Dielectric material and functional element

Abstract

This dielectric material 1a includes a metal oxide having Zn, a rare earth element, and Mn.

Description

Dielectric materials and functional elements

[0001] The present disclosure relates to dielectric materials and functional devices.

[0002] Materials such as barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), (Pb,La)(Zr,Ti)O3, and BiFO3 are known as ferroelectric dielectric materials. (Zr,Ti) indicates the inclusion of at least one element selected from the group consisting of Zr and Ti, and (Pb,La) indicates the inclusion of at least one element selected from the group consisting of Pb and La. These dielectric materials are complex oxides with a perovskite structure.

[0003] On the other hand, it has been reported recently that an oxide in which a part of Zn in ZnO having a wurtzite structure is substituted with a specific element exhibits ferroelectricity. ZnO exhibits paraelectricity. For example, Non-Patent Document 1 states that Zn 1-x Mg x It is disclosed that when x is 0.34 to 0.37 in an O thin film, the thin film exhibits ferroelectricity.

[0004] K. Ferri et al, Journal of Applied Physics 130, 044101 (2021)

[0005] The technology described in Non-Patent Document 1 needs to be reconsidered from the viewpoint of achieving desired dielectric properties without using Mg as an element to substitute for a portion of Zn in ZnO. Therefore, the present disclosure provides a novel dielectric material containing a metal oxide having Zn and an element other than Mg.

[0006] The dielectric material of the present disclosure includes a metal oxide having Zn, a rare earth element, and Mn.

[0007] According to the present disclosure, a novel dielectric material containing Zn and an element other than Mg can be provided.

[0008] FIG. 1 is a cross-sectional view showing an example of a dielectric material according to the present disclosure. FIG. 2 is a diagram schematically showing another example of a dielectric material according to the present disclosure. FIG. 3 is a diagram schematically showing an example of a functional element according to the present disclosure. FIG. 4 is an X-ray diffraction (XRD) pattern of a sample according to Example 1. FIG. 5 is a graph showing the relationship between polarization and electric field strength in a metal oxide film of a sample according to Example 1. FIG. 6 is a graph showing the relationship between polarization and electric field strength in a metal oxide film of a sample according to Comparative Example 1. FIG. 7 is a graph showing the relationship between polarization and electric field strength in a metal oxide film of a sample according to Comparative Example 2. FIG. 8 is a graph showing the relationship between the composition ratio of Mn and the composition ratio of rare earth elements in the metal oxides of samples according to Examples 1 to 8 and Comparative Examples 2 to 11.

[0009] (Findings that form the basis of the present disclosure) According to Non-Patent Document 1, Zn 1-x Mg x It is understood that when x is 0.34 to 0.37 in a ZnO thin film, the thin film exhibits ferroelectricity. On the other hand, it has not been confirmed that a Zn-containing oxide exhibits predetermined dielectric properties such as ferroelectricity without the addition of Mg. Therefore, the inventors conducted extensive research to determine whether a Zn-containing oxide could exhibit predetermined dielectric properties such as ferroelectricity without the addition of Mg. As a result, the inventors have newly discovered that a metal oxide containing Zn and a predetermined metal element other than Mg can exhibit predetermined dielectric properties such as ferroelectricity. Based on this new finding, the inventors have devised the dielectric material of the present disclosure.

[0010] (Summary of one aspect of the present disclosure) A dielectric material according to a first aspect of the present disclosure includes a metal oxide having Zn, a rare earth element, and Mn.

[0011] According to the first aspect, the metal oxide contains a rare earth element and Mn in addition to Zn, and exhibits predetermined dielectric properties such as ferroelectricity even if the metal oxide does not contain Mg. Therefore, a novel dielectric material can be provided that contains a metal oxide containing Zn and an element other than Mg.

[0012] In a second aspect of the present disclosure, for example, in the dielectric material according to the first aspect, the metal oxide may have ferroelectricity. According to the second aspect, a novel dielectric material exhibiting ferroelectricity can be provided.

[0013] In a third aspect of the present disclosure, for example, in the dielectric material according to the first or second aspect, the rare earth element may be at least one selected from the group consisting of Nd and Y. According to the third aspect, by using Mn and at least one selected from the group consisting of Nd and Y as elements other than Mg, it is possible to provide a novel dielectric material containing a metal oxide having predetermined dielectric properties such as ferroelectricity.

[0014] In a fourth aspect of the present disclosure, for example, in the dielectric material according to the first or second aspect, the rare earth element may be Nd. According to the fourth aspect, by using Nd and Mn as elements other than Mg, it is possible to provide a novel dielectric material containing a metal oxide having predetermined dielectric properties such as ferroelectricity.

[0015] In a fifth aspect of the present disclosure, for example, in the dielectric material according to any one of the first to fourth aspects, the metal oxide is Zn 1-x-y A x Mn y O z In the composition, A may be a rare earth element. In the composition, z may be a value for maintaining the electrical neutrality of the metal oxide. The composition may satisfy the conditions of 0.025≦x≦0.05 and 0.7≦y / x≦1.5. According to the fifth aspect, the metal oxide has predetermined dielectric properties such as ferroelectricity even when the rare earth element content and Mn content in the metal oxide are small. Therefore, compared to when a portion of Zn in ZnO is replaced with Mg to exhibit predetermined dielectric properties such as ferroelectricity, the content of metal elements other than Zn can be reduced in a metal oxide having predetermined dielectric properties such as ferroelectricity.

[0016] In a sixth aspect of the present disclosure, for example, in the dielectric material according to any one of the first to fifth aspects, the metal oxide may have a wurtzite structure. According to the fifth aspect, the metal oxide is likely to have desired ferroelectricity.

[0017] In a seventh aspect of the present disclosure, for example, the dielectric material according to any one of the first to sixth aspects may include crystal grains containing the metal oxide, and a filler containing an inorganic oxide different from the metal oxide and filling spaces between the crystal grains. According to the seventh aspect, the dielectric material is likely to have properties suitable for a capacitor.

[0018] A functional device according to an eighth aspect of the present disclosure includes: a dielectric material including the dielectric material according to any one of the first to seventh aspects; and a pair of electrodes.

[0019] According to the eighth aspect, it is possible to provide a functional element that makes use of the dielectric properties, for example, ferroelectricity, of the metal oxide contained in the dielectric material.

[0020] In a ninth aspect of the present disclosure, for example, the functional element according to the eighth aspect may be at least one selected from the group consisting of a capacitor, an electro-optical element, a memory element, a transistor, a ferroelectric data storage, a piezoelectric element, and a pyroelectric element. According to the ninth aspect, a functional element such as a capacitor that makes use of the dielectric properties, for example, ferroelectricity, of the metal oxide contained in the dielectric material can be provided.

[0021] In a tenth aspect of the present disclosure, for example, the functional element according to the eighth aspect may be disposed in at least one selected from the group consisting of an actuator, an inkjet head, a gyro sensor, a vibration power generating element, a surface acoustic wave resonator, a film bulk resonator, a piezoelectric mirror, and a piezoelectric sensor. According to the tenth aspect, the dielectric properties, for example, ferroelectricity, of the metal oxide contained in the dielectric material can be utilized in the actuator or the like.

[0022] Embodiments Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0023] Fig. 1 is a cross-sectional view showing an example of a dielectric material according to the present disclosure. As shown in Fig. 1, the dielectric material 1a is formed, for example, in a film shape. The dielectric material 1a may be formed in a shape other than a film shape, such as a cylindrical shape, a powder shape, or a wire shape.

[0024] The dielectric material 1a contains a metal oxide containing Zn, a rare earth element, and Mn. This metal oxide does not contain, for example, Mg. The metal oxide has predetermined dielectric properties such as ferroelectricity even without containing Mg. This metal oxide may contain Mg as necessary. It is believed that the metal oxide containing Zn, a rare earth element, and Mn makes it easier for the metal oxide crystal to form so that spontaneous polarization occurs. For example, it is believed that the dimension of the crystal unit cell in the c-axis direction tends to increase.

[0025] The dielectric properties of the metal oxide contained in the dielectric material 1a are not limited to a specific one, and the metal oxide contained in the dielectric material 1a may have, for example, ferroelectricity.

[0026] The above metal oxides can have predetermined dielectric properties such as ferroelectricity even if they contain only a small amount of metal elements other than Zn. Therefore, the composition and crystal structure of the metal oxides are less variable, making the above metal oxides advantageous from the viewpoint of reproducibility. In addition, the spontaneous polarization of metal oxides tends to be large even if the metal oxides do not contain toxic elements such as Pb.

[0027] The rare earth element in the metal oxide is not limited to a specific rare earth element. The rare earth element in the metal oxide is, for example, at least one selected from the group consisting of Nd and Y. This makes it easier for the metal oxide to have the desired ferroelectric properties. The rare earth element in the metal oxide may be an element other than Nd and Y. The ionic radii of ions derived from rare earth elements are close to each other, as shown in Table 1. Therefore, even if the rare earth element in the metal oxide is an element other than Nd and Y, it is believed that the metal oxide crystal is easily formed so as to generate spontaneous polarization. The rare earth element in the metal oxide may be at least one selected from the group consisting of Y, La, Ce, Pr, and Nd. The ionic radii in Table 1 are Shannon ionic radii reported in R.D. Shannon, Acta Crystallogr. Sect. A, 32, 751 (1976).

[0028]

[0029] The rare earth element in the metal oxide is preferably Nd, which makes it easier for the metal oxide to have the desired ferroelectricity.

[0030] The composition of the metal oxide is not limited to a specific composition as long as the metal oxide contains Zn, a rare earth element, and Mn. 1-x-y A x Mn y O z In this composition, A is a rare earth element, and z is a value for maintaining the electrical neutrality of the metal oxide. This composition satisfies the conditions of 0.025≦x≦0.05 and 0.7≦y / x≦1.5. When the metal oxide has such a composition, the metal oxide has predetermined dielectric properties such as ferroelectricity even if the rare earth element content and Mn content in the metal oxide are small. Compared to when a portion of Zn in ZnO is replaced with Mg to exhibit predetermined dielectric properties such as ferroelectricity, the content of metal elements other than Zn can be reduced in a metal oxide having predetermined dielectric properties such as ferroelectricity.

[0031] In the above composition, z can vary depending on the contents of the rare earth element A and Mn, and the manufacturing process of the dielectric material 1a. For example, z satisfies the condition 0.9≦z≦1.1.

[0032] The crystal structure of the metal oxide is not limited to a specific one as long as the metal oxide contains Zn, a rare earth element, and Mn. The metal oxide may have, for example, a wurtzite structure. In this case, the metal oxide is likely to have desired ferroelectric properties. For example, the remanent polarization is likely to be large in the metal oxide.

[0033] The dielectric material 1a is, for example, configured as a material consisting only of a metal oxide. The dielectric material 1a may also be configured as a composite material containing a metal oxide. Figure 2 is a diagram schematically showing another example of the dielectric material of the present disclosure. The dielectric material 1a may be modified, for example, to the dielectric material 1b shown in Figure 2.

[0034] The method for fabricating the dielectric material 1a is not limited to a specific method. The dielectric material 1a can be fabricated by a vacuum process such as RF magnetron sputtering, pulsed laser deposition (PLD), atomic layer deposition (ALD), and chemical vapor deposition (CVD). The dielectric material 1a may also be fabricated by a wet process such as chemical solution deposition (CSD), a sol-gel process, and a hydrothermal process.

[0035] As shown in Figure 2, the dielectric material 1b includes crystal grains 1g and a filler 1f. The crystal grains 1g contain the above-mentioned metal oxide. The filler 1f contains an inorganic oxide different from the above-mentioned metal oxide and fills the spaces between the crystal grains 1g. With this configuration, the dielectric material 1b is likely to have characteristics suitable for a capacitor.

[0036] The method for producing the dielectric material 1b is not limited to a specific method. The dielectric material 1b can be produced, for example, by the following method. First, a powder containing the above-mentioned metal oxide raw materials and the raw materials of the filler 1f is mixed with a binder to obtain a mixture. This mixture is formed into a sheet by a method such as screen printing to obtain a green sheet. The dielectric material 1b can be produced by firing this green sheet.

[0037] A predetermined functional element can be provided using the dielectric material 1a or 1b. FIG. 3 is a diagram schematically illustrating an example of a functional element according to the present disclosure. As shown in FIG. 3, the functional element 2 includes, for example, a dielectric 10 and a pair of electrodes 20. The dielectric 10 includes the dielectric material 1a. The dielectric 10 may also include the dielectric material 1b. Since the functional element 2 includes the dielectric 10, it can be used in applications that utilize the dielectric properties, such as ferroelectricity, of the metal oxide included in the dielectric material 1a of the dielectric 10.

[0038] As shown in FIG. 3, in the functional element 2, the dielectric 10 is disposed between a pair of electrodes 20, for example.

[0039] The functional element 2 is not limited to a specific element. For example, the functional element 2 is at least one selected from the group consisting of a capacitor, an electro-optical element, a memory element, a transistor, a ferroelectric data storage, a piezoelectric element, and a pyroelectric element. For example, in these functional elements, the dielectric properties, such as ferroelectricity, of the metal oxide contained in the dielectric material 1a of the dielectric 10 can be utilized.

[0040] The functional element 2 is disposed in at least one selected from the group consisting of an actuator, an inkjet head, a gyro sensor, a vibration power generating element, a surface acoustic wave resonator, a film bulk resonator, a piezoelectric mirror, and a piezoelectric sensor. In this case, the actuator or the like can utilize the piezoelectric effect associated with the dielectric properties of the metal oxide contained in the dielectric material 1a of the dielectric 10.

[0041] The present disclosure will be described in more detail below based on examples, although the present disclosure is not limited to the following examples.

[0042] Example 1: A Pt (111) film having a thickness of 100 nm was epitaxially grown on a c-plane sapphire single crystal substrate by RF magnetron sputtering to obtain a Pt electrode. Next, a metal oxide film having a thickness of 200 nm was formed on the Pt electrode by RF magnetron sputtering. The metal oxide film contained Zn, Nd, and Mn as metals. In the metal oxide film, the ratio of the number of Nd atoms to the number (total number) of Zn, Nd, and Mn atoms was 0.045. In the metal oxide film, the ratio of the number of Mn atoms to the number (total number) of Zn, Nd, and Mn atoms was 0.042. In this RF magnetron sputtering, a composite oxide containing Zn, Nd, and Mn was used as the target. This target satisfied the condition of Zn atomic number: Nd atomic number: Mn atomic number = 1:0.87:0.05. Additionally, during this RF magnetron sputtering, the Pt electrode was heated to 300°C in an atmosphere containing a 25% by volume mixture of oxygen and argon. Next, a 100 nm thick Au film was formed on the metal oxide film by vacuum deposition to obtain an Au electrode. In this manner, the sample according to Example 1 was obtained.

[0043] The crystal structure of the metal oxide film of the sample according to Example 1 was evaluated using an X-ray diffraction (XRD) device, X'Pert Pro MPD, manufactured by Panalytical. Cu-Kα radiation (wavelength λ = 0.15418 nm) was used as the X-ray in the XRD. FIG. 4 shows the XRD pattern of the sample according to Example 1. As shown in FIG. 4, in addition to the diffraction peaks originating from the substrate, a diffraction peak of the (00L) plane of the wurtzite structure appears with high intensity. This confirmed that the metal oxide film of the sample according to Example 1 has a wurtzite structure and that the metal oxide film has grown epitaxially so that the c-plane of the wurtzite structure is parallel to the substrate.

[0044] The composition of the metal oxide film of the sample according to Example 1 was determined using an ESCA5600 X-ray photoelectron spectroscopy (XPS) analyzer manufactured by ULVAC-PHI, Inc. Table 1 shows the ratio x of the number of rare earth element atoms to the total number of Zn atoms, rare earth element atoms, and Mn atoms in the metal oxide film, and the ratio y of the number of Mn atoms to the total number.

[0045] A polarization-electric field measurement was performed on the sample according to Example 1 using a Radiant Technology ferroelectric tester, Premier II, to obtain a P-E curve for the sample according to Example 1. The dielectric properties of the metal oxide of the sample according to Example 1 were evaluated based on this P-E curve. The results are shown in Table 1. In Table 1, an electrical insulation rating of "A" means that the metal oxide has good electrical insulation properties. An electrical insulation rating of "X" means that the metal oxide exhibits conductivity. A ferroelectricity rating of "A" means that the metal oxide exhibits ferroelectricity. A ferroelectricity rating of "X" means that the metal oxide does not have ferroelectricity. The metal oxide film of the sample according to Example 1 was confirmed to be a ferroelectric having good electrical insulation properties and high polarization.

[0046] 5 is a P-E curve of the sample according to Example 1, showing the relationship between polarization and electric field strength in the metal oxide film. In FIG. 5, the vertical axis represents polarization, and the horizontal axis represents electric field strength. As shown in FIG. 5, the metal oxide film of the sample according to Example 1 has a polarization of about 130 μC / cm 2 It was confirmed that the metal oxide film was a ferroelectric material exhibiting high polarization.

[0047] Example 2 A sample according to Example 2 was prepared in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.53:0.05 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 2 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 2 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 2 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 2 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 2 was a ferroelectric having good electrical insulation and high polarization.

[0048] Example 3 A sample according to Example 3 was prepared in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.053:0.04 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 3 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 3 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 3 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 3 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 3 was a ferroelectric having good electrical insulation and high polarization.

[0049] Example 4 A sample according to Example 4 was prepared in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.087:0.04 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 4 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 4 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 4 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 4 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 4 was a ferroelectric having good electrical insulation and high polarization.

[0050] Example 5 A sample according to Example 5 was fabricated in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.087:0.07 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 5 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 5 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 5 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 5 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 5 was a ferroelectric having good electrical insulation and high polarization.

[0051] Example 6 A sample according to Example 6 was prepared in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.087:0.08 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 6 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 6 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 6 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 6 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 6 was a ferroelectric having good electrical insulation and high polarization.

[0052] Example 7 A sample according to Example 7 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.053:0.03 was satisfied. The crystal structure of the metal oxide film of the sample according to Example 7 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 7 had a wurtzite structure and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 7 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 7 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 7 was a ferroelectric having good electrical insulation and high polarization.

[0053] Example 8 A sample according to Example 8 was prepared in the same manner as in Example 1, except for the following points. The composite oxide target contained Y instead of Nd as a rare earth element, and satisfied the condition of the ratio of Zn atoms:Y atoms:Mn atoms = 1:0.075:0.05. The crystal structure of the metal oxide film of the sample according to Example 8 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the metal oxide film of the sample according to Example 8 had a wurtzite structure, and that the metal oxide film had grown epitaxially so that the c-plane of the wurtzite structure was parallel to the substrate. The composition of the metal oxide film of the sample according to Example 8 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Example 8 were evaluated in the same manner as in Example 1. The results are shown in Table 1. It was confirmed that the metal oxide film of the sample according to Example 8 was a ferroelectric having good electrical insulation and high polarization.

[0054] Comparative Example 1 A sample according to Comparative Example 1 was prepared in the same manner as in Example 1, except for the following points. The composite oxide target contained Mg without any rare earth elements, and satisfied the condition of the ratio of Zn atoms:Mg atoms:Mn atoms = 1:0.55:0.02. The dielectric properties of the metal oxide film of the sample according to Comparative Example 1 were evaluated in the same manner as in Example 1. The results are shown in Table 1. FIG. 6 is a graph showing the relationship between polarization and electric field strength in the metal oxide film of the sample according to Comparative Example 1. As shown in FIG. 6, the metal oxide film of the sample according to Comparative Example 1 had good electrical insulation properties, but had paraelectric dielectric properties and was not ferroelectric.

[0055] Comparative Example 2 A sample according to Comparative Example 2 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.053:0.02 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 2 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 2 were evaluated in the same manner as in Example 1. The results are shown in Table 1. FIG. 7 is a graph showing the relationship between polarization and electric field strength in the metal oxide film of the sample according to Comparative Example 2. As shown in FIG. 7, the metal oxide film of the sample according to Comparative Example 2 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0056] Comparative Example 3 A sample according to Comparative Example 3 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.087:0.03 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 3 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 3 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 3 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0057] Comparative Example 4 A sample according to Comparative Example 4 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.031:0.03 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 4 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 4 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 4 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0058] Comparative Example 5 A sample according to Comparative Example 5 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.031:0.04 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 5 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 5 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 5 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0059] Comparative Example 6 A sample according to Comparative Example 6 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.031:0.05 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 6 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 6 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 6 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0060] Comparative Example 7 A sample according to Comparative Example 7 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.053:0.06 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 7 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 7 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 7 exhibited conductivity, and a large current leakage was observed in the measurement for obtaining the P-E curve.

[0061] Comparative Example 8 A sample according to Comparative Example 8 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.053:0.07 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 8 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 8 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 8 had low electrical insulation and exhibited conductivity, and a large current leak was observed in the measurement for obtaining the P-E curve.

[0062] Comparative Example 9 A sample according to Comparative Example 9 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.11:0.07 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 9 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 9 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 9 had low electrical insulation and exhibited conductivity, and a large current leak was observed in the measurement for obtaining the P-E curve.

[0063] Comparative Example 10 A sample according to Comparative Example 10 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.11:0.05 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 10 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 10 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 10 had low electrical insulation and exhibited conductivity, and a large current leak was observed in the measurement for obtaining the P-E curve.

[0064] Comparative Example 11 A sample according to Comparative Example 11 was produced in the same manner as in Example 1, except that the composite oxide target was changed so that the condition of the number of Zn atoms: the number of Nd atoms: the number of Mn atoms = 1:0.087:0.1 was satisfied. The composition of the metal oxide film of the sample according to Comparative Example 11 was determined in the same manner as in Example 1. The results are shown in Table 1. The dielectric properties of the metal oxide film of the sample according to Comparative Example 11 were evaluated in the same manner as in Example 1. The results are shown in Table 1. The metal oxide film of the sample according to Comparative Example 11 had low electrical insulation and exhibited conductivity, and a large current leak was observed in the measurement for obtaining the P-E curve.

[0065] 8 is a graph showing the relationship between the Mn composition ratio y and the rare earth element composition ratio x in the metal oxide samples according to Examples 1 to 8 and Comparative Examples 2 to 11. In this graph, "◯" indicates an Example and "×" indicates a Comparative Example. As shown in FIG. 8, the metal oxide samples according to Examples 1 to 8 satisfied the conditions of 0.025≦x≦0.05 and 0.7≦y / x≦1.5. On the other hand, the metal oxide samples according to Comparative Examples 2 to 11 did not satisfy at least one of the conditions of 0.025≦x≦0.05 and 0.7≦y / x≦1.5.

[0066]

[0067] The dielectric material of the present disclosure can have predetermined dielectric properties such as ferroelectricity even without using Mg as an element to substitute for a portion of Zn in ZnO.

Claims

1. A metal oxide having Zn, a rare earth element, and Mn, The metal oxide has a composition represented by Zn1-xyAxMnyOz, In the above composition, A is a rare earth element; In the above composition, z is a value for maintaining the electrical neutrality of the metal oxide, The composition satisfies the conditions of 0.025≦x≦0.05 and 0.7≦y / x≦1.5, Dielectric materials.

2. The metal oxide has ferroelectric properties. The dielectric material of claim 1 .

3. The rare earth element is at least one selected from the group consisting of Nd and Y. The dielectric material of claim 1 .

4. The rare earth element is Nd. The dielectric material of claim 1 .

5. The metal oxide has a wurtzite structure. The dielectric material of claim 1 .

6. The dielectric material includes crystal grains containing the metal oxide, and a filler containing an inorganic oxide different from the metal oxide and filling spaces between the crystal grains. The dielectric material of claim 1 .

7. A dielectric material comprising the dielectric material according to any one of claims 1 to 6; A pair of electrodes; Functional element.

8. The functional element is at least one selected from the group consisting of a capacitor, an electro-optical element, a memory element, a transistor, a ferroelectric data storage, a piezoelectric element, and a pyroelectric element. The functional element according to claim 7 .

9. the functional element is disposed in at least one selected from the group consisting of an actuator, an inkjet head, a gyro sensor, a vibration power generating element, a surface acoustic wave resonator, a film bulk resonator, a piezoelectric mirror, and a piezoelectric sensor; The functional element according to claim 7 .