CN102219501A - Lithium-based low-loss temperature-stabilized microwave medium ceramic material and preparation method thereof - Google Patents

Abstract

The invention discloses a lithium-based low-loss temperature-stabilized microwave medium ceramic material and a preparation method thereof. The structure expression of the lithium-based low-loss temperature-stabilized microwave medium ceramic is Li1+2xZn0.5-xTi1.5-3xO4-2x, wherein x is more than or equal to 0.05 and less than or equal to 0.45. A solid-phase reaction sintering method is adopted for preparation. The ceramic material is sintered in the temperature scope of 1100-1200oC, has the dielectric constant Epsilon r which is more than or equal to 20.2 and less than or equal to 25, has the temperature coefficient of resonance frequency being adjustable near zero (wherein TCF is more than or equal to minus 9.5ppm/oC and less than or equal to plus 33ppm/oC), and has low microwave dielectric loss (wherein the high quality factor Qf value is more than or equal to 31,500GHz and less than or equal to 88,600GHz).

Description

A kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials and preparation method thereof

Technical field

The invention belongs to electronic ceramics and preparation field thereof, particularly a kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials and preparation method thereof.

Background technology

Microwave dielectric ceramic materials is the new function electronic ceramics that develops rapidly over nearly 30 years, characteristics such as loss is low, frequency-temperature coefficient is little, specific inductivity height that it has.Can make dielectric resonator (Dielectric Resonator is called for short DR) with this microwave dielectric material, compare with the metal chamber resonator, dielectric resonator has characteristics such as volume is little, in light weight, temperature stability is good, low price.The device of microwave ceramics manufacturing has: microwave-medium antenna, dielectric resonator oscillator (being called for short DRO), Medium Wave Guide transmission line etc. are widely used in various fields such as mobile communication, satellite television broadcasting communication, radar, NAVSTAR at present.

The development trend of microwave-medium ceramics device is microminiaturization, low-loss, high stable and chip type, produces change, low cost etc. on a large scale.The development trend of corresponding microwave dielectric material is nearly zero, the ultralow dielectric loss (ultrahigh Q-value) of specific inductivity seriation, temperature coefficient of resonance frequency.For middle K(specific inductivity with ultrahigh Q-value (Q value＞10000) between 20 to 40) the microwave dielectric material system, at present that commonly used is MgNb ₂O ₆(sintering temperature 1300 ^oC, specific inductivity 21.4, Qf=93800GHz, temperature coefficient of resonance frequency TCF=-70ppm/ ^oC), its sintering temperature is higher, and TCF is bigger negative value, does not satisfy the industrial application requirement.Use TiO ₂Perhaps SrTiO ₃Regulate MgNb ₂O ₆The TCF value can cause the reduction of Qf value again, phase composite is wayward.Therefore, research and development have that ultrahigh Q-value, TCF value are nearly zero, the mutually manageable middle K microwave dielectric ceramic materials of thing has become one of key point of microwave current mechanics of communication development and application.

In sum, for satisfying the demand for development of microwave-medium ceramics device miniatureization, high stable and chip type, research and development have ultrahigh Q-value, TCF value near zero, thing is mutually easy to control, production cost is low and the middle K microwave dielectric ceramic materials of environmental protection is a vital task of novel material development field.

Summary of the invention

The invention provides a kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials and preparation method thereof, to overcome the deficiency that the middle K microwave dielectric ceramic materials system with ultrahigh Q-value that prior art exists lacks.

For overcoming the problem that prior art exists, technical scheme provided by the invention is: a kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials, its structure expression is: Li _1+2xZn _0.5-xTi _1.5-3xO _4-2x, 0.05≤x in the formula≤0.45.

Above-mentioned lithium base low-loss temperature-stable microwave dielectric ceramic materials preparation method comprises the steps: successively

1) with chemical feedstocks ZnO, TiO ₂And Li ₂CO ₃By prescription general formula Li _1+2xZn _0.5-xTi _1.5-3xO _4-2x, 0.05≤x in the formula≤0.45;

2) chemical feedstocks after will preparing mixes, and puts into the nylon jar, adds the alcohol ball milling 4 hours, and thorough mixing is levigate, takes out the back 200 ^oFlash baking under the C is pressed into bulk behind 100 orders that sieve;

3) Ya Zhi block is through 900 ^oC pre-burning 4 hours can obtain sample and burn piece;

4) sample is burnt piece and pulverizes, and through 6 hours secondary ball milling, thorough mixing was levigate, 200 ^oC is oven dry, granulation down, and granulation obtains required powder after 80 orders and 120 eye mesh screen bilayers sieve;

5) with powder compression moulding on demand, 1100 ^oC ~ 1200 ^oSintering became porcelain in 2 hours under the C, can obtain lithium base low-loss temperature-stable microwave dielectric ceramic materials.

Compared with prior art, advantage of the present invention is:

1, excellent property: the relative permittivity behind the sintering is 20.2 ~ 25, low low-frequency dielectric loss (tan δ＜2 * 10 ^-4, 1MHz), good microwave dielectric property (31,500 GHz≤Qf≤123,600 GHz), temperature coefficient of resonance frequency is adjustable (9.5 ppm/ near zero ^oC≤TCF≤+ 33 ppm/ ^oC).

2, lithium base low-loss temperature-stable microwave dielectric ceramic materials of the present invention has following characteristics: relative permittivity (20.2 ~ 25) placed in the middle, little (tan δ＜2 * 10 of dielectric loss under the low frequency ^-4, 1MHz), microwave property excellence (31,500 GHz≤Qf≤88,600 GHz), near adjustable (the 9.5 ppm/ temperature coefficient of resonance frequency zero ^oC≤TCF≤+ 33 ppm/ ^oC), chemical constitution and preparation technology are simple.

The specific inductivity of the ceramics sample that obtains changes between 20.2 ~ 25 with composition, and Qf is distributed in 31,500 GHz ~ 88,600 GHz, temperature coefficient of resonance frequency at TCF at-9.5 ppm/ ^oC ~+33 ppm/ ^oAdjustable between the C, sintering temperature 1100 ~ 1200 ^oC.

3, thing is mutually adjustable: the phase ratio can be regulated with the variation of composition.

4, preparation technology is simple: the present invention has adopted simple and effective solid state reaction agglomerating method to realize the foregoing invention purpose.It at first is the prescription of choosing proper ratio, choose suitable initial oxide and carbonate, make raw material mix by a ball milling, make raw material carry out preliminary reaction by the presintering process, by the particle size of secondary ball milling refinement reactant, obtain needed ceramics sample by sintering process at last again.

5, applied range: can be used as microwave dielectric resonator, wave filter, duplexer, ceramic substrate, the use of mcm dielectric materials such as (MCM), can play a great role at aspects such as portable mobile phone, automobile telephone, microwave base station, cordless telephone, telestar receptor, wireless access, W-LAN and military radars, application prospect is very wide.

Embodiment

Below in conjunction with embodiment content of the present invention is described in further detail.

A kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials provided by the invention, its structure expression is: Li _1+2xZn _0.5-xTi _1.5-3xO _4-2x, 0.05≤x in the formula≤0.45.

Its principal feature of lithium base low-loss temperature-stable microwave dielectric ceramic materials of the present invention is with ZnO, TiO ₂And Li ₂CO ₃As pivot,, designed the compound phase ceramics of temperature complementary type according to ternary phase diagrams and monophasic space structure.

Embodiment 1: a kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials is made by following preparation method: comprise the steps: successively

1) with chemical feedstocks ZnO, the TiO of purity assay ₂And Li ₂CO ₃By prescription Li _1.1Zn _0.45Ti _1.35O _3.9Batching.

2) chemical feedstocks after will preparing mixes, and puts into the nylon jar, adds the alcohol ball milling 4 hours, and thorough mixing is levigate, takes out the back 200 ^oFlash baking under the C is pressed into bulk behind 100 orders that sieve;

3) Ya Zhi block is through 900 ^oC pre-burning 4 hours can obtain sample and burn piece;

4) sample burns and to carry out secondary ball milling again 6 hours after piece is pulverized, and thorough mixing is levigate, 200 ^oC is oven dry, granulation down, and granulation can obtain required porcelain after 80 orders and 120 eye mesh screen bilayers sieve.

5) with porcelain compression moulding on demand (sheet or column), then 1100 ^oC ~ 1200 ^oSintering became porcelain in 2 hours under the C air, can obtain lithium base low-loss temperature-stable microwave dielectric ceramic materials.

The performance of this group stupalith reaches following index:

1100 ^oC ~ 1200 ^oSinter porcelain in the C air, the dielectric properties ε under the microwave _r=25(7.2 GHz), quality factor q=9,100, Qf=65, the temperature coefficient of resonance frequency TCF=-9.5ppm/ under 500 GHz, microwave ^oC(25 ^oC ~ 85 ^oC).

Embodiment 2:

A kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials is made by following preparation method:

The places different with embodiment 1 are: 1) with chemical feedstocks ZnO, the TiO of purity assay ₂And Li ₂CO ₃By prescription Li _1.3Zn _0.35Ti _1.05O _3.7Batching.Other step is with embodiment 1.

The performance of this group stupalith reaches following index:

1100 ^oC ~ 1200 ^oSinter porcelain in the C air, the dielectric properties ε under the microwave _r=24.3(7.23 GHz), quality factor q=12,200, Qf=88, the temperature coefficient of resonance frequency TCF=-0.8ppm/ under 600 GHz, microwave ^oC(25 ^oC ~ 85 ^oC).

Embodiment 3:

A kind of lithium base low-loss temperature-stable microwave dielectric ceramic materials is made by following preparation method:

The places different with embodiment 1 are: 1) with chemical feedstocks ZnO, the TiO of purity assay ₂And Li ₂CO ₃By prescription Li _1.9Zn _0.15Ti _1.05O _3.1Batching.Other step is with embodiment 1.The performance of this group stupalith reaches following index:

1100 ^oC ~ 1200 ^oSinter porcelain in the C air, the dielectric properties ε under the microwave _r=20.2(7.5 GHz), quality factor q=4,200, Qf=31, the temperature coefficient of resonance frequency TCF=+33 ppm/ under 500 GHz, microwave ^oC(25 ^oC ~ 85 ^oC).

It is pointed out that according to technical scheme of the present invention, the foregoing description can also be enumerated many, prove,, all can reach purpose of the present invention in the scope that claims of the present invention proposed according to applicant's lot of experiment results.

Claims (2)

1. a lithium base low-loss temperature-stable microwave dielectric ceramic materials is characterized in that this stupalith structure expression is: Li _1+2xZn _0.5-xTi _1.5-3xO _4-2x, 0.05≤x in the formula≤0.45.

2. realize the preparation method of the described lithium base of claim 1 low-loss temperature-stable microwave dielectric ceramic materials, it is characterized in that, carry out according to the following steps:

1) with chemical feedstocks ZnO, TiO ₂And Li ₂CO ₃By prescription general formula Li _1+2xZn _0.5-xTi _1.5-3xO _4-2x, 0.05≤x in the formula≤0.45;

2) chemical feedstocks after will preparing mixes, and puts into the nylon jar, adds the alcohol ball milling 4 hours, and thorough mixing is levigate, takes out the back 200 ^oFlash baking under the C is pressed into bulk behind 100 orders that sieve;

3) Ya Zhi block is through 900 ^oThe C pre-burning, and be incubated 4 hours, can obtain sample and burn piece;

4) sample is burnt piece and pulverizes, and through 6 hours secondary ball milling, thorough mixing was levigate, 200 ^oC is oven dry, granulation down, and granulation obtains required powder after 80 orders and 120 eye mesh screen bilayers sieve;

5) with powder compression moulding on demand, 1100 ^oC ~ 1200 ^oSintering became porcelain in 2 hours under the C air atmosphere, can obtain lithium base low-loss temperature-stable microwave dielectric ceramic materials.