KR101236893B1 - Single crystal and fabrication process of (Na,K)NbO3 based Pb-free piezoelectric materials using solid state synthesis - Google Patents

Abstract

The present invention relates to a (Ka, K) NbO ₃ based single crystal lead-free piezoelectric material prepared by using a solid phase synthesis method and a method for manufacturing the same, and more specifically, (1-x) (Na, K) NbO ₃ -xY (Cu (Na, K) NbO ₃ -based lead-free piezoelectric material and BaCO ₃ , SrCO having a composition of _1/3 Nb _2/3 ) O ₃ (where 0.01 ≦ x ≦ 0.02, Y = Ba, Sr or Ca) and formed as a single crystal Mixing 1 type selected from the group consisting of ₃ and CaCO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO by first milling (step 1); Calcining the mixture prepared in step 1 (step 2); Second milling the mixture calcined in step 2 (step 3); And a step (step 4) of sintering the mixture prepared in step 3; and a method of manufacturing a (Ka, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method. In addition, using the prepared single crystal as a seed includes the contents of growing a (Ka, K) NbO _3- based lead-free piezoelectric material into a single crystal.

Description

Single crystal and fabrication process of (Na, K) NbO3-based Pb-free piezoelectric materials using solid state synthesis}

The present invention relates to a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material manufactured using a solid phase synthesis method and a method of manufacturing the same.

Piezoelectric ceramic materials have excellent piezoelectric properties and are currently widely used for piezoelectric transformers, actuators, transducers, sensors, resonators, and filters. Although piezoelectric ceramics have been used commercially for a long time, they have grown very large in recent decades. This is due to the successful change in manufacturing technology of multilayer capacitors used in multilayer actuators. In the application area, the technology development and demand for new applications have greatly increased in many other areas, such as piezoelectric fuel injection devices and piezoelectric motor piezoelectric presses. Piezoelectric ceramics used for a long time are Pb (Zr _{1 - x} Ti _x ) O ₃ or PZT. In general, a composition close to the MPB (morphotropic phase boundaries) near x = 0.48 where characteristics such as piezoelectric constants, permittivity, and coupling factors are maximized is generally used. The increased use of PZT, formed primarily of lead oxide or lead zirconate titanate, has led to the manufacture, use, and disposal of many leads that are harmful to the environment. The volatilization of PbO occurs during the calcination and sintering processes and the hard machining of parts, causing serious problems in recycling and waste disposal that follow after use.

Therefore, in the European Union, the Waste Electrical and Electronic Equipment (WEEE) policy and hazardous materials are included to protect the environment and human health by preventing and recycling waste from electrical and electronic devices, and by replacing hazardous materials with safer materials. Has adopted the RoHS Directive (RoHS) policy, and countries such as Switzerland, Norway, Turkey, and California, California, have adopted EU regulations, have already been implemented as state law, or have a deadline until 2009. The need for coupled piezoceramics is growing rapidly.

To date, the application of lead-free piezoceramics has been concentrated on bulk ceramic sintered bodies such as resonators, sensors, transducers, or actuators, which have been used commercially, and efforts have been made to produce single crystals using the solid state single crystal growth method.

Republic of Korea Patent Registration No. 10-0564092 (Registration Date March 20, 2006) describes a single-phase single crystal growth method through a common and simple heat treatment process, but it is a complex problem because it must control the abnormal grain growth occurs in the polycrystals There is.

Accordingly, the present inventors, while studying lead-free piezoelectric ceramics, the production method is simple by synthesizing (Na, K) NbO ₃ (NKN) -based single-crystal lead-free piezoelectric material and solid materials without a separate seed (seed), The production method of lead-free piezoelectric material, which can produce a large amount of crystals, is much faster than the conventional method. In addition, a method of growing a (Na, K) NbO ₃ (NKN) -based single crystal by solid phase single crystal growth using the prepared single crystal as a seed, and completed the present invention.

An object of the present invention is to provide a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material.

Another object of the present invention is to provide a method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material.

To achieve the above object, the present invention is (1-x) (Na, K) NbO 3 -xY (Cu 1/3 Nb 2/3) O 3 ( where, 0.01≤x≤0.02, Y = Ba, Sr Or (Na, K) NbO ₃ based lead-free piezoelectric material having a composition of Ca) and formed into a single crystal.

In addition, the present invention is a step of mixing the first one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO by the first milling (step 1) ; Calcining the mixture prepared in step 1 (step 2); Second milling the mixture calcined in step 2 (step 3); And a step (step 4) of sintering the mixture prepared in step 3; and a method of manufacturing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method.

In addition, the present invention comprises the steps of mixing in a first milling, CuO and Nb ₂ O ₃ selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ (step A); Calcining the mixture prepared in step A (step B); Second milling by adding Na ₂ CO ₃ , K ₂ CO ₃ and Nb ₂ O ₅ to the mixture calcined in step B (step C); Calcining the mixture prepared in step C (step D); Third milling the mixture calcined in step D (step E); And a step (step F) of sintering the mixture of step E. It provides a method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method.

Furthermore, the present invention comprises the steps of mixing in a first milling, CuO and Nb ₂ O ₃ selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ (step a); Calcining the mixture prepared in step a (step b); To the mixture calcined in step b, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ And adding a additive to second milling (step c); Calcining the mixture prepared in step c (step d); Third milling the mixture calcined in step d (step e); And sintering the mixture of step e together with seeds, which are (Na, K) NbO ₃ based single crystal lead-free piezoelectric materials (prepared in step 4 or step E) prepared by the method (step f); It provides a method for producing a (Na, K) NbO _3- based single crystal lead-free piezoelectric material using a solid phase synthesis method comprising a.

The (Na, K) NbO _3- based single crystal lead-free piezoelectric material according to the present invention has no advantage of using a separate seed, and has a merit in that the crystal formation rate is much faster than that of the conventional method, thereby enabling mass production. The (Na, K) NbO ₃ -based single crystal can be prepared as a single crystal lead-free piezoelectric material using the seed material of the conventional solid-state single crystal growth method (SSCG method), and formed into a single crystal to improve piezoelectric properties (piezoelectric voltage constant, etc.) Therefore, it can be usefully used for sensors, transducers, piezo energy harvesting elements, transformers, and the like.

1, 2 and 3 are flowcharts of a method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to the present invention;
Embodiment 4 is produced by the production method of the (Na, K) NbO ₃ system single crystal lead-free piezoelectric material according to the invention Example 1 (0.985 (Na, K) NbO 3 -0.015Ba (Cu 1/3 Nb 2/3) O ₃ );
The exemplary FIG. 5 is made of a (Na, K) NbO _3-based method of manufacturing a single crystal lead-free piezoelectric material according to the invention Example 2 (0.985 (Na, K) NbO 3 -0.015Ba (Cu 1/3 Nb 2/3) O ₃ );
Embodiment 6 is prepared by the production method of the (Na, K) NbO ₃ system single crystal lead-free piezoelectric material according to the invention Example 3 (0.985 (Na, K) NbO 3 -0.015Ba (Cu 1/3 Nb 2/3) O ₃ );
Figure 7 is an exemplary production method for producing the (Na, K) NbO ₃ system single crystal lead-free piezoelectric material according to the invention Example 2 (0.985 (Na, K) NbO 3 -0.015Ba (Cu 1/3 Nb 2/3) O ₃ ) scanning electron microscopy (SEM) and X-ray laue images;
8, 9, 10 and 11 according to the invention (Na, K) NbO ₃ embodiment is manufactured by the manufacturing method of the single-crystal-based lead-free piezoelectric material, for example, _{3 (0.99 (Na 0 .5 K} 0 .5) NbO 3 -0.01 _{Ba (Cu 1/3 Nb 2} /3) O 3), example _{4 (0.9825 (Na 0.5 K 0.5} ) NbO 3 -0.0175Ba (Cu 1/3 Nb 2/3) O 3), example 5 (0.985 _{(Na 0 .5 K 0 .5)} NbO 3 -0.015Sr (Cu 1/3 Nb 2/3) O 3) and example _{6 (0.985 (Na 0 .5 K} 0 .5) NbO 3 -0.015Ca ( _{Cu 1/3 Nb 2/3} ) O 3) of a photograph by scanning electron microscopy (SEM).

Having a composition of the present invention is (1-x) (Na, K) NbO 3 -xY (Cu 1/3 Nb 2/3) O 3 ( where, 0.01≤x≤0.02, Y = Ba, Sr or Ca), Provided is a (Na, K) NbO _3- based lead-free piezoelectric material that is formed as a single crystal using a solid phase synthesis method without using a seed.

(Na, K) NbO ₃ system single crystal lead-free piezoelectric material according to the invention is (Na, K) Ba (Cu 1/3 Nb 2/3) O 3, Sr (Cu 1/3 Nb 2/3) to NbO ₃ O _3, and Ca, or comprises a _{(Cu 1/3 Nb 2/} 3) O 3, is formed of a single crystal is excellent in piezoelectric properties (piezoelectric constant voltage, and so on).

In addition, the present invention is a step of mixing the first one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO by the first milling (step 1) ;

Calcining the mixture prepared in step 1 (step 2);

Second milling the mixture calcined in step 2 (step 3); And

It provides a method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method comprising the step (step 4) of sintering the mixture prepared in step 3.

A method of manufacturing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention will be described in detail step by step.

In the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step 1 is one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO are mixed by first milling.

At this time, one kind selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ of step 1, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO is (1-x) (Na, K) _{NbO 3 -xY (Cu 1/3} Nb 2/3) O 3 ( where, 0.01≤x≤0.02, Y = Ba, Sr or Ca) is preferably mixed in order to have quantitative composition.

In addition, the first milling of the step 1 is preferably carried out for 10-300 rpm for 0.5-48 hours. When the first milling speed is out of the above range or when the milling time is less than 0.5 hours, the mixed raw material (BaCO ₃ , SrCO ₃ and CaCO ₃ , one selected from the group consisting of, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O _5, and CuO) have a problem in that the particle size miniaturization and mixing effects are insufficient, and if it exceeds 48 hours, there is a problem in that single crystal growth is limited.

Next, in the method for producing a (Na, K) NbO _3- based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step 2 is to calcined the (Na, K) NbO _3- based mixture prepared in step 1 Step.

The calcination of step 2 is preferably carried out at 850-1150 ℃ for 0.5-20 hours. If the calcination temperature is less than 850 ℃, there is a problem that the single crystal formation is limited due to the lack of partial melting phenomenon formed by the reaction between CuO and other raw materials, and if the calcination temperature exceeds 1150 ℃ all raw materials melt If less than 0.5 hours, there is a problem that the phase synthesis is not performed smoothly, if more than 20 hours there is a problem that the single crystal composition is uneven due to the volatilization of Na.

Next, in the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step 3 is a step of second milling the mixture calcined in step 2.

The second milling of step 3 is preferably performed at 10-350 rpm for 0.5-48 hours. When the milling speed is out of the above range or when the milling time is less than 0.5 hours, there is a problem in that the particle size of the mixed raw material is refined and the mixing effect is insufficient, and when it exceeds 48 hours, single crystal growth is limited. there is a problem.

Next, in the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step 4 is a step of sintering the mixture prepared in step 3.

Sintering of the step 4 is preferably carried out at 900-1150 ℃ for 0.5-300 hours. If the sintering temperature is less than 900 ℃, there is a problem that the sintering between the raw material is not performed, if the sintering temperature is higher than 1150 ℃ there is a problem that the manufactured piezoelectric material is fused, if less than 0.5 hours the formed single crystal size is There is a limited problem, and if it exceeds 300 hours, high dielectric loss due to excessive volatilization of Na there is a problem.

In addition, the present invention comprises the steps of mixing in a first milling, CuO and Nb ₂ O ₃ selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ (step A);

Calcining the mixture prepared in step A (step B);

Second milling by adding Na ₂ CO ₃ , K ₂ CO ₃ and Nb ₂ O ₅ to the mixture calcined in step B (step C);

Calcining the mixture prepared in step C (step D);

Third milling the mixture calcined in step D (step E); And

Provided is a method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method comprising the step of sintering the mixture of step E (step F).

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step A is selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , CuO and Nb ₂ Mixing O ₃ by first milling. One member selected from BaCO _3, SrCO _3, and the group consisting of CaCO ₃ in the step A, CuO and Nb ₂ O _3, respectively _{Ba (Cu 1/3 Nb 2/3) O} 3, Sr (Cu 1/3 Nb _{2/3) O 3, Ca} ( preferably by mixing amount in accordance with the composition of _{Cu 1/3 Nb 2/3} ) O 3. In addition, the first milling of the step A is preferably carried out at 10-350 rpm for 0.5-48 hours. When the first milling speed is out of the above range or when the milling time is less than 0.5 hours, there is a problem in that the particle size of the mixed raw material is refined and the mixing effect is insufficient, and may exceed 48 hours but the particle size is too small. Problems may arise in terms of crystal growth.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step B is a step of calcining the mixture prepared in step A. The calcination of step B is preferably carried out at 850-1150 ℃ for 0.5-20 hours. If the calcination temperature is less than 850 ℃ there is a problem that the phase synthesis is limited, if it exceeds 1150 ℃ calcined powder is agglomerated there is a problem that the secondary milling process is not performed smoothly.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step C is Na ₂ CO ₃ , K ₂ CO ₃ and Nb ₂ O in the mixture calcined in step B ₅ is the second milling step. In step _{C Na 2 CO 3, K 2} CO 3 and Nb ₂ O ₅ is (1-x) (Na, K) NbO 3 -xY (Cu 1/3 Nb 2/3) O 3 , respectively (wherein 0.01 It is preferable to mix quantitatively to have a composition of ≦ x ≦ 0.02, Y = Ba, Sr or Ca).

The second milling of step C is preferably carried out at 10-300 rpm for 0.5-48 hours. When the second milling speed is out of the above range or when the milling time is less than 0.5 hours, there is a problem in that the particle size of the mixed raw materials and the mixing effect are insufficient, and when it exceeds 48 hours, single crystal growth is limited. there is a problem.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step D is a step of calcining the mixture prepared in step C. The calcination of step D is preferably performed at 850-1150 ° C for 0.5-20 hours, and the reason for limitation is the same as the reason for the calcination limitation.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step E is a third milling of the mixture calcined in step D. The third milling of step E is preferably carried out at 10-350 rpm for 0.5-48 hours. If the third milling speed is out of the above range or if the milling time is less than 0.5 hours, there is a problem in that the particle size of the mixed raw materials and the mixing effect is insufficient, and if it exceeds 48 hours, single crystal growth is limited. there is a problem.

In the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step F is a step of sintering the mixture of step E. Sintering of the step F is preferably carried out at 900-1150 ℃ for 0.5-300 hours, the reason for limitation is the same as the reason for the sinter limitation.

In addition, the present invention comprises the steps of mixing in a first milling, CuO and Nb ₂ O ₃ selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ (step a);

Calcining the mixture prepared in step a (step b);

To the mixture calcined in step b, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ And adding a additive to second milling (step c);

Calcining the mixture prepared in step c (step d);

Third milling the mixture calcined in step d (step e); And

Sintering the mixture of step e together with seed, which is a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material prepared by the above method (step f); ) Provides a method for producing a NbO ₃ single crystal lead-free piezoelectric material.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step a is selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , CuO and Nb ₂ Mixing O ₃ by first milling. One member selected from the group consisting of the steps of a BaCO _3, SrCO ₃ and CaCO _3, CuO and Nb ₂ O _3, respectively _{Ba (Cu 1/3 Nb 2/3) O} 3, Sr (Cu 1/3 Nb _{2/3) O 3, Ca} ( preferably by mixing amount in accordance with the composition of _{Cu 1/3 Nb 2/3} ) O 3. In addition, the first milling of the step a is preferably carried out at 10-350 rpm for 0.5-48 hours.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step b is a step of calcining the mixture prepared in step a. The calcination of step b is preferably carried out at 850-1150 ℃ for 0.5-20 hours.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step c is Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O in the mixture calcined in step b ₅ and the additive is a second milling step. In step _{c Na 2 CO 3, K 2} CO 3 and Nb ₂ O ₅ is (1-x) (Na, K) NbO 3 -xY (Cu 1/3 Nb 2/3) O 3 , respectively (wherein 0.01 It is preferable to mix quantitatively to have a composition of ≦ x ≦ 0.02, Y = Ba, Sr or Ca). The additive may be Mn ₂ O ₃ or the like, and (1-x) (Na, K) NbO for the purpose of reducing high dielectric loss or improving piezoelectric properties of the (Na, K) NbO ₃ based single crystal lead-free piezoelectric material. ₃ -xY 0.1 with respect to the _{(Cu 1/3 Nb 2/} 3) O 3 - is preferably 5 mol%.

The second milling of step c is preferably carried out at 10-300 rpm for 0.5-48 hours.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step d is a step of calcining the mixture prepared in step c. The calcination of step d is preferably carried out at 850-1150 ℃ for 0.5-20 hours.

In the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step e is a third milling of the mixture calcined in step d. The third milling of step e is preferably carried out at 10-350 rpm for 0.5-48 hours.

In the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using the solid phase synthesis method according to the present invention, step f is a (Na, K) NbO ₃ prepared using the solid phase synthesis method in the mixture of the step e It is a step of sintering using a stepped single crystal lead-free piezoelectric material (prepared in step 4 or step E) as a seed material. Sintering of the step f is preferably carried out at 900-1150 ℃ for 0.5-300 hours.

The (Na, K) NbO _3- based single crystal lead-free piezoelectric material according to the present invention has no advantage of using a separate seed, and has a merit in that the crystal formation rate is much faster than that of the conventional method, thereby enabling mass production. The (Na, K) NbO ₃ -based single crystal can be prepared as a single crystal lead-free piezoelectric material by using the seed material in the conventional solid-state single crystal growth method, and formed into a single crystal to improve piezoelectric properties (piezoelectric voltage constant, etc.). It can be usefully used for sensors, transducers, piezoelectric energy harvesting devices, transformers, actuators, sonars, and the like. In addition, the (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to the present invention can be grown as a single crystal using a seed material.

Hereinafter, the present invention will be described in more detail by way of examples. It should be noted, however, that the following examples are illustrative of the invention and are not intended to limit the scope of the invention.

Example 1 Fabrication of (Na, K) NbO _3- based Single Crystal Lead-Free Piezoelectric Materials 1

Step 1: First Milling Step

Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , BaCO ₃ and CuO were mixed at 0.24625 mol%, 0.24625 mol%, 0.4975 mol%, 0.015 mol% and 0.005 mol%, respectively, and the final composition was 0.985 (Na _{0 .5} K _{0 .5)} was such that the _{NbO 3 -0.015Ba (Cu 1/3 Nb 2/3} ) O 3, was the first milling for 24 hours with 200 rpm.

Step 2: calcination step

The mixture prepared in step 1 was calcined at 950 ° C. for 3 hours.

Step 3: Second Milling Step

The mixture calcined in step 2 above was second milled at 200 rpm for 24 hours.

Step 4: Sintering Step

The mixture prepared in step 3 was sintered at 1020 ° C, 1030 ° C, 1040 ° C, 1060 ° C, 1080 ° C, 1090 ° C, and 1100 ° C for 2 hours to prepare a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material. .

Example 2 Fabrication of (Na, K) NbO ₃ -based Single Crystal Lead-Free Piezoelectric Materials 2

Step A: First Milling Step

BaCO ₃ , CuO and Nb ₂ O ₃ were mixed at 1 mol%, 1/3 mol%, 1/3 mol%, respectively, and first milled at 200 rpm for 24 hours.

Step B: Calcination Step

The mixture prepared in step A was calcined at 900 ° C. for 3 hours.

Step C: Second Milling Step

The mixture is calcined in step _{B Na 2 CO 3, K 2} CO 3 and Nb ₂ O _5, respectively mol% 16.1704, 16.1704 mol%, 32.3408 mixed in a mol% in the final composition is 0.985 (Na _{0 .5} K _{0. 5} ) NbO ₃ −0.015Ba (Cu _1/3 Nb _2/3 ) O ₃ and second milling at 200 rpm for 24 hours.

Step D: Calcination Step

The mixture prepared in step C was calcined at 950 ° C. for 3 hours.

Step E: Third Milling Step

The mixture calcined in step D was third milled at 200 rpm for 12 hours.

Step F: Sintering Step

The mixture of step E was sintered at 1020 ° C., 1030 ° C., 1040 ° C., 1060 ° C., 1080 ° C., 1090 ° C., and 1100 ° C. for 2 hours to prepare a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material.

Example 3 Fabrication of (Na, K) NbO ₃ -based Single Crystal Lead-Free Piezoelectric Materials 3

_{Na 2 CO 3, K 2 CO} 3, Nb 2 O 5, BaCO 3 and CuO to the final composition of _{0.99 (Na 0 .5 K 0 .5} ) NbO 3 -0.01Ba (Cu 1/3 Nb 2/3) O (Na, K) NbO ₃ based single crystal lead-free piezoelectric material was manufactured in the same manner as in Example 2, except that the mixture was quantitatively mixed to ₃ and sintered at 1070 ° C. for 2 hours.

Example 4 Fabrication of (Na, K) NbO ₃ -based Single Crystal Lead-Free Piezoelectric Materials 4

Such that the _{Na 2 CO 3, K 2 CO} 3, Nb 2 O 5, BaCO 3 and CuO to _{0.9825 (Na 0 .5 K 0 .5} ) NbO 3 -0.0175Ba (Cu 1/3 Nb 2/3) O 3 (Na, K) NbO ₃ based single crystal lead-free piezoelectric material was prepared in the same manner as in Example 2, except that the mixture was quantitatively mixed and sintered at 1080 ° C. for 2 hours.

Example 5 Fabrication of (Na, K) NbO ₃ -based Single Crystal Lead-Free Piezoelectric Materials 5

Such that the _{Na 2 CO 3, K 2 CO} 3, Nb 2 O 5, SrCO 3 and CuO to _{0.985 (Na 0 .5 K 0 .5} ) NbO 3 -0.015Sr (Cu 1/3 Nb 2/3) O 3 (Na, K) NbO ₃ based single crystal lead-free piezoelectric material was prepared in the same manner as in Example 2, except that the mixture was quantitatively mixed and sintered at 1080 ° C. for 2 hours.

Example 6 Fabrication of (Na, K) NbO ₃ -based Single Crystal Lead-Free Piezoelectric Materials 6

_{Na 2 CO 3, K 2 CO} 3, Nb 2 O 5, CaCO 3 , and the final composition _{0.985 CuO (Na 0 .5 K 0} .5) NbO 3 -0.015Ca (Cu 1/3 Nb 2/3) O (Na, K) NbO ₃ based single crystal lead-free piezoelectric material was manufactured in the same manner as in Example 2, except that the mixture was quantitatively mixed to ₃ and sintered at 1100 ° C. for 2 hours.

Example 7 Fabrication of (Na, K) NbO _{3 Based} Single Crystal Lead-Free Piezoelectric Materials 7

Step a: first milling step

BaCO _3, the CuO and Nb ₂ O ₃ The final composition was mixed in amount such that the Ba _{(Cu 1/3 Nb 2/} 3) O 3 , and the first milled for 24 hours with 200 rpm.

Step b: calcination step

The mixture prepared in step a was calcined at 900 ° C. for 3 hours.

Step c: second milling step

In the mixture calcined in step b, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , and Mn ₂ O ₃ to the final _{composition, (Na 0 .5 K 0 .5} ) the Mn ₂ O ₃ of 1 mol% was added 0.985 NbO ₃ -0.015Ba was such that the _{(Cu 1/3 Nb 2/} 3) O 3 , Second milled at 200 rpm for 24 hours.

Step d: calcination step

The mixture prepared in step c was calcined at 950 ° C. for 3 hours.

Step e: third milling step

The mixture calcined in step d above was third milled at 200 rpm for 12 hours.

Step f: sintering step

The (Na, K) NbO ₃ based single crystal lead-free piezoelectric material prepared in Example 1 or 2 was placed in the mixture of step e as a seed material, press-molded, and then sintered at 1100 ° C. for 2 hours. (Na, K) NbO ₃ -based single crystal lead-free piezoelectric material was prepared.

Experimental Example 1 External Analysis of (Na, K) NbO ₃ Single Crystal Lead-Free Piezoelectric Materials

In order to confirm the single crystal growth size of Example 1 and Example 2 prepared by the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to the present invention, the appearance was observed and the results are shown in FIGS. 4 and 5. And FIG. 6.

As shown in FIG. 4, the lead-free piezoelectric material sintered at 1020 ° C., 1030 ° C., 1040 ° C., 1060 ° C., 1080 ° C., 1090 ° C., and 1100 ° C. for 2 hours in the composition of Example 1 was formed of a single crystal. It was confirmed that, when sintered at 1100 ℃ for 2 hours, the size of the single crystal was about 3 mm.

In addition, as shown in Figure 5, the lead-free piezoelectric material sintered for 2 hours at 1020 ℃, 1030 ℃, 1040 ℃, 1060 ℃, 1080 ℃, 1090 ℃, 1100 ℃ in the composition of Example 2 is a single crystal It was confirmed that it was formed, and the size of the single crystal was about 13 mm.

At this time, it was confirmed that the growth rate of 1.3 cm was shown by sintering for about 2 hours in the method for producing a (Na, K) NbO _3- based single crystal lead-free piezoelectric material according to the present invention.

In addition, as shown in FIG. 6, the lead-free piezoelectric material sintered at 1100 ° C. for 200 hours in the composition of Example 7 was confirmed to be formed as a single crystal, and the size of the single crystal was about 20 mm.

Experimental Example 2 Phase Analysis of (Na, K) NbO _3- based Single Crystal Lead-Free Piezoelectric Materials 1

In order to analyze the phase of Example 2 prepared by the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to the present invention, a scanning electron microscope (SEM) and an X-ray Lauer image were analyzed. 7 is shown.

As shown in Figure 7, the Example 2 was confirmed that formed of a single crystal (Fig. 5 (a): scanning electron micrograph, (b): scanning electron micrograph enlarged view, (c): x-ray lau On the image).

Experimental Example 3 Phase Analysis of (Na, K) NbO ₃ Single Crystal Lead-Free Piezoelectric Materials 2

Examples 3, 4, 5 and 6 prepared by the method for preparing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to the present invention were analyzed by scanning electron microscopy (SEM) for phase analysis, and the results are illustrated. 8, 9, 10 and 11 are shown.

As shown in FIGS. 8, 9, 10, and 11, Examples 3, 4, 5, and 6 were confirmed to be formed of single crystals, respectively. One picture).

S110: first milling step S120: calcination step
S130: second milling step S140: sintering step
S210: first milling step S220: calcination step
S230: second milling step S240: calcination step
S250: third milling step S260: sintering step
S310: first milling step S320: calcination step
S230: second milling step S240: calcination step
S350: third milling step S360: seed mixing and sintering step

Claims (15)

(1-x) (Na, K) NbO 3 -xY (Cu 1/3 Nb 2/3) O 3 has a composition of (where, 0.01≤x≤0.02, Y = Ba, Sr or Ca) which is formed of a single crystal (Na, K) NbO _3- based lead-free piezoelectric material.
Mixing in a first milling one step selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO (step 1);
Calcining the mixture prepared in step 1 (step 2);
Second milling the mixture calcined in step 2 (step 3); And
A method of manufacturing the (Na, K) NbO ₃ based single crystal lead-free piezoelectric material of claim 1 using the solid phase synthesis method comprising the step of sintering the mixture prepared in step 3 (step 4).
The method according to claim 2, wherein at least one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ of step 1, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ and CuO are (1-x) ( _{Na, K) NbO 3 -xY (} Cu 1/3 Nb 2/3) O 3 ( here, a solid phase characterized in that the mixed amount so as to have a composition of 0.01≤x≤0.02, Y = Ba, Sr or Ca) (Na, K) NbO _3- based single crystal lead-free piezoelectric material using a synthesis method.
The method of claim 2, wherein the first mill 10 in step 1 at 300 rpm 0.5 - using the solid phase synthesis method, characterized in that is carried out for 48 hours (Na, K) NbO _3-based method of producing a single crystal lead-free piezoelectric material.
The method according to claim 2, wherein the calcination of step 2 is performed at 850-1150 ° C for 0.5-20 hours, and the method for producing a (Na, K) NbO ₃ based single crystal lead-free piezoelectric material using a solid phase synthesis method.
The method of claim 2, wherein the second mill 10 in the third step from 300 rpm 0.5 - using the solid phase synthesis method, characterized in that is carried out for 48 hours (Na, K) NbO _3-based method of producing a single crystal lead-free piezoelectric material.
The method of claim 2, wherein the sintering of step 4 is 900 - (Na, K) NbO 3 -based method of producing a single crystal lead-free piezoelectric material using a solid-phase synthesis method, characterized in that is carried out for 300 hours from 1150 ℃ 0.5.
Mixing in a first milling one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , CuO and Nb ₂ O ₃ (step A);
Calcining the mixture prepared in step A (step B);
Second milling by adding Na ₂ CO ₃ , K ₂ CO ₃ and Nb ₂ O ₅ to the mixture calcined in step B (step C);
Calcining the mixture prepared in step C (step D);
Third milling the mixture calcined in step D (step E); And
A method of manufacturing the (Na, K) NbO ₃ based single crystal lead-free piezoelectric material according to claim 1, comprising the step (S) of sintering the mixture of step E.
The method of claim 8, wherein one selected from BaCO _3, SrCO _3, and the group consisting of CaCO ₃ in the step A, CuO and Nb ₂ O ₃ is O _3, Sr respectively, _{Ba (Cu 1/3 Nb 2} /3) _{(Cu 1/3 Nb 2/} 3) O 3, Ca (Cu 1/3 Nb 2/3) O 3 and quantified so that a composition using the solid phase synthesis method characterized in that the mixture of (Na, K) NbO ₃ based Method for producing single crystal lead-free piezoelectric material.
The method according to claim 8, wherein Na ₂ CO ₃ , K ₂ CO ₃ and Nb ₂ O ₅ of step C is (1-x) (Na, K) NbO ₃ -xY (Cu _1/3 Nb _2/3 ) O ₃ (here, 0.01 ≦ x ≦ 0.02, Y = Ba, Sr or Ca), and quantitatively mixed to prepare a (Na, K) NbO _3- based single crystal lead-free piezoelectric material using a solid phase synthesis method.
The method of claim 8, wherein the third milling of the step E is performed at 10-350 rpm for 0.5-48 hours. The method of manufacturing a (Na, K) NbO _3- based single crystal lead-free piezoelectric material using the solid phase synthesis method.
The method of claim 8, wherein the sintering of the step F is carried out at 900-1150 ℃ for 0.5-300 hours, the method of producing a (Na, K) NbO _3- based single crystal lead-free piezoelectric material using a solid phase synthesis method.
Mixing in a first milling one selected from the group consisting of BaCO ₃ , SrCO ₃ and CaCO ₃ , CuO and Nb ₂ O ₃ (step a);
Calcining the mixture prepared in step a (step b);
To the mixture calcined in step b, Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ And adding a additive to second milling (step c);
Calcining the mixture prepared in step c (step d);
Third milling the mixture calcined in step d (step e); And
Sintering the mixture of step e together with the seed (Na, K) NbO ₃ based single crystal lead-free piezoelectric material prepared by the method of claim 2 or 8 (step f). (Na, K) NbO _3- based single crystal lead-free piezoelectric material using a synthesis method.
The method of claim 13 wherein the additive is Mn ₂ O ₃ and, 0.1 - 5 mol% of that using the solid phase synthesis method according to claim (Na, K) NbO _3-based method of producing a single crystal lead-free piezoelectric material.
The (Na, K) NbO _3- based single crystal lead-free piezoelectric material according to claim 1, which is used for any one selected from the group consisting of sensors, transducers, energy harvesting devices, transformers, actuators, and sonars.

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