CN105060886A - Method for preparation of high permittivity multilayer ceramic capacitor dielectric material by doping nano-powder - Google Patents

Abstract

The invention discloses a method for preparation of high permittivity multilayer ceramic capacitor dielectric material by doping nano-powder. The method includes: taking BaTiO3 powder as the base material, on the basis, additionally adding 0.6-1.2% by mass of (NiO)1-x(NbO2.5)x, wherein x=0.6-0.8, and 3.0-4.0% of CaZrO3; wherein, (NiO)1-x(NbO2.5)x is synthesized from Ni(NO3)2.6H2O and Nb2O5 according to a mole ratio of 1-x:x/2 by a sol-gel technique, with x being 0.6-0.8, and CaZrO3 is synthesized from CaCO3 and ZrO2 in a mole ratio of 1:1; sintering the green body at 1250 DEG C, and performing heat preservation for 3h. In a temperature zone ranging from -55DEG C to 150DEG C, the dielectric material provided by the invention has a capacitance change rate within +/-15%, and has a high room temperature permittivity (about 4500).

Description

Dope nano-power prepares the method for high dielectric multi-layer ceramic capacitor dielectric material

Technical field

The invention belongs to a kind of take composition as the ceramic composition of feature, is specifically related to a kind ofly adopt Dope nano-power to prepare unleaded, to be highly situated between and to have the method for the X8R type medium material for multilayer ceramic capacitors of excellent temperature stability.

Background technology

Along with the high speed development of multiple mobile electronic device such as notebook computer, mobile telephone, digital camera, automotive electronics etc., chip electronic component progressively instead of conventional wire type electronic component.Chip multilayer ceramic capacitor (MultilayerCeramicCapacitor, be called for short MLCC), in order to the requirement such as meet miniaturization, Large Copacity, apply in hot environment, ceramic medium material not only will possess high dielectric properties, and requires that its rate of temperature change presents smooth variation characteristic in wide temperature range.X8R (-55 DEG C ~ 150 DEG C, Δ C/C _{25 DEG C}≤ ± 15%) type MLCC dielectric material is widely used in the industries such as Military Electronic Equipment and petroleum prospecting such as aerospace, tank electronics, military mobile communication, the control of weapon bullet and military signal monitoring.Barium titanate (BaTiO ₃) base temperature-stable MLCC dielectric material because of its environmental sound, be always research focus.

But, the X8R dielectric material of present stage research, its material adopting Traditional dopant method to prepare, room temperature dielectric constant is (lower than 3000) less than normal generally, growth requirement or the room temperature dielectric constant that can not meet miniaturization are high, and normal existence is unfavorable for that industrialization is produced or synthesizes in component leaded, harm environment.Utilize sol-gel method to prepare mixed nanometer powder, chemical reaction can be controlled at atom and molecular level compared with conventional solid-state method, the ceramic powder purity of preparation is high, stoicheiometry accurately controls, distributed components, particle size and morphology controllable.In addition, the powder specific-surface area detection that these class methods obtain is large and activity is high, and it spreads at barium phthalate base dielectric material to be beneficial to raising.

Summary of the invention

Object of the present invention, though the Capacitance Shift Rate being to overcome the ceramic capacitor dielectric adopting Traditional dopant method to prepare can reach the requirement of X8R, its specific inductivity is on the low side, even contains heavy metal Pb in component, harm environment.A kind of unleaded height is provided to be situated between and X8R type medium material for multilayer ceramic capacitors being beneficial to suitability for industrialized production and preparation method thereof.

The present invention is achieved by following technical solution

Dope nano-power prepares a method for high dielectric multi-layer ceramic capacitor dielectric material, with BaTiO ₃powder is base-material, and on this basis, additional mass percent is (NiO) of 0.6 ~ 1.2% _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8, and the CaZrO of 3.0 ~ 4.0% ₃;

Described (NiO) _1-x(NbO _2.5) _xcompound, utilizes sol-gel method by raw material Ni (NO ₃) ₂6H ₂o and Nb ₂o ₅1-x:x/2 in molar ratio, wherein x=0.6 ~ 0.8 is synthesized;

Described CaZrO ₃by CaCO ₃and ZrO ₂1: 1 synthesis in molar ratio;

This Dope nano-power prepares the preparation method of high dielectric multi-layer ceramic capacitor dielectric material, has following steps:

(1) sol-gel method synthesis (NiO) _1-x(NbO _2.5) _xcompound, wherein x=0.6 ~ 0.8

1. the aqueous citric acid solution of niobium is prepared

A () is according to (NiO) _1-x(NbO _2.5) _x, wherein the stoichiometric ratio of x=0.6 ~ 0.8 takes Nb ₂o ₅, by Nb ₂o ₅add in hydrofluoric acid, Nb ₂o ₅be 1:3 with the mol ratio of hydrofluoric acid, heating in water bath is to Nb ₂o ₅whole dissolving;

B () adds ammoniacal liquor, adjust ph to 9 in above-mentioned solution, generate niobic acid precipitation;

C the above-mentioned precipitation of () filtering and washing, then adds in lemon aqueous acid respectively by niobic acid, obtain the aqueous citric acid solution of niobium, and wherein the mol ratio of niobium ion and citric acid is 1:6;

Add ethylene glycol in the aqueous citric acid solution of the niobium 2. step 1. obtained, heated and stirred, citric acid and ethylene glycol mole be 1:3;

3. Ni is prepared ²⁺ethylene glycol solution

By (NiO) _1-x(NbO _2.5) _x, wherein the stoichiometric ratio of x=0.6 ~ 0.8 takes six water nickelous nitrates and is dissolved in ethylene glycol and stirs;

4. (NiO) _1-x(NbO _2.5) _xthe formation of colloidal sol and (NiO) _1-x(NbO _2.5) _xthe formation of nano-powder

D Ni that 3. step configures by () ²⁺ethylene glycol solution joins in the liquid that 2. step configure, and stirs and obtains (NiO) _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8 colloidal sol;

E () is by (NiO) of step 4. (d) _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8 colloidal sol is placed in baking oven, in 80 ~ 120 DEG C of oven dry, forms xerogel;

F the xerogel of step 4. (e) is placed in High Temperature Furnaces Heating Apparatus by (), obtain (NiO) 1-x (NbO in 900 DEG C of thermal treatments _2.5) x, wherein x=0.6 ~ 0.8 nano-powder, then ball milling 4 ~ 6 hours, crosses 80 order sub-sieves for subsequent use;

(2) CaZrO is synthesized ₃

By CaCO ₃, ZrO ₂1:1 batching in molar ratio, ball milling 4 hours after raw material mixes with deionized water, in 120 DEG C of oven dry, crosses 40 order sub-sieves, in 1000 DEG C of insulations 2 hours, obtained CaZrO ₃;

(3) with BaTiO ₃as base-material, add (NiO) of 0.6 ~ 1.2% _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8, and the CaZrO of 3.0 ~ 4.0% ₃; After being mixed with deionized water by joined raw material, ball milling 4 ~ 8 hours, adds the binding agent that mass percent is 7% after oven dry, crosses 80 order sub-sieves, granulation;

(4) the granulation powder of step (3) is pressed into green compact, after binder removal, in 1250 DEG C of sintering, is incubated 2 hours, obtained high dielectric multi-layer ceramic capacitor dielectric material.

Described CaZrO ₃addition be 3.0wt%.

The green compact of described step (4) are the disk green compact of Ф 15 × 1 ~ 1.3mm.

The green compact of described step (4) were warming up to 550 DEG C of binder removals through 3.5 hours, then rose to 1250 DEG C of sintering through 1 hour, is incubated 3 hours.

Beneficial effect of the present invention is as follows:

1. the present invention is by the interpolation of nano-powder, and effectively improve the microtexture of pottery, improve dielectric properties, the equal environmental friendliness of ceramic composition, is beneficial to suitability for industrialized production.

2. the present invention has excellent dielectric properties: in-55 DEG C ~ 150 DEG C warm areas, and rate of change of capacitance within ± 15%, and has higher room temperature dielectric constant (~ 4500).

Embodiment

Below with reference to specific embodiment, the present invention is described in further detail.

Embodiment 1

(1) sol-gel method synthesis (NiO) _0.4(NbO _2.5) _0.6nano-ceramic powder

1. the aqueous citric acid solution of niobium is prepared

A () takes 7.8853gNb ₂o ₅, by Nb ₂o ₅put into 40mL hydrofluoric acid, heating in water bath is to Nb ₂o ₅whole dissolving;

B () adds ammoniacal liquor in above-mentioned solution, adjust ph is 9, generates niobic acid precipitation;

C the above-mentioned precipitation of () filtering and washing, then adds in lemon aqueous acid respectively by niobic acid, obtain the aqueous citric acid solution of niobium, and wherein the mol ratio of niobium ion and citric acid is 1:6;

Add ethylene glycol in the aqueous citric acid solution of the niobium 2. step 1. obtained, heated and stirred, citric acid and ethylene glycol mole be 1:3;

3. Ni is prepared ²⁺ethylene glycol solution

By (NiO) _0.4(NbO _2.5) _0.6stoichiometric ratio claim 11.6293g six water nickelous nitrate to be dissolved in 30ml ethylene glycol to stir;

4. (NiO) _0.4(NbO _2.5) _0.6the formation of colloidal sol and (NiO) _0.4(NbO _2.5) _0.6the formation of nano-powder

D Ni that 3. step configures by () ²⁺ethylene glycol solution add step and 2. configure in liquid, 60 DEG C of heated and stirred 2h, obtain (NiO) _0.4(NbO _2.5) _0.6colloidal sol;

E () is by (NiO) of step (d) _0.4(NbO _2.5) _0.6colloidal sol is placed in baking oven, in 100 DEG C of oven dry, forms xerogel;

F the xerogel of step (f) is placed in High Temperature Furnaces Heating Apparatus by (), obtain (NiO) in 900 DEG C of thermal treatments _0.4(NbO _2.5) _0.6nano-powder, then ball milling 6 hours, cross 80 order sub-sieves for subsequent use;

(2) by 22.3291gCaCO ₃and 27.5114gZrO ₂mixing, using deionized water as ball-milling medium, ball milling 4 hours post-dryings, to sieve, obtains CaZrO in 1000 DEG C of calcinings ₃.

(3) by 50gBaTiO ₃, 0.55g (NiO) _0.4(NbO _2.5) _0.6and 1.50gCaZrO ₃ball milling 4 hours after mixing with deionized water, after drying, additional mass percent is the paraffin of 7%, crosses 80 order sub-sieve granulations.

(4) shaping with sintering:

Powder after step (3) granulation is pressed under 3MPa the disk green compact of Ф 15 × 1.2mm, 550 DEG C of binder removals are warming up to through 3.5 hours, rose to 1250 DEG C of sintering through 1 hour again, be incubated 3 hours, obtained unleaded high dielectric multi-layer ceramic capacitor dielectric material.

Evenly apply silver slurry in resulting product upper and lower surface, prepare electrode through 850 DEG C of burning infiltrations, obtained high dielectric multi-layer ceramic capacitor dielectric material, tests its dielectric properties and TC characteristic.

The concrete proportioning raw materials of embodiment 1-5 and main technologic parameters refer to table 1, and other manufacture craft is all identical with embodiment 1.

Table 1

Testing method of the present invention and test set as follows:

(1) dielectric properties test (AC test signals: frequency is 1kHz, voltage is 1V)

Use electrical capacity C and the loss tan δ of HEWLETTPACKARD4278A type capacitance tester test sample, and calculate the specific inductivity of sample, calculation formula is:

$\mathrm{\ϵ}=\frac{14.4\×C\×d}{D^2}$

(2) TC characteristic test

GZ-ESPECMPC-710P type high/low temperature circulation incubator, HM27002 type electrical condenser C-T/V characteristic dedicated tester and HEWLETTPACKARD4278A is utilized to test.The electrical capacity of measure sample in warm area-55 DEG C ~ 150 DEG C, adopts following formulae discovery rate of change of capacitance:

The dielectric properties detected result of the ceramic disks of 1-5 embodiment refers to table 2.

Table 2

The present invention is not limited to above-described embodiment, and the change of a lot of details is possible, but therefore this do not run counter to scope and spirit of the present invention.

Claims (4)

1. Dope nano-power prepares a method for high dielectric multi-layer ceramic capacitor dielectric material, with BaTiO ₃powder is base-material, and on this basis, additional mass percent is (NiO) of 0.6 ~ 1.2% _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8, and the CaZrO of 3.0 ~ 4.0% ₃;

Described (NiO) _1-x(NbO _2.5) _xcompound, utilizes sol-gel method by raw material Ni (NO ₃) ₂6H ₂o and Nb ₂o ₅1-x:x/2 in molar ratio, wherein x=0.6 ~ 0.8 is synthesized;

Described CaZrO ₃by CaCO ₃and ZrO ₂1: 1 synthesis in molar ratio.

This Dope nano-power prepares the preparation method of high dielectric multi-layer ceramic capacitor dielectric material, has following steps:

(1) sol-gel method synthesis (NiO) _1-x(NbO _2.5) _xcompound, wherein x=0.6 ~ 0.8

1. the aqueous citric acid solution of niobium is prepared

A () is according to (NiO) _1-x(NbO _2.5) _x, wherein the stoichiometric ratio of x=0.6 ~ 0.8 takes Nb ₂o ₅, by Nb ₂o ₅add in hydrofluoric acid, Nb ₂o ₅be 1:3 with the mol ratio of hydrofluoric acid, heating in water bath is to Nb ₂o ₅whole dissolving;

B () adds ammoniacal liquor, adjust ph to 9 in above-mentioned solution, generate niobic acid precipitation;

C the above-mentioned precipitation of () filtering and washing, then adds in lemon aqueous acid respectively by niobic acid, obtain the aqueous citric acid solution of niobium, and wherein the mol ratio of niobium ion and citric acid is 1:6;

Add ethylene glycol in the aqueous citric acid solution of the niobium 2. step 1. obtained, heated and stirred, citric acid and ethylene glycol mole be 1:3;

3. Ni is prepared ²⁺ethylene glycol solution

By (NiO) _1-x(NbO _2.5) _x, wherein the stoichiometric ratio of x=0.6 ~ 0.8 takes six water nickelous nitrates and is dissolved in ethylene glycol and stirs;

4. (NiO) _1-x(NbO _2.5) _xthe formation of colloidal sol and (NiO) _1-x(NbO _2.5) _xthe formation of nano-powder

D Ni that 3. step configures by () ²⁺ethylene glycol solution joins in the liquid that 2. step configure, and stirs and obtains (NiO) _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8 colloidal sol;

E () is by (NiO) of step 4. (d) _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8 colloidal sol is placed in baking oven, in 80 ~ 120 DEG C of oven dry, forms xerogel;

F the xerogel of step 4. (e) is placed in High Temperature Furnaces Heating Apparatus by (), obtain (NiO) 1-x (NbO in 900 DEG C of thermal treatments _2.5) x, wherein x=0.6 ~ 0.8 nano-powder, then ball milling 4 ~ 6 hours, crosses 80 order sub-sieves for subsequent use;

(2) CaZrO is synthesized ₃

By CaCO ₃, ZrO ₂1:1 batching in molar ratio, ball milling 4 hours after raw material mixes with deionized water, in 120 DEG C of oven dry, crosses 40 order sub-sieves, in 1000 DEG C of insulations 2 hours, obtained CaZrO ₃;

(3) with BaTiO ₃as base-material, add (NiO) of 0.6 ~ 1.2% _1-x(NbO _2.5) _x, wherein x=0.6 ~ 0.8, and the CaZrO of 3.0 ~ 4.0% ₃; After being mixed with deionized water by joined raw material, ball milling 4 ~ 8 hours, adds the binding agent that mass percent is 7% after oven dry, crosses 80 order sub-sieves, granulation;

(4) the granulation powder of step (3) is pressed into green compact, after binder removal, in 1250 ~ 1280 DEG C of sintering, is incubated 2 ~ 4 hours, obtained high dielectric multi-layer ceramic capacitor dielectric material.

2. Dope nano-power according to claim 1 prepares the method for high dielectric multi-layer ceramic capacitor dielectric material, it is characterized in that, described CaZrO ₃addition be 3.0wt%.

3. Dope nano-power according to claim 1 prepares the method for high dielectric multi-layer ceramic capacitor dielectric material, it is characterized in that, the green compact of described step (4) are the disk green compact of Ф 15 × 1 ~ 1.3mm.

4. Dope nano-power according to claim 1 prepares the method for high dielectric multi-layer ceramic capacitor dielectric material, it is characterized in that, the green compact of described step (4) were warming up to 550 DEG C of binder removals through 3.5 hours, then rose to 1250 DEG C of sintering through 1 hour, is incubated 3 hours.