CN102351241A

CN102351241A - Synthetic method for giant dielectric constant material copper-calcium titanate

Info

Publication number: CN102351241A
Application number: CN2011101962128A
Authority: CN
Inventors: 崔斌; 张庆; 畅柱国; 阎雯青; 刘宇; 景帅帅
Original assignee: Northwest University
Current assignee: Northwest University
Priority date: 2011-07-14
Filing date: 2011-07-14
Publication date: 2012-02-15
Anticipated expiration: 2031-07-14
Also published as: CN102351241B

Abstract

The invention discloses a synthetic method for a giant dielectric constant copper-calcium titanate ceramic material. The method is as follows: the sol-gel method is used and combined with the characteristics of the self-propagating method, calcium nitrate, copper nitrate and titanate are used as raw materials, water and ethanol are used as solvents, nitric acid is used as a catalyst and oxidizing agent, and long chain organic acid is used as a surfactant and a reducing agent in an oxidation reduction reaction; sol and gel containing Ti, Cu and Ca are prepared in proportion and are subjected to drying, calcining and complete oxidation reduction reaction so as to eventually obtain copper-calcium titanate powder with controllable composition and good dispersibility and the copper-calcium titanate ceramic material with high dielectric properties. The method provided in the invention enables reaction temperature for preparing copper-calcium titanate powder to be reduced, and nitrate is used as a raw material to substitute acetate used in the conventional sol-gel method, which enables production cost to be substantially reduced; added long chain organic acid functioning as a surfactant and nitrate radicals can undergo an oxidation reduction reaction, which enables reaction temperature to decrease, and the process of the reaction is safe and reliable.

Description

A kind of synthesis method of huge dielectric constant material CaCu 3 Ti 4 O

Technical field

The present invention relates to a kind of synthesis method of huge dielectric constant material CaCu 3 Ti 4 O, be specifically related to use improved sol-gel method to synthesize the CaCu 3 Ti 4 O material, belong to the high dielectric ceramic material preparing technical field.

Background technology

Huge dielectric constant material CaCu 3 Ti 4 O CaCu ₃Ti ₄O ₁₂(CCTO), obtained paying close attention to widely because of its high-k.Though also have dispute for the mechanism that produces this huge dielectric constant at present, its huge dielectric constant and good temperature stability will be with a wide range of applications in the actual production life.

The synthesis method of CCTO mainly contains solid phase method and liquid phase method two big classes.The CCTO powder major part of bibliographical information all adopts traditional solid phase method synthetic, and this method technology is simple, yield rate is high, but the subsurface defect of material is many.Liquid phase method comprises sol-gel method and chemical coprecipitation; Wherein to have a diameter of particle little for sol-gel method; Narrow particle size distribution; Component is controlled easily; The advantage that chemically reactive is good; But the compound of employed calcium of this method and copper is acetate or nitrate (Thin Solid Films, 2007,516:454-459; Solid State Communications, 2007,142:573-576).The cost of acetate is very high, almost is the twice of nitrate; And nitrate produces great amount of heat and gas because of decomposing fast easily in heat treated process, and blast causes danger easily.Liu Laijun (CN 101891460 A) etc. utilizes sol-gel method to synthesize CCTO, and the employing ethylene glycol monomethyl ether is as solvent and need in glove box, operate process complicacy and cost height.Traditional sol-gel is to utilize excessive citric acid complex metal ion and self-propagating reaction takes place at low temperatures and a kind of new method of synthetic CCTO powder from the method for spreading; This method need not carried out pre-burning to powder and handled; Simplified course of reaction and the (MaterialsLetters that cuts down the consumption of energy; 2007; 61:1404-1407); But this method need use a large amount of expensive citric acids as complexing agent; To guarantee to form the citric acid complex of solubility; And the carbon source that takes place as self-propagating reaction; Cost is higher, and the CCTO room temperature dielectric constant of being synthesized only is 6000-10000.

Summary of the invention

Raw materials cost is high in the existing sol-gel method, environmental pollution is big and calcining temperature is high in order to overcome; The deficiency that sintering time is long; The purpose of this invention is to provide the synthetic CCTO of a kind of improved sol-gel method; Advantage in conjunction with self-propagating reaction; With the higher nitrate of the nitrate displacement cost of copper and calcium; Through adding the reductive agent of long chain organic acid as the aftercombustion reaction; Play influence of surfactant simultaneously, reach the purpose that reduces the synthetic huge dielectric materials production cost of CaCu 3 Ti 4 O.

Implementation procedure of the present invention is following:

A kind of synthesis method of huge dielectric constant material CaCu 3 Ti 4 O may further comprise the steps:

(1) A solution: titanic acid ester and long chain organic acid are dissolved in ethanol and the acetic acid mixing solutions; The mol ratio of titanic acid ester and long chain organic acid is: (1:1) ~ (8:1); Ethanol: acetic acid: the volume ratio of titanic acid ester is: (2.4 ~ 6.0): (4.8 ~ 8.0): 10.0, and said titanic acid ester [Ti (OR) ₄] in, R is butyl, sec.-propyl, octyl group or n-propyl;

(2) B solution: the amount with titanic acid ester is a benchmark, is that the ratio of 1:3:4 is (like CaCu according to the Ca:Cu:Ti mol ratio ₃Ti ₄O ₁₂Stoichiometric ratio) nitrocalcite and cupric nitrate are dissolved in the aqueous ethanolic solution, and add concentrated nitric acid, obtain homogeneous solution, wherein long chain organic acid and nitric acid mol ratio are 1.50 ~ 0.33, the volume ratio of alcohol and water is 3:1 ~ 1:3 in the aqueous ethanolic solution;

(3) B solution is joined in the A solution make colloidal sol, and then form gel;

(4) 60 ~ 90 ℃ of oven dry gels get dry gel powder, make it that self-propagating reaction take place in 300 ° of C-500 ° of C dry gel powder and obtain the CaCu 3 Ti 4 O powder;

(5) the CaCu 3 Ti 4 O powder is added PVA and glycerine, grind granulation, process base substrate, moulding, ° C sintering obtained the CaCu 3 Ti 4 O material in 2-8 hour in 960 ° of C ~ 1180.

Said long chain organic acid is capric acid, lauric acid, stearic acid, n-caproic acid or contains carbon-carbon double bond and the long-chain unsaturated fatty acid of carboxyl, long-chain unsaturated fatty acid such as octadecenic acid.

Aforesaid method adopts sol-gel method; With titanic acid ester, nitrocalcite and cupric nitrate is raw material; With water, acetic acid and ethanol is solvent; Nitric acid is the catalyzer and the oxygenant of holding concurrently; With the supplementary carbon source of long chain organic acid, through heating and causing that combustion reactions prepares the CaCu 3 Ti 4 O material as tensio-active agent and double self-propagating combustion reaction.

The invention has the beneficial effects as follows: (1) has reduced raw materials cost with the calcium acetate and the neutralized verdigris of cheap nitrocalcite and the alternative expensive of cupric nitrate; (2) sol gel reaction process material component can strict be controlled; System causes in heat treatment process spreads the heat energy that oxidation-reduction reaction can provide reaction to take place certainly; The effect of high-temperature calcination be can play, thereby energy-saving and emission-reduction and safe and reliable purpose reached effectively; (3) with long chain organic acid as tensio-active agent, and, can synthesize good dispersity, the CaCu that thing is mutually pure and dielectric properties are good as the method for the synthetic CaCu 3 Ti 4 O powder of the supplementary carbon source of oxidation-reduction reaction ₃Ti ₄O ₁₂Pottery, the long chain organic acid of Jia Ruing can make temperature of reaction reduce with nitrate radical generation redox reaction simultaneously; (4) chemical constitution and the dielectric properties of improving material of this method ability strict control of material; Prevent the explosion hazard of nitrate in the sol-gel method heat treatment process simultaneously, and avoid sol-gel from spreading of the waste of the employed a large amount of Hydrocerol As of method as complexing agent.

Description of drawings

Fig. 1 is the powder diagram of the synthetic calcium copper titanate ceramics that obtains of the inventive method (embodiment 1-3).

Embodiment

Below in conjunction with instance the present invention is described in further detail, the present invention is not limited to instance.

Embodiment 1

(1) tetrabutyl titanate 25.3368g is placed the exsiccant beaker, keep stirring, add oleic acid 5.86ml, stir, and, stir the solution that obtains homogeneous to wherein adding ethanol (10ml) and acetic acid (16ml);

(2) according to the metering ratio; Take by weighing nitrocalcite 4.4171g and cupric nitrate 13.4891g; Be dissolved in aqueous ethanolic solution (among alcohol: water=3:1 ~ 1:3); Obtain the solution of homogeneous; And join in the above-mentioned solution, add the 2ml concentrated nitric acid again, keep magnetic agitation during mixing; Topple over the back restir 0.1 ~ 2 hour that finishes, obtain uniform sol;

(3) gel places crucible, and 80 ° of C/12h oven dry obtain xerogel in baking oven;

(4) xerogel is placed 400 ° of C retort furnaces, make it that self-propagating reaction take place, obtain fluffy powder;

(5) powder that obtains in the step (3) is added PVA and glycerine, grind granulation, pressed by powder is become base substrate, forming pressure is 3 ~ 4MPa;

(6) blank sintering, 1120 ° of C/4h sintering;

(7) sintered ceramic polishing, coated silver slurry, the electrical property of test pottery, its powdery diffractometry is as shown in Figure 1.

Embodiment 2

(1) tetrabutyl titanate 25.6258g is placed the exsiccant beaker, keep magnetic agitation, add lauric acid 5.1307g, stir about 30min, and, stir the solution that obtains homogeneous to wherein adding ethanol (9ml) and acetic acid (16ml);

(2) according to the metering ratio, take by weighing nitrocalcite 4.4675g and cupric nitrate 13.6430g, be dissolved in the aqueous ethanolic solution; Obtain uniform solution, join in the above-mentioned solution, add the 2.5ml concentrated nitric acid again; Keep magnetic agitation during mixing, topple over the back restir 0.1 ~ 2 hour of finishing, obtain uniform sol;

(3) 80 ° of C/12h oven dry in baking oven obtain xerogel, in 400 ° of C self-propagating reaction take place, and obtain fluffy powder;

(4) powder that obtains in the step (3) is added PVA and glycerine, grind granulation, be pressed into base substrate;

(5) 1140 ° of C/4h sintering of base substrate, ceramic polished behind the sintering, coated silver slurry, the electrical property of test pottery, its powdery diffractometry is as shown in Figure 1.

Embodiment 3

(1) tetrabutyl titanate 25.8576g is placed the exsiccant beaker, keep magnetic agitation, add palmitic acid 4.8951g, stir about 30min, and, stir and obtain uniform solution to wherein adding ethanol (10ml) and acetic acid (20ml);

(2) according to the metering ratio; Take by weighing nitrocalcite 4.5079g and cupric nitrate 13.7664g; Be dissolved in the aqueous ethanolic solution; Obtain uniform solution; And join in the above-mentioned solution, add the 2.8ml concentrated nitric acid again, keep magnetic agitation during mixing; Topple over the back restir 0.1 ~ 2 hour that finishes, obtain uniform sol;

Embodiment 4

Dielectric properties parameter among the embodiment 1-3 under each sample different frequency is seen table 1.

The meaning of each parameter representative is following in the table 1:

ε (25 ° of C): specific inductivity during room temperature, test voltage 1.0V;

Tan δ (25 ° of C): dielectric loss during room temperature, test voltage 1.0V.

Claims

1. the synthesis method of a huge dielectric constant material CaCu 3 Ti 4 O is characterized in that may further comprise the steps:

(1) A solution: titanic acid ester and long chain organic acid are dissolved in ethanol and the acetic acid mixing solutions;

(2) B solution: the amount with titanic acid ester is a benchmark; The ratio that according to the Ca:Cu:Ti mol ratio is 1:3:4 is dissolved in nitrocalcite and cupric nitrate in the aqueous ethanolic solution; And the adding concentrated nitric acid, obtain homogeneous solution, wherein long chain organic acid and nitric acid mol ratio are 1.50 ~ 0.33;

(4) 60 ~ 90 ℃ of oven dry gels get dry gel powder, make it that self-propagating reaction take place in 300 ° of C ~ 500 ° C dry gel powder and obtain the CaCu 3 Ti 4 O powder.

2. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1; It is characterized in that: the CaCu 3 Ti 4 O powder is added PVA and glycerine; Grind granulation, process base substrate, moulding, ° C sintering obtained the CaCu 3 Ti 4 O material in 2 ~ 8 hours in 960 ° of C ~ 1180.

3. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1 and 2 is characterized in that: described long chain organic acid is capric acid, lauric acid, stearic acid, n-caproic acid or contains carbon-carbon double bond and the long-chain unsaturated fatty acid of carboxyl.

4. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 3 is characterized in that: described long-chain unsaturated fatty acid is octadecenic acid or oleic acid.

5. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1 is characterized in that: said titanic acid ester [Ti (OR) ₄] in, R is butyl, sec.-propyl, octyl group or n-propyl.

6. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1 and 2 is characterized in that: the mol ratio of titanic acid ester and long chain organic acid is: (1:1) ~ (8:1).

7. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1 and 2 is characterized in that: ethanol: acetic acid: the volume ratio of titanic acid ester is: (2.4 ~ 6.0): (4.8 ~ 8.0): 10.0.

8. the synthesis method of huge dielectric constant material CaCu 3 Ti 4 O according to claim 1 and 2 is characterized in that: alcohol is (3:1) ~ (1:3) with the volume ratio of water in the aqueous ethanolic solution.