A dielectric ceramic, a method for preparing the same, and a terminal device containing the same

Abstract

The present application belongs to the technical field of ceramic dielectric materials, and relates to a dielectric ceramic, a preparation method thereof, and a terminal device containing the same. The dielectric ceramic is sintered from a mixture containing main component raw materials and auxiliary component raw materials. The main component raw materials include a perovskite compound (Ba 1‑1.5y Bi y )(Zr x Ti 1‑x )O3, and the auxiliary component raw materials include 1-5 parts of Ca elements or compounds thereof, 0.5-5 parts of Sr elements or compounds thereof, 0.1-1 parts of Mg elements or compounds thereof, 0.1-1 parts of Mn elements or compounds thereof, and 0.2-5 parts of SiO2 or silicon-containing compounds providing an equivalent amount of Si, in terms of 100 parts of the molar amount of Ba elements in the main component raw materials. The dielectric ceramic has an ultra-low loss of ≤0.11%, a negative temperature coefficient, and X8R temperature characteristics.

Description

Technical Field

[0001] This invention belongs to the field of ceramic dielectric materials technology, and relates to a dielectric ceramic, its preparation method, and terminal devices containing it. Background Technology

[0002] X7R and X8R are two types of temperature-stable dielectric systems widely used in industrial and automotive electronics, requiring capacitance changes of no more than ±15% within temperature ranges of -55℃ to +125℃ and -55℃ to +150℃, respectively. Existing X7R / X8R formulations are mostly based on modified barium titanate (BaTiO3)-based ceramics, using rare earth or transition metal doping to control Curie peak broadening to achieve wide-temperature stability. However, these materials generally suffer from high dielectric losses (typically greater than 1%), and their temperature characteristics often exhibit a bimodal structure near room temperature and near 125℃, reflecting insufficient suppression of phase transition behavior and affecting capacitance stability under high-frequency and high-temperature conditions.

[0003] With the increasing demands of fields such as 5G communication, new energy vehicles, and high-density power modules, the market urgently needs new dielectric materials that combine ultra-low dielectric loss, negative temperature coefficient (used to compensate for positive temperature coefficient components in circuits), and meet the wide temperature range characteristics of X8R. However, currently, no material system in the industry can simultaneously meet these requirements, which restricts the improvement of integration efficiency and reliability of high-end electronic devices. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a dielectric ceramic that can achieve ultra-low loss ≤0.11%, has a negative temperature coefficient and meets the X8R temperature characteristics, its preparation method, and terminal devices containing it.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a dielectric ceramic, which is sintered from a mixture comprising a main component raw material and a secondary component raw material; said main component raw material includes a perovskite-type compound (Ba). 1-1.5y Bi y (Zr) x Ti 1-x O3, 0 < x < 1, 0.001 ≤ y ≤ 0.40; relative to 100 molar parts of Ba in the main component raw material, the secondary component raw material includes: 1 to 5 parts of elemental Ca or its compounds; 0.5 to 5 parts of Sr element or its compounds; 0.1 to 1 part of Mg or its compounds; 0.1 to 1 part of Mn element or its compound; 0.2 to 5 parts of SiO2 or a silicon-containing compound providing an equal amount of Si; The dielectric ceramic provided by this invention exhibits temperature characteristics that meet the X8R requirements, possesses a negative temperature coefficient, and has a dielectric loss ≤0.11%. In the field of dielectric ceramics, there is a challenge in achieving a balance between high dielectric constant εr and low loss: for traditional BaTiO3 high-dielectric systems, while εr can be increased, it is difficult to simultaneously control loss tanδ and temperature stability. Therefore, the dielectric loss tanδ ≤0.11% achieved by this invention approaches the requirements of temperature-compensated low-loss ceramics, exceeding the 1% loss level commonly found in ordinary X7R / X8R (temperature-stable) high-dielectric materials, representing a significant improvement. Meanwhile, for X8R, there is also a problem of incompatibility between its temperature stability and "negative temperature coefficient". X8R requires the capacitance change rate to be controlled within ±15% within the range of -55℃ to 150℃. If we only pursue the conventional positive temperature coefficient X8R, we can obtain a relatively flat TCC curve (temperature-capacitance characteristic curve) through optimization. However, it is more difficult to have a negative temperature coefficient than conventional X8R. This requires the capacitance to gradually decrease after the temperature rises, and there should be no sharp peak near room temperature. The curve should decrease slowly, continuously and controllably.

[0006] Therefore, the present invention provides (Ba 1-1.5y Bi y (Zr) x Ti 1-x O3 is used as the main crystalline phase, through Bi 3+ Substitution of Ba sites and introduction of corresponding A site vacancies can enhance local polarization and disrupt the long-range ferroelectric order of BaTiO3; simultaneously, through Zr... 4+ Equivalent substitution at Ti sites can regulate BO6 octahedral distortion and broaden the dielectric temperature response, thereby avoiding the problem of abrupt dielectric constant changes near phase transitions in traditional BaTiO3 ceramics. Building upon this, the present invention further introduces Ca, Sr, Mg, Mn, and SiO2: the Sr component can be used to adjust the average ionic radius and Curie temperature at A sites, enabling the material to exhibit a controllable negative temperature coefficient; the Ca component, in synergy with Sr, regulates the lattice tolerance factor and the low-temperature capacitance change rate, keeping the capacitance change within the X8R allowable range from -55℃ to 150℃; the Mg component can suppress abnormal grain growth, improve microstructure uniformity, and reduce domain wall motion losses; the Mn component can further reduce leakage conduction and dielectric losses through defect association, electron trapping, and domain wall pinning; and SiO2 can improve grain boundary insulation and further reduce high-temperature losses by promoting sintering densification and regulating grain boundary states.

[0007] Therefore, this invention is not a simple modification of BaTiO3 by a single component, but rather achieves a balance of high dielectric constant, X8R temperature characteristics, negative temperature coefficient, and tanδ≤0.11% (more preferably <0.1%) through the synergistic effect of Bi-Zr main phase adjustment, Ca-Sr temperature coefficient adjustment, Mg-Mn defect / grain adjustment, and SiO2 grain boundary adjustment. This is beneficial for supporting miniaturized, high-power, high-frequency, and all-weather reliable terminal devices.

[0008] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0009] In some embodiments, the perovskite-type compound (Ba) of the main component raw material described in this invention 1-1.5y Bi y (Zr) x Ti 1-x O3, 0 < x < 1, 0.001 ≤ y ≤ 0.40; where x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9, preferably 0.2 < x < 0.6; y can be 0.001, 0.003, 0.005, 0.01, 0.05, 0.08, 0.1, 0.15, 0.154, 0.18, 0.20, 0.23, 0.25, 0.28, 0.30 The molar amounts of Bi can be 0.33, 0.35, 0.38, or 0.40, preferably 0.01 ≤ y ≤ 0.2; that is, relative to 100 molar parts of Ba in the main component raw material, the molar amount of Bi can be 1 part, 3 parts, 5 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts, etc., so that it is doped into the main component raw material and together with Ba as A-site ions in the perovskite structure formula ABX3, while B-site ions are occupied by Zr and Ti.

[0010] In some embodiments, relative to 100 parts of Ba in the main component raw material, the molar amount of Ca or its compound can be 1 part, 2 parts, 3 parts, 4 parts, or 5 parts, etc.; the molar amount of Sr or its compound can be 0.5 parts, 0.8 parts, 1 part, 2 parts, 3 parts, 4 parts, or 5 parts, etc., preferably 1 part to 4 parts; the molar amount of Mg or its compound can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, or 1 part, etc.; the molar amount of Mn or its compound can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, or 1 part, etc., preferably 0.4 parts to 0.9 parts; the molar amount of SiO2 or silicon-containing compounds providing an equal amount of Si can be 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts, etc., preferably 0.3 parts to 5 parts.

[0011] In some embodiments, the by-product raw material includes CaZrO3 to provide Ca.

[0012] In some embodiments, the by-product raw material includes SrTiO3 to provide Sr element.

[0013] In some embodiments, the by-product raw material includes MgO to provide Mg element.

[0014] In some embodiments, the by-product raw material includes MnO to provide Mn element.

[0015] In some embodiments, the by-product raw material includes a glass component, the glass component system including Zn-B-Si, Ba-B-Si, Ba-B-Si-Al or Ba-Ca-Si, to provide SiO2.

[0016] In a second aspect, the present invention provides a method for preparing the dielectric ceramic described in the first aspect, the method comprising: The barium source, bismuth source, zirconium source and titanium source are first ball-milled and mixed, and then first calcined to obtain the first calcined product; The first calcined material is mixed with the by-product raw materials by a second ball mill, and then granulated, shaped, and debinded in sequence, followed by a second calcination to obtain dielectric ceramic.

[0017] In some embodiments, the barium source includes BaCO3.

[0018] In some embodiments, the zirconium source includes ZrO2.

[0019] In some embodiments, the titanium source includes TiO2.

[0020] In some embodiments, the bismuth source includes Bi2O3.

[0021] In some embodiments, the barium source, bismuth source, zirconium source, and titanium source are configured according to a perovskite compound (Ba 1- 1.5y Bi y (Zr) x Ti 1-x The stoichiometric amount of O3 is controlled, where 0 < x < 1, 0.001 ≤ y ≤ 0.40; that is, the first calcination forms a perovskite-type compound (Ba). 1-1.5y Bi y (Zr) x Ti 1-x O3, the first calcined product obtained is used as the main component raw material.

[0022] In some embodiments, the temperature of the first calcination is 800℃~1000℃, for example, it can be 800℃, 850℃, 900℃, 950℃ or 1000℃; the time is 1h~4h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h.

[0023] In some implementations, the by-product raw material for providing Ca includes CaZrO3.

[0024] In some implementations, the by-product raw material for providing Sr element includes SrTiO3.

[0025] In some embodiments, the by-product raw material for providing Mg element includes MgO.

[0026] In some embodiments, the by-component raw materials providing SiO2 include glass components, wherein the glass component system includes Zn-B-Si, Ba-B-Si, Ba-B-Si-Al, or Ba-Ca-Si.

[0027] In some implementations, the by-product raw materials providing Mn include MnO.

[0028] It should be noted that the chemical formula of the main component raw material perovskite-type compound in this invention (Ba 1-1.5y Bi y (Zr) x Ti 1-x O3 is determined by the amount of barium source, bismuth source, zirconium source and titanium source used. If the secondary raw materials used subsequently also include Ba, Bi, Zr or Ti elements of the main raw material, they are not included in the chemical formula of the main raw material.

[0029] In this invention, the amount of each auxiliary raw material should be controlled and adjusted according to the molar proportions of each element or component in the target generated or designed dielectric ceramic.

[0030] In some embodiments, the method for forming the dielectric ceramic includes dry pressing at a pressure of 0.2 T / cm. 2 ~1.8T / cm 2 For example, it could be 0.2T / cm 2 0.4T / cm 2 0.6T / cm 2 0.8T / cm 2 1T / cm 2 1.3T / cm 2 1.5T / cm 2 Or 1.8T / cm 2 wait.

[0031] In some embodiments, the second calcination temperature of the dielectric ceramic is 1100℃~1200℃, for example, it can be 1100℃, 1120℃, 1140℃, 1160℃, 1180℃ or 1200℃, etc.; the time is 1h~4h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, etc.

[0032] Thirdly, the present invention provides a terminal device comprising the dielectric ceramic described in the first aspect, or the dielectric ceramic obtained by the preparation method described in the second aspect.

[0033] It should be noted that, due to space limitations and to avoid redundancy, this invention does not exhaustively list all point values ​​within the above numerical range, but it is not limited to the listed values ​​either; other unlisted values ​​within the above numerical range are also applicable.

[0034] Compared with existing technical solutions, the present invention has at least the following beneficial effects: The dielectric ceramic provided by this invention, through reasonable composition and proportion, can achieve an ultra-low loss of ≤0.11%, while having a negative temperature coefficient and meeting the X8R temperature characteristics. The capacitance change rate does not exceed ±15% in the temperature range of -55℃ to +150℃, which is beneficial for supporting miniaturized, high-power, high-frequency and all-weather reliable terminal devices. Attached Figure Description

[0035] Figure 1 This is a test graph of the temperature-capacitance characteristic curve (TCC curve) of the dielectric ceramic obtained in Example 1.

[0036] Figure 2 This is a scanning electron microscope (SEM) image of the first calcined powder obtained in Example 1.

[0037] Figure 3 The image shows the SEM image of the first calcined powder obtained in Comparative Example 7.

[0038] Figure 4 The image shows the SEM image of the first calcined powder obtained in Comparative Example 8.

[0039] Figure 5 This is the elemental distribution test diagram of the dielectric ceramic obtained in Example 1 by EDS energy dispersive spectroscopy analysis.

[0040] Figure 6 This is the elemental distribution test diagram of the dielectric ceramic obtained in Comparative Example 7 using EDS energy dispersive spectroscopy.

[0041] Figure 7 This is the elemental distribution test diagram of the dielectric ceramic obtained in Comparative Example 8, obtained from EDS energy dispersive spectroscopy analysis.

[0042] Figure 8 The image shows the SEM test results of the dielectric ceramic obtained in Example 1.

[0043] Figure 9 This is a SEM image of the dielectric ceramic obtained in Comparative Example 7.

[0044] Figure 10 This is a SEM image of the dielectric ceramic obtained in Comparative Example 8. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0047] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0048] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0049] In this invention, the order in which the steps are written in the methods described in the various embodiments does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any conflict-free order, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0050] Example 1 This embodiment provides a dielectric ceramic, which is sintered from a mixture of main component raw materials and auxiliary component raw materials; the main component raw material is a perovskite-type compound (Ba).0.822 Bi 0.118 (Zr) 0.2 Ti 0.8 O3; relative to 100 molar parts of Ba in the main component raw material, the secondary component raw material includes: CaZrO3, to provide 3 parts of Ca element; SrTiO3, to provide 1.2 parts of Sr element; MgO, to provide 0.48 parts of Mg element; MnO, to provide 0.85 parts of Mn element; The glass composition is Zn-B-Si, providing 5 parts of SiO2.

[0051] This embodiment also provides a method for preparing the dielectric ceramic: According to the stoichiometric ratio of Ba, Bi, Zr and Ti, barium source BaCO3, bismuth source Bi2O3, zirconium source ZrO2 and titanium source TiO2 were first ball-milled and mixed, dried and then calcined at 900℃ for 2 hours to obtain the first calcined product; wherein, BaCO3 provided 100 molar amounts of Ba and Bi2O3 provided 14.4 molar amounts of Bi. The first calcined product was mixed with by-products containing Ca, Sr, Mg, SiO2, and Mn elements in a second ball mill. These by-products were CaZrO3, SrTiO3, MgO, glass component Zn-B-Si, and MnO, respectively. With Ba as the molar amount per 100 parts, the molar amounts of SiO2 and MnO in CaZrO3, SrTiO3, MgO, and glass component Zn-B-Si were controlled to be 3 parts, 1.2 parts, 0.48 parts, 5 parts, and 0.85 parts, respectively. The mixture was then dried, granulated, and milled at 1 T / cm³. 2 The material is dry-pressed under pressure, debinded, and then calcined at 1130℃ for 2 hours to obtain a dielectric ceramic.

[0052] Characterization and testing: I. Dielectric constant ε r Test: At standard room temperature of 25±1℃, a frequency of 1kHz was applied, and an AC test voltage of 1Vrms was used for testing; the ε of the dielectric ceramic obtained in this embodiment... r (25℃) is 706.

[0053] II. Loss Test: and Dielectric Constant ε r The test was conducted simultaneously to obtain the dielectric loss tangent tanδ value; the tanδ of the dielectric ceramic obtained in this embodiment is 0.09%.

[0054] III. Capacitor Temperature Characteristic (TCC) Test: The percentage change in capacitance value relative to a 25°C reference value at specified high and low temperatures, such as... Figure 1 The figure shown is the TCC curve obtained in this embodiment. It can be seen that the capacitance change rate of the dielectric ceramic obtained in this embodiment does not exceed ±15% in the temperature range of -55℃ to +150℃, which meets the X8R temperature characteristics. Moreover, the capacitance change rate shows a continuous decreasing trend from -55℃ to 25℃ and then to 150℃. This dielectric ceramic has a negative temperature coefficient.

[0055] IV. Insulation Resistance (IR) Test: At 25°C, a DC voltage is applied, and the resistance value is tested and calculated; the IR of the dielectric ceramic obtained in this embodiment is 209 × 10⁻⁶. 10 Ω.

[0056] Example 2 This embodiment provides a dielectric ceramic, which is sintered from a mixture of main component raw materials and auxiliary component raw materials; the main component raw material is a perovskite-type compound (Ba). 0.935 Bi 0.043 (Zr) 0.25 Ti 0.75 O3; relative to 100 molar parts of Ba in the main component raw material, the secondary component raw material includes: CaZrO3, to provide 1 part of Ca element; SrTiO3 provides 4.6 parts of Sr element; MgO, to provide 0.92 parts of Mg element; MnO, to provide 0.2 parts of Mn element; The glass composition is Ba-B-Si-Al, providing 3 parts of SiO2.

[0057] This embodiment also provides a method for preparing the dielectric ceramic: According to the stoichiometric ratio of Ba, Bi, Zr and Ti, barium source BaCO3, bismuth source Bi2O3, zirconium source ZrO2 and titanium source TiO2 were first ball-milled and mixed, dried and then calcined at 800℃ for 4 hours to obtain the first calcined product; wherein, BaCO3 provided 100 molar amounts of Ba and Bi2O3 provided 4.6 molar amounts of Bi. The first calcined product was mixed with by-products containing Ca, Sr, Mg, SiO2, and Mn elements in a second ball mill. These by-products were CaZrO3, SrTiO3, MgO, the glass composition Ba-B-Si-Al, and MnO, respectively. With Ba as the molar amount of 100 parts, the molar amounts of CaZrO3, SrTiO3, MgO, SiO2 in the Zn-B-Si glass composition, and MnO were controlled to be 1 part, 4.6 parts, 0.92 parts, 3 parts, and 0.2 parts, respectively. The mixture was then dried, granulated, and milled at 1 T / cm³. 2 The material is dry-pressed under pressure, debinded, and then calcined at 1190℃ for 2 hours to obtain a dielectric ceramic.

[0058] Example 3 This embodiment provides a dielectric ceramic, which is sintered from a mixture of main component raw materials and auxiliary component raw materials; the main component raw material is a perovskite-type compound (Ba). 0.876 Bi 0.082 (Zr) 0.3 Ti 0.7 O3; relative to 100 molar parts of Ba in the main component raw material, the secondary component raw material includes: CaZrO3, to provide 2 parts of Ca element; SrTiO3 provides 2.8 parts of Sr element; MgO, to provide 0.26 parts of Mg element; MnO, to provide 0.62 parts of Mn element; The glass composition is Zn-B-Si, providing 1 part SiO2.

[0059] This embodiment also provides a method for preparing the dielectric ceramic: According to the stoichiometric ratio of Ba, Bi, Zr and Ti, barium source BaCO3, bismuth source Bi2O3, zirconium source ZrO2 and titanium source TiO2 were first ball-milled and mixed, dried and then calcined at 1000℃ for 1 hour to obtain the first calcined product; wherein, BaCO3 provided 100 molar amounts of Ba and Bi2O3 provided 9.4 molar amounts of Bi. The first calcined product was mixed with by-products containing Ca, Sr, Mg, SiO2, and Mn elements in a second ball mill. These by-products were CaZrO3, SrTiO3, MgO, glass component Zn-B-Si, and MnO, respectively. With Ba as the molar amount of 100 parts, the molar amounts of SiO2 and MnO in CaZrO3, SrTiO3, MgO, and glass component Zn-B-Si were controlled to be 2 parts, 2.8 parts, 0.26 parts, 1 part, and 0.62 parts, respectively. The mixture was then dried, granulated, and milled at 1 T / cm³. 2 The material is dry-pressed under pressure, debinded, and then calcined at 1160℃ for 2 hours to obtain a dielectric ceramic.

[0060] Examples 4 to 6 and Comparative Examples 1 and 7 The difference from Example 1 is that the amount of bismuth source Bi2O3 added is adjusted so that the molar amount of Bi element provided is changed from 14.4 parts to 1 part, 7 parts, 20 parts, 0 parts (i.e. no bismuth source Bi2O3 is added) and 45 parts respectively. Apart from the above, the other conditions are exactly the same as those in Example 1.

[0061] Examples 7 to 8 and Comparative Example 2 The difference from Example 1 is that the amount of CaZrO3 added is adjusted so that the molar amount of Ca provided is changed from 3 parts to 1 part, 5 parts and 0 parts respectively (i.e. no CaZrO3 is added). Apart from the above, the other conditions are exactly the same as those in Example 1.

[0062] Examples 9 to 10 and Comparative Example 3 The difference from Example 1 is that the amount of SrTiO3 added is adjusted so that the molar amount of Sr element provided is changed from 1.2 parts to 0.5 parts, 2.5 parts and 0 parts respectively (i.e. no SrTiO3 is added). Apart from the above, the other conditions are exactly the same as those in Example 1.

[0063] Examples 11 to 12 and Comparative Example 4 The difference from Example 1 is that the amount of MgO added is adjusted so that the molar amount of Mg provided is changed from 0.48 parts to 0.1 parts, 1 part and 0 parts (i.e. no MgO is added). Apart from the above, the other conditions are exactly the same as those in Example 1.

[0064] Examples 13 to 14 and Comparative Example 5 The difference from Example 1 is that the amount of MnO added is adjusted so that the molar amount of Mn element provided is changed from 0.85 parts to 0.4 parts, 1 part and 0 parts (i.e. no MnO is added). Apart from the above, the other conditions are exactly the same as those in Example 1.

[0065] Examples 15 to 16 and Comparative Examples 6 and 8 The difference from Example 1 is that the amount of Zn-B-Si added to the glass composition is adjusted so that the molar amount of SiO2 provided is changed from 5 parts to 0.2 parts, 2 parts, 0 parts (i.e. no SiO2 is added) and 8 parts respectively. Apart from the above, the other conditions are exactly the same as those in Example 1.

[0066] Examples 17 to 18 The difference from Example 1 is that the second calcination temperature was adjusted from 1130°C to 1100°C and 1200°C respectively. Apart from the above, the other conditions are exactly the same as those in Example 1.

[0067] The dielectric ceramics obtained in each embodiment and comparative example were tested according to the characterization and testing methods in Example 1, and the results are recorded in Table 1.

[0068] Table 1

[0069] As shown in Table 1, the dielectric ceramics provided in Examples 1 to 3 of this invention, through reasonable composition and proportioning, can achieve ultra-low losses of ≤0.11%, while possessing a negative temperature coefficient and meeting X8R temperature characteristics. The capacitance change rate within the temperature range of -55℃ to +150℃ does not exceed ±15%, which is beneficial for supporting miniaturized, high-power, high-frequency, and all-weather reliable terminal devices. Comparing Example 1 with Examples 4 to 18 and Comparative Examples 1 to 6, it can be seen that in the dielectric ceramics provided by this invention, the amount of Bi element is controlled according to a molar amount of 1 to 20 parts, i.e., the main component raw material chemical formula (Ba 1-1.5y Bi y (Zr) x Ti 1-x In O3, a value of y of 0.01 to 0.2 is preferred; at the same time, the content of the by-component raw materials is preferably 1 to 5 parts of Ca element or its compound, 1 to 4 parts of Sr element or its compound, 0.1 to 1 part of Mg element or its compound, 0.4 to 0.9 parts of Mn element or its compound, 0.3 to 5 parts of SiO2 or silicon compound providing an equal amount of Si, which can achieve better synergistic optimization effect and further improve the performance of dielectric ceramics.

[0070] Further analysis using characterization test charts: (one) Figure 2The image shows a scanning electron microscope (SEM) image of the first calcined powder obtained in Example 1. As can be seen from the image, the powder particles have a diameter range of 200 nm to 500 nm, with a relatively concentrated particle size distribution and good dispersion. The SEM image of the dielectric ceramic obtained after further ball milling and second calcination using this first calcined powder is shown below. Figure 8 As shown, the grain boundaries of the grains after calcination and hot corrosion are relatively clear, and the grains are mainly distributed in the range of 0.5μm to 2μm, exhibiting multiphase composite and small-to-medium grain gradation characteristics. This microstructure is consistent with the mechanisms of Mg inhibiting abnormal grain growth, Mn regulating defects and domain wall movement, and SiO2 promoting densification and regulating grain boundary state. At the same time, Ca, Sr, and Zr have a regulatory effect on the lattice parameters, phase transition temperature, and BO6 octahedral distortion of the BaTiO3-based main crystalline phase. Furthermore, the small-to-medium grain gradation helps to limit domain size growth and long-range domain wall movement, reducing the sharp dielectric peak of BaTiO3 near the phase transition. Multi-component solid solution and grain boundary regulation disperse the polarization response and phase transition temperature range of different microregions, thus promoting the formation of dispersed phase transition behavior. Therefore, the TCC curve of the dielectric ceramic obtained in Example 1 is more likely to remain flat in the range of -55℃ to 150℃, and the dielectric loss and leakage conduction are suppressed. At the same time, it avoids the local electric field concentration caused by abnormally large grains, which is beneficial to improving insulation resistance and breakdown stability.

[0071] at the same time, Figure 5 EDS-Mapping tests on the dielectric ceramic of Example 1 showed that no significant large-area enrichment or depletion of the major elements, indicating that Bi, Zr, Ca, Sr, Mg, Mn, and Si components have good dispersion consistency in the ceramic matrix and grain boundary regions. This result further confirms that Bi... 3+ Replaces the Ba bit and is accompanied by a vacancy at the A bit and Zr 4+ Equivalent substitution of Ti sites can regulate BO6 octahedral distortion, corresponding to the mechanism by which Ca, Sr, Mg, Mn, and SiO2 synergistically regulate microstructure and dielectric properties. Uniform distribution of elements facilitates the uniform occurrence of local lattice distortion, A-site vacancy compensation, grain boundary modification, and domain wall regulation within the sample, avoiding the formation of localized Bi-enriched phases, Zr-enriched phases, or glassy phase agglomerations. This, on the one hand, helps to weaken the long-range ferroelectric order of BaTiO3 and broaden the dielectric peak, resulting in a smoother capacitance change rate in the -55℃ to 150℃ range; on the other hand, it helps to maintain the continuity of grain boundary insulation, reducing local leakage channels and electric field concentration, thereby lowering dielectric loss and improving insulation resistance and breakdown stability.

[0072] (ii) Compared with the results of Example 1, Figure 3 and Figure 9 The images shown are SEM images of the first calcined powder and the dielectric ceramic obtained in Comparative Example 7, respectively. Figure 3 The sample contained abnormally large powder particles with a diameter of 770nm. Figure 9 The results show that the dielectric ceramic obtained in this comparative example exhibits significantly abnormally large grains, with the largest grain reaching approximately 5.75 μm. This indicates that an excess of Bi-related low-melting-point enriched phases or liquid phases promotes rapid migration of local grain boundaries, leading to uneven grain growth rates. Simultaneously, Bi segregation results in uneven distribution of A-site vacancies and defect compensation, thus diminishing the potential benefits of Bi for regulating long-range ferroelectric order and widening the phase transition range. 3+ The substitution effect shifts from "uniform regulation" to "local enrichment." Based on this, anomalously large grains typically have larger domain sizes and more active domain wall motion, easily increasing dielectric loss and temperature sensitivity. The significant differences in grain boundary curvature, defect concentration, and stress state between large grains and surrounding fine grains easily lead to localized electric field concentration. Therefore, the inhibitory effect of fine-grained structures on domain wall motion weakens, and the TCC planarization effect decreases. Leakage channels or breakdown initiation points are more likely to form at the junctions of segregated regions and anomalous grains, resulting in increased Tanδ, decreased IR, and reduced breakdown reliability.

[0073] at the same time, Figure 6 The figure shows the EDS-Mapping test results of the dielectric ceramic obtained in Comparative Example 7. It indicates that excessive Bi leads to significant uneven distribution and segregation, suggesting that excessive Bi... 3+ Bi cannot completely penetrate the BaTiO3-based main crystalline phase through homogeneous solid solution and defect compensation, and tends to form Bi-enriched phases, low-melting-point phases, or Bi-rich second phases at grain boundaries or triple points. This phenomenon will cause "Bi 3+ The effect of Bi substitution at Ba sites and the introduction of A-site vacancies to regulate polarization and disrupt long-range ferroelectric order has shifted from uniform regulation to localized concentrated regulation. In other words, Bi enrichment leads to uneven local A-site vacancy concentrations, lattice distortion, and charge compensation states, resulting in increased differences in polarization intensity, dielectric response, and conductivity across different microregions. Consequently, segregated regions are prone to forming localized electric field concentrations and leakage conduction channels, leading to decreased insulation resistance and breakdown stability. Excessive low-melting-point phases may also promote liquid-phase sintering and abnormal grain growth, causing uncontrolled grain gradation, further increasing dielectric loss and reducing temperature stability.

[0074] It should be noted that, Figure 6 as well as Figure 7 In the process, due to the automatic identification and misjudgment of EDS software, background noise or weak peaks were identified as Co elements when automatically matching elements. Due to peak overlap or insufficient background subtraction, false positive distribution maps were easily generated in weak signal areas. It is also possible that due to sample preparation or sample stage contamination, trace amounts of foreign contamination may produce extremely weak signals. Co element raw materials were not added during product preparation, and it is not an actual component contained in dielectric ceramics.

[0075] (iii) Compared with the results of Example 1, Figure 4 and Figure 10 The images shown are SEM images of the first calcined powder and the dielectric ceramic obtained in Comparative Example 8, respectively. Figure 4 Not only were there abnormally large 789nm powder particles, but there was also obvious powder agglomeration. Figure 10 The data shows that the dielectric ceramic obtained in this comparative example has a large number of grains larger than 2 μm, with the largest grain being approximately 4.35 μm. This indicates that excessive glass, as a sintering aid, leads to an overly strong liquid-phase sintering effect, easily promoting selective grain growth in some areas. Simultaneously, the enriched glass phase may remain at grain boundaries and triple points. Excessive glass phase, on the one hand, reduces the effective dielectric constant through a "low-dielectric phase series dilution effect," and on the other hand, introduces interface regions with significant differences in dielectric constant, conductivity, and thermal expansion coefficients at grain boundaries and triple points, causing Maxwell-Wagner type interface polarization, local electric field distortion, and increased high-temperature leakage conductance. This results in decreased εr, increased Tanδ, decreased IR and breakdown stability, and makes the high-temperature capacitance change rate more prone to deviating from the target range. Therefore, the amount of SiO2 should be controlled appropriately to promote sintering densification and regulate grain boundary conditions, avoiding the formation of low-dielectric-constant inactive glass phases and local weak interfaces caused by excessive SiO2, which leads to an uneven spatial distribution of the main crystalline phase, grain boundary phase, and pores.

[0076] from Figure 10 The results obtained can be further corroborated with the Si-Zn segregation observed in EDS-Mapping tests, such as... Figure 7 The EDS-Mapping test results of the dielectric ceramic obtained in Comparative Example 8 are shown. It can be seen that excessive glass content leads to significant Si-Zn segregation, indicating that the glass sintering aid failed to maintain a uniform, discrete grain boundary distribution, instead forming enriched glass phases in localized areas. This further verifies that an appropriate amount of SiO2 can promote sintering densification, improve grain boundary insulation, and regulate grain boundary state; however, when the glass phase content is too high or unevenly distributed, the glass phase will form local enrichments at grain boundaries and triple points, even forming a nearly continuous low-dielectric phase network. Comparing the data of Comparative Example 8 with Example 1 demonstrates that this segregation in Comparative Example 8 has the following adverse effects: First, the low-dielectric-constant glass phase dilutes the effective polarization volume fraction of the BaTiO3-based main crystal phase, leading to a decrease in dielectric constant; second, the difference in dielectric constant and conductivity between the enriched glass phase and the ceramic grains easily causes interfacial polarization and local electric field concentration, increasing Tanδ; third, the enriched grain boundary phase may increase leakage conductance at high temperatures, reducing IR and breakdown stability. Therefore, the glass composition should be controlled within a range that promotes densification without causing significant segregation.

[0077] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A dielectric ceramic, characterized in that, It is formed by sintering a mixture containing a main component raw material and a secondary component raw material; the main component raw material is a perovskite-type compound (Ba). 1-1.5y Bi y (Zr) x Ti 1-x )O3, 0<x<1, 0.001≤y≤0.40; Based on a molar amount of 100 parts of Ba in the main component raw material, the secondary component raw material includes: 1 to 5 parts of elemental Ca or its compounds; 0.5 to 5 parts of Sr element or its compounds; 0.1 to 1 part of Mg or its compounds; 0.1 to 1 part of Mn element or its compound; 0.2 to 5 parts of SiO2 or a silicon-containing compound providing an equal amount of Si.

2. The dielectric ceramic according to claim 1, characterized in that, The temperature characteristics of the dielectric ceramic meet the X8R requirements, have a negative temperature coefficient, and have a dielectric loss ≤0.11%.

3. The dielectric ceramic according to claim 1 or 2, characterized in that, 0.2<x<0.6, 0.01≤y≤0.2; And / or, the by-product raw materials include: 1 to 5 parts of elemental Ca or its compounds; 1 to 4 parts of Sr element or its compounds; 0.1 to 1 part of Mg or its compounds; 0.4 to 0.9 parts of Mn element or its compounds; 0.3 to 5 parts of SiO2 or a silicon-containing compound providing an equal amount of Si.

4. The dielectric ceramic according to claim 1 or 2, characterized in that, The by-product raw material includes CaZrO3 to provide Ca element; And / or, the by-product raw material includes SrTiO3 to provide Sr element; And / or, the by-product raw material includes MgO to provide Mg element; And / or, the by-product raw material includes MnO to provide Mn element; And / or, the by-product raw materials include glass components, the glass component system including Zn-B-Si, Ba-B-Si, Ba-B-Si-Al or Ba-Ca-Si, to provide SiO2.

5. A method for preparing a dielectric ceramic according to any one of claims 1-4, characterized in that, The preparation method includes: The barium source, bismuth source, zirconium source and titanium source are first ball-milled and mixed, and then first calcined to obtain the first calcined product; The first calcined material is mixed with the by-product raw materials by a second ball mill, and then granulated, shaped, and debinded in sequence, followed by a second calcination to obtain dielectric ceramic.

6. The method for preparing dielectric ceramics according to claim 5, characterized in that, The barium source includes BaCO3; And / or, the bismuth source includes Bi2O3; And / or, the zirconium source includes ZrO2; And / or, the titanium source includes TiO2.

7. The method for preparing dielectric ceramics according to claim 5, characterized in that, The first calcination temperature is 800℃~1000℃, and the time is 1h~4h.

8. The method for preparing dielectric ceramics according to claim 5, characterized in that, The by-product raw materials that provide Ca include CaZrO3; And / or, the by-product raw materials providing Sr elements include SrTiO3; And / or, by-product raw materials providing Mg element include MgO; And / or, the by-component raw materials providing SiO2 include glass components, wherein the glass component system includes Zn-B-Si, Ba-B-Si, Ba-B-Si-Al or Ba-Ca-Si; And / or, the by-product raw materials for providing Mn element include MnO.

9. The method for preparing dielectric ceramics according to claim 5, characterized in that, The molding method includes dry pressing, with a pressure of 0.2 T / cm. 2 ~1.8T / cm 2 ; And / or, the second calcination temperature is 1100℃~1200℃, and the time is 1h~4h.

10. A terminal device, characterized in that, The dielectric ceramic comprising any one of claims 1-4, or the dielectric ceramic comprising any one of claims 5-9.

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