CN115057703A - Composite ceramic composed of antiferroelectric and GaN semiconductor and preparation method thereof - Google Patents

Abstract

The invention discloses a composite ceramic composed of antiferroelectric and GaN semiconductor, the structural formula of which is (1-x) PNZST: xGaN, wherein x is more than or equal to 0.01 and less than or equal to 0.10; the specific structural formula of PNZST is Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _1‑y Ti _y ] _0.98 O ₃ Y is more than or equal to 0.060 and less than or equal to 0.067. The composite material is prepared by a two-step solid phase sintering reaction method, the matrix material is converted from an antiferroelectric phase to a ferroelectric phase by adding the GaN, the composite material can generate ferroelectric-antiferroelectric phase change along with the change of temperature through temperature induction, and the higher polarization strength change rate is realized, so that the excellent pyroelectric performance is obtained. The new process develops a new material design idea for the development of pyroelectric materials and provides a new material design idea for the technical field of uncooled infrared detectionAnd (5) material foundation.

Description

A composite ceramic composed of antiferroelectric and GaN semiconductor and preparation method thereof

technical field

The invention relates to the technical field of ceramic materials, in particular to a composite ceramic composed of an antiferroelectric and a GaN semiconductor and a preparation method thereof.

Background technique

The main function of pyroelectric detectors is to detect changes in ambient temperature, so they can be used to observe and detect target radiation at night. Due to this feature, pyroelectric detectors have received extensive attention, especially by the military industry. Vigorously pay attention to make it used in military reconnaissance fields such as infrared early warning and infrared imaging.

Nowadays, pyroelectric detectors have been used in all walks of life, and pyroelectric imaging technology has become one of the three major sensing systems together with radar and TV. The core part of pyroelectric devices is pyroelectric materials. It can be said that the development of pyroelectric materials directly affects the development of detectors. Therefore, it is of great significance to discuss the research progress of pyroelectric materials. The reason why the pyroelectric detector can detect is by the function of the pyroelectric sensitive unit, so the sensitive unit is the core part of the detector, and the core material of the sensitive unit is the pyroelectric material. The simple explanation of the working mechanism of pyroelectricity is that the pyroelectric sensitive material senses the external environment (change in temperature), generates corresponding induced charges, and then flows out and amplifies through the external circuit. Therefore, the research of pyroelectric materials becomes crucial. From the microscopic level, the pyroelectric effect is that the polarization intensity of the material generates an induced charge with the change of the external ambient temperature, and from the macroscopic level, it generates an electric current with the change of the temperature.

At present, pyroelectric materials can be mainly divided into single crystal materials (such as LiTaO ₃ , SBN, LiNbO ₃ , KTN, etc.); composite materials and organic polymers (such as PVDF, PVF, PVDF-PZT, etc.); piezoelectric ceramic materials ( Such as BaTiO ₃ , ZnO, PMN, PLZT, PbTiO ₃ , PZT, etc.). Single-crystal pyroelectric materials have high detection quality, easy crystal growth, small thermal diffusivity, and low dielectric constant. The disadvantages are that they are easily decomposed by moisture, need to be well sealed, are inconvenient to process and use, and have complex process; composite materials and high Molecular organic polymers have high Curie temperature, stable physicochemical properties, low thermal conductivity, and easy processing. They are suitable for making large-area electronic devices. Their disadvantages are low pyroelectric coefficient, relatively low strength, and poor compatibility with microelectronics technology.

Piezoelectric ceramic materials, especially PZT-based ceramics, have moderate pyroelectric properties and Curie temperature. Compared with single crystal materials, the preparation process is simple and the production cost is low, so they are popular materials in the field of pyroelectricity.

SUMMARY OF THE INVENTION

In view of the above problems existing in the prior art, the present invention provides a composite ceramic composed of an antiferroelectric and a GaN semiconductor and a preparation method thereof. The composite ceramic of the present invention can obtain an ultra-high pyroelectric coefficient p at room temperature.

The technical scheme of the present invention is as follows:

A 0-3 type composite ceramic composed of an antiferroelectric and a GaN semiconductor, the structural formula of the composite ceramic is (1-x)PNZST:xGaN, wherein 0.01≤x≤0.10;

PNZST is an abbreviation for antiferroelectric, and its specific structural formula is Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _1-y Ti _y ] _0.98 O ₃ , 0.060≤y≤0.067.

A preparation method of a composite ceramic composed of an antiferroelectric and a GaN semiconductor adopts a preparation process of a two-step solid-phase method. Composite ceramics.

The preparation method comprises the following steps:

(1) Preparation of PNZST powder:

Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _1-y Ti _y ] _0.98 O ₃ , 0.060≤y≤0.067, weigh the raw materials PbO, TiO ₂ , ZrO ₂ , Nb ₂ O ₅ and SnO ₂ according to the element stoichiometric ratio, ball-milling, drying and then calcining, pre-sintering the calcined powder at high temperature again, ball-milling and drying again to obtain the PNZST powder;

High temperature pre-sintering can improve the phase stability of PNZST;

(2) Introducing GaN semiconductors to form composite ceramics with PNZST:

According to the chemical formula (1-x) PNZST:xGaN, 0.01≤x≤0.10, the PNZST powder and GaN nano-powder obtained in step (1) were weighed respectively, and the powder was uniformly mixed by ball milling, and the mixed powder was dried. The composite ceramic is obtained by post-press molding, and then placed in a crucible for rapid high-temperature sintering.

In step (1), ball milling is performed in absolute ethanol for 12 hours.

In step (1), the calcination conditions are calcination at 850-900° C. for 4-5 hours; the high-temperature pre-sintering conditions are pre-sintering at 1200-1300° C. for 2-4 hours.

In step (2), the temperature rise and fall rate during rapid high temperature sintering is 9-10°C/min, and the sintering condition is sintering at 1000-1100°C for 0.5-1 h.

In step (2), the particle size of the GaN nano-powder is 30-50 nm.

In step (2), the mixed powder is also mixed with a binder PVA, and is pressed and formed, and the green body is debonded at 650°C.

The beneficial technical effects of the present invention are:

The GaN in the composite ceramic of the invention is distributed at the grain boundary position of the antiferroelectric PNZST, and a local stress field is generated due to the mismatch of thermal expansion coefficients between the two phases, and the transition from the antiferroelectric phase to the ferroelectric phase is realized. A ferroelectric/antiferroelectric phase boundary was constructed near room temperature, and an ultra-high pyroelectric coefficient p was obtained under the drive of temperature, resulting in excellent pyroelectric performance.

The preparation method of the composite ceramic of the present invention is simple and efficient, without complicated processes and expensive equipment, and the cost is low; compared with the traditional solid solution based on similar materials, the present invention utilizes the addition of GaN to construct ferroelectric/antiferroelectric The phase boundary reduces the potential barrier of polarization reversal, promotes polarization reversal and enhances the pyroelectric effect, providing material and physical basis for pyroelectric infrared sensors.

Description of drawings

FIG. 1 is the ferroelectric loop of the composite ceramic sample obtained in Example 1 of the present invention.

FIG. 2 is the pyroelectric coefficient value of the composite ceramic sample obtained in Example 1 of the present invention as a function of temperature.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Example 1:

An antiferroelectric and a GaN semiconductor form a 0-3 type composite ceramic, the chemical formula of the composite ceramic is 0.99Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _0.937 Ti _0.063 ] _0.98 O ₃ :0.01GaN, and a preparation method thereof for:

(1) Using analytically pure PbO (99.99%), TiO ₂ (99.5%), ZrO ₂ (99.99%), Nb ₂ O ₅ (99.9%), SnO ₂ (99.5%) as raw materials, according to the element stoichiometric ratio, Weigh 27.0843g of PbO, 0.5977g of TiO ₂ , 7.7403g of ZrO ₂ , 0.3193g of Nb ₂ O ₅ , 7.1768g of SnO ₂ , ball-milled in absolute ethanol for 12 hours to make the raw materials fully mixed, and dried. , calcined at 900°C for 4h, pre-sintered the calcined PNZST powder at 1250°C for 3h, ball milled again for 12h to make the powder finely ground, and dried to obtain a pure perovskite phase structure PNZST powder.

(2) According to the chemical formula 0.99PNZST:0.01GaN, 29.9282g of the PNZST powder obtained in step (1) and 0.0718g of GaN nano-powder (particle size: 30nm) were respectively weighed, ball milled for 12h, dried, mixed with the binder PVA, Press molding, after the green body is degummed at 650 °C, it is rapidly heated to 1050 °C for sintering at 9 °C per minute, and kept for 1 hour, and also rapidly cooled to room temperature at 9 °C per minute to obtain the composite ceramic. The structure has good compactness .

Example 2:

An antiferroelectric and a GaN semiconductor form a 0-3 type composite ceramic, the chemical formula of the composite ceramic is 0.97Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _0.937 Ti _0.063 ] _0.98 O ₃ :0.03GaN, and a preparation method thereof Refer to Example 1; wherein, the calcination temperature of PNZST powder is 850°C for 5h, the pre-sintering temperature is 1200°C, and the temperature is kept for 4h. The mass is 0.2187g, the sintering temperature is 1030°C, and the temperature is kept for 1h.

Example 3:

An antiferroelectric and a GaN semiconductor form a 0-3 type composite ceramic, the chemical formula of the composite ceramic is 0.90Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _0.937 Ti _0.063 ] _0.98 O ₃ : 0.10GaN, and a preparation method thereof Refer to Example 1; wherein, the calcination temperature of PNZST powder is 870°C, the temperature is kept for 4h, the pre-sintering temperature is 1230°C, and the temperature is kept for 3h. The mass of the particle size is 50nm) is 0.7713g, the sintering temperature is 1020°C, and the temperature is kept for 1h.

Test case:

The performance of the composite ceramics obtained in Examples 1-3 was tested by a pyroelectric tester, and the test results are shown in Table 1.

Table 1

From the data in Table 1, it can be seen that with the addition of the semiconductor GaN, the matrix material is transformed from the antiferroelectric phase to the ferroelectric phase. Through temperature induction, the composite material will undergo ferroelectric-antiferroelectricity with the change of temperature. phase transition, and achieve a large polarization change rate, thereby obtaining excellent pyroelectric performance; with the increase of semiconductor GaN content, the ferroelectric-antiferroelectric phase transition temperature increases, and the temperature stability of pyroelectric performance improve.

Claims (7)

1. The composite ceramic composed of the antiferroelectric and the GaN semiconductor is characterized in that the structural formula of the composite ceramic is (1-x) PNZST: xGaN, wherein x is more than or equal to 0.01 and less than or equal to 0.10;

PNZST is a abbreviation of antiferroelectric, and the specific structural formula is Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _1-y Ti _y ] _0.98 O ₃ ，0.060≤y≤0.067。

2. A method for preparing a composite ceramic composed of the antiferroelectric and the GaN semiconductor according to claim 1, wherein the method comprises the steps of:

(1) preparing PNZST powder:

Pb _0.99 Nb _0.02 [(Zr _0.57 Sn _0.43 ) _1-y Ti _y ] _0.98 O ₃ y is more than or equal to 0.060 and less than or equal to 0.067, and raw materials PbO and TiO are weighed according to the element metering ratio ₂ 、ZrO ₂ 、Nb ₂ O ₅ And SnO ₂ Then ball milling, drying and calcining, performing high-temperature presintering on the calcined powder again, and performing ball milling and drying again to obtain PNZST powder;

(2) introducing a GaN semiconductor to form a composite ceramic with PNZST:

and (2) respectively weighing the PNZST powder and the GaN nano powder prepared in the step (1) according to a chemical formula (1-x) PNZST: xGaN, wherein x is more than or equal to 0.01 and less than or equal to 0.10, performing ball milling treatment to uniformly mix the powder and the GaN nano powder, drying the uniformly mixed powder, performing compression molding, placing the powder in a crucible, and performing rapid high-temperature sintering to obtain the composite ceramic.

3. The preparation method according to claim 2, wherein in the step (1), the ball milling is performed in absolute ethyl alcohol for 12 hours.

4. The preparation method according to claim 2, wherein in the step (1), the calcination is performed at 850-900 ℃ for 4-5 h; the high-temperature presintering condition is presintering for 2-4 h at 1200-1300 ℃.

5. The preparation method according to claim 2, wherein in the step (2), the temperature rise and fall rate during the rapid high-temperature sintering is 9-10 ℃/min, and the sintering condition is 1000-1100 ℃ for 0.5-1 h.

6. The preparation method according to claim 2, wherein in the step (2), the particle size of the GaN nano powder is 30-50 nm.

7. The preparation method according to claim 2, wherein in the step (2), the adhesive PVA is further added into the uniformly mixed powder, the mixture is pressed and formed, and the blank is subjected to binder removal at 650 ℃.

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