JP2015127280A - Phosphorus compound and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new phosphorus compound useful also for an application as a nonsuperconductor portion of a superconductor-nonsuperconductor junction.SOLUTION: The phosphorus compound has a PbFCl type crystal structure, and a chemical composition represented by the formula APX, where A is one or more elements selected from group 1 elements, group 2 elements, group 3 elements, group 4 elements, group 5 elements and group 6 elements, and X is one or more elements selected from group 14 elements, group 15 elements and group 16 elements, excluding the combination of A=Zr and X=S.

Description

  The present invention relates to phosphorus compounds and uses thereof.

So far, phosphide-based intermetallic compound superconductors MoRuP (superconducting transition temperature T _c = 15K) and ZrRuP (T _c = 13K) having a PbFCl type crystal structure have been reported (Non-Patent Document 1 and 2).

Further, ZrP _1.4 S _0.6, which is a phosphorus compound different from the phosphide-based intermetallic superconductor, has been reported to have a PbFCl type crystal structure (see Non-Patent Document 3). ).

Ichimin Shirotani, et. al. , “Superconductivity and crystal structure of ZrRu1-xRhxP allotted pre-prepared at high pressure”, Journal of Physics, 3rd. I. Shirotani, M .; Takaya, I .; Kaneko, C.I. Sekine, T .; Yagi, “Superconductivity of MRuP and MNiP (M = Moor W) prepared at high pressure”, Solid State Communications 116 (2000) 683-686. Andrew Schlechte, Katrin Meier, Rainer Niewa, Yurii Prots, Marcus Schmidt and Rudiger Knipe, “Crystal structure of zirconium phsph. Kristallogr. NCS 224 (2009) 375-376.

  The above-described phosphide-based intermetallic compound superconductors represented by MoRuP and ZrRuP have an orthorhombic crystal structure. It is known that the lattice constant of these phosphide-based intermetallic compound superconductors and, for example, the lattice constant of MgO single crystals vary greatly. Therefore, it is difficult to form the phosphide-based intermetallic compound superconductor on a single crystal substrate such as MgO.

  Therefore, although there are reports on the properties of MoRuP-based or ZrRuP-based intermetallic compound superconductors that have been reported so far, there is no substrate material suitable for thin-film stacking in the technology for specifically thinning this, It was difficult to form a laminate on a substrate, and there were no reports of superconducting elements using these materials. Therefore, when fabricating a superconducting device using these compounds, for example, the materials used for the non-superconductor portion in the superconducting-nonsuperconducting junction found in superconducting transistors must also be considered. .

  The present invention has been made in view of the above problems, and its purpose is to provide a non-superconductor portion in a superconducting-nonsuperconductor junction found in, for example, a superconducting transistor in the production of a superconducting element. It is to provide a new phosphorus compound that is also useful when used.

  In order to solve the above problems, a phosphorus compound according to one embodiment of the present invention has a PbFCl type crystal structure and has a chemical composition of the formula APX (A = Group 1 element, Group 2 element, Group 3 element) , One or more elements selected from Group 4 elements, Group 5 elements and Group 6 elements, X = one or more elements selected from Group 14 elements, Group 15 elements and Group 16 elements) ( Provided that A = Zr and X = S are excluded).

  In order to solve the above problems, a method for manufacturing a phosphorus compound according to one embodiment of the present invention includes A, P, and X (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element) , One or more elements selected from Group 5 elements and Group 6 elements, and X = one or more elements selected from Group 14 elements, Group 15 elements and Group 16 elements). After mixing in an active gas atmosphere, the synthesis is performed at 1,000 to 2,000 ° C. under normal pressure to 5 Gpa.

  The present invention provides a new phosphorus compound that is also useful in the production of a superconducting device, for example, when used in a non-superconductor portion in a superconducting-nonsuperconductor junction found in superconducting transistors and the like.

It is a figure which shows the crystal structure of the phosphorus compound which concerns on one Embodiment of this invention. Is a diagram showing an X-ray diffraction pattern of _ZrP 1.25 _{Se 0.75} according to Example 1 of the present invention. It is a diagram illustrating a Rietveld analysis result of _ZrP 1.4 _{Se 0.6} according to Example 1 of the present invention. Is another diagram showing the Rietveld analysis results of _ZrP 1.4 _{Se 0.6} according to Example 1 of the present invention. Is a diagram showing an x dependence of the lattice constant of _{ZrP 2-x} Se _x according to a first embodiment of the present invention. The temperature dependence of the resistivity of Example _ZrP 1.25 _{Se 0.75} according to 1 of the present invention. FIG. It is a graph showing the temperature dependence of the magnetization of _ZrP 1.35 _{Se 0.65} and _ZrP 0.4 _{Se 1.40} according to a first embodiment of the present invention. _{ZrP 2-x} Se _x according to a first embodiment of the present invention, and a diagram showing the x dependency of the superconducting transition temperature of _{ZrP 2-x S x} according to the second embodiment. _ZrP 1.6 _S 0.4 according to Example 2 of the present _invention, is a diagram showing an X-ray diffraction pattern of ZrP _{1.4 S 0.6} and _{ZrP 1.25} S _0.75. Is a diagram showing an X-ray diffraction pattern of _{HfP 2-x S} x according to a third embodiment of the present invention. It is a diagram showing an x dependence of the lattice constant of _{HfP 2-x S x} according to a third embodiment of the present invention. Is a diagram showing an X-ray diffraction pattern of _{HfP 2-x} Se x according to a fourth embodiment of the present invention. Is a diagram showing an x dependence of the lattice constant of _{HfP 2-x} Se _x according to a fourth embodiment of the present invention. Is a graph showing the temperature dependence of the magnetic susceptibility of _{HfP 2-x} Se x according to a fourth embodiment of the present invention. (A) shows HfP _1.3 Se _0.7 , (b) shows HfP _1.4 Se _0.6 , (c) shows HfP _1.5 Se _0.5 , (d) shows HfP _1.6 Se _0.4 is shown, (e) shows HfP _1.7 Se _0.3 . It is a diagram showing an x dependence of the superconducting transition temperature of HfP _2-x Se _x according to a fourth embodiment of the present invention.

[Phosphorus compounds]
The phosphorus compound according to the present invention has a PbFCl type crystal structure and has a chemical composition of the formula APX (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group A One or more elements selected from Group 6 elements, X = one or more elements selected from Group 14 elements, Group 15 elements, and Group 16 elements (where A = Zr and X = (Excluding those that are S).

  The molar ratio of A, P, and X is not limited and may vary in composition due to lattice defects or the like, but is preferably 1: 1: 1. Although details will be described later in Example 1, the phosphorus compound APX according to the present invention has a PbFCl type crystal structure even when the composition ratio A: P: X deviates from the stoichiometric composition ratio of 1: 1: 1. It can be held stably.

  FIG. 1 shows a crystal structure of an example of the phosphorus compound according to the present invention. As shown in FIG. 1, the phosphorus compound of the present invention is formed by a site occupied by A (A site), a site occupied by P (P site), and a site occupied by X (X site). . In the phosphorus compound according to the present invention, the P site forms a two-dimensional square lattice. In the phosphorus compound according to the present invention, part of the X site may be substituted with P. A part of the P site may be replaced by X.

Phosphorus compound according to the present invention, the chemical composition formula _{(A 1-w A 'w} ) 1-t P 1-u (X 1-z X' z) 1-v ( where, A = Ti, Zr and Hf One or more elements selected from: A ′ is one or more elements selected from Group 1 elements, Group 2 elements, Group 3 elements, Group 4 elements, Group 5 elements and Group 6 elements or One or more elements selected from a lanthanoid element and an actinoid element, X is one or more elements selected from a Group 14 element, a Group 15 element, and a Group 16 element, and X ′ is a 14th element. One or more elements selected from group elements, group 15 elements and group 16 elements, 0 ≦ w <1, 0 ≦ z <1 (if any), 0 ≦ t <1, 0 ≦ It is more preferable that u <1, 0 ≦ v <1 (when there is a lattice defect).

The phosphorus compound represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1-z X ′ _z ) _1-v is a part of A in the phosphorus compound represented by the formula APX Is replaced with A ′, and a part of X is replaced with X ′. In other words, the phosphorus compound represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1−z X ′ _z ) _1-v is a part of the A site 2 shown in FIG. Is replaced with A ′ and a part of the X site 4 is replaced with X ′. The phosphorus compound represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1-z X ′ _z ) _1-v is similar to the phosphorus compound represented by the formula APX as PbFCl. It is considered to have a type crystal structure.

Specific examples of the phosphorus compound represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1-z X ′ _z ) _1-v include A = Zr, A ′ = Nb, (Zr _0.5 Nb _0.5 ) P (Se _0.5 Te _0.5 ) with w = 0.5, X = Se, X ′ = Te, and z = 0.5. ZrP from _2-x Se _x measurement results of X-ray diffraction pattern using _lattice constants a and c of _{ZrP 2-x} Se _x, it is found that changes linearly with respect to the substitution ratio of X atoms. From this, it is represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1−z X ′ _z ) _1-v in which A is replaced with A ′ and X is replaced with X ′. The phosphorous compound is considered to have a PbFCl type crystal structure.

  Further, it is more preferable that A is Zr and X is Se. More preferably, the A is Hf and the X is Se or S.

  Further, the phosphorus compound according to the present invention is more preferably one having a lattice constant of a = 3.5 to 3.9３ and c = 7.7 to 8.1Å.

  Further, the phosphorus compound according to the present invention more preferably exhibits a conductivity of 0.3 to 0.5 mΩ · cm at room temperature. By having such properties, the phosphorus compound according to the present invention can be used as a conductor such as a wiring. In the phosphorus compound according to the present invention, when A is Zr, X is Se, and the charged composition ratio is Zr: P: Se = 1: 1.25: 0.75, the phosphorus compound is The conductivity is 0.3 to 0.5 mΩ · cm.

  Moreover, it is more preferable that the phosphorus compound according to the present invention exhibits a metallic behavior up to a low temperature of 50K or less at room temperature. By having such properties, there is an advantage that the phosphorus compound according to the present invention can be used as a material used for a resistance thermometer. In the phosphorus compound according to the present invention, when A is Zr, X is Se, and the charged composition ratio is Zr: P: Se = 1: 1.25: 0.75, the phosphorus compound is Below, it will exhibit metallic behavior up to a low temperature of 50K.

  Moreover, it is more preferable that the phosphorus compound according to the present invention exhibits superconductivity at less than 50K. By having such a property, there exists an advantage that it can utilize for a superconducting element, for example.

  The phosphorus compound according to the present invention is more preferably nonmagnetic at 50K or more. In other words, it is more preferable that it exhibits non-magnetism in a temperature region that does not exhibit superconductivity. By having such a property, there is an advantage that it can be used for wiring for electrically connecting between superconducting elements sensitive to magnetism.

[Use as superconducting material]
It has a PbFCl type crystal structure, and its chemical composition is selected from the formula APX (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group 6 element 1 A compound represented by the above element, X = one or more elements selected from Group 14 element, Group 15 element, and Group 16 element) can be in a superconducting state. Therefore, the phosphorus compound which is the said compound and exists in a superconductive state is also the category of this invention.

  The conditions for achieving the superconducting state can be found by those skilled in the art by placing each compound in a low temperature state and lowering the temperature.

〔Production method〕
The method for producing a phosphorus compound according to the present invention is selected from A, P and X (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group 6 element) 1 or more elements, X = one or more elements selected from Group 14 element, Group 15 element and Group 16 element) are mixed in an inert gas atmosphere, and then 1,000 The synthesis is performed at a temperature of 2,000 to 2,000 ° C. under normal pressure to 5 Gpa.

Examples of the inert gas include N ₂ gas, Ar gas, CO ₂ gas, and the like.

  As a material for synthesizing a phosphorus compound (hereinafter also referred to as a starting material), a metal powder material can be suitably used. The starting material is not limited to the metal powder material, but may be a bulk metal material. In addition, when the synthesis is performed in a sealed environment that can be expressed as a reducing atmosphere, an oxide raw material can be used as a starting raw material. When an oxide material is used as a starting material, the reducing atmosphere at the time of synthesis may be appropriately adjusted according to the degree of oxidation of the starting material.

  It is preferable that the starting materials are mixed by putting A, P and X starting materials in an agate mortar and using an agate pestle in a glove box filled with an inert gas. By mixing the starting materials in an inert gas, it is possible to avoid phosphorus reacting with oxygen and burning. In addition, the mixing method of a starting material is not limited to the said method, You may mix using a giant stirrer in the room filled with the inert gas.

  The mixed materials A, P and X are synthesized in a temperature range of 1000 ° C. to 2000 ° C. and under a pressure of normal pressure to 5 GPa. As an example of the synthesis method, a high-pressure synthesis method can be used. As a high-pressure synthesizer used for the high-pressure synthesis method, for example, a general-purpose multiple anvil type 700 ton ultra-high pressure and high temperature generator (CAP-07 manufactured by Riken Kikai Co., Ltd.) may be used. Further, as another synthesis apparatus, for example, a high pressure apparatus such as a hot press may be used. The synthesis apparatus used in the method for producing a phosphorus compound according to the present invention is not particularly limited as long as the temperature and pressure of the material at the time of synthesis can be controlled to desired numerical values. In the present embodiment, description will be made assuming that CAP-07 manufactured by Riken Kikai Co., Ltd. is used as the high-pressure synthesis apparatus.

  The sample synthesis cell filled with the mixed materials A, P and X is preferably made of a material that hardly reacts with the mixed material during the synthesis of the phosphorus compound. Examples of preferred sample synthesis cells include, but are not limited to, a BN cell made of boron nitride (BN) and a C cell made of carbon (C).

  When synthesizing using the phosphorus compound according to the present invention in a high-pressure synthesis method, the temperature condition during synthesis is preferably in the range of 1000 ° C to 2000 ° C. Moreover, it is preferable that the pressure conditions at the time of a synthesis | combination are in the range of 1GPa-5GPa. The vapor pressure of phosphorus is higher than the vapor pressures of other A and X. However, by setting the pressure condition within the range of 1 GPa to 5 GPa, phosphorus deficiency is suppressed, and a phosphorus compound having a desired composition ratio Can be synthesized. Moreover, it is preferable that the holding time of the said temperature conditions and pressure conditions exists in the range of 30 minutes-3 hours, and it is preferable that the sample after a synthesis | combination is rapidly cooled.

  The above-mentioned conditions are for the case where the mixed materials are synthesized using a high-pressure synthesizer. Instead of the high-pressure synthesizer, the phosphorus compound according to the present invention can be synthesized also by heating the mixed material in a closed system typified by a closed vessel. Here, an example of the closed container is a crucible with a lid. The phosphorus compound according to the present invention can also be synthesized by using (1) a solid phase reaction method under normal pressure, or (2) a normal combustion method using a sintering aid. When using the solid-phase reaction method, the pressure condition is not limited to normal pressure, and may be under reduced pressure or under pressure. The phosphorus compound according to the present invention can also be synthesized using a sputtering method, an MO-CVD method, or the like.

〔Crystal structure〕
The phosphorus compound obtained by the above manufacturing method has a PbFCl type crystal structure shown in FIG. The lattice constant a in the a-axis direction in the phosphorus compound according to the present invention is preferably in the range of a = 3.5 to 3.9Å, and the lattice constant c in the c-axis direction is c = 7.7 to 8 It is preferable to be within the range of 1 cm. Specific methods and results of crystal structure analysis will be described later in Examples.

When a thin film layer containing a superconductor has a laminated structure, if there is a mismatch between the lattice constant of the thin film to be laminated and the lattice constant of a single crystal used for the substrate, the thin film to be laminated is distorted. The strain degrades the superconducting properties of the superconductor, such as reducing the superconducting transition temperature (hereinafter also referred to as _Tc ) of the superconductor layer to be laminated. By using the phosphorus compound according to one embodiment of the present invention as an intermediate layer disposed between the substrate and the superconductor layer, the lattice constant of the thin film to be stacked and the lattice constant of the single crystal used for the substrate are reduced. The mismatch can be reduced, and as a result, deterioration of superconducting characteristics in the superconductor layer to be stacked can be suppressed.

[Superconductivity and lattice constant]
It is considered that the superconducting property exhibited by the phosphorus compound according to the present invention depends on the inter-atomic distance between P sites forming a two-dimensional square lattice. In the phosphorus compound according to the present invention, the lattice constants a and c can be changed within the above-mentioned range by selecting A that occupies the A site and X that occupies the X site. The lattice constants a and c can also be changed within the above-mentioned range by changing the amount of substitution of P that substitutes the X site. Therefore, in the phosphorus compound according to the present invention, the superconducting properties, more specifically, T _c, can be controlled by selecting A and X and selecting the substitution amount of P that substitutes the X site. it can.

[Use]
The phosphorus compound according to the present invention can be used as a material such as an electronic material, a catalyst material, a high hardness material, an abrasion resistant material, and a heat resistant material.

As described above, the phosphorus compound according to the present invention is a non-superconductor having a resistivity (hereinafter also expressed as ρ) of about 0.3 to 0.5 mΩ · cm at room temperature. The electron transport property of the phosphorus compound according to one embodiment of the present invention exhibits a metallic behavior in a temperature range from room temperature to Tc. The phosphorus compound according to one embodiment of the present invention, which differs depending on the composition represented by the formula APX or the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1−z X ′ _z ) _1-v shows a _{T c} of 6～50K.

  In addition, the phosphorus compound according to the present invention can be used as an electronic material because it exhibits metallic electron transport characteristics in a temperature region in which it behaves as a non-superconductor. Here, examples of the electronic material include an element, a substrate, a crystal, and a thin film. More specifically, it can be suitably used as a substrate material for an element containing an intermetallic compound typified by a MoRuP superconductor. Moreover, it can utilize suitably as a material which comprises the superconductor-non-superconductor junction (it is hereafter described as SN junction) with which a superconducting transistor etc. are equipped.

Further, as is apparent from the temperature dependence of magnetization described later in Examples (see FIG. 7), the phosphorus compound according to one embodiment of the present invention exhibits non-magnetic magnetic characteristics in a temperature region of _Tc or higher. Therefore, the phosphorus compound according to one embodiment of the present invention can be used as a metal wiring that can connect superconducting elements even under a magnetic field.

  Moreover, it is thought that the hardness of the phosphorus compound which concerns on this invention is about 8-9 in a Mohs hardness meter display (10 steps) from hardness comparison with an agate mortar. Since the phosphorus compound according to the present invention has the above-mentioned electron transport properties, high hardness, and excellent wear resistance, it can be used as a high-hardness material and wear-resistant material. Here, examples of the high-hardness material and the wear-resistant material include various nozzles, mechanical seals, engine parts, furnace materials, and abrasive materials represented by files. In the present specification, the “high hardness material” is, for example, a material having a hardness of Mohs hardness system indication 8 or more.

  Further, the phosphorus compound according to the present invention is insoluble without dissolving in hydrochloric acid and nitric acid. Therefore, the phosphorus compound according to the present invention has corrosion resistance to acids and can be used as a surface coating material.

[Example 1]
In this example, among the phosphorus compounds represented by the formula APX, the case where Zr is selected as A and Se is selected as X, that is, the phosphorus compound represented by the formula ZrPSe will be described.

In order to synthesize the phosphorus compound ZrPSe, the powder raw materials of Zr, P and Se were weighed, respectively, and the charging composition was ZrP _2-x Se _x (x = 0.65, 0.75, 0.85, 1.0 and 1.4). In this example, the mixing step was performed in an agate mortar installed in a glove box filled with N ₂ gas, which is an inert gas. In the following description, unless otherwise specified, the composition ratio of the formula representing the phosphorus compound according to the present example means the above-mentioned charged composition.

The powder raw material mixed in N ₂ gas is enclosed in a BN cell, and high pressure synthesis is performed using a CAP-07 ultra-high pressure and high temperature generator manufactured by Riken Kikai Co., Ltd., whereby ZrP _2-x Se _x according to this example is used. (X = 0.65, 0.75, 0.85, 1.0 and 1.4) were synthesized. In this example, the synthesis conditions at the time of synthesis are as follows.
・ The combined pressure P is 2 GPa,
・ The synthesis temperature is 1325 ℃
-The synthesis time is rapid cooling after firing for 1 hour.

  After completion of the synthesis under the above synthesis conditions, the phosphorus compound was removed from the ultrahigh pressure and high temperature generator.

The crystal structure of ZrP _1.25 Se _0.75 was analyzed using a sample obtained by pulverizing ZrP _1.25 Se _0.75 produced as described above in an alumina mortar. Specifically, the crystal structure was determined by a powder X-ray diffraction method using an X-ray powder diffractometer Ultimate IV X-ray diffractometer manufactured by Rigaku. A copper target was used for the X-ray tube, and CuKα rays were used as X-rays. The X-ray acceleration voltage was 40 kV and the output was 40 mA.

FIG. 2 is a diagram showing an X-ray diffraction pattern of ZrP _1.25 Se _0.75 . Plot 11 shows the X-ray diffraction pattern of ZrP _1.25 Se _0.75 . On the other hand, the bar graph 10 shows an X-ray diffraction pattern of ZrSiSe having a PbFCl type crystal structure. The bar graph 10 is shown for comparison and reference to the X-ray diffraction pattern of ZrP _1.25 Se _0.75 .

As shown in FIG. 2, the plot 11 could be indexed as a PbFCl type crystal structure. Therefore, ZrP _1.25 Se _0.75 according to the present example has a PbFCl type crystal structure.

The composition analysis of ZrP _1.25 Se _0.75 according to this example was performed by SEM-EDX. Specifically, the composition ratio of Zr, P and Se in ZrP _1.25 Se _0.75 was measured using the SEM-EDX function provided in the desktop microscope TM3000 Miniscope manufactured by Hitachi High-Technologies Corporation. . As a result, the composition ratio of ZrP _1.25 Se _0.75 is Zr: P: Se = 36.52-37.50: 37.88-38.39: 24.95-25.25, and the composition fluctuation It was confirmed that there is. Possible causes of this composition fluctuation are 1) some P atoms occupy X sites where Se atoms should enter, and 2) Se atoms are missing.

As described above, the composition ratio of the phosphorus compound ZrP _1.25 Se _0.75 having the charge composition of 1: 1.25: 0.75 deviates from the 1: 1: 1 stoichiometric composition ratio. However, the crystal structure of ZrP _1.25 Se _0.75 has a PbFCl type crystal structure as shown by the X-ray diffraction pattern (plot 11) in FIG.

In addition, Rietveld analysis that optimizes lattice constants and atomic coordinates using ZrP _1.4 Se _0.6 produced with a charged composition ratio of Zr: P: Se = 1: 1.4: 0.6 went. The results of fitting in the Rietveld analysis are shown in FIGS.

FIG. 3 is a diagram showing a result of fitting an X-ray diffraction pattern of ZrP _1.4 Se _0.6 . More specifically, the fitting of a Rietveld analysis using a fixed occupancy model in which the P occupancy at the X site of the phosphorus compound is fixed at 0.4 and the Se occupancy is fixed at 0.6. It is a figure which shows a result. Of the X sites, a site occupied by P is also referred to as a P1 site, and a site occupied by Se is also referred to as a Se1 site. The A site is also referred to as a Zr1 site, and the P site is also referred to as a P2 site.

Plot 12 in FIG. 3 is an X-ray diffraction pattern of ZrP _1.4 Se _0.6 . The method for measuring the X-ray diffraction pattern is the same as in the case of ZrP _1.25 Se _0.75 described above, and is omitted here. Plot 13 shows the result of fitting using the occupation rate fixed model. Plot 14 shows the difference between plot 12 and plot 13. The results of Rietveld analysis using the occupation rate fixed model are as shown in Table 1.

以上のように、配向因子補正なし（選択配向因子を使用せず）であっても、重みつきの残差（Ｒｗｐ）はＲｗｐ＝９．３９％であり、Ｒｐ＝１７．８７％という良好なフィッティング結果が得られた。したがって、本実施例に係るＺｒＰ_１．４Ｓｅ_０．６の整形は良好であることがわかった。なお、格子定数は、ａ＝３．６３９６±０．０００１Å、ｃ＝７．９２０９±０．０００１Åが得られた。

As described above, the weighted residual (Rwp) is Rwp = 9.39% and Rp = 17.87%, even without orientation factor correction (without using a selective orientation factor). A fitting result was obtained. Therefore, it was found that the shaping of ZrP _1.4 Se _0.6 according to the present example was good. The lattice constants were a = 3.6396 ± 0.0001０．００ and c = 7.9209 ± 0.0001０．００.

FIG. 4 is another diagram showing the result of fitting the X-ray diffraction pattern of ZrP _1.4 Se _0.6 . Specifically, Rietveld analysis using a variable occupancy model in which (1) P and Se occupancy at X site are variable and (2) P and Se occupancy at P site are variable. It is a figure which shows the result of fitting at the time of performing. Here, among the X sites, the site occupied by P is also described as P1 site, the site occupied by Se is also described as Se1 site, the occupation rate of P1 site is described as O (P1), and the occupation rate of Se1 site Is described as O (Se1). Of the P sites, the site occupied by P is also referred to as the P2 site, the site occupied by Se is also referred to as the Se2 site, the occupation rate of the P2 site is described as O (P2), and the occupation rate of the Se2 site is expressed as It is described as O (Se2).

  In the occupation ratio variable model, it is not preferable to change the occupation ratios of O (P1), O (Se1), O (P2), and O (Se2) as independent parameters. Therefore, in this embodiment, the constraint conditions of O (P1) = 1−O (Se1) and O (P2) = 1−O (Se2) are applied, and two occupancy parameters independent from each other are used. Diffraction pattern fitting was performed.

Plot 12 in FIG. 4 is an X-ray diffraction pattern of ZrP _1.4 Se _0.6 , which is the same as plot 12 in FIG. Plot 15 shows the result of fitting using the occupation rate variable model. Plot 16 shows the difference between plot 12 and plot 15. Table 2 shows the result of Rietveld analysis using the variable occupation ratio model.

以上のように、配向因子補正なし（選択配向因子を使用せず）であっても、Ｒｗｐ＝８．６４％、および、Ｒｐ＝１７．３９％という良好なフィッティング結果が得られた。上述した占有率固定モデルを用いてリートベルト解析を行った場合と比較して、フィッティングが改善され、Ｒｗｐは０．７５％低くなった。

As described above, good fitting results of Rwp = 8.64% and Rp = 17.39% were obtained even without alignment factor correction (without using a selective alignment factor). Compared with the case where Rietveld analysis was performed using the fixed occupation rate model described above, the fitting was improved and Rwp was reduced by 0.75%.

As a result of using the variable occupancy model, as shown in Table 2, O (P1) to 0.3714, O (Se) to 0.6285, O (P2) to 0.9398, and O (Se) to 0 0.0602 was obtained. These results show a change of about 3% at the P1 and Se1 sites and about 6% at the P2 and Se2 sites compared to the case of using the occupation rate fixed model. Considering only the error bar, it can be said to be a significant change. However, considering the general reliability of the powder X-ray diffraction intensity, the determination accuracy of the occupation ratio is about 10%. Therefore, when the reliability of the powder X-ray diffraction intensity is taken into consideration, it is considered that the change between the occupation rate fixed model and the occupation rate variable model falls within the measurement error range. From the above, ZrP _1.4 Se _{0.6 according} to the present example has a PbFCl type crystal structure, and is a composition ratio at the time of raw material charging Zr: P: Se = 1.4: 1: 0. It can be concluded that the composition ratio is close to 6.

FIG. 5 is a diagram illustrating the x dependency of the lattice constant of ZrP _2-x Se _{x according to} the present embodiment. An X-ray diffraction pattern was measured for each phosphorus compound of x = 0.65, 0.75, 0.85, 1.0 and 1.4 produced using the above-described manufacturing method, and each phosphorus compound was determined from the measurement result. Lattice constants a and c were obtained. Plot 17 shows the lattice constant a of each phosphorus compound, and broken line 18 shows the result of fitting plot 17 with a straight line. Plot 19 shows the lattice constant c of each phosphorus compound, and broken line 20 shows the result of fitting plot 19 with a straight line.

As shown in FIG. 5, it was found that the lattice constants a and c of ZrP _2-x Se _x change linearly with respect to the substitution amount x in which P is substituted with Se.

FIG. 6 is a diagram showing the temperature dependence of the resistivity (ρ) of the phosphorus compound ZrP _1.25 Se _{0.75 according to} the present example (plot 21). The resistivity was measured using a four-terminal method, and was measured in a temperature range of 2 to 300K. The inset of FIG. 6 shows an enlarged view of the temperature range of 2 to 10 K in the above temperature range.

ZrP _1.25 Se _0.75 shown in plot 21 showed ρ to 0.35 mΩ · cm at room temperature (300 K). Moreover, as a result of measuring the resistivity of a plurality of phosphorus compounds ZrP _1.25 Se _0.75 other than those shown in plot 21, the resistivity was 0.3 to 0.5 mΩ · cm at room temperature.

As shown in plot 21, ZrP _1.25 Se _0.75 showed a metallic behavior in which the resistivity decreased with decreasing temperature in the temperature range from room temperature to about 50K. When the temperature was further decreased, the decrease in the resistivity of ZrP _1.25 Se _0.75 was saturated in the temperature range up to about 8K. However, when the temperature was further lowered, the resistivity of ZrP _1.25 Se _0.75 rapidly decreased to 0 in the temperature range of 7 to 6.5K. In other words, ZrP _1.25 Se _0.75 was in a superconducting state in a temperature range of 6.5 K or lower. From the above, it was found that the phosphorus compound ZrP _1.25 Se _{0.75 according} to the present example is a superconductor of T _{c to} 6.5 K.

As described above, ZrP _1.25 Se _0.75 exhibits a metallic behavior in a temperature range from room temperature to about 50 K, and can therefore be used as a material constituting a resistance thermometer.

FIG. 7 is a diagram showing the temperature dependence of the magnetic susceptibility of Zr _1.35 PSe _0.65 and Zr _0.6 PSe _{1.40 according} to this example. The magnetic susceptibility was measured using MPMS XL manufactured by Quantum Design, Inc., and measured in a temperature range of 1.8 to 10K. The measurement of magnetic susceptibility was performed for the following two measurements for one phosphorus compound.
In a magnetic field, the phosphorus compound is cooled to 1.8 K, and then heated to 10 K in a state where a magnetic field of 20 gauss (G) is applied. This measurement is also referred to as cooling in zero magnetic field (ZFC).
-Cool the phosphorous compound from 10K to 1.8K with 20G magnetic field applied. This measurement is also referred to as cooling in a magnetic field (FC).

In FIG. 7, Zr _1.35 PSe _0.65 Z. F. C is shown by plot 31; C is shown in plot 32. Further, Zr _0.6 PSe _1.40 Z. F. C is shown by plot 33; C is shown in plot 34.

As is apparent from plots 31 and 32, Zr _1.35 PSe _0.65 exhibited a diamagnetic behavior characteristic of a superconductor in a temperature region of about 6K or less. On the other hand, Zr _1.35 PSe _0.65 showed non-magnetism in a temperature region of 7 K or more.

As is apparent from plots 33 and 34, Zr _0.6 PSe _1.40 exhibited a diamagnetic behavior characteristic of a superconductor in a temperature region of about 3.5 K or less. On the other hand, Zr _0.6 PSe _1.40 showed non-magnetism in a temperature region of 4K or higher.

From the above measurement results, Zr _1.35 PSe _0.65 is a superconductor of T _{c to} 6.3K, and Zr _0.6 PSe _1.40 is a superconductor of T _{c to} 4.2K. I understood.

FIG. 8 is a diagram illustrating the x dependence of the superconducting transition temperature _Tc of ZrP _2-x Se _{x according} to the present example and ZrP _2-x S _{x according to} the _second example. Here, ZrP _2-x Se _{x according} to the present embodiment will be described.

In FIG. 8, plot 51 shows the T _c of ZrP _2−x Se _x (x = 0.5, 0.65, 0.75, 0.85, 0.9, 1.0 and 1.4). . A broken line 52 indicates a curve obtained by fitting the plot 51. From the plot 51 and the broken line 52, the x dependency of T _c of ZrP _2-x Se _{x according to} the present embodiment shows a curve having a vertex near x = 0.7, and the highest T _c is about 6. 3K.

From the above results, it was found that _Tc indicated by ZrP _2-x Se _x can be controlled by changing the substitution amount of P that substitutes the X site.

[Example 2]
In this example, among the phosphorus compounds represented by the formula APX, a case where Zr is selected as A and S is selected as X, that is, a phosphorus compound represented by the formula ZrPS will be described. The manufacturing method of the phosphorus compound ZrPS according to the present example is the same as the manufacturing method of the phosphorus compound ZrPSe according to the example 1 except that the starting materials are different. Therefore, details of the manufacturing method are omitted here.

As described above, FIG. 8 is a diagram illustrating the x dependency of T _c of ZrP _2-x Se _{x according to the first} embodiment and ZrP _2-x S _{x according to} the present embodiment. Here, ZrP _2-x S _{x according} to the present embodiment will be described.

In FIG. 8, plot 53 shows the T _c of ZrP _2-x S _x (x = 0.2, 0.3, 0.4, 0.69, 0.75 and 1.0). A broken line 54 shows a curve obtained by fitting the plot 53. The plot 53 shows the dispersion of T _c that is considered to be due to the individual difference of the samples. From the broken line 54, the x dependency of T _c of ZrP _2-x S _{x according} to this example is x = 0.7. A curve having a vertex at the vicinity is shown, and the highest T _c is about 5.0K.

From the above results, by changing the substitution of P substituting the X site, it was found to be controlled T _c indicated ZrP _2-x S _x.

An X-ray diffraction pattern of ZrP _2-x S _x (x = 0.4, 0.6, and 0.75) was measured using a sample pulverized into a powder in an alumina mortar, and the crystal structure was analyzed. FIG. 9 is a diagram showing an X-ray diffraction pattern of ZrP _2-x S _x (x = 0.4, 0.6, and 0.75). The apparatus and measurement conditions used to measure the X-ray diffraction pattern are the same as those described in Example 1.

Plot 41 shows the X-ray diffraction pattern of ZrP _1.6 S _0.4 , plot 42 shows the X-ray diffraction pattern of ZrP _1.4 S _0.6 , and plot 43 shows the ZrP _1.25 S _0.75 . An X-ray diffraction pattern is shown. On the other hand, the bar graph 40 shows an X-ray diffraction pattern of ZrP _1.4 S _0.6 having a PbFCl type crystal structure. The bar graph 40 is shown for comparison and reference to the X-ray diffraction pattern of ZrP _2-x S _x (x = 0.4, 0.6 and 0.75).

As shown in FIG. 9, plots 41 to 43 could be indexed as PbFCl type crystal structures. Therefore, the present embodiment according to Example _{ZrP 2-x S x (x} = 0.4,0.6 and 0.75) was confirmed to have a PbFCl type crystal structure.

Example 3
In this example, among the phosphorus compounds represented by the formula APX, the case where Hf is selected as A and S is selected as X, that is, the phosphorus compound represented by the formula HfPS will be described. The method for producing the phosphorus compound HfPS according to this example is the same as the method for producing the phosphorus compound ZrPSe according to Example 1 except that the starting materials are different.

Mixing composition of all HfPS manufactured in this Example, synthesis conditions, the crystal structure and T _c, shown in Table 3. Specifically, each phosphorus compound of HfP _2-x S _x (x = 0.3 to 0.9) was produced in this example.

表３の合成条件におけるＰは、高圧合成時に印加した圧力を示す。本実施例において、高圧合成時に印加した圧力は、いずれの燐化合物においてもＰ＝２ＧＰａとした。合成条件における温度は、高圧合成時の試料温度を表し、時間は、高圧合成時の合成時間を表す。本実施例において高圧合成時の試料温度は１５００℃を基本とし、比較参照用に、１４００℃でも合成を試みた。また、合成時間は、０．５〜１時間とした。

P in the synthesis conditions of Table 3 indicates the pressure applied during high-pressure synthesis. In this example, the pressure applied during high-pressure synthesis was P = 2 GPa in any phosphorus compound. The temperature under the synthesis conditions represents the sample temperature during high-pressure synthesis, and the time represents the synthesis time during high-pressure synthesis. In this example, the sample temperature during high-pressure synthesis was basically 1500 ° C., and the synthesis was attempted even at 1400 ° C. for comparative reference. The synthesis time was 0.5 to 1 hour.

In the same manner as the phosphorus compound ZrPSe described in Example 1, the X-ray diffraction pattern of the phosphorus compound HfP _2-x S _{x according} to this example was measured. FIG. 10 shows that HfP _1.6 S _0.4 , HfP _1.5 S _0.5 and HfP _1.1 S ₀ corresponding to x = _0.4 , _0.5 and 0.9 successfully converted into a single phase. _.9 is a diagram showing an X-ray diffraction pattern of each phosphorus compound of _.9 . Plots 61, 62 and 63 in FIG. 10 show the X-ray diffraction patterns of HfP _1.6 S _0.4 , HfP _1.5 S _0.5 and HfP _1.1 S _0.9 , respectively. From the X-ray diffraction pattern shown in FIG. 10, each of the phosphorous compounds of HfP _1.6 S _0.4 , HfP _1.5 S _0.5 and HfP _1.1 S _0.9 has a substantially single structure having a PbFCl type crystal structure. It was found to be a phase crystal.

FIG. 11 is a diagram illustrating the x dependency of the lattice constant of HfP _2-x S _x (x = 0.4, 0.5, and 0.9) according to the present example. _{HfP 2-x} S x shown in FIG. 11 (x = 0.4, 0.5 and 0.9), respectively, _HfP 1.6 _S 0.4 shown in FIG. _10, HfP _{1.5 S 0.5} And the same phosphorus compound as HfP _1.1 S _0.9 . From the X-ray diffraction pattern of each phosphorus compound shown in FIG. 10, the lattice constants a and c in each phosphorus compound shown in FIG. 11 were obtained. The plot 71 shows the lattice constant a of each phosphorus compound, and the broken line 13 shows the result of fitting the plot 71 with a straight line. The plot 73 shows the lattice constant c of each phosphorus compound, and the broken line 74 shows the result of fitting the plot 73 with a straight line.

From the results shown in FIG. 11, it was found that the lattice constants a and c of ZrP _2-x Se _x change linearly with respect to the substitution amount x in which P is substituted with S.

Similarly to the phosphorus compound ZrPSe described in Example 1, the temperature dependence of the magnetic susceptibility of the phosphorus compound HfP _2-x S _{x according} to this example was measured. The method for measuring the temperature dependence of the magnetic susceptibility is the same as the method described in the first embodiment, and is omitted here. Table 3 shows T _c determined from the measurement results of the temperature dependence of the resistivity and the temperature dependence of the magnetic susceptibility. ZrP _2-x Se _x synthesized at a synthesis temperature of 1500 ° C. exhibited superconductivity, and its T _c was 2.5 to 4.6K. On the other hand, ZrP _1.3 Se _0.7 synthesized at a synthesis temperature of 1400 ° C. did not show superconductivity.

Moreover, the result of estimating the volume of the superconducting phase with respect to the volume of the measured sample is shown in Table 3 as a volume percentage. The volume percentage of the superconducting phase estimated for each of the phosphorus compounds of HfP _1.6 S _0.4 , HfP _1.5 S _0.5 and HfP _1.1 S _0.9 from which crystals that can be said to be almost single phase was obtained. , 50%, 137% and 92%, respectively. The reason why the volume percentage of the superconducting phase exceeds 100% in HfP _1.5 S _0.5 is that the apparent superconducting phase volume is largely estimated due to the complete diamagnetism of the superconducting phase. is there.

In addition, among the phosphorus compounds according to the present example described in Table 3, the phosphorus compounds having compositions other than x = 0.4, 0.5, and 0.9 are not optimized because the synthesis conditions are not optimized. It is believed that the _Tc and the volume percentage of the superconducting phase are low.

Example 4
In this example, among the phosphorus compounds represented by the formula APX, the case where Hf is selected as A and Se is selected as X, that is, the phosphorus compound represented by the formula HfPSe will be described. The manufacturing method of the phosphorus compound HfPSe according to the present example is the same as the manufacturing method of the phosphorus compound ZrPSe according to the example 1 except that the starting materials are different.

The X-ray diffraction pattern of the phosphorus compound HfP _2-x Se _{x according} to this example was measured. The method for measuring the X-ray diffraction pattern is the same as that for the phosphorus compound ZrPSe described in Example 1. FIG. 12 is a diagram showing an X-ray diffraction pattern of HfP _2-x Se _x (x = 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7) according to this example. It is. For reference, an X-ray diffraction pattern of HfP ₂ where x = 0 is also shown as a plot 81. Plots 82 to 87 in FIG. 12 show the X-ray diffraction patterns of the phosphorus compounds with x = 0.2 to 0.7, respectively. The bar graph 80 shows an X-ray diffraction pattern of ZrP _1.4 S _0.6 having a PbFCl type crystal structure. The bar graph 80 is shown for comparison with the X-ray diffraction pattern of HfP _2-x Se _x .

As shown in FIG. 12, the plots 82 to 87 could be indexed as PbFCl type crystal structures. Therefore, HfP _2-x Se _x (x = 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7) according to this example has a PbFCl type crystal structure.

FIG. 13 is a diagram illustrating the x dependency of the lattice constant of HfP _2-x Se _x (x = 0.2, 0.3, 0.4, and 0.5) according to the present example. From the measurement result of the X-ray diffraction pattern shown in FIG. 12, the lattice constants a and c of each phosphorus compound were obtained. Plot 101 shows the lattice constant c of each phosphorus compound, and broken line 102 shows the result of fitting plot 101 with a straight line. Plot 103 shows the lattice constant a of each phosphorus compound, and broken line 104 shows the result of fitting plot 103 with a straight line.

As shown in FIG. 13, the lattice constant c of ZrP _2-x Se _x did not show a clear change with respect to the substitution amount x in which P was substituted with Se. On the other hand, the lattice constant a showed a positive correlation with the substitution amount x. Therefore, the interatomic distance at the P site of ZrP _2-x Se _x can be controlled by changing the substitution amount x in which P is substituted with Se.

FIG. 14 is a diagram illustrating the temperature dependence of the magnetic susceptibility of HfP _2-x Se _{x according to} the present example. Figure 14 (a) ~ (e) respectively show the temperature dependence of the magnetic susceptibility of _{HfP 2-x} Se x where the x = 0.3 to 0.7. The method for measuring the magnetic susceptibility in this example is the same as the method for measuring the magnetic susceptibility of Zr _1.35 PSe _0.65 and Zr _0.6 PSe _{1.40 according} to Example 1. Plots 91, 93, 95, 97 and 99 are shown in Z. F. The magnetic susceptibility in the case of C is shown. Also, plots 92, 94, 96, 98 and 100 are shown in F.A. The magnetic susceptibility in the case of C is shown.

The temperature dependence of magnetic susceptibility of FIG _{14, HfP} 1.3 _{Se 0.7} is _T c _{~5.8K, HfP} 1.4 _{Se 0.6} is _T c _{~5.0K, HfP} 1.5 Se _{0 .5 T} c _{~5.8K, HfP} 1.6 _{Se 0.4} is _T c _{~3.8K, HfP} 1.7 _{Se 0.3} was _T c _~4.0K.

FIG. 15 is a diagram illustrating x dependency of T _c of HfP _2-x Se _x (x = 0.3, 0.5, and 0.7) according to the present example. In FIG. 15, plot 111 shows the T _c of HfP _2-x Se _x (x = 0.3, 0.5, and 0.7). _{T c} of _{ZrP 2-x} Se x according to the present embodiment, x = when 0.3 _{T c} = about 4.0K, _{T c} = about 5 in the case of x = 0.5 and 0.7. 5K was shown. From the similarity to the Z dependence (see FIG. 8) of the superconducting transition temperature T _c of ZrP _2-x Se _{x according} to Example 1 and ZrP _2-x S _{x according} to Example 2, _{T c} of HfP _2-x Se x can be inferred and becomes highest at the near x = 0.6.

  The present invention can be used for phosphorus compounds, electronic materials, catalyst materials, high hardness materials, wear resistant materials, and heat resistant materials.

Claims (15)

  It has a PbFCl type crystal structure, and its chemical composition is selected from the formula APX (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group 6 element 1 In the above elements, X = one or more elements selected from Group 14 elements, Group 15 elements, and Group 16 elements (excluding those in which A = Zr and X = S) A phosphorus compound characterized in that it is a compound shown. It has a PbFCl type crystal structure, and the chemical composition is represented by the formula (A _1-w A ′ _w ) _1-t P _1-u (X _1−z X ′ _z ) _1−v (where A = Ti, Zr and Hf One or more elements selected from: A ′ is one or more elements selected from Group 1 elements, Group 2 elements, Group 3 elements, Group 4 elements, Group 5 elements and Group 6 elements or One or more elements selected from a lanthanoid element and an actinoid element, X is one or more elements selected from a Group 14 element, a Group 15 element, and a Group 16 element, and X ′ is a 14th element. One or more elements selected from group elements, group 15 elements and group 16 elements, 0 ≦ w <1, 0 ≦ z <1, 0 ≦ t <1, 0 ≦ u <1, 0 ≦ The phosphorous compound according to claim 1, wherein v <1.).   2. The phosphorus compound according to claim 1, wherein A is Zr and X is Se, or A is Hf, and X is Se or S. 3.   The phosphorus compound according to any one of claims 1 to 3, wherein the lattice constant is a = 3.5 to 3.9Å and c = 7.7 to 8.1Å.   5. The phosphorus compound according to claim 1, which exhibits a conductivity of 0.3 to 0.5 mΩ · cm at room temperature.   The phosphorus compound according to any one of claims 1 to 5, which exhibits a metallic behavior up to a low temperature of 50K or less at room temperature.   The phosphorus compound according to any one of claims 1 to 6, which exhibits superconductivity at less than 50K.   The phosphorus compound according to any one of claims 1 to 7, wherein the phosphorus compound exhibits nonmagnetic properties at 50K or more.   The electronic material containing the phosphorus compound of any one of Claims 1-8.   The catalyst material containing the phosphorus compound of any one of Claims 1-8.   A high-hardness material containing the phosphorus compound according to claim 1.   A wear-resistant material comprising the phosphorus compound according to any one of claims 1 to 8.   A heat-resistant material containing the phosphorus compound according to any one of claims 1 to 8.   It has a PbFCl type crystal structure, and its chemical composition is selected from the formula APX (A = Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group 6 element 1 A compound represented by the above element, X = one or more elements selected from Group 14 element, Group 15 element, and Group 16 element) and in a superconducting state.   A, P and X (A = one or more elements selected from Group 1 element, Group 2 element, Group 3 element, Group 4 element, Group 5 element and Group 6 element, X = 14 After mixing each material of group element, one or more elements selected from group 15 element and group 16 element) in an inert gas atmosphere, the temperature is 1,000 ° C. to 2,000 ° C. under normal pressure. A method for producing a phosphorus compound, which is synthesized under a pressure of 5 Gpa.

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