CN105272238A - High-Curie point positive temperature coefficient resistor material LiSr4V3O12 and preparation method thereof - Google Patents

Abstract

The invention discloses a leadless high-Curie point positive temperature coefficient resistor material and a preparation method thereof. The chemical composition formula of the high-Curie point positive temperature coefficient resistor material is LiSr4V3O12. The preparation method comprises the following steps: weighing and proportioning original powders with the purity of 99.9% (wt) or above of Li2CO3, SrCO3, and V2O5 according to LiSr4V3O12, carrying out ball milling, calcining, carrying out secondary ball milling, granulating, molding, debinding, carrying out high temperature sintering, adding to an Ag electrode to prepare the leadless positive temperature coefficient resistor material with high Curie point of 420DEG C. The resistor material prepared in the invention contains no lead, and avoids harms of lead to the body health of people and pollution of lead to environment. The resistor material has the advantages of low sintering temperature, low raw material cost, reaching of practical level, and suitableness for industrial large-scale production.

Description

A kind of high curie point positive temperature coefficient resistance material LiSr 4v 3o 12and preparation method thereof

Technical field

The present invention relates to a kind of unleaded positive temperature coefficient resistance material and preparation method thereof, belong to thermo-sensitive material field.

Background technology

PTC pottery (positive temperature coefficient thermal sensitive ceramic) has resistivity and raises and the feature of increase with temperature.It is development in recent years one of electronic material rapidly.Posistor can be divided into switching mode and the large class of offset-type two, and its characteristic and application is also different.Switching mode positive temperature coefficient thermo-sensitive material is mainly used in the protection etc. of rectifier cell of motor, transformer, bearing, high-power silicon, and it is also applied to the aspects such as current limliting, current stabilization, voltage stabilizing and velocity measurement as hear rate element.Offset-type positive temperature coefficient thermo-sensitive material can be used as the temperature compensation of transistor.

Barium titanate-based positive temperature coefficient thermo-sensitive material is a kind of Ferro-Electric Semiconductor material, is development in recent years one of electronic material rapidly.But the Curie temperature of barium titanate only has 120 DEG C, the PTC thermo-sensitive material of Curie temperature more than 120 DEG C is all leaded in the market.Domestic and international raising barium titanate positive temperature coefficient transition temperature mainly realizes by adding lead element.Although this kind of method and technology is more ripe and obtained good effect, lead has very strong toxicity.Products containing lead uses from being prepared into and even all there is very strong harm to last recycling use.Start to completely forbid use in the world in 2006 and had plumbous piezo component.In recent years, along with the demand of environment protection and human kind sustainable development, research novel lead-free PTC resistive material is extremely urgent.Nowadays unleaded positive temperature coefficient thermo-sensitive material mainly macromolecular material, but due to the hot mastication of macromolecular material, greatly limit its use range.Therefore find unleaded high-curie temperature positive temperature coefficient thermo-sensitive material tool and have very important significance.A lot of Chinese patent is had to report environment-friendly type positive temperature coefficient thermo-sensitive material, as (Ba _x sr _y ca _z ) Ti _u o ₃, wherein, x: 0.6 ~ 0.9, y: 0 ~ 0.3, z: 0.02 ~ 0.2, u: 0.98 ~ 1.02; : (Bi _1/2k _{1/2- a/ 2} na _a/2) Ce _{1- b} dbO ₃, wherein a=0 ~ 1, b=0.0005 ~ 0.005 etc., but Curie temperature not high (lower than 160 DEG C).Tang Xingui etc. report BaTiO ₃-Bi _0.5na _0.5tiO ₃-Bi _0.5k _0.5tiO ₃be positive temperature coefficient thermo-sensitive material, it comprehensively employs sol-gel method, solid reaction process, discharge plasma sintering method, and by adulterating prepared by one or more metal oxides, but the highest Curie temperature is also no more than 250 DEG C.

Summary of the invention

The object of this invention is to provide a kind of unleaded high curie point positive temperature coefficient resistance material and preparation method thereof.

The unleaded high curie point positive temperature coefficient resistance material that the present invention relates to chemical constitution formula be: LiSr ₄v ₃o ₁₂.

Preparation method's concrete steps of above-mentioned unleaded high curie point positive temperature coefficient resistance material are:

(1) be 99.9%(weight percent by purity) more than Li ₂cO ₃, SrCO ₃and V ₂o ₅starting powder press LiSr ₄v ₃o ₁₂composition weigh batching.

(2) material step (1) prepared through ball milling 4 hours, 700 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, calcine 3 hours for 800 ~ 850 DEG C, upper Ag electrode, i.e. obtained high curie point positive temperature coefficient resistance material LiSr ₄v ₃o ₁₂.

High curie point positive temperature coefficient resistance material LiSr prepared by the present invention ₄v ₃o ₁₂have the following advantages: have high Curie temperature, sintering temperature is low, and raw materials cost is low; Composition is unleaded, can not work the mischief to environment with to human body.

Embodiment

embodiment 1:

Be 99.9%(weight percent by purity) more than Li ₂cO ₃, SrCO ₃and V ₂o ₅starting powder press LiSr ₄v ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 700 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 800 DEG C of calcinings 3 hours, upper Ag electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 420 DEG C, resistivity is 8.8 Ω m, temperature factor is 8.9%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 9.8 × 10 ³.

embodiment 2:

Be 99.9%(weight percent by purity) more than Li ₂cO ₃, SrCO ₃and V ₂o ₅starting powder press LiSr ₄v ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 700 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 825 DEG C of calcinings 3 hours, upper Ag electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 420 DEG C, resistivity is 6.4 Ω m, temperature factor is 12.2%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 1.2 × 10 ⁴.

embodiment 3:

Be 99.9%(weight percent by purity) more than Li ₂cO ₃, SrCO ₃and V ₂o ₅starting powder press LiSr ₄v ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 700 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 850 DEG C of calcinings 3 hours, top electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 420 DEG C, resistivity is 7.5 Ω m, temperature factor is 15.5%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 8.3 × 10 ³.

Claims (1)

1. high curie point positive temperature coefficient resistance material and preparation method thereof, is characterized in that the chemical constitution formula of described positive temperature coefficient resistance material is: LiSr ₄v ₃o ₁₂;

Preparation method's concrete steps of described positive temperature coefficient resistance material are:

(1) be 99.9%(weight percent by purity) more than Li ₂cO ₃, SrCO ₃and V ₂o ₅starting powder press LiSr ₄v ₃o ₁₂composition weigh batching;

(2) material step (1) prepared through ball milling 4 hours, 700 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, calcine 3 hours for 800 ~ 850 DEG C, upper Ag electrode, i.e. obtained high curie point positive temperature coefficient resistance material LiSr ₄v ₃o ₁₂.