonal system2Crystal, preparation method and application thereof ) 是由 吕洋洋 卢浩敏 姚淑华 陈延彬 周健 陈延峰 于 2021-07-02 设计创作，主要内容包括：本发明公开了一种RhO-(2)晶体,所述RhO-(2)晶体属于三方晶系,空间群为(No.164),其晶格常数为该晶体显示新颖的输运性质及磁性,即在高温下表现为金属行为,在100-150K出现金属绝缘体转变,低于该温度表现绝缘体行为,同时在2-300K时,沿(001)晶面方向呈现反铁磁性。分析表明,该金属绝缘体转变是由电子关联和自旋轨道耦合共同导致的一种Mott(莫特)转变,即该结构的RhO-(2)是一种莫特绝缘体。(The invention discloses a RhO 2 Crystal of said RhO 2 The crystal belongs to a trigonal system and the space group is (No.164) having a lattice constant of The crystal shows novel transport properties and magnetism, namely, the crystal shows metal behavior at high temperature, metal insulator transition occurs at 100-150K, insulator behavior is shown below the temperature, and meanwhile, the crystal shows antiferromagnetic property along the (001) crystal plane direction at 2-300K. Analysis shows that the metal-insulator transition is a Mott transition caused by electron association and spin-orbit coupling, i.e., the RhO of the structure 2 Is a mott insulator.)

1. RhO₂Crystal, characterized in that said RhO₂The crystal belongs to a trigonal system and the space group isHaving a lattice constant of

2. The crystal according to claim 1, wherein the crystal exhibits metallic behavior at high temperature, metallic insulator transition at 100-150K, insulator behavior below that temperature, and antiferromagnetic behavior along (001) plane direction at 2-300K.

3. The crystal of claim 1, wherein the formula is according to Mott's hopping conductance theory: ρ (T) ═ Aexp (1/T)^1/4) Where ρ (T) is the resistivity at temperature T and A is a constant; t is temperature (in K);

according to Mott jump conductance theory, resistance temperature dependence test analysis shows that the metal-insulator transition of the crystal is a Mott transition caused by electron association and spin-orbit coupling, namely the RhO₂The crystal is a mott insulator.

4. The crystal of claim 1, wherein the RhO is₂The crystal is a single crystal, and the RhO is₂The size of at least one dimension of the single crystal is in the order of millimeters.

Preferably, the RhO₂The size of the single crystal in at least one dimension is 1mm or more, preferably 1 to 4 mm.

5. The crystal according to claim 1, wherein the single crystal is flaky and yellowish, has a sharp XRD diffraction peak and a narrow half-value width, and has excellent single crystal quality.

6. The crystal according to any one of claims 1 to 5, wherein said RhO₂The crystals have an EDS spectrum substantially as shown in figure 1b, or figure 2b, or figure 3 b.

Preferably, the RhO₂The crystal has an XRD pattern substantially as shown in figure 1c, or figure 2c, or figure 3 c.

7. The RhO of any one of claims 1-6₂The preparation method of the crystal is characterized by comprising the following steps: a is to be_xRhO₂Preparation of RhO by heating in deionized water₂A crystal;

wherein A is selected from one of K, Rb and Cs; x is selected from a number between 0.2 and 0.9, preferably between 0.4 and 0.8.

Preferably, a is Cs.

8. The crystal of claim 1, wherein a is_xRhO₂The mass volume ratio of the deionized water to the deionized water is 30-100mg/L, and preferably 50 mg/L.

9. Crystal according to claim 1, characterized in that the heating temperature is 30-100 ℃, preferably 60-90 ℃.

10. The RhO of any one of claims 1 to 9₂Use of a crystal, characterized by application in electronic components, preferably for temperature-sensitive sensors or switches;

preferably, the method is applied to electronic elements with low energy consumption and electronic logic elements.

Technical Field

The invention belongs to the technical field of new materials and crystal growth, and particularly relates to a trigonal RhO₂Crystals and a preparation method and application thereof.

Background

4d and 5d transition metal oxide materials have been the focus of research in both basic and applied sciences due to their unique electronic properties. For example, MoO₂Exhibit a giant magnetoresistive effect (q.chen, z.f.lou, et al, phys.rev.b 102,165133 (2020); ReO₂Is a novel topological material (s.s.wang, y.liu, et al., nat. commun.8,1844 (2017)); RuO₂Not only is a nodal-line topological semi-metallic material with a surface state characterized by flat bands, but also exhibits anomalous antiferromagnetic properties (v.jovic, r.j.koch, s.k.panda, et al, phys.rev.b 98,241101(R) (2018.; z.h.zhu, j.strempfer, et al, phys.rev.lett.122,017202 (2019)); IrO₂Has strong spin-orbit coupling effect (J.N.Nelson, J.P.Ruf, et al., Phys.Rev.materials.3,064205 (2019)); HfO₂Flat polar bands in the film induce robust independently reversible dipoles that make them ferroelectric (h.j.lee, m.lee, et al., science.369,1343-1347 (2020)). These properties are of great significance for the development of research fields such as topological physics, associative electronics, spintronics, etc. Due to special electronic properties, 4d and 5d transition metal oxides have great application potential in the aspects of catalysts, energy storage and the like. In addition, its unique physical properties provide more possibilities for developing new generations of functional devices.

The structure of the material is closely related to the performance of the material, and the function and application of the material are determined. Studies have reported that the properties of 4d and 5d transition metal oxides having the same chemical formula but different structures also show great differences. By PtO₂For example, experimental studies show that PtO₂Having three phases, i.e. alpha-phase, beta-phaseBeta' phase; in which PtO of alpha-phase and beta-phase₂Show high-efficiency catalytic performance and respectively have hexagonal CdI₂Structure and orthogonal CaCl₂Structure (r.kim, b.j.yang, et al, phys.chem.chem.phys.8,1566-1574 (2006)); PtO of beta' phase₂Has a tetragonal rutile structure, but is a dirac semimetal (r.kim, b.j.yang, et al, phys.rev.b 99,045130 (2019)).

RhO₂Is a 4d transition metal oxide having a rutile structure (tetragonal system) and a space group P4₂At nm, are used primarily as electrocatalysts (V.Sch. nemann, B.Adelman, et al, Catalysis Letters 27,259-265 (1994)).

The invention discovers a new structure of RhO₂Single crystal, RhO of this new structure₂The discovery of the crystal has important research and application values in the aspects of associated physics, spintronics, high-temperature superconducting exploration and the like, can promote the development of basic disciplines, and can be used for developing new-generation functional devices, such as temperature-sensitive sensors or switches, low-energy-consumption electronic elements, novel electronic logic elements and the like.

Disclosure of Invention

The invention aims to provide a trigonal RhO₂Crystal and high-temperature aqueous solution method-based preparation of trigonal RhO₂Method for preparing RhO crystals by adjusting solution temperature and preparation time₂And (4) crystals.

The technical scheme of the invention is as follows:

RhO₂Crystal of said RhO₂The crystal belongs to a trigonal system and the space group isIts lattice constant

According to the invention, the crystal shows a metallic behavior at high temperature, a metal insulator transition occurs at 100-150K, an insulator behavior is shown below the temperature, and an antiferromagnetic property is shown along the (001) crystal plane direction at 2-300K.

According to the Mott jump conductance theory, the formula is as follows: ρ (T) ═ Aexp (1/T)^1/4) Where ρ (T) is the resistivity at temperature T and A is a constant; t is temperature (in K);

according to Mott jump conductance theory, resistance temperature dependence test analysis shows that the metal-insulator transition of the crystal is a Mott transition caused by electron association and spin-orbit coupling, namely the RhO₂The crystal is a mott insulator.

According to the invention, the RhO₂The crystal is a single crystal, and the RhO is₂The size of at least one dimension of the single crystal is in the order of millimeters.

According to the invention, the RhO₂The size of the single crystal in at least one dimension is 1mm or more, preferably 1 to 4mm, for example, 1.0mm, 1.5mm, 1.8mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0 mm.

According to the invention, the single crystal is flaky and light yellow, and has sharp XRD diffraction peak, narrow half-peak width and excellent single crystal quality.

According to the invention, the RhO₂The crystals have an EDS spectrum substantially as shown in figure 1b, or figure 2b, or figure 3 b.

According to the invention, the RhO₂The crystal has an XRD pattern substantially as shown in figure 1c, or figure 2c, or figure 3 c.

The invention also provides the RhO₂The preparation method of the crystal comprises the following steps:

by using a high-temperature aqueous solution method, mixing A_xRhO₂Preparation of RhO by heating in deionized water₂A crystal; wherein A is selected from one of K, Rb and Cs; x is selected from a number between 0.2 and 0.9, preferably between 0.4 and 0.8.

Wherein, A is_xRhO₂Is prepared by methods customary in the art, for example by the paper S.H.Yao et al, Structure and physical properties of K_0.63RhO₂ single crystals,AIP Advances 2,042140(2012)(DOI: 10.1063/1.4767464).

According to the invention, A is preferably Cs; x is a decimal number, for example, x is 0.2, 0.63, 0.5, 0.72, 0.8, 0.85, 0.9.

According to the invention, A is_xRhO₂The mass volume ratio of the deionized water to the deionized water is 30-100mg/L, and preferably 50 mg/L.

According to the invention, the heating temperature is 30-100 ℃, preferably 60-90 ℃, for example, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃; the heating time is 0.5h to 10h, and may be, for example, 0.5h, 1h, 2h, 4h, 5h, 7h, 8h, 9h, or 10 h.

The invention also provides the RhO₂The application of the single crystal is applied to electronic components, preferably a temperature-sensitive sensor or a switch; or in low power consumption electronic components and electronic logic components.

Compared with the prior art, the invention has the advantages that:

(1) RhO of the invention₂The crystal has a new structure which has never been reported before, namely in a trigonal system, the space group of the crystal isLattice constantThe crystal shows novel transport properties and magnetism, namely, the crystal shows metal behavior at high temperature, metal insulator transition occurs at 100-150K, insulator behavior is shown below the temperature, and meanwhile, the crystal shows antiferromagnetic property along the (001) crystal plane direction at 2-300K. Theoretical fitting analysis shows that the metal-insulator transition is a Mott transition caused by electron correlation and spin-orbit coupling, namely RhO of a new structure₂Is a mott insulator.

(2) RhO of the invention₂The size of the single crystal reaches the millimeter level, and the single crystal has high crystal quality.

(3) RhO of the invention₂The preparation method of the high-temperature solution of the crystal has simple device and easy operationAnd the like.

(4) The RhO₂As a mott insulator material, the crystal has important research value in the aspects of relevant physics, spintronics, high-temperature superconducting exploration and the like on one hand, can promote the development of basic subjects, and on the other hand, the crystal can also be used for developing new-generation functional devices, such as temperature-sensitive sensors or switches, low-energy-consumption electronic elements and novel electronic logic elements.

Drawings

FIG. 1 shows RhO prepared in example 1 of the present invention₂Optical photograph of single crystal; (b) an EDS map; (c) an XRD spectrum; (d) resistance temperature dependence curve.

FIG. 2 shows RhO prepared in example 2 of the present invention₂Optical photograph of single crystal; (b) an EDS map; (c) an XRD spectrum; (d) resistance temperature dependence curve.

FIG. 3 shows RhO prepared in example 3 of the present invention₂Optical photograph of single crystal; (b) an EDS map; (c) an XRD spectrum; (d) resistance temperature dependence curve.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

In the experiment, water is adopted as high-purity deionized water, and a precursor A_xRhO₂(A. K, Rb, Cs) can be prepared by a person skilled in the art according to the prior art, see for example the paper S.H. Yao et al, Structure and physical properties of K_0.63RhO₂ single crystals,AIP Advances 2,042140(2012)(DOI：10.1063/1.4767464)。

Example 1

By high temperature solution method with Cs_0.5RhO₂Preparation of RhO by using single crystal as precursor₂Crystal

5mg of Cs are taken_0.5RhO₂The crystal is put into a beaker, 100ml of deionized water is poured into the beaker, the beaker is put into a heat collection type constant temperature heating magnetic stirrer, the heating temperature is set to be 60 ℃, and after 1 hour, the millimeter-scale new structure RhO with smooth surface and luster can be obtained₂The single crystal, which has a maximum size of about 3mm, is shown in FIG. 1(a) as an optical photograph.

As shown in FIG. 1(b), X-ray energy spectrum analysis (EDS) tests revealed that the above-mentioned crystals contained only Rh and O elements; as shown in fig. 1(c), according to the X-ray diffraction (XRD) test result, the diffraction peak is sharp and the half-peak width is narrow, indicating that the above-prepared substance is a single crystal; all diffraction peaks were (00l) peaks, indicating that the sample grew along the ab-plane and no hetero-peaks were present. As shown in fig. 1(d), the resistivity of the above crystal at 2 to 300K was measured by a comprehensive Physical Property Measurement System (PPMS), and the result showed that the transport property of the above crystal exhibited an insulator behavior. The fitting result in the upper right corner of FIG. 1(d) shows that the RhO₂Is a mott insulator.

Example 2

By high temperature solution method with Cs_0.5RhO₂Preparation of RhO by using single crystal as precursor₂Crystal

5mg of Cs are taken_0.5RhO₂The crystal is put into a beaker, 100ml of deionized water is poured into the beaker, the beaker is put into a heat collection type constant temperature heating magnetic stirrer, the heating temperature is set to be 90 ℃, and after 1 hour, the new structure RhO with millimeter level, smooth surface and luster can be obtained₂The single crystal, which had a maximum size of about 3mm, was optically photographed as shown in FIG. 2 (a).

As shown in FIG. 2(b), X-ray energy spectrum analysis (EDS) tests revealed that the above-mentioned crystal contained only Rh and O elements. As shown in fig. 2(c), according to the X-ray diffraction (XRD) test result, the diffraction peak is sharp and the half-peak width is narrow, indicating that the above-prepared substance is a single crystal; all diffraction peaks were (00l) peaks, indicating that the sample grew along the ab-plane and no hetero-peaks were present. As shown in FIG. 2(d), the resistivity of the crystal at 2 to 300K was measured by a comprehensive Physical Properties Measuring System (PPMS), and the results showed that the crystal had transport propertiesThe material exhibits insulator behavior. The fitting result in the upper right corner of FIG. 2(d) shows that the RhO₂Is a mott insulator.

Example 3

By high temperature solution method with Cs_0.5RhO₂Preparation of RhO by using single crystal as precursor₂Crystal

5mg of Cs are taken_0.5RhO₂The crystal is put into a beaker, 100ml of deionized water is poured into the beaker, the beaker is put into a heat collection type constant temperature heating magnetic stirrer, the heating temperature is set to be 60 ℃, and after 2 hours, the new structure RhO with millimeter level, smooth surface and luster can be obtained₂The single crystal, which had a maximum size of about 4mm, was optically photographed as shown in FIG. 3 (a).

As shown in FIG. 3(b), X-ray energy spectrum analysis (EDS) tests revealed that the above-mentioned crystal contained only Rh and O elements. As shown in fig. 3(c), according to the X-ray diffraction (XRD) test result, the diffraction peak is sharp and the half-peak width is narrow, indicating that the above-prepared substance is a single crystal; all diffraction peaks were (00l) peaks, indicating that the sample grew along the ab-plane and no hetero-peaks were present. As shown in fig. 3(d), the resistivity of the above crystal at 2 to 300K was measured by a comprehensive Physical Property Measurement System (PPMS), and the result showed that the transport property of the above crystal exhibited an insulator behavior. The fitting result in the upper right corner of FIG. 3(d) shows that the RhO₂Is a mott insulator.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.