CN111848151B - A kind of titanium magnesium aluminum lithium phosphate LAMTP single-phase ceramic wave absorbing material and its preparation method and application - Google Patents

Abstract

The invention discloses a lithium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material and a preparation method and application thereof. The preparation method is as follows: the raw materials are Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ and Al ₂ O ₃ , MgO, the ratio of the amount of substances is 1.1 (0.65+0.5x): 3: 1.7: 0.15‑0.5x: x, x is 0.01 ~ 0.1; Then plasma discharge sintering is carried out at 980°C to 1020°C. The invention does not need to use composite materials, directly prepares a titanium magnesium aluminum phosphate LAMTP single-phase ceramic wave absorbing material with remarkable wave absorbing properties, and avoids the problems of oxidation and interface reaction existing in the long-term use of the composite materials.

Description

A kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material and preparation method thereof application

technical field

The invention belongs to the technical field of wave absorbing material preparation, and relates to a titanium magnesium aluminum phosphate LAMTP single-phase ceramic wave absorbing material and a preparation method and application thereof.

Background technique

With the further development of military science and technology, modern information warfare has put forward the requirement of use under high temperature for the stealth performance of weapons. Common high-temperature absorbing materials usually adopt the method of absorbing agent and matrix. The matrix is generally made of ceramic or glass that can withstand high temperature. The absorbing agent is generally a carbon-based material with high electrical conductivity, such as SiC, ZnO and Ti ₃ SiC ₂ , etc. The electromagnetic parameters can be regulated by adjusting the type, content, size, morphology and distribution state of the absorbent. However, there are problems of oxidation and interfacial reaction when the composite material is used for a long time.

Li _1.3 ^Al _0.3 Ti _1.7 (PO ₄ ) ₃ is composed of a framework structure composed of TiO ₆ hexahedron ^and PO ₄ tetrahedron. It shuttles in the gap, has high ionic conductance, and is widely used in the field of energy storage. Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic is used as the wave absorbing material. The dielectric constant has a dispersion effect, which can effectively expand the absorption bandwidth. The loss mechanism is conductivity loss, and the electromagnetic parameters can be adjusted by adjusting the conductivity. Optimizing the absorbing properties can avoid the interfacial reaction and diffusion problems that exist in the long-term use of low-conductivity ceramic matrix/high-conductivity absorber composites. At present, the conductivity of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramics prepared by solid-phase method is in the range of 1×10 ^-4 S·cm ^-3 to 4×10 ^-4 S·cm ^-3 . The real part of the dielectric constant of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramics is 10.2-13.1, and the imaginary part is 2.2-3.3; in the X-band, the reflectivity is lower than the absorption of -10dB The bandwidth is 2.25GHz, the absorption bandwidth needs to be expanded, the minimum reflectivity is -13.4dB, and the absorption peak needs to be deepened.

Therefore, in view of the above problems, it is necessary to modify the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramics to improve its electrical conductivity, increase the absorption bandwidth, and deepen the absorption peak, so as to improve its wave absorbing performance and expand its Scope of application.

SUMMARY OF THE INVENTION

In order to achieve the above purpose, the present invention provides a single-phase ceramic wave absorbing material of titanium magnesium aluminum phosphate LAMTP and its preparation method and application, which solve the problem of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase existing in the prior art. The absorbing performance of ceramics needs to be improved.

Among them, lithium magnesium aluminum titanium phosphate is the Chinese name of Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ ; LAMTP is the English name of Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ Abbreviation.

The technical scheme adopted in the present invention is, a titanium magnesium aluminum lithium phosphate LAMTP single-phase ceramic wave absorbing material, the general chemical formula is Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ , the value of x is 0.01 to 0.1.

Further, the electrical conductivity of Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ is 2×10 ^-3 S·cm ^-3 to 5×10 ^-3 S·cm ^-3 ; the Li _1.3 The real part of the dielectric constant of _+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ ranges from 11.3 to 14.2, and the imaginary part ranges from 3.0 to 4.0.

Another object of the present invention is to provide a method for preparing the above-mentioned lithium magnesium aluminum titanate phosphate LAMTP single-phase ceramic wave absorbing material, comprising the following steps:

S10, prepare raw materials: weigh Li ₂ CO ₃ , NH ₄ H 2 PO 4 , NH 4 H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , MgO; wherein, the x is 0.01 to 0.1; the purity of each raw material is greater than 99.99%; in order to make up for the high temperature volatilization of Li element, the addition ratio of Li ₂ CO ₃ in the raw materials is stoichiometric 10 wt% more than the calculated amount of substance;

S20, one ball milling and drying: after mixing the raw materials prepared in S1, carry out a ball milling and drying treatment to obtain the precursor powder; the purpose of performing one ball milling in S20 is to mix the raw materials evenly, so that a high-temperature solid-phase reaction occurs for the pre-sintering in S30 prepare;

S30, pre-sintering: put the precursor powder obtained in S20 into a crucible, transfer it to an air furnace, raise the temperature to 880 ℃～920 ℃ at a heating rate of 5 ℃/min, keep the temperature for 4h～8h, and then cool with the furnace, the obtained The product is ground to obtain single-phase Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles; wherein, the crucible is preferably a corundum crucible;

Among them, in S30, the purpose of calcination is to synthesize single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ ; the calcination temperature and time are based on Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , According to the DSC curve _of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ produced by the reaction of TiO ₂ and Al ₂ O _{3 0.3} Ti _1.7 (PO ₄ ) ₃ or impurities appear, and Mg cannot enter the Al site.

The single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ of the calcined product obtained by S30 cannot be directly used as a wave absorbing material because it must have a high density to be used as a wave absorbing material. If The precursor powder obtained by S20 is directly molded and then calcined by S30 to obtain a molded body or directly used as a coating material. There is a large amount of air between the particles of the obtained molded body or coating, which will reduce its dielectric constant and conductivity loss. Therefore, the single-phase Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ obtained from S30 must be densified to obtain materials with good wave absorbing properties;

S40, secondary ball milling and drying: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles obtained in S30 are subjected to secondary ball milling and drying to obtain single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles;

S50, sintering: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles obtained in S40 are placed in a graphite mold, and then transferred to a plasma discharge sintering furnace, under a temperature of 20MPa～40MPa Under pressure conditions, the temperature is raised to 980°C to 1020°C at a heating rate of 80°C/min～120°C/min, kept for 4min～8min, and then cooled with the furnace to obtain a chemical formula of Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ titanium magnesium aluminum lithium phosphate LAMTP single-phase ceramic wave absorbing material.

Among them, in S50, the purpose of placing single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles into a graphite mold for plasma discharge sintering is to use discharge plasma sintering while pressing and sintering. According to the principle, a dense Li _1.3+x Al _{0.3- x} Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material was obtained.

Among them, the shrinkage rate is calculated according to the volume difference of the samples before and after sintering. The sintering temperature is lower than 980 ℃, the sample is not dense, and the sintering temperature is higher than 1020 ℃, the sample is over-burned, and the shrinkage rate of the sample varies greatly with the sintering temperature; When the temperature is 980°C to 1020°C, the shrinkage rate of the sample remains unchanged with the change of the sintering temperature. Therefore, the present invention selects the sintering temperature to be 980°C to 1020°C. Due to the different contents of doped Mg, the sintering temperature is within a range, and the sintering temperature is slightly different for different contents.

Further, in S10, the value of x is 0.04.

Further, in S20, one ball milling and drying specifically includes the following steps:

S21, one-time ball milling: mix the raw materials prepared in S10 and pour into the ball mill tank and add the grinding balls, the mass ratio of the balls to the material is 20:1, and add absolute ethanol to submerge the grinding balls and the mixed raw materials to 2/2 of the ball mill tank. 3 places, and then carry out a ball milling treatment at a speed of 250rad/min for 8h to obtain a precursor slurry;

S22, primary drying: after the primary ball milling, the precursor slurry in the ball milling tank is poured out, and after the anhydrous ethanol in the precursor slurry is volatilized, it is placed in an 80°C oven for primary drying to obtain the precursor material. Grind and pass through a 200-mesh sieve to obtain precursor powder. Among them, the specific process of primary drying is: pour the precursor slurry in the ball mill tank into a clean stainless steel plate and put it in a fume hood. After the anhydrous ethanol of the precursor slurry is volatilized and becomes viscous, the Put it in an oven at 80 °C, and take it out after the material is cracked and there is no trace of wetness to obtain the precursor material;

Further, in S30, pre-sintering is specifically: placing the precursor powder obtained in S20 into a crucible, transferring it to an air furnace, heating up to 900°C at a heating rate of 5°C/min, holding for 6 hours, and then cooling with the furnace , the obtained product is ground to obtain single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles.

Further, in S40, the secondary ball milling and drying are specifically:

S41, secondary ball milling: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles obtained in S30 are poured into the ball milling jar and the grinding balls are added, the ratio of ball to material is 30:1, and Add anhydrous ethanol to submerge the grinding balls and single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ to coarsely grind the particles to 2/3 of the ball mill jar, and then perform secondary ball milling at a speed of 300rad/min 8h, single-phase Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ slurry was obtained; wherein, the purpose of secondary ball milling of S41 is to reduce the synthesized single-phase Li _1.3+x Al _{0.3- x} Mg _x Ti _1.7 (PO ₄ ) ₃ particle size of coarsely ground particles;

S42, secondary drying: after the secondary ball milling, pour out the single-phase Li _{1.3 +x} Al _{0.3 -x} Mg _x Ti _1.7 (PO ₄ ) ₃ slurry in the ball _-x Mg _x Ti _1.7 (PO ₄ ) ₃ slurry is placed in an oven at 80°C for secondary drying after volatilization of absolute ethanol to obtain single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ materials; single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ materials are ground and passed through a 200-mesh sieve to obtain single-phase Li _1.3+x Al _0.3 -x Mg _x Ti _1.7 (PO 4 ) 3 materials; ₄ ) ₃ Grind the particles finely. Wherein, the specific process of secondary drying is as follows: pour the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ slurry in the ball mill jar into a clean stainless steel plate and put it into a fume hood, wait until The anhydrous ethanol of the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ slurry was volatilized, and it became viscous and then placed in an 80°C oven until the material was cracked and After there is no trace of wetting, it is taken out to obtain a single-phase Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ material.

Among them, in S21 and S41, the material of the ball mill jar is any one of stainless steel, nylon, PTFE, alumina, and zirconia; the material of the grinding ball is any one of stainless steel, alumina, and zirconia.

Further, in S50, the sintering treatment is specifically: placing the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles obtained in S40 into a graphite mold, and then transferring it to a plasma discharge sintering furnace , under the pressure of 30MPa, the temperature was raised to 1000°C at a heating rate of 100°C/min, kept for 5 minutes, and then cooled with the furnace to obtain a single phase of Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ Ceramic absorbers.

Further, the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles obtained by S40 can also be used as the raw material of stealth coating, and the surface of the object to be stealth is subjected to supersonic plasma spraying to obtain Li _{1.3 +x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic coating.

Another object of the present invention is to provide an application of the above-mentioned lithium magnesium aluminum titanate phosphate LAMTP single-phase ceramic wave absorbing material in the field of wave absorbing materials.

The beneficial effects of the present invention are:

(1) The present invention uses low-valence element Mg to dope Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , so that the doping element partially replaces the Al site, reduces the binding force of framework ions to Li ⁺ ions, and optimizes Li ⁺ The channel size of ion migration increases the number of carrier Li ⁺ ions, effectively improves its conductivity and dielectric constant, adjusts its dispersion effect, and improves its wave absorbing performance.

(2) The conductivity of the Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared by the present invention is (2-5)×10 ^-3 S·cm ^-3 , which is higher than The conductivity of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is improved by an order of magnitude; the real part of its dielectric constant is 11.3-14.2, and the imaginary part is 3.0-4.0, which is higher than that of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ The dielectric properties have been significantly improved; in the X-band, the absorption bandwidth with reflectivity lower than -10dB is 2.98GHz, and the absorption bandwidth is significantly improved compared with Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , and the minimum reflectivity is - 17.2dB, the absorption peak is significantly deeper than that of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(3) The dielectric constant of the Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ (0.01≤x≤0.1) single-phase ceramic prepared by the present invention has a dispersion effect, which is beneficial to the expansion of the absorption bandwidth , the polarization mechanism is thermionic relaxation polarization, the activation energy of Li ⁺ ion migration determines the polarization ability, and the loss mechanism is conductivity loss, and the conductivity determines the loss value.

(4) The present invention directly prepares a Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material without using a composite material, avoiding the oxidation and interface existing when the composite material is used for a long time response question.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is an XRD pattern of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 of the present invention.

2 is a SEM image of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 of the present invention.

Fig. 3 is the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 of the present invention and the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic adsorbent prepared in Example 3 A graph of the dielectric constant of a wave material.

4 is a graph showing the reflectivity of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 of the present invention under different thicknesses.

5 is the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 and the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 Graph of reflectance at respective optimum thicknesses.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

A preparation method of Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material, comprising the following steps:

(1), prepare raw materials: respectively weigh Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , and MgO in a ratio of 0.7205: 3: 1.7: 0.145: 0.01; Wherein, the purity of each raw material is greater than 99.99%;

(2), one-time ball milling: mix the raw materials prepared in (1) and pour them into a PTFE ball mill tank and add zirconia grinding balls. The mixed raw materials are brought to 2/3 of the ball mill tank, and then ball-milled at a speed of 250 rad/min for 8 hours to obtain a precursor slurry;

(3), primary drying: after the first ball milling, pour the precursor slurry in the ball milling tank into a clean stainless steel plate and put it into a fume hood. Then put it in an oven at 80°C, and take it out after the material is cracked and there is no trace of wetness (completely dried) to obtain a precursor material, which is manually ground with an agate mortar until completely dispersed, and then sieved with a 200-mesh sieve. Sieve to obtain precursor powder;

(4), pre-sintering: put the precursor powder obtained in (3) into a corundum crucible, transfer it to an air furnace, heat up to 880°C at a heating rate of 5°C/min, keep the temperature for 4h, and then cool with the furnace, the resulting The product is manually ground with an agate mortar to completely disperse the product to obtain single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ coarsely ground particles;

(5), secondary ball milling: Pour the single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ obtained in (4) into the teflon ball mill jar and add zirconia grinding balls. 30:1, and add absolute ethanol to submerge the grinding balls and single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ to coarsely grind the particles to 2/3 of the ball mill jar, and then carry out two steps at a speed of 300rad/min. Secondary ball milling for 8h to obtain single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ slurry;

(6), secondary drying: after the secondary ball milling, the single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ slurry in the ball milling jar was poured into a clean stainless steel plate, and then placed in a fume hood. The anhydrous ethanol of the single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ slurry was volatilized, and it became viscous and then placed in an 80°C oven until the material was cracked and there was no trace of wetting (completely dried), take it out to obtain a single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ material; the single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ material is manually ground with an agate mortar, Pass through a 200-mesh sieve to obtain single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ finely ground particles;

(7), sintering: the single-phase Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ obtained from S40 was finely ground into a graphite mold, and then transferred to a plasma discharge sintering furnace. Under the pressure of 20MPa, The temperature was raised to 980°C at a heating rate of 80°C/min, kept for 4 minutes, and then cooled in a furnace to obtain a Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material.

The electrical conductivity of the Li _1.31 Al _0.29 Mg _0.01 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 1 was 2×10 ^{- 3} S·cm ^-3 .

Example 2

A preparation method of Li _1.4 Al _0.2 Mg _0.1 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material, comprising the following steps:

In the division (1), according to the ratio of the amount of the substance is 0.77:3:1.7:0.1:0.1, weigh Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , MgO respectively;

(3) The temperature was raised to 920°C at a heating rate of 5°C/min, and kept for 8h;

In (7), under the pressure condition of 40MPa, the temperature is raised to 1020°C at a heating rate of 120°C/min, and the temperature is kept for 8 minutes.

The rest of the steps are the same as in Example 1.

The conductivity of the Li _1.4 Al _0.2 Mg _0.1 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 2 was 4×10 ^{- 3} S·cm ^-3 .

Example 3

A preparation method of Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material, comprising the following steps:

In the division (1), according to the ratio of the amount of the substance is 0.737:3:1.7:0.13:0.04, respectively weigh Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , MgO;

(3) The temperature is raised to 900°C at a heating rate of 5°C/min, and the temperature is kept for 6h;

(7) Under the pressure condition of 30MPa, the temperature is raised to 1000°C at a heating rate of 100°C/min, and the temperature is kept for 5 minutes.

The rest of the steps are the same as in Example 1.

The electrical conductivity of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 was 5×10 ^{- 3} S·cm ^-3 .

Example 4

A preparation method of Li _1.37 Al _0.23 Mg _0.07 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material, comprising the following steps:

In the division (1), according to the ratio of the amount of the substance is 0.754:3:1.7:0.115:0.07, respectively weigh Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , MgO;

The rest of the steps are the same as in Example 3.

The electrical conductivity of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 4 was 4.5×10 ^-3 S·cm ^-3 .

Comparative Example 1

A preparation method of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material, comprising the following steps:

In the division (1), respectively weigh Li ₂ CO ₃ , NH ₄ H ₂ PO ₄ , TiO ₂ , and Al ₂ O ₃ according to the ratio of the amount of substances to 0.65:3:1.7:0.15;

The rest of the steps are the same as in Example 3.

The electrical conductivity of the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 was 2×10 ^-4 S·cm ^-3 .

Experimental example 1

离子的Mg²⁺

离子成功掺杂进Li_1.3Al_0.3Ti_1.7(PO₄)₃，形成Li_1.34Al_0.26Mg_0.04Ti_1.7(PO₄)₃单相陶瓷吸波材料。其中，图1的24°～25°位置的衍射峰放大图中虚线位置表示无掺杂的Li_1.3Al_0.3Ti_1.7(PO₄)₃的衍射峰。XRD test was performed on the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3, and the test results are shown in FIG. 1 . It can be seen from FIG. 1 that the crystal phase of the wave absorbing material prepared in Example 1 of the present invention is a single phase of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , but it can be seen from the enlarged view of the diffraction peak at 24° to 25° , the diffraction peak position of this position is shifted to a small angle compared with the diffraction peak of this position when Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ pure phase, which indicates that the absorbing material prepared in the embodiment has the existence of doped product magnesium , and since the diffraction peak shifts to a small angle, according to the Bragg equation 2dsinθ=nλ, where d is the interplanar spacing, θ is the diffraction angle, λ is the wavelength, and n is the reflection series. The decrease in the diffraction angle indicates the interplanar spacing. increases, which further proves that the ionic radius is larger than that of Al ³⁺

Ionic Mg ²⁺

The ions were successfully doped into Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ to form Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material. The dotted line positions in the enlarged view of the diffraction peaks at 24° to 25° in FIG. 1 represent the diffraction peaks of undoped Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

Experimental example 2

The microscopic morphology of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 was tested by SEM, and the test results are shown in FIG. 2 . It can be seen from FIG. 2 that the grain size of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 is between 1 μm and 18 μm, and the density is above 95%.

Experimental example 3

The wave absorbing properties of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 were tested, and the test results are shown in FIGS. 3 to 5 .

First of all, for the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 and the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 The dielectric constant is tested, and the dielectric constant curve is shown in Figure 3. It can be seen from Fig. 3 that the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 and the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase prepared in Comparative Example 1 The dielectric constants of ceramic materials all exhibit a dispersion effect with frequency. The real part of the dielectric constant of the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 is 10.2-13.1, and the imaginary part is 2.2-3.3. The real part of the dielectric constant of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 is 11.3-14.2, and the imaginary part is 3.0-4.0, both of which are better than those of Comparative Example 1. Increase.

Next, test the reflectivity curves of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 under different thicknesses, and the test results are shown in FIG. 4 . It can be seen from Fig. 4 that with the increase of thickness, the absorption peak shifts to low frequency. The thickness with the widest absorption bandwidth is selected as the optimum thickness under the thinnest possible thickness, then the optimum thickness of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 is 2.1mm.

Finally, for the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 and the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 The reflectivity curves under the respective optimum thicknesses are tested, and the test results are shown in Figure 5. It can be seen from Figure 5 that the optimal thickness of the Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic material prepared in Comparative Example 1 is 2.2 mm, and the bandwidth with reflectivity lower than -10 dB in the X-band is 2.25 GHz, The minimum reflectivity is -13.4dB. Compared with Comparative Example 1, the optimum thickness of the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 is 2.1 mm, which is lower than that of Comparative Example 1, and is in the X-band The bandwidth with reflectivity lower than -10dB is 2.98GHz, which is significantly increased compared with Comparative Example 1, the minimum reflectivity is -17.2dB, and the absorption peak is also deeper. This is because the Li _1.34 Al _0.26 Mg _0.04 Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material prepared in Example 3 is doped with an appropriate amount of Mg ²⁺ ions to obtain a suitable size of Li ⁺ ion migration channels, reducing The migration activation energy is improved, the conductivity of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ceramics is significantly improved, the conductivity loss is increased, and better wave absorbing properties are obtained.

It should be noted that in this application, relational terms such as first, second, third, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these There is no such actual relationship or sequence between entities or operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion such that a process, method, article or device comprising a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (8)

1. a preparation method of titanium magnesium aluminum lithium LAMTP single-phase ceramic wave absorbing material, is characterized in that, comprises the following steps: S10, prepare raw materials: weigh Li ₂ CO ₃ , NH ₄ H 2 PO 4 , NH 4 H ₂ PO ₄ , TiO ₂ , Al ₂ O ₃ , MgO; wherein, the value of x is 0.01-0.1; S20, ball milling and drying once: the raw materials prepared in S10 are mixed and then ball milling and drying are performed to obtain the precursor powder; S30, pre-sintering: put the precursor powder obtained in S20 into a crucible, transfer it to an air furnace, raise the temperature to 880 ℃～920 ℃ at a heating rate of 5 ℃/min, keep the temperature for 4h～8h, and then cool with the furnace, the obtained The product is ground to obtain single-phase Li _1.3+x Al _{0.3- x} Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles; S40, secondary ball milling and drying: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles obtained in S30 are subjected to secondary ball milling and drying to obtain single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles; S50, sintering: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ finely ground particles obtained in S40 are placed in a graphite mold, and then transferred to a plasma discharge sintering furnace, under a temperature of 20MPa～40MPa Under pressure conditions, the temperature is increased to 980°C to 1020°C at a heating rate of 80°C/min to 120°C/min, kept for 4min to 8min, and then cooled with the furnace to obtain a chemical formula of Li _1.3+x Al _{0.3- x} Mg _x Ti _1.7 (PO ₄ ) ₃ titanium magnesium aluminum lithium phosphate LAMTP single-phase ceramic wave absorbing material; The chemical formula of the lithium magnesium aluminum titanium phosphate LAMTP single-phase ceramic wave absorbing material is Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ , and the value of x is 0.01-0.1; The electrical conductivity of the Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ is 2×10 ^-3 S·cm ^-1 to 5×10 ^-3 S·cm ^-1 ; the Li _1.3+ The real part of the dielectric constant of _x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ ranges from 11.3 to 14.2, and the imaginary part ranges from 3.0 to 4.0. 2 . The preparation method of a lithium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1 , wherein, in S10 , the value of the x is 0.04. 3 . 3. the preparation method of a kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1, is characterized in that, in S20, described primary ball milling, drying, specifically comprises the following steps: S21, one-time ball milling: mix the raw materials prepared in S10 and pour into the ball mill tank and add the grinding balls, the mass ratio of the balls to the material is 20:1, and add absolute ethanol to submerge the grinding balls and the mixed raw materials to 2/2 of the ball mill tank. 3 places, and then carry out a ball milling treatment at a speed of 250rad/min for 8h to obtain a precursor slurry; S22, primary drying: after the primary ball milling, the precursor slurry in the ball milling tank is poured out, and after the anhydrous ethanol in the precursor slurry is volatilized, it is placed in an 80°C oven for primary drying to obtain the precursor material. Grind and pass through a 200-mesh sieve to obtain precursor powder. 4. the preparation method of a kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1, is characterized in that, in S30, described calcination is specially: the precursor powder obtained by S20 is placed put into a crucible, transferred to an air furnace, heated to 900 °C at a heating rate of 5 °C/min, kept for 6 h, and then cooled with the furnace, the obtained product was ground to obtain single-phase Li _{1.3+ x} Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground granules. 5. the preparation method of a kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1, is characterized in that, in S40, described secondary ball milling, drying, is specially: S41, secondary ball milling: the single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ coarsely ground particles obtained in S30 are poured into the ball milling jar and the grinding balls are added, the ratio of ball to material is 30:1, and Add anhydrous ethanol to submerge the grinding balls and single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ to coarsely grind the particles to 2/3 of the ball mill jar, and then perform secondary ball milling at a speed of 300rad/min 8h, single-phase Li _1.3+x Al _{0.3- x} Mg _x Ti _1.7 (PO ₄ ) ₃ slurry was obtained; S42, secondary drying: after the secondary ball milling, pour out the single-phase Li _{1.3 +x} Al _{0.3 -x} Mg _x Ti _1.7 (PO ₄ ) ₃ slurry in the ball _-x Mg _x Ti _1.7 (PO ₄ ) ₃ slurry is placed in an oven at 80°C for secondary drying after volatilization of absolute ethanol to obtain single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ materials; single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ materials are ground and passed through a 200-mesh sieve to obtain single-phase Li _1.3+x Al _0.3 -x Mg _x Ti _1.7 (PO 4 ) 3 materials; ₄ ) ₃ Grind the particles finely. 6. the preparation method of a kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1, is characterized in that, in S50, described sintering treatment is specifically: the single-phase Li _1.3+ obtained by S40 The finely ground particles of _x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ were placed in a graphite mold, and then transferred to a plasma discharge sintering furnace. ℃, hold the temperature for 5 min, and then cool with the furnace to obtain Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic wave absorbing material. 7. the preparation method of a kind of titanium magnesium aluminum phosphate lithium LAMTP single-phase ceramic wave absorbing material according to claim 1, is characterized in that, the described single-phase Li _1.3+x Al _0.3-x Mg _x Ti _1.7 obtained by S40 (PO ₄ ) ₃ finely ground particles can also be used as the raw material for stealth coating, supersonic plasma spraying is performed on the surface of the object to be stealth to obtain Li _1.3+x Al _0.3-x Mg _x Ti _1.7 (PO ₄ ) ₃ single-phase ceramic coating . 8 . The application of the titanium magnesium aluminum phosphate LAMTP single phase ceramic wave absorbing material obtained by the preparation method of the titanium magnesium aluminum phosphate LAMTP single-phase ceramic wave absorbing material according to claim 1 in the field of wave absorbing materials. 9 .

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