CN108249918B - Low-temperature sintered giant dielectric constant fine-grain ceramic material, and preparation method and application thereof - Google Patents

Abstract

The invention discloses a low-temperature sintered giant dielectric constant fine-grained ceramic material, a preparation method and application thereof_0.98Ca_0.02Zr_0.12Ti_0.88O₃The modifier is MnCO₃、Nb₂O₅、Y₂O₃、MgO、SiO₂Two or more of them. The main material and the modifier are subjected to ball milling, drying, grinding and sieving to prepare a medium porcelain; the dielectric ceramic material can be made into fine-grained ceramic with high density by discharge plasma sintering (SPS). The invention realizes the low-temperature sintering of the giant dielectric constant ceramic to obtain the ceramic with high density and fine crystal grains; the dielectric ceramic material has the advantages of high dielectric constant, low loss, good capacity-temperature characteristic and excellent comprehensive electrical property, and the raw material of the dielectric ceramic material is low in cost, does not contain toxic elements such as lead, cadmium, mercury, hexavalent chromium and the like, and is an environment-friendly high-dielectric ceramic material.

Description

Low-temperature sintered giant dielectric constant fine-grain ceramic material, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of functional ceramic materials, relates to a dielectric ceramic material and a preparation method thereof, and particularly relates to a low-temperature sintered giant dielectric constant fine-grained ceramic material and a preparation method thereof.

Background

At present, the development of electronic complete machines is rapid, strict requirements are put forward on the miniaturization, high specific volume, low cost, high reliability and the like of electronic components such as ceramic capacitors, and higher requirements are put forward on the performance of corresponding dielectric ceramic materials. Under the condition that the capacitor structure and the process condition are determined, the capacitance of the capacitor is mainly determined by the dielectric constant of the dielectric ceramic material, so that the improvement of the dielectric constant of the material is the key to realizing the miniaturization of the capacitor. The room temperature dielectric constant of the existing high dielectric constant materials is usually lower than 5000, and the materials are difficult to be continuously improved. Further development of electronic technology requires giant dielectric constant dielectric materials with dielectric constant over 10000. In the field of capacitor dielectric ceramics, a few high-dielectric-constant ceramic products such as Y5V/Z5U ceramic powder on the market have the dielectric constant of 15000, usually the sintering temperature is up to 1300 ℃, the change of the temperature coefficient of capacity is large, the use temperature zone is narrow, even part of the ceramic products are lead-containing systems, and the ceramic products are only limited to special fields. In the field of material research and development, for example, CCTO and Nb-Ln-Ti systems (Ln is a positive trivalent element such as Bi, Al, Y and the like) have a huge dielectric constant, but generally have high loss or low insulation resistance and are very sensitive to the process, and at present, the material is still in the research stage and has a certain distance from practical application.

Disclosure of Invention

Aiming at the defects in the problems, it is necessary to develop a high dielectric constant material system which is environment-friendly, low in sintering temperature and good in comprehensive electrical property. The invention provides a low-temperature sintered giant dielectric constant fine-grain ceramic material and a preparation method thereof, which can be sintered into compact fine-grain ceramic at 950 +/-50 ℃ and maintain very high dielectric constant, low loss and good temperature characteristics.

In order to achieve the purpose, the invention provides a low-temperature sintered giant dielectric constant fine-grained ceramic material, which consists of a main material and a modifier;

the main material is Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃；

The modifier is MnCO₃、Nb₂O₅、Y₂O₃、MgO、SiO₂Two or more of them.

As a further improvement of the invention, the dielectric ceramic material contains 100 weight parts of Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃The base material comprises the following components in percentage by weight:

main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃100 parts of the raw materials;

modifier MnCO₃0.05 to 0.50 portion;

modifier Nb₂O₅0.02-0.40 parts;

modifier Y₂O₃0 to 0.20 portion;

0-0.20 part of modifier MgO;

modifier SiO₂0 to 0.10 portion.

The invention also provides a preparation method of the low-temperature sintered giant dielectric constant fine-grained ceramic material, which comprises the following steps:

step 1, preparing main material Ba by adopting a hydrothermal method_0.98Ca_0.02Zr_0.12Ti_0.88O₃；

And 2, weighing the main material and the modifier, putting the main material and the modifier into a ball milling tank filled with zirconia balls, adding deionized water for ball milling, drying, grinding and sieving, and bagging for later use to prepare the dielectric porcelain.

As a further improvement of the present invention, the step 1 comprises:

step 11, preparing a solution: selecting deionized water and analytically pure raw material BaCl₂、CaCl₂、ZrOCl₂、TiCl₄NaOH, and TiCl is respectively prepared after weighing according to the mixture ratio₄Ice water solution, barium-calcium-zirconium mixed solution and NaOH solution;

step 12, precursor preparation: mixing the barium-calcium-zirconium mixed solution with TiCl₄Weighing ice water solutions in proportion, mixing, heating to 60-70 ℃, heating NaOH solution to 80-100 ℃, uniformly injecting the two heated solutions into a reaction kettle, and stirring for 10-20 minutes to obtain a precursor which is a mixed suspension;

step 13, hydrothermal treatment: transferring the mixed turbid liquid into a hydrothermal kettle, carrying out hydrothermal treatment at 180-240 ℃ for 3-8 hours, then filtering, washing with deionized water until the conductivity is less than or equal to 100 mu S/cm, drying, and sieving with a 40-mesh sieve to obtain the main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃。

As a further improvement of the invention, BaCl in the mixed solution of barium, calcium and zirconium₂：CaCl₂：ZrOCl₂The molar ratio is 98: 2: 12; TiCl (titanium dioxide)₄TiCl in ice water solution, barium-calcium-zirconium mixed solution and NaOH solution₄：(BaCl₂+CaCl₂+ZrOCl₂): molar ratio of NaOH 88: 112: 600.

as a further improvement of the invention, in the step 2, ball milling is carried out for 12 hours, drying is carried out for 8-12 hours at 120 ℃ until drying, grinding is carried out, a 40-mesh sieve is sieved, and bagging is carried out for later use.

The invention also provides an application of the preparation method of the low-temperature sintered giant dielectric constant fine-grained ceramic material, the prepared medium ceramic material is put into a graphite die, sintered into ceramic at 950 +/-50 ℃ by adopting an SPS (spark plasma sintering) furnace, and then thermally treated at 650 ℃ in a muffle furnace to prepare a fine-grained ceramic wafer.

Compared with the prior art, the invention has the beneficial effects that:

the invention realizes the low-temperature sintering of the giant dielectric constant ceramic and obtains the ceramic with high density and fine crystal grains. The dielectric ceramic material has the advantages of high dielectric constant, low loss, good capacity-temperature characteristic and excellent comprehensive electrical property, and the raw material of the dielectric ceramic material is low in cost, does not contain toxic elements such as lead, cadmium, mercury, hexavalent chromium and the like, and is an environment-friendly high-dielectric ceramic material.

Drawings

FIG. 1 shows an embodiment of the present invention disclosing a main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃XRD spectrum of (1);

FIG. 2 is a fracture morphology graph of formula 7 of the present invention after SPS sintering;

fig. 3 is a graph of the electrical properties of inventive formulation 7 after SPS sintering.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The raw materials selected by the invention can be purchased through commercial channels if no special description is provided.

The invention is described in further detail below with reference to the attached drawing figures:

the invention provides a low-temperature sintered giant dielectric constant fine-grained ceramic material, which consists of a main material and a modifier;

the main material is Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃，Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃The preparation method adopts a hydrothermal method;

the modifier is MnCO₃、Nb₂O₅、Y₂O₃、MgO、SiO₂Two or more than two of the above-mentioned materials are selected, and different doping modifiers are selected to improve the comprehensive performance of the medium porcelain material.

The dielectric porcelain material of the invention takes 100 weight portions of Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃The base material comprises the following components in percentage by weight:

main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃100 parts of the raw materials;

modifier MnCO₃0.05 to 0.50 portion;

modifier Nb₂O₅0.02-0.40 parts;

modifier Y₂O₃0 to 0.20 portion;

0-0.20 part of modifier MgO;

modifier SiO₂0 to 0.10 portion.

The invention also provides a preparation method of the low-temperature sintered giant dielectric constant fine-grained ceramic material, which comprises the following steps:

step 1, preparing main material Ba by adopting a hydrothermal method_0.98Ca_0.02Zr_0.12Ti_0.88O₃(ii) a The method specifically comprises the following steps:

step 11, preparing a solution: selecting deionized water and analytically pure raw material BaCl₂、CaCl₂、ZrOCl₂、TiCl₄NaOH, respectively weighed according to the mixture ratioPreparing TiCl₄Ice water solution, barium-calcium-zirconium mixed solution and NaOH solution; wherein: BaCl in barium-calcium-zirconium mixed solution₂：CaCl₂：ZrOCl₂The molar ratio is 98: 2: 12.

step 12, precursor preparation: mixing the barium-calcium-zirconium mixed solution with TiCl₄The ice water solution is taken in proportion, mixed and heated to 60-70 ℃ (preferably to 60 ℃), and TiCl is added₄TiCl in ice water solution, barium-calcium-zirconium mixed solution and NaOH solution₄：(BaCl₂+CaCl₂+ZrOCl₂): molar ratio of NaOH 88: 112: 600, preparing a mixture; heating the NaOH solution to 80-100 ℃ (preferably to 95 ℃), uniformly injecting the two heated solutions into a reaction kettle, and stirring for 10-20 minutes (preferably for 15 minutes) to obtain a precursor which is a mixed suspension;

step 13, hydrothermal treatment: transferring the mixed suspension into a hydrothermal kettle, carrying out hydrothermal treatment at 180-240 ℃ for 3-8 hours (preferably at 200-220 ℃ and further preferably at 220 ℃), then filtering, washing with deionized water until the conductivity is less than or equal to 100 MuS/cm (preferably less than or equal to 50 MuS/cm), drying, and sieving with a 40-mesh sieve to obtain a main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃。

The method for preparing the main material by the hydrothermal method in the step 1 can ensure the ion-level mixing reaction of barium, calcium, zirconium and titanium elements, and can prepare high-purity Ba with higher crystallinity_0.98Ca_0.02Zr_0.12Ti_0.88O₃A material.

Step 2, weighing the main material and the modifier, putting the main material and the modifier into a ball milling tank filled with zirconia balls, adding deionized water for ball milling, drying, grinding and sieving, and bagging for later use to prepare a medium porcelain; the method specifically comprises the following steps:

weighing the main material and the modifier by weight according to 100 parts by weight of Ba by using an electronic balance_0.98Ca_0.02Zr_0.12Ti_0.88O₃The base material comprises the following components in percentage by weight: main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃100 portions of modifier MnCO₃0.05 to 0.50 portionModifier Nb₂O₅0.02-0.40 part of modifier Y₂O₃0 to 0.20 portion of modifier MgO, 0 to 0.20 portion of modifier SiO ₂0 to 0.10 portion. Putting the weighed main materials and the modifier into a ball milling tank filled with zirconia balls, adding deionized water for ball milling for 12 hours, drying for 8-12 hours at 120 ℃ until the materials are dried, grinding by using an agate mortar, sieving by using a 40-mesh sieve to obtain the giant dielectric constant fine crystalline ceramic material capable of being sintered at low temperature, and bagging for later use.

According to the invention, the deionized water wet mixing is adopted in the step 2, so that the efficient and uniform mixing of materials can be guaranteed, the method is safer and lower in cost compared with the method adopting alcohol, and the low-temperature sintering giant dielectric constant fine-grain ceramic material can be prepared.

When the low-temperature sintered giant dielectric constant fine-grained ceramic material is prepared, the material can be weighed according to 10 formulas in the following table 1, wherein the unit is weight parts, the formula 1 in the table 1 is used as a pair of proportions, and the formulas 2 to 10 are used as examples, and are specifically shown in the table 1.

TABLE 1

The invention carries out spark plasma sintering and treatment on the 10 formula dielectric porcelain powder samples according to the following steps, and tests related performances:

step 1, sintering to form porcelain: putting the dielectric ceramic powder into a graphite die with the diameter of 20mm, then placing the graphite die into a discharge plasma sintering furnace, sintering at 950 +/-50 ℃ (the axial pressure on the die is about 50MPa), and preparing a ceramic wafer with the diameter of 15mm and the thickness of about 1 mm;

step 2, heat treatment: cleaning the surface of the ceramic wafer, placing the cleaned ceramic wafer on a zirconia burning bearing plate, placing the ceramic wafer into a resistance furnace, and carrying out heat treatment at 650 ℃ for 8 hours;

step 3, sample treatment: polishing the surface of the wafer after heat treatment, measuring the thickness and the diameter, and then silver coating and silver firing are carried out on two surfaces of the wafer to form a simple wafer capacitor;

step 4, electrical property testing:the series values of the capacity, the loss, the insulation resistance and the capacity of the wafer capacitor along with the temperature are tested, and the relative dielectric constant and the Temperature Coefficient (TC) of the capacity are calculated, and the performance parameters are shown in the table 2. The capacity temperature coefficient is calculated according to the following formula, where Ct and C_25℃Capacities corresponding to temperature points t ℃ and 25 ℃ respectively:

TC＝(C_t-C_25℃)/C_25℃×100％

the spark plasma sintering has a characteristic of hot press sintering, and more importantly, it has a very high thermal efficiency by uniformly self-heating each particle inside a sintered body and activating the particle surface by the instantaneously generated spark plasma, and can make the sintered body dense in a relatively short time.

TABLE 2

Formulation of	Sintering temperature (. degree. C.)	Relative dielectric constant	Loss of power	Insulation resistance (x 10)12Ω)
					1	1000	18926	0.22	1.7
2	980	16110	0.17	0.8
					3	980	16433	0.13	3.5
4	960	11802	0.10	3.1
					5	950	12554	0.07	1.4
6	950	16012	0.04	2.3
					7	950	17900	0.03	2.7
8	950	15053	0.05	1.8
					9	920	13648	0.03	2.0
10	900	12542	0.04	2.1

The invention mainly prepares the main component Ba with higher activity by a hydrothermal method_0.98Ca_0.02Zr_0.12Ti_0.88O₃The method does not need to add a sintering aid, selects different doping modified elements to improve the comprehensive performance of the dielectric porcelain, sinters the dielectric porcelain at about 950 ℃ to obtain the optimal dielectric porcelain, has the room temperature dielectric constant as high as 17900 and the loss of 0.03, has the capacity temperature coefficient of-7.57 to +21.27 percent within the range of-55 ℃ to 125 ℃, meets the requirement of X7S (-55 ℃ to 125 ℃ and the capacity temperature coefficient of +/-22 percent) of American EIA, can be used for preparing electronic elements such as capacitors and the like, and has great practical value and market value.

The invention realizes the low-temperature sintering of huge dielectric constant, obtains the ceramic with fine crystal grains and high density, the dielectric ceramic material has the characteristics of high dielectric constant, low loss, high insulation resistance, ideal capacity temperature coefficient and the like, and the dielectric ceramic material does not contain toxic elements such as lead, cadmium, mercury, hexavalent chromium and the like, and meets the requirement of environmental protection.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (2)

1. The low-temperature sintered giant dielectric constant fine-grained ceramic material is characterized by comprising a main material and a modifier;

the main material is Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃；

The modifier is MnCO₃、Nb₂O₅、Y₂O₃、MgO、SiO₂Two or more of them;

the ceramic material is prepared by 100 parts by weight of Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃The base material comprises the following components in percentage by weight:

main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃100 parts of the raw materials;

modifier MnCO₃0.05 to 0.50 portion;

modifier Nb₂O₅0.02-0.40 parts;

modifier Y₂O₃0 to 0.20 portion;

0-0.20 part of modifier MgO;

modifier SiO₂0 to 0.10 portion;

the preparation method of the low-temperature sintered giant dielectric constant fine-grained ceramic material comprises the following steps:

step 1, preparing main material Ba by adopting a hydrothermal method_0.98Ca_0.02Zr_0.12Ti_0.88O₃；

Step 2, weighing the main material and the modifier, putting the main material and the modifier into a ball milling tank filled with zirconia balls, adding deionized water for ball milling, drying, grinding and sieving, and bagging for later use to prepare a medium porcelain; in the step 2, ball-milling for 12 hours, drying for 8-12 hours at 120 ℃ until drying, grinding, sieving with a 40-mesh sieve, and bagging for later use;

step 3, putting the prepared dielectric ceramic material into a graphite die, sintering the dielectric ceramic material into a ceramic at 950 +/-50 ℃ by using an SPS (spark plasma sintering) sintering furnace, and then performing heat treatment at 650 ℃ in a muffle furnace to prepare a fine-grain ceramic wafer;

the step 1 is as follows:

step 11, preparing a solution: selecting deionized water and analytically pure raw material BaCl₂、CaCl₂、ZrOCl₂、TiCl₄NaOH, and TiCl is respectively prepared after weighing according to the mixture ratio₄Ice water solution, barium-calcium-zirconium mixed solution and NaOH solution; BaCl in the barium-calcium-zirconium mixed solution₂：CaCl₂：ZrOCl₂The molar ratio is 98: 2: 12; TiCl (titanium dioxide)₄TiCl in ice water solution, barium-calcium-zirconium mixed solution and NaOH solution₄：(BaCl₂+CaCl₂+ZrOCl₂): molar ratio of NaOH 88: 112: 600, preparing a mixture;

step 12, precursor preparation: mixing the barium-calcium-zirconium mixed solution with TiCl₄Weighing ice water solutions in proportion, mixing, heating to 60-70 ℃, heating NaOH solution to 80-100 ℃, uniformly injecting the two heated solutions into a reaction kettle, and stirring for 10-20 minutes to obtain a precursor which is a mixed suspension;

step 13, hydrothermal treatment: transferring the mixed turbid liquid into a hydrothermal kettle, carrying out hydrothermal treatment at 180-240 ℃ for 3-8 hours, then filtering, washing with deionized water until the conductivity is less than or equal to 100 mu S/cm, drying, and sieving with a 40-mesh sieve to obtain the main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃。

2. The method of preparing a low temperature sintered giant dielectric constant fine crystalline ceramic material of claim 1, comprising the steps of:

step 1, preparing main material Ba by adopting a hydrothermal method_0.98Ca_0.02Zr_0.12Ti_0.88O₃；

Step 2, weighing the main material and the modifier, putting the main material and the modifier into a ball milling tank filled with zirconia balls, adding deionized water for ball milling, drying, grinding and sieving, and bagging for later use to prepare a medium porcelain; in the step 2, ball-milling for 12 hours, drying for 8-12 hours at 120 ℃ until drying, grinding, sieving with a 40-mesh sieve, and bagging for later use;

step 3, putting the prepared dielectric ceramic material into a graphite die, sintering the dielectric ceramic material into a ceramic at 950 +/-50 ℃ by using an SPS (spark plasma sintering) sintering furnace, and then performing heat treatment at 650 ℃ in a muffle furnace to prepare a fine-grain ceramic wafer;

the step 1 is as follows:

step 11, preparing a solution: selecting deionized water and analytically pure raw material BaCl₂、CaCl₂、ZrOCl₂、TiCl₄NaOH, and TiCl is respectively prepared after weighing according to the mixture ratio₄Ice water solution, barium-calcium-zirconium mixed solution and NaOH solution; BaCl in the barium-calcium-zirconium mixed solution₂：CaCl₂：ZrOCl₂The molar ratio is 98: 2: 12; TiCl (titanium dioxide)₄TiCl in ice water solution, barium-calcium-zirconium mixed solution and NaOH solution₄：(BaCl₂+CaCl₂+ZrOCl₂): molar ratio of NaOH 88: 112: 600, preparing a mixture;

step 12, precursor preparation: mixing the barium-calcium-zirconium mixed solution with TiCl₄Weighing ice water solutions in proportion, mixing, heating to 60-70 ℃, heating NaOH solution to 80-100 ℃, uniformly injecting the two heated solutions into a reaction kettle, and stirring for 10-20 minutes to obtain a precursor which is a mixed suspension;

step 13, hydrothermal treatment: transferring the mixed turbid liquid into a hydrothermal kettle, carrying out hydrothermal treatment at 180-240 ℃ for 3-8 hours, then filtering, washing with deionized water until the conductivity is less than or equal to 100 mu S/cm, drying, and sieving with a 40-mesh sieve to obtain the main material Ba_0.98Ca_0.02Zr_0.12Ti_0.88O₃。

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