TW201917110A - Ceramic sintered body and passive component including the same - Google Patents

Abstract

The present disclosure provides a ceramic sintered body having a favorable dielectric constant. In some embodiments of the present disclosure, the ceramic sintered body includes a semiconductor ceramic phase dispersed in a dielectric ceramic phase, wherein the semiconductor ceramic phase and the dielectric ceramic phase jointly form a percolative composite, and a volume fraction of the semiconductor ceramic phase is close to and less than a percolation threshold.

Description

Ceramic sintered body and passive components including the same

The present invention relates to a ceramic sintered body and a passive component comprising the same, in particular to a ceramic sintered body having a preferred dielectric constant, and a passive component comprising the ceramic sintered body .

Passive components such as capacitors are typically made of a dielectric material. In general, the capacitance of a capacitor is related to the dielectric constant of the dielectric material from which the capacitor is made. That is, the dielectric constant of the dielectric material is higher so that the capacitance of the capacitor is higher. Since an ideal capacitor should have a small size and a high capacitance, it is necessary to provide a material having a high dielectric constant.

The present invention provides a ceramic sintered body having a preferred dielectric constant.

In some embodiments of the present invention, the ceramic sintered body comprises a semiconductor ceramic phase dispersed in a dielectric ceramic phase, wherein the semiconductor ceramic phase and the dielectric ceramic are in common A percolative composite is formed and the volume fraction of the semiconductive ceramic phase is close to and below a percolation threshold.

The present invention further provides a passive component comprising the aforementioned ceramic sintered body.

In theory, ferroelectric materials are expected to have very high dielectric constants only in a very narrow temperature range close to a ferroelectric-paraelectric phase transition. However, it is conventional to obtain a capacitor having an acceptable dielectric constant by a multilayer structure. Specifically, a plurality of ferroelectric ceramic material layers are placed between a plurality of conductive layers to form a multilayered ceramic capacitor (MLCC). In the conventional MLCC, the thickness of the ferroelectric ceramic layer is a key factor affecting its capacitance. The capacitance of the MLCC can be increased by reducing the thickness of the ferroelectric ceramic layer using a ferroelectric ceramic material having a smaller grain size. However, due to the so-called "Size-Effect", ferroelectric ceramic materials having a small particle size exhibit a small dielectric constant. The conventional criteria for obtaining a higher capacitance of the MLCC by a thinner dielectric layer will theoretically be deadlocked.

Another way to obtain a capacitor with an acceptable dielectric constant is by means of a percolation complex, which can be explained in terms of percolation theory. In general, "percolation theory" describes the behavior of a connected cluster in a random graph. In the field of capacitor related art, percolation theory can be used to describe the case where conductive grains form a current path to pass through a space filled by insulating grains. When the conductive particles are mixed with the insulating particles, the conductive particles are sufficient to form a current path to define a "permeation threshold" through the lowest volume fraction of the space filled by the insulating particles. In other words, when the volume fraction of the conductive particles reaches the percolation threshold, a portion of the conductive particles are connected to each other to form a current path to pass through the space filled by the insulating particles. An increase in the volume fraction of the conductive particles causes an increase in the dielectric constant exhibited by the composite. The composite exhibits a large dielectric constant when the volume fraction of the conductive particles is just before the percolation threshold (this is the highest conductive particle volume fraction before the percolation threshold). The percolative threshold power law is described below.

The above-mentioned percolation composite uses a metal material and a dielectric ceramic material as the conductive particles and the insulating particles, respectively. The fine metal particles have a large surface energy. When mixed with dielectric ceramic particles, the metal particles tend to agglomerate together and thus cannot be uniformly dispersed in the mixture. When the mixing process is carried out on a large scale, the aggregation of metal particles may even be more serious. In addition, since the melting point of the metal particles (such as nickel) is usually lower than the melting point of the ceramic particles, the metal particles melt earlier than the insulating particles during the sintering process, resulting in a large grain growth during the sintering process (abnormal grain growth). ). Metal particles made of a noble metal having a high melting point such as platinum can be used to avoid abnormal grain growth during the sintering process, while the cost may be correspondingly increased. In view of the above, such percolation composites cannot meet industrial requirements.

In order to at least solve the above problems, the present invention provides a ceramic sintered body comprising a semiconductor ceramic phase dispersed in a dielectric ceramic phase, wherein the semiconductor ceramic phase and the dielectric ceramic phase together form a percolation composite, and the volume of the semiconductor ceramic phase is divided. The rate is close to and below the percolation threshold. By using a semiconductor ceramic material instead of the aforementioned metal material as the conductive phase, aggregation of the conductive phase and abnormal grain growth can be avoided. Therefore, such percolation composites having a good dielectric constant can be successfully produced.

As used herein, the terms "substantially", "substantially", "substantial" and "about" are used to describe and account for minor changes. When used in connection with an event or circumstance, the term can refer to the circumstances in which the event or circumstance occurs explicitly and the event or circumstance is very similar. For example, when used in connection with a value, the terms may mean a range of variation less than or equal to ±10% of the value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, Less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.

In addition, quantities, ratios, and other values are sometimes presented in a range format herein. It is to be understood that the scope of the present invention is to be construed as being limited to the scope of the Each value and sub-range are explicitly specified.

In the present invention, the term "ceramic sintered body" means a sintered body which is made of a ceramic material. The ceramic sintered body may be sintered from two or more ceramic materials. For example, the ceramic sintered body may be sintered from a plurality of ceramic grains, and these ceramic particles are combined to form a monolithic structure.

In the present invention, the term "phase" refers to a spatial region in which all physical properties of the material throughout the spatial region are substantially uniform. Examples of physical properties include, but are not limited to, density, refractive index, magnetization, electrical conductivity, dielectric constant, and chemical composition. The phase is preferably a physically and chemically uniform region of material and is physically distinct. For example, in some embodiments of the invention, the ceramic sintered body includes a semiconducting ceramic phase dispersed in a dielectric ceramic phase. The semiconducting ceramic phase is substantially made of a material having a conductivity that is substantially uniform within the semiconducting ceramic phase. Similarly, the dielectric ceramic phase is substantially made of another material having a conductivity that is substantially uniform within the dielectric ceramic phase. In addition, the electrical conductivity of the semiconducting ceramic phase is different from the electrical conductivity of the dielectric ceramic phase.

In some embodiments of the invention, the dielectric ceramic phase is more similar to a continuous phase when compared to a semiconducting ceramic. On the other hand, the semiconducting ceramic phase is more similar to the dispersed phase dispersed in the dielectric ceramic phase. For purposes of illustration, Figure 1 shows the microstructure of a ceramic sintered body in accordance with some embodiments of the present invention. The ceramic phase 11 is dispersed in the dielectric ceramic phase 12 to form a percolation composite. It is noted that the ceramic sintered body according to some embodiments of the present invention may include more than one semiconducting ceramic phase and/or more than one dielectric ceramic phase.

In certain embodiments of the invention, the dielectric ceramic phase refers to a phase composed of a ceramic material having dielectric properties. For example, the dielectric ceramics have a resistivity greater than about 10 ⁸ Ω-cm.

In certain embodiments of the invention, the semiconducting ceramic phase refers to a phase composed of a ceramic material having semiconducting properties. For example, the semiconducting ceramic phase can be an n-type semiconductor and have an electrical conductivity greater than about 0.5 S/m, or greater than about 1.0 S/m.

In some embodiments of the invention, percolation capacitance refers to the highest volume fraction of the semiconducting ceramic phase that is just prior to forming a current path through the dielectric ceramic phase. The percolation threshold is the fraction of the semiconductor ceramic phase that is just sufficient to form a current path through the dielectric ceramic phase. The exact value of the percolation threshold can be determined by the material of the semiconducting ceramic phase and the dielectric ceramic phase, the particle size of the material, and the sintering temperature of the ceramic sintered body. The percolation threshold can be obtained by measurement or simulation, which can be understood by those of ordinary skill in the art.

In the present invention, the volume fraction of the semiconductive ceramic phase of the percolation composite is very close to the percolation threshold. The volume fraction of the semiconductive ceramic phase in the percolation composite may be several percentage points below the percolation threshold.

The dielectric constant of the ceramic sintered body (including the dielectric ceramic phase and the semiconductive ceramic phase) diverge at the percolation threshold. Therefore, since the dielectric ceramic phase and the semiconductive ceramic phase together form a percolative structure, and the volume fraction of the semiconductive ceramic phase is very close to the percolation threshold, the ceramic sintered body can have an elevated dielectric constant. That is, as the volume fraction of the semiconductive ceramic phase increases in a region close to the percolation threshold, the dielectric constant of the ceramic sintered body increases exponentially.

In some embodiments, the volume fraction of the semiconductive ceramic phase in the percolation composite can be from about 0.05% to about 20% below the percolation threshold. For example, if the percolation threshold under specific conditions is 30%, the volume fraction of the semiconductive ceramic in the sub-percolative composite under the same conditions may be about 30-0.05%. Up to about 30-20%. In some embodiments, the volume fraction of the semiconductive ceramic phase in the percolation composite can be from about 0.05% to about 10%, from about 0.05% to about 5%, or from about 0.05% to about 3% below the percolation threshold. . In some embodiments of the invention, the volume fraction of the semiconducting ceramic phase is near and below the percolation threshold. In some embodiments, the volume fraction of the semiconducting ceramic phase can be from about 0.999 to about 0.33 times the exact value of the percolation threshold. For example, if the percolation threshold under specific conditions is 30%, the volume fraction of the semiconductive ceramic phase in the sub-permeability composite under the same conditions may be about (30 × 0.999)% to about (30) × 0.33)%. In some embodiments, the volume fraction of the semiconducting ceramic phase can be from about 0.999 to about 0.65, about 0.999 to about 0.75, about 0.999 to about 0.85, or about 0.999 times the exact value of the percolation threshold. Up to about 0.9 times.

In some embodiments, for example, the percolation threshold under predetermined conditions can be calculated. The model used to calculate the percolation threshold under predetermined conditions can be found at least in CD Lorenz and RM Ziff, J. Chem. Phys . 114 3659 (2001), S. Kirkpatrick, Rev. Mod. Phys . 45 574 (1973), D Stauffer, Phys Rep . 54 1 (1979), and TG Castner, et al., Phys. Rev. Lett. 3 4 1627 (1975) and others.

The exact value of the volume fraction of the semiconducting ceramic phase in the sub-permeate composite can be largely determined by the particle size of the semiconducting ceramic phase and the dielectric ceramic phase and its geometrical distribution. For example, if the particle size of the dielectric ceramic phase is much smaller than the particle size of the semiconductive ceramic phase, and if it is distributed very uniformly, the volume fraction of the semiconducting ceramic phase may be large. On the other hand, if the particle size of the dielectric ceramic phase is much larger than the particle size of the semiconductive ceramic phase, and if it is geometrically well distributed, the volume fraction of the semiconductive ceramic phase may be small. However, in some embodiments, if the semiconductor ceramic phase has a particle size of about 3.0 microns and the dielectric ceramic phase has a particle size of about 0.2 microns, the volume fraction of the semiconductive ceramic phase is preferably from about 5% to about 60. More preferably, it is from about 15% to about 40%; still more preferably from about 20% to about 35%. If the semiconductor ceramic phase has a particle size of about 1.0 μm and the dielectric ceramic phase has a particle size of about 0.2 μm, the volume fraction of the semiconductive ceramic phase is preferably from about 5% to about 60%, more preferably about 15%. Up to about 40%, more preferably from about 25% to about 35%. And if the semiconductor ceramic phase has a particle size of about 0.2 μm and the dielectric ceramic phase has a particle size of about 0.1 μm, the semiconductor ceramic phase has a volume fraction of 5% to 55%, more preferably 15% to 35%. More preferably, it is about 20% to 30%. However, in some embodiments, the shape of the semiconducting ceramic phase can significantly affect the exact value of the percolation threshold.

For example, materials of the dielectric ceramic phase according to some embodiments of the present invention include CaZrTi ₂ O ₇ (zirconolite), CaZrO ₃ , SrZrO ₃ , BaZrO ₃ , TiO ₂ (rutile, rutile), ZrO ₂ , or a solid solution thereof (for example, a solid solution thereof may include Ti _{1 - x} Zr _x O ₂ , where x is a reasonable number between 0 and 1; or Ca _{1 - x} Sr _x ZrO ₃ , wherein x is a reasonable number between 0 and 1.) In the case where the dielectric ceramic phase comprises calcium-titanium zircon, the dielectric ceramic phase can be clearly distinguished from the semiconducting ceramic phase.

For example, materials for semiconductor ceramic phases in accordance with some embodiments of the present invention include perovskite materials. As will be readily understood by those skilled in the art, "perovskite material" refers to a class of compounds having the same type of crystal structure ^XII A ^{2 + VI} B ^{4 +} X ^{2 −} ₃ . "A" and "B" are two cations with extremely different sizes, and "X" is an anion bonded to both. The "A" atom is larger than the "B" atom. The ideal cubic symmetry has a 6-coordinate "B" cation surrounded by an anionic octahedron; and a 12-coordinated cubic octahedral "A" cation. In some embodiments of the present invention, the perovskite material comprises strontium titanate (SrTiO _3), barium titanate (BaTiO _3), calcium titanate (CaTiO _3), Ni (NiTiO ₃₎ titanate, manganese titanate ( MnTiO ₃ ), cobalt titanate (CoTiO ₃ ), copper titanate (CuTiO ₃ ), magnesium titanate (MgTiO ₃ ) or a complex thereof. Preferably, the perovskite material can be in a reduced state, such as reduced by, for example, a reducing atmosphere. In some embodiments of the present invention, the semiconductor material of the ceramic phase comprises the reduction of TiO ₂ (rutile), i.e., TiO _{2 - x;} hypoxia (oxygen deficient state) of the semiconductor. The reduced TiO ₂ (rutile) can be reduced, for example, by a reducing atmosphere.

Although there is a lattice mismatch in the perovskite material, CaZrTi ₂ O ₇ , TiO ₂ (rutile) and ZrO ₂ , because Ti will be in the perovskite material during the sintering process (where ^XII A ^{2 +} "B" of ^VI B ^{4 +} X ^{2 −} ₃ is Ti) and mutual diffusion between CaZrTi ₂ O ₇ and TiO ₂ (rutile), and Zr will be in CaZrTi ₂ O ₇ , CaZrO ₃ , SrZrO _{3. The} interdiffusion between BaZrO ₃ and ZrO ₂ can solve the problem of such lattice mismatch. Therefore, when the above materials are used as the semiconductive ceramic phase and the dielectric ceramic phase, they can be sintered together without cracking, rupture, brittle failure, and fracture, thereby providing ceramics. Good structural strength of the sintered body.

Moreover, in some embodiments of the invention, the dielectric ceramic phase is further doped with another additive. For example, the additive is an acceptor-type additive such as V, Nb, Cr. Further, the additive may be a manganese compound, a magnesium compound, a phthalate compound, a tungsten compound or an alumina compound to improve dielectric properties. In some embodiments of the invention, the dielectric ceramic phase may be further doped with a dopant such as MnO ₂ , MgO or WO ₃ . Such dopants can enhance the dielectric properties of the dielectric ceramic phase, for example, increasing the resistivity and reliability of the dielectric ceramic phase.

Similarly, in some embodiments of the invention, the semiconducting ceramic phase is further doped with an additive. For example, the additive is a donor-type additive such as Y, Nb or La, thus forming Y ₂ O ₃ , Nb ₂ O ₅ , La ₂ O ₃ in the semiconductor ceramic phase. Such additives can enhance the semiconducting properties of the semiconducting ceramic phase, for example, to increase the electrical conductivity of the semiconducting ceramic phase. The reduced donor perovskite compound is doped with a donor additive to form a high donor density n-type semiconducting material.

The present invention further provides a passive component comprising the aforementioned ceramic sintered body. In the present invention, a passive component is an electronic component that does not require energy to operate in addition to the available alternating current (AC) circuitry to which it is connected. Passive components do not have power gain and are not energy sources. For example, passive components include two-terminal components such as resistors, capacitors, inductors, and transformers.

The present invention relates to a method of producing the above ceramic sintered body. The method comprises mixing semiconductor ceramic particles and dielectric ceramic particles to form a mixture, and sintering the mixture under a neutral atmosphere.

In some embodiments of the invention, the semiconducting ceramic particles are made of the same material as the semiconducting ceramic described above. However, it is worth noting that both rutile and anatase structures provide TiO ₂ particles. The semiconductor ceramic particles may range in size from about 0.1 microns to about 5 microns, preferably from about 0.2 microns to about 2 microns. Similarly, the dielectric ceramic particles are made of the same material as the dielectric phase described above. The dielectric ceramic particles may range in size from about 0.1 microns to about 5 microns, preferably from about 0.2 microns to about 2 microns. The mixing of the semiconductive ceramic particles with the dielectric ceramic particles can be achieved by, for example, a bead miller. After mixing, the mixture is sintered under a neutral atmosphere such as N ₂ , He, Ar or the like. The sintering temperature can be, for example, from about 1100 ° C to about 1500 ° C.

In some embodiments of the invention, the method further comprises mixing the semiconductor particles, dielectric particles, and binder in a solvent, and removing the binder and solvent prior to sintering. For example, the binder includes polyvinyl alcohol (PVA), polyacrylate, and ethyl cellulose. The solvent includes ethanol, toluene, methyl ethyl ketone (MEK), diethylene glycol monobutyl ether (BC), and butyl carbitol acetate (butyl carbitol acetate, BCA) and combinations thereof. Other sintering aids such as SiO ₂ , GeO ₂ , B ₂ O ₃ and the like may also be added to increase the sintered density and lower the sintering temperature. Solvent refers to a liquid used to mix semiconductor ceramic particles and dielectric ceramic particles. Preferably, the solvent does not react with the semiconducting ceramic particles, the dielectric ceramic particles and/or the binder. For example, the solvent includes an alcohol, an ether, and the like.

The following examples are merely illustrative of the invention, but the scope of the invention is not limited thereto.

Example 1: A ceramic sintered body comprising a TiO ₂ -ZrO ₂ solid solution as a dielectric ceramic phase and a SrTiO ₃ -CaTiO ₃ solid solution as a semiconductor ceramic phase

Figure 2 shows a schematic manufacturing flow of Example 1. 0.075 moles of strontium carbonate (SrCO ₃ ), 0.075 moles of calcium carbonate (CaCO ₃ ), and 0.15 moles of TiO ₂ (rutile) were mixed in a bead mill (zirconia beads, 0.1 mm in diameter) in ethanol. After mixing, the mixed powder was dried in a stream of nitrogen. The resulting mixture was dry-ground and calcined at 1,000 ° C for 5 hours in a stream of N ₂ + H ₂ (95% + 5%) to obtain a black semiconductor (Sr _0.5 Ca _0.5 )TiO ₃ powder. 0.5 mol of zirconia (ZrO ₂ ) and 0.5 mol of titanium oxide (TiO ₂ ) (rutile) were added to the dry milled powder and mixed again by a bead mill.

100 parts by weight of the powder thus formed was mixed in ethanol and ground, and then mixed with 15 parts by weight of PVA binder, 0.1 part by weight of SiO ₂ and 0.05 part by weight of Al ₂ O ₃ to form a slurry. The slurry was coated on a polyethylene terephthalate carrier tape using a coater to form a green sheet. The green sheets are stamped to form a plurality of pellets. The billet was heated at a partial pressure of oxygen above 0.015 atm and a temperature of 550 ° C for 60 minutes to remove the organic binder. The billet was then sintered at a temperature of 1250 ° C for 30 minutes under an atmosphere containing N ₂ to form a ceramic sintered body. The theoretical percolation threshold of the above conditions is about 28.95%, and the volume fraction of the semiconductive ceramic phase (SrTiO ₃ -CaTiO ₃ ) in the ceramic sintered body is about 27%. In order to verify the uniform mixing state of the semiconducting ceramic particles and the dielectric ceramic particles in the sintered ceramic body, the samples were re-oxidized in air at 800 ° C, 900 and 1000 ° C, respectively, before measuring the dielectric properties. minute. During reoxidation, the semiconducting ceramic particles can be oxidized from the grain boundary region by diffusion of oxygen at the grain boundary. At the same time, in the dielectric ceramic grains, oxygen diffusion also occurs at the grain boundaries. Appropriate reoxidation conditions enhance the properties of the sintered ceramic body. However, at higher reoxidation temperatures, oxygen diffusion occurs not only at the grain boundaries, but also at the bulk of the grain. The strong oxygen diffusion leads to the degradation of the semiconducting ceramic particles, thus reducing their electrical conductivity. The resulting sintered body was polished to a depth of 100 μm from both sides to deposit an Au electrode for dielectric measurement.

3A shows a high angle annular dark field (HAADF) image of the ceramic sintered body of Example 1. The difference in contrast of the image shows at least a first ceramic phase (lighter particles) and a second ceramic phase (darker particles). In addition, STEM-EDX chemical analysis (Fig. 3B to Fig. 3E) demonstrates the presence of the first ceramic phase (Sr-Ca-Ti) and the second ceramic phase (Ti-Zr).

4A shows a selected area electron diffraction pattern (SAED) obtained from a first ceramic phase (lighter particles exhibiting Sr, Ca, and Ti in STEM-EDX chemical analysis). The results show a first ceramic phase (lighter particles) is _{(213) (Sr 0. 5} Ca 0. 5) TiO 3. 4B shows a selected area electron diffraction pattern (SAED) obtained from a second ceramic phase (dark particles exhibiting Ti and Zr in STEM-EDX chemical analysis). The results show that the second ceramic phase (darker particles) is (001) TiO ₂ (rutile) and is inferred to be a rutile TiO ₂ -ZrO ₂ solid solution.

Fig. 5 shows XRD (X-ray diffraction) of the ceramic sintered body in Example 1. Several peaks also showed the presence of a first ceramic phase _{(i.e., (Sr 0. 5 Ca 0} . 5) TiO 3 phase) and a second ceramic phase (i.e., rutile TiO ₂ -ZrO ₂ solid ceramic sintered body Solution phase).

6A, 6B, and 6C show the relative dielectric constant, dielectric loss, and resistivity of the ceramic sintered body of Example 1 under several different reoxidation conditions. And the dielectric loss decreases and showed improved resistivity _{(Sr 0. 5 Ca 0.} 5) TiO ₃ semiconductor reoxidation degree of the rise phase. The dielectric constant of the obtained sintered ceramic body (6A to 6D are marked as "sintering"), significantly higher than that of _{(Sr 0. 5 Ca 0.} 5) TiO 2 -ZrO ₂ and TiO ₃ dielectric constant, the dielectric and The constant decreases corresponding to an increase in the reoxidation temperature. The semiconductor ceramic phase corresponding to _{((Sr 0. 5 Ca 0} . 5) TiO 3) dielectric constant decreases the degree of oxidation of the sintered ceramic body is a display sub-percolation composite. That is, the large relative dielectric constant exhibited is derived from its sub-permeability structure.

Thus, the above results show an example of a ceramic sintered body comprising a semiconductor ceramic phase _{(i.e., (Sr 0. 5 Ca 0} . 5) TiO 3 phase) are dispersed in the dielectric ceramic phase (i.e., rutile TiO ₂ In the -ZrO ₂ solid solution phase, wherein the semiconductive ceramic phase and the dielectric ceramic phase together form a sub-permeation composite.

Example 2: A ceramic sintered body comprising a TiO ₂ -ZrO ₂ solid solution as a dielectric ceramic phase and a SrTiO ₃ -CaTiO ₃ solid solution as a semiconductor ceramic phase

Figure 7 shows a schematic manufacturing flow of Example 2. 0.11 moles of strontium carbonate (SrCO ₃ ), 0.046 moles of calcium carbonate (CaCO ₃ ), and 0.154 moles of TiO ₂ (rutile) were mixed in a bead mill (zirconia beads, 0.1 mm in diameter) in ethanol. After mixing, the mixed powder was dried in a stream of nitrogen. The resulting mixture was dry-milled and calcined at 1,100 ° C for 5 hours in a stream of N ₂ + H ₂ (95% + 5%) to obtain a black semiconductor (Sr _0.7 Ca _0.3 )TiO ₃ powder. 0.7 mole of zirconia (ZrO ₂ ) and 0.3 mole of titanium oxide (TiO ₂ ) (rutile) were added to the dry milled powder and mixed again by a bead mill.

100 parts by weight of the powder thus formed was ground in a solution containing 20% MEK and 80% BCA (v/v), and then with 15 parts by weight of ethyl cellulose, 0.3 parts by weight of CaSiO ₃ , 0.1 part by weight of GeO ₂ and 0.05 parts by weight of Al ₂ O _{3 were} mixed to form a slurry. The slurry was coated on a polyethylene terephthalate (PET) carrier tape using a coater to form a green sheet. The green sheets are stamped to form a plurality of blanks. The billet was heated at a partial pressure of oxygen above 0.015 atm and a temperature of 450 ° C for 60 minutes to remove the binder. The billet was then sintered at a temperature of 1300 ° C for 30 minutes in an atmosphere containing N ₂ to form a ceramic sintered body. The theoretical percolation threshold of the above conditions is about 28.95%, and the volume fraction of the semiconductive ceramic phase (SrTiO ₃ -CaTiO ₃ ) in the ceramic sintered body is about 27.3%. In order to verify the uniform mixing state of the semiconducting ceramic particles and the dielectric ceramic particles in the sintered ceramic body, the samples were respectively reoxidized in air at 800 ° C, 900 ° C, and 1000 ° C for 30 minutes before measuring the dielectric properties. The resulting sintered body was polished to a depth of 100 μm from both sides to deposit an Au electrode for dielectric measurement.

Fig. 8A shows a high angle annular dark field (HAADF) image of the ceramic sintered body in Example 2. The difference in contrast of the image shows several ceramic phases. In addition, STEM-EDX chemical analysis (Fig. 8B to Fig. 8E) demonstrates the existence of the first ceramic phase (Sr-Ca-Ti), the second ceramic phase (Ti-Zr) and the third ceramic phase (Ca-Zr-Ti). .

Figure 9A shows a selected area electron diffraction pattern (SAED) obtained from a first ceramic phase (particles exhibiting Sr, Ca, and Ti in STEM-EDX chemical analysis). The results show that the first ceramic phase is (212) (Sr _{0 .7} Ca _{0 .3} ) TiO ₃ . Figure 9B shows a selected area electron diffraction pattern (SAED) obtained from a second ceramic phase (particles exhibiting Ti and Zr in STEM-EDX chemical analysis). The results show that the second ceramic phase is (311) TiO ₂ (rutile) and is inferred to be a rutile TiO ₂ -ZrO ₂ solid solution. Figure 9C shows a selected area electron diffraction pattern (SAED) obtained from a third ceramic phase (particles exhibiting Ca, Zr, and Ti in STEM-EDX chemical analysis). Comparing the results of the simulation of (150) CaZrTiO ₇ (calcium titanium zircon) shown in Fig. 9D, the third ceramic phase is (150) CaZrTiO ₇ (calcium titanium zircon).

Fig. 10 shows XRD (X-ray diffraction) of the ceramic sintered body in Example 2. Also shows several peaks a first ceramic phase _{(i.e., (Sr 0. 5 Ca 0} . 5) TiO 3 phase), the presence of the ceramic sintered body, a second ceramic phase (i.e., rutile TiO ₂ -ZrO ₂ solid Solution phase) and a third ceramic phase (ie, CaZrTiO ₇ phase).

11A, 11B and 11C show the relative dielectric constant, dielectric loss and electrical resistivity of the ceramic sintered body of Example 2 under several different reoxidation conditions. And the dielectric loss decreases and showed improved resistivity _{(Sr 0. 5 Ca 0.} 5) TiO ₃ semiconductor reoxidation degree of the rise phase. The dielectric constant of the obtained sintered ceramic body (labeled in FIGS. 11A to 11C as "sintering"), significantly higher than that of _{(Sr 0. 5 Ca 0.} 5) TiO 3, CaZrTiO 7 and TiO ₂ -ZrO ₂ of the dielectric constant, And the dielectric constant decreases in response to an increase in the reoxidation temperature. The semiconductor ceramic phase corresponding to _{((Sr 0. 5 Ca 0} . 5) TiO 3) dielectric constant decreases the degree of oxidation of the sintered ceramic body is a display sub-percolation composite. That is, the large relative dielectric constant exhibited is derived from its sub-permeability structure.

Accordingly, the ceramic sintered body of Example 2 above analysis shows a semiconductor ceramic phase _{(i.e., (Sr 0. 5 Ca 0} . 5) TiO 3 phase) are dispersed in the dielectric ceramic phase (i.e., rutile TiO ₂ -ZrO ₂ solid solution phase and CaZrTiO ₇ phase), wherein the semiconductive ceramic phase and the dielectric ceramic phase together form a sub-permeate composite.

Example 3: A ceramic sintered body comprising a TiO ₂ -ZrO ₂ solid solution as a dielectric ceramic phase and a SrTiO ₃ solid solution as a semiconductor ceramic phase

Figure 12 shows a schematic manufacturing flow of Example 3. 0.25 mol of strontium carbonate (SrCO ₃ ) and 0.25 mol of TiO ₂ (anatase) were mixed in a bead mill (zirconia beads, 0.1 mm in diameter) in ethanol. After mixing, the mixed powder was dried in a stream of nitrogen. The resulting mixture was dry-milled and calcined at 1,000 ° C for 5 hours in a stream of N ₂ + H ₂ (95% + 5%) to obtain a black semiconductor SrTiO ₃ powder. 0.5 mol of zirconia (ZrO ₂ ) and 0.5 mol of titanium oxide (TiO ₂ ) (anatase) were added to the dry milled powder and mixed again by a bead mill.

100 parts by weight of the powder thus formed was ground in a solution containing 35% toluene and 65% MEK (v/v), and then with 15 parts by weight of polyacrylate, 0.3 parts by weight of SrSiO ₃ , 0.1 parts by weight of GeO ₂ And 0.1 part by weight of MnO _{2 was} mixed to form a slurry. The slurry was coated on a PET carrier tape using a coater to form a green sheet. The green sheets are stamped to form a plurality of blanks. The billet was heated at a partial pressure of oxygen above 0.015 atm and a temperature of 450 ° C for 60 minutes to remove the organic binder. The billet was then sintered at a temperature of 1300 ° C for 30 minutes in an atmosphere containing N ₂ to form a ceramic sintered body. The theoretical percolation threshold of the above conditions is about 28.95%, and the volume fraction of the semiconductive ceramic phase (SrTiO ₃ ) in the ceramic sintered body is about 27.8%. In order to verify the uniform mixing state of the semiconducting ceramic particles and the dielectric ceramic particles in the sintered ceramic body, the samples were respectively reoxidized in air at 800 ° C, 900 ° C, and 1000 ° C for 30 minutes before measuring the dielectric properties. The resulting sintered body was polished to a depth of 100 μm from both sides to deposit an Au electrode for dielectric measurement.

Figure 13A shows a high angle annular dark field (HAADF) image of the ceramic sintered body of Example 3. The difference in contrast of the image shows several ceramic phases. In addition, STEM-EDX chemical analysis (Fig. 13B to Fig. 13D) demonstrates the presence of the first ceramic phase (Sr-Ti) and the second ceramic phase (Ti-Zr).

Figure 14A shows a selected area electron diffraction pattern (SAED) obtained from a first ceramic phase (particles exhibiting Sr and Ti in STEM-EDX chemical analysis). The results show that the first ceramic phase is (112) SrTiO ₃ . Figure 14B shows a selected area electron diffraction pattern (SAED) obtained from a second ceramic phase (particles exhibiting Ti and Zr in STEM-EDX chemical analysis). The results show that the second ceramic phase is (101) TiO ₂ (rutile) and is inferred to be a rutile TiO ₂ -ZrO ₂ solid solution.

Fig. 15 shows XRD (X-ray diffraction) of the ceramic sintered body in Example 3. Several peaks also indicate the presence of a first ceramic phase (i.e., SrTiO ₃ phase) and a second ceramic phase (i.e., a rutile structure TiO ₂ -ZrO ₂ solid solution phase) in the ceramic sintered body.

16A, 16B and 16C show the relative dielectric constant, dielectric loss and electrical resistivity of the ceramic sintered body of Example 3 under several different reoxidation conditions. The decrease in dielectric constant and dielectric loss and the increase in resistivity indicate an increase in the degree of reoxidation of the SrTiO ₃ semiconductor phase. The dielectric constant of the obtained sintered ceramic body (labeled as "sintering" in FIGS. 16A to 16C) is remarkably higher than the dielectric constant of SrTiO ₃ and TiO ₂ -ZrO ₂ , and the dielectric constant corresponds to an increase in the reoxidation temperature. Reduced. The semiconductor ceramic phase corresponding to _{((Sr 0. 5 Ca 0} . 5) TiO 3) dielectric constant decreases the degree of oxidation of the sintered ceramic body is a display sub-percolation composite. That is, the large relative dielectric constant exhibited is derived from its sub-permeability structure.

Example 4: A ceramic sintered body comprising a solid solution of CaZrTi ₂ O ₇ as a dielectric ceramic phase and a solid solution of SrTiO ₃ as a semiconductor ceramic phase

Figure 17 shows a schematic manufacturing flow of Example 4. 0.56 moles of strontium carbonate (SrCO ₃ ), 0.56 moles of TiO ₂ (anatase), and 0.015 moles of Y ₂ O ₃ were mixed in a bead mill (zirconia beads, 0.1 mm in diameter) in ethanol. After mixing, the mixed powder was dried in a stream of nitrogen. The resulting mixture was dry-milled and calcined at 1,000 ° C for 5 hours in a stream of N ₂ + H ₂ (95% + 5%) to obtain a black semiconductor SrTiO ₃ powder. 1 mol of calcium titanium zircon (CaZrTi ₂ O ₇ ) was added to the dry milled powder and mixed again by a bead mill.

100 parts by weight of the powder thus formed is ground in a solution containing toluene and MEK, and then with 15 parts by weight of ethyl cellulose binder, 0.3 parts by weight of SrSiO ₃ , 0.1 part by weight of GeO ₂ and 0.1 part by weight of MnO ₂ Mix to form a slurry. The slurry was coated on a PET carrier tape using a coater to form a green sheet. The green sheets are stamped to form a plurality of blanks. The billet was heated at a partial pressure of oxygen above 0.015 atm and a temperature of 550 ° C for 60 minutes to remove the organic binder. The billet was then sintered at a temperature of 1300 ° C for 30 minutes in an atmosphere containing N ₂ to form a ceramic sintered body. The theoretical percolation threshold of the above conditions is about 28.95%, and the volume fraction of the semiconductive ceramic phase (SrTiO ₃ ) in the ceramic sintered body is about 28%. In order to verify the uniform mixing state of the semiconducting ceramic particles and the dielectric ceramic particles in the sintered ceramic body, the samples were respectively reoxidized in air at 800 ° C, 900 ° C, and 1000 ° C for 30 minutes before measuring the dielectric properties. The resulting sintered body was polished to a depth of 100 μm from both sides to deposit an Au electrode for dielectric measurement.

Figure 18A shows a high angle annular dark field (HAADF) image of the ceramic sintered body of Example 4. The difference in contrast of the image shows several ceramic phases. In addition, STEM-EDX chemical analysis (Fig. 18B to Fig. 18ED) demonstrates the presence of the first ceramic phase (Sr-Ti) and the second ceramic phase (Ca-Zr-Ti).

Figure 19A shows a selected area electron diffraction pattern (SAED) obtained from a first ceramic phase (particles exhibiting Sr and Ti in STEM-EDX chemical analysis). The results show that the first ceramic phase is (102) SrTiO ₃ . Figure 19B shows a selected area electron diffraction pattern (SAED) obtained from a second ceramic phase (particles exhibiting Ca, Ti, and Zr in STEM-EDX chemical analysis). The results show that the second ceramic phase is (011) CaZrTi ₂ O ₇ (calcium titanium zircon). Comparing the results of the simulation of (011) CaZrTiO ₇ (calcium titanium zircon) shown in Fig. 19C, the second ceramic phase of the salt is (011) CaZrTiO ₇ (calcium titanium zircon).

Fig. 20 shows XRD (X-ray diffraction) of the ceramic sintered body in Example 4. Several peaks also indicate the presence of a first ceramic phase (i.e., SrTiO ₃ phase) and a second ceramic phase (i.e., CaZrTi ₂ O ₇ (calcium titanium zircon)) in the ceramic sintered body.

21A, 21B and 21C show the relative dielectric constant, dielectric loss and electrical resistivity of the ceramic sintered body of Example 4 under several different reoxidation conditions. The decrease in dielectric constant and dielectric loss and the increase in resistivity indicate an increase in the degree of reoxidation of the SrTiO ₃ semiconductor phase. The dielectric constant of the obtained sintered ceramic body (labeled as "sintering" in FIGS. 11A to 11C) is remarkably higher than the dielectric constant of SrTiO ₃ and CaZrTi ₂ O ₇ , and the dielectric constant is decreased corresponding to the increase in the reoxidation temperature. small. The dielectric constant corresponding to the reduced degree of oxidation of the semiconducting ceramic phase (SrTiO ₃ ) indicates that the sintered ceramic body is a sub-permeate composite. That is, the large relative dielectric constant exhibited is derived from its sub-permeability structure.

Although the invention has been described and illustrated with reference to the particular embodiments thereof It will be understood by those skilled in the art that various changes and alternatives may be made without departing from the true spirit and scope of the invention as defined by the appended claims. The description may not necessarily be drawn to scale. Due to manufacturing procedures and tolerances, there may be differences between the artistic representations of the present invention and actual devices. There may be other embodiments of the invention that are not explicitly described. The description and drawings are to be regarded as illustrative and not limiting. Modifications may be made to adapt a particular situation, material, material composition, method or process to the objectives, spirit and scope of the invention. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a particular order, it is understood that the operations can be combined, sub-segmented, or re-sequenced to form equivalents without departing from the teachings of the present invention. method. Therefore, the order of operations and groupings are not limiting of the invention unless explicitly indicated herein.

11‧‧‧Ceramic phase

12‧‧‧Dielectric ceramic phase

Figure 1 schematically illustrates the microstructure of a ceramic sintered body in accordance with some embodiments of the present invention.

Figure 2 shows a schematic manufacturing flow of Example 1.

3A shows a high-angle annular dark-field (HAADF) image of the ceramic sintered body in Example 1.

3B shows STEM-EDX chemical analysis of Sr in the ceramic sintered body of Example 1.

3C shows STEM-EDX chemical analysis of Ca in the ceramic sintered body of Example 1.

3D shows STEM-EDX chemical analysis of Ti in the ceramic sintered body of Example 1.

3E shows STEM-EDX chemical analysis of Zr in the ceramic sintered body of Example 1.

4A shows selected area electron diffraction (SAED) obtained from the first ceramic phase in the ceramic sintered body of Example 1 (lighter particles exhibiting Sr, Ca, and Ti in STEM-EDX chemical analysis). Map.

4B shows a selected area electronic diffraction (SAED) pattern obtained from the second ceramic phase in the ceramic sintered body of Example 1 (dark particles exhibiting Ti and Zr in STEM-EDX chemical analysis).

Fig. 5 shows an x-ray diffraction (XRD) pattern of the ceramic sintered body in Example 1.

Figure 6A shows the relative dielectric constant of the ceramic sintered body of Example 1 under several different re-oxidation conditions.

Figure 6B shows the dielectric loss of the ceramic sintered body of Example 1 under several different reoxidation conditions.

Figure 6C shows the resistivity of the ceramic sintered body of Example 1 under several different reoxidation conditions.

Figure 7 shows a schematic manufacturing flow of Example 2.

Fig. 8A shows a high angle annular dark field (HAADF) image of the ceramic sintered body in Example 2.

Fig. 8B shows STEM-EDX chemical analysis of Sr in the ceramic sintered body of Example 2.

Fig. 8C shows STEM-EDX chemical analysis of Ca in the ceramic sintered body of Example 2.

Fig. 8D shows STEM-EDX chemical analysis of Ti in the ceramic sintered body of Example 2.

Figure 8E shows a STEM-EDX chemical analysis of Zr in the ceramic sintered body of Example 2.

9A shows a selected area electron diffraction (SAED) pattern obtained from the first ceramic phase in the ceramic sintered body of Example 2 (particles exhibiting Sr, Ca, and Ti in STEM-EDX chemical analysis).

9B shows a selected area electron diffraction (SAED) pattern obtained from the second ceramic phase in the ceramic sintered body of Example 2 (particles exhibiting Ti and Zr in STEM-EDX chemical analysis).

9C shows a selected area electron diffraction (SAED) pattern obtained from the third ceramic phase in the ceramic sintered body of Example 2 (particles exhibiting Ca, Zr, and Ti in STEM-EDX chemical analysis).

Figure 9D shows a simulation pattern of (150) selected area electron diffraction (SAED) of CaZrTiO ₇ (zirconolite).

Figure 10 shows an X-ray diffraction (XRD) pattern of the ceramic sintered body of Example 2.

Figure 11A shows the relative dielectric constant of the ceramic sintered body of Example 2 under several different reoxidation conditions.

Figure 11B shows the dielectric loss of the ceramic sintered body of Example 2 under several different reoxidation conditions.

Figure 11C shows the electrical resistivity of the ceramic sintered body of Example 2 under several different reoxidation conditions.

Figure 12 shows a schematic manufacturing flow of Example 3.

Figure 13A shows a high angle annular dark field (HAADF) image of the ceramic sintered body of Example 3.

Fig. 13B shows STEM-EDX chemical analysis of Zr in the ceramic sintered body of Example 3.

Figure 13C shows STEM-EDX chemical analysis of Ti in the ceramic sintered body of Example 3.

Fig. 13D shows STEM-EDX chemical analysis of Sr in the ceramic sintered body of Example 3.

14A shows a selected area diffraction (SAD) pattern obtained from the first ceramic phase in the ceramic sintered body of Example 3 (particles exhibiting Sr, Ca, and Ti in STEM-EDX chemical analysis).

14B shows a selected area diffraction (SAD) pattern obtained from the second ceramic phase in the ceramic sintered body of Example 3 (particles exhibiting Zr and Ti in STEM-EDX chemical analysis).

Figure 15 shows an X-ray diffraction (XRD) pattern of the ceramic sintered body of Example 3.

Figure 16A shows the relative dielectric constant of the ceramic sintered body of Example 3 under several different reoxidation conditions.

Figure 16B shows the dielectric loss of the ceramic sintered body of Example 3 under several different reoxidation conditions.

Figure 16C shows the electrical resistivity of the ceramic sintered body of Example 3 under several different reoxidation conditions.

Figure 17 shows a schematic manufacturing flow of Example 4.

Fig. 18A shows a high angle annular dark field (HAADF) image of the ceramic sintered body in Example 4.

Figure 18B shows STEM-EDX chemical analysis of Ca in the ceramic sintered body of Example 4.

Figure 18C shows STEM-EDX chemical analysis of Ti in the ceramic sintered body of Example 4.

Figure 18D shows STEM-EDX chemical analysis of Zr in the ceramic sintered body of Example 4.

Figure 18E shows STEM-EDX chemical analysis of Sr in the ceramic sintered body of Example 4.

Figure 19A shows a selected area diffraction (SAD) pattern obtained from the first ceramic phase in the ceramic sintered body of Example 4 (particles exhibiting Sr and Ti in STEM-EDX chemical analysis).

19B shows a selected area diffraction (SAD) pattern obtained from the second ceramic phase in the ceramic sintered body of Example 4 (particles exhibiting Ca, Zr, and Ti in STEM-EDX chemical analysis).

Figure 19C shows a simulated map of (011) selected area electron diffraction (SAED) of CaZrTiO ₇ .

Figure 20 shows an X-ray diffraction (XRD) pattern of the ceramic sintered body in Example 4.

Figure 21A shows the relative dielectric constant of the ceramic sintered body of Example 4 under several different reoxidation conditions.

Figure 21B shows the dielectric loss of the ceramic sintered body of Example 4 under several different reoxidation conditions.

Figure 21C shows the electrical resistivity of the ceramic sintered body of Example 4 under several different reoxidation conditions.

Claims (11)

A ceramic sintered body comprising a semiconductor ceramic phase dispersed in a dielectric ceramic phase, wherein the semiconductive ceramic phase and the dielectric ceramic phase together form a percolative composite And the volume fraction of the semiconductive ceramic phase is close to and below a percolation threshold. The ceramic sintered body of claim 1, wherein the semiconductor ceramic phase has a volume fraction of from about 0.05% to about 20% below the percolation threshold. The ceramic sintered body of claim 1, wherein the volume fraction of the semiconductive ceramic phase is from about 0.999 to about 0.33 times the percolation threshold. The ceramic sintered body of claim 1, wherein the material of the dielectric ceramic phase is selected from the group consisting of CaZrTi ₂ O ₇ (calcium titanium zircon), CaZrO ₃ , SrZrO ₃ , BaZrO ₃ , TiO ₂ (gold) Redstone), ZrO ₂ and its solid solution. The ceramic sintered body of claim 1, wherein the material of the semiconductive ceramic phase is selected from the group consisting of a perovskite material and reduced TiO ₂ (rutile). The ceramic sintered body of claim 5, wherein the perovskite material is selected from the group consisting of strontium titanate (SrTiO ₃ ), barium titanate (BaTiO ₃ ), calcium titanate (CaTiO ₃ ), and titanic acid. Nickel (NiTiO ₃ ), manganese titanate (MnTiO ₃ ), cobalt titanate (CoTiO ₃ ), copper titanate (CuTiO ₃ ), magnesium titanate (MgTiO ₃ ), and complexes thereof. The ceramic sintered body of claim 1, wherein the semiconductor ceramic phase is doped with an additive. The ceramic sintered body of claim 7, wherein the additive is a donor-type additive selected from the group consisting of ruthenium, osmium and iridium. The ceramic sintered body of claim 1, wherein the dielectric ceramic phase is doped with an additive. The ceramic sintered body of claim 9, wherein the additive is an acceptor-type additive selected from the group consisting of vanadium, niobium, chromium, manganese compounds, magnesium compounds, niobate compounds, and alumina compounds. Group. A passive component comprising the ceramic sintered body of any one of claims 1 to 10.