WO2022177262A1 - 무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법 - Google Patents

무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법 Download PDF

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WO2022177262A1
WO2022177262A1 PCT/KR2022/002209 KR2022002209W WO2022177262A1 WO 2022177262 A1 WO2022177262 A1 WO 2022177262A1 KR 2022002209 W KR2022002209 W KR 2022002209W WO 2022177262 A1 WO2022177262 A1 WO 2022177262A1
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lead
piezoelectric ceramic
free piezoelectric
ceramic composition
mixture
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PCT/KR2022/002209
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French (fr)
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성태현
김경범
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한양대학교 산학협력단
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Priority to US18/277,308 priority Critical patent/US20240124362A1/en
Publication of WO2022177262A1 publication Critical patent/WO2022177262A1/ko

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Definitions

  • the present invention relates to a lead-free piezoelectric ceramic composition and a lead-free piezoelectric ceramic manufacturing method, and more particularly, to a lead-free piezoelectric ceramic composition and a lead-free piezoelectric ceramic manufacturing method capable of exhibiting high speaker characteristics in a high frequency band.
  • Piezoelectric ceramic material is a material that exhibits piezoelectric phenomenon, and has been applied to various fields such as LCD backlight transformers, ultra-precision actuators, ultrasonic motors, sensors and energy harvesting fields.
  • the mainstream piezoelectric ceramic material is a PZT (Pb(Zr,Ti)O 3 )-based material, which is a ferroelectric compound having a lead-based perovskite structure. Since PZT-based materials cause fatal poisoning to the human body, and lead volatilization causes environmental pollution, interest in the development of environmentally friendly piezoelectric ceramic materials is increasing to fundamentally solve this problem.
  • the BCTZ((Ba,Ca)(Ti,Zr)O 3 )-based lead-free piezoelectric ceramic material newly discovered by Liu and Ren has a perovskite structure, and has a relatively high electromechanical conversion constant (k p ) and piezoelectric Research on BCTZ-based lead-free piezoelectric ceramics showing the charge constant (d 33 ) has been actively conducted recently.
  • An object of the present invention is to provide a BCTZ-based lead-free piezoelectric ceramic composition with improved piezoelectric properties and a method for manufacturing a BCTZ-based lead-free piezoelectric ceramic.
  • the present invention is to provide a lead-free piezoelectric ceramic composition and a lead-free piezoelectric ceramic manufacturing method for a speaker capable of providing ultra-high sound quality in a high frequency band.
  • preparing a mixture in which copper oxide is added to the BCTZ-based parent material; and sintering the mixture at a temperature of 1300 degrees (°C) to 1600 degrees (°C) for 1 hour to 5 hours, wherein the weight ratio of the copper oxide in the mixture is 0.6 wt% provide a way
  • a lead-free piezoelectric ceramic comprising a BCTZ-based parent material and copper oxide (CuO), wherein in the lead-free piezoelectric ceramic composition, the weight ratio of the copper oxide is 0.6 wt% A composition is provided.
  • the piezoelectric properties of the BCTZ-based lead-free piezoelectric ceramic composition may be improved.
  • FIG. 1 is a view showing a field emission scanning electron microscope (FE-SEM) image of a lead-free piezoelectric ceramic according to a sintering temperature.
  • FE-SEM field emission scanning electron microscope
  • FIG. 2 is a diagram illustrating an XRD graph of a lead-free piezoelectric ceramic according to a sintering temperature.
  • the lead-free piezoelectric ceramic composition according to the present invention is a BCTZ-based lead-free piezoelectric ceramic composition that provides improved piezoelectric properties and can provide high gain in a high frequency band, and includes a BCTZ-based parent material and copper oxide (CuO).
  • a lead-free piezoelectric ceramic composition according to an embodiment of the present invention is a composition in which copper oxide is added as an auxiliary material to a BCTZ-based base material (Ba 0.85 Ca 0.15 ) (Ti 0.9 Zr 0.1 )O 3 . Copper oxide may be added so that, in the lead-free piezoelectric ceramic composition, the weight ratio of copper oxide is 0.6 wt%.
  • the lead-free piezoelectric ceramic composition according to an embodiment of the present invention exhibits the characteristics of a speaker providing high gain in a high-frequency band of 10 kHz, it can be used for a speaker providing ultra-high sound quality in a high-frequency band, in particular, an earphone.
  • components that provide high gain at high frequencies have already been used in speakers and earphones, most of the components are components made of a piezoelectric ceramic composition containing lead. According to an embodiment of the present invention, an environmentally friendly lead-free piezoelectric ceramic composition that provides excellent speaker characteristics even though lead is not included may be provided.
  • FIG. 1 and 2 are views for explaining a method of manufacturing a lead-free piezoelectric ceramic according to an embodiment of the present invention
  • FIG. 1 is a field emission scanning electron microscope (FE-SEM) image of a lead-free piezoelectric ceramic according to a sintering temperature.
  • FE-SEM field emission scanning electron microscope
  • FIG. 2 the x-axis represents 2 ⁇ , and the y-axis represents intensity.
  • the method for manufacturing a lead-free piezoelectric ceramic according to the present invention includes preparing a mixture in which copper oxide is added to a BCTZ-based parent material, and sintering the mixture.
  • (Ba 0.85 Ca 0.15 ) (Ti 0.9 Zr 0.1 )O 3 is used as the BCTZ-based parent material, and a mixture in which copper oxide is added is prepared so that the weight ratio of copper oxide in the mixture is 0.6wt% can be And BaCO 3 (barium carbonate) and CaCO 3 (calcium carbonate) in a molar ratio of 0.85:0.15, TiO 2 (titanium dioxide) and ZrO 2 (zirconium dioxide) in a molar ratio of 0.9:0.1 by mixing and grinding (Ba 0.85 Ca 0.15 ) (Ti 0.9 Zr 0.1 )O 3 can be prepared.
  • a lead-free piezoelectric ceramic By sintering this mixture at a sintering temperature of 1300 degrees (°C) to 1600 degrees (°C) for 1 to 5 hours, a lead-free piezoelectric ceramic can be manufactured, and when sintered at 1550 degrees for 2 hours, better A lead-free piezoelectric ceramic exhibiting piezoelectric properties and speaker properties can be manufactured.
  • the grain size of the lead-free piezoelectric ceramic increases as the sintering temperature increases from 1300°C to 1550°C, whereas when sintering at 1600°C, the grain size decreases and the surface of the lead-free piezoelectric ceramic melts. became Also, referring to FIG. 2 , as the sintering temperature increased from 1300°C to 1550°C, the tetragonal phase appeared clearly, but when sintered at 1600°C, a phenomenon in which the tetragonal phase disappeared was observed.
  • [Table 1] shows the piezoelectric characteristics and speaker characteristics of lead-free piezoelectric ceramics.
  • a sheet on which a lead-free piezoelectric ceramic composition according to an embodiment of the present invention is laminated is cut to a size of 1 cm 2 , sintered for 2 hours, and then a silver (Ag) electrode is baked at 650 degrees
  • a silver (Ag) electrode is baked at 650 degrees
  • One lead-free piezoelectric ceramic sample was used.
  • 8Vp-p voltage was applied at a frequency of 10kHz to measure the speaker characteristics.
  • the piezoelectric voltage constant, the piezoelectric charge constant, and the piezoelectric conversion constant increase as the sintering temperature is increased at 1300°C, and exhibit the highest value at the sintering temperature of 1550°C. That is, when sintered at a sintering temperature of 1550 degrees for 2 hours, the best piezoelectric properties are exhibited. And it can be seen that the piezoelectric voltage constant, the piezoelectric charge constant, and the piezoelectric conversion constant are all sharply lowered at 1600°C, which is a sintering temperature higher than 1550°C.
  • the gain value (db) representing the speaker characteristics also increases as the sintering temperature is increased at 1300°C, showing the highest value at the sintering temperature of 1550°C. And it can be seen that the gain value is sharply lowered at 1600°C, which is a sintering temperature higher than 1550°C.
  • [Table 2] shows the characteristics of lead-free piezoelectric ceramics sintered at a sintering temperature of 1500 degrees for 1 hour to 5 hours.

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Abstract

높은 압전 특성과 스피커 특성을 제공하는 BCTZ계 무연 압전 세라믹 조성물 및 BCTZ계 무연 압전 세라믹의 제조 방법이 개시된다. 개시된 무연 압전 세라믹의 제조 방법은 BCTZ계 모재료에 산화 구리가 첨가된 혼합물을 제조하는 단계; 및 1300도(℃) 내지 1600도(℃)의 온도에서, 1시간 내지 5시간동안 상기 혼합물을 소결하는 단계를 포함하며, 상기 혼합물에서 상기 산화 구리의 중량비는 0.6wt%이다.

Description

무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법
본 발명은 무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법에 관한 것으로서, 특히 고주파 대역에서 높은 스피커 특성을 나타낼 수 있는 무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법에 관한 것이다.
압전 세라믹 재료는 압전 현상을 나타내는 재료로서, LCD 백라이트용 트랜스포머, 초정밀 액츄에이터, 초음파 모터, 센서와 에너지 하베스팅 분야 등 다양한 분야에 응용되고 있어 지난 수십 년간 많은 연구가 진행되어 왔다.
현재, 주류를 이루고 있는 압전 세라믹 재료는 PZT(Pb(Zr,Ti)O3)계 재료로서 납을 기본으로 한 페로브스카이트 구조의 강유전체 화합물이다. PZT계 재료는 인체에 치명적인 중독 문제를 야기시키며, 납의 휘발은 환경오염을 유발시키기 때문에 이를 원천적으로 해결하기 위해 환경 친화적인 압전 세라믹 재료의 개발에 대한 관심이 점차 고조되고 있다.
따라서 일반적인 무연 압전 세라믹 재료인　BNT((BiNa)TiO3)계, NKN((NaK)NbO5)계 재료의 압전 특성을 향상시키기 위해 많은 연구가 진행되어 왔다. 그럼에도 불구하고 이들의 압전　특성은 PZT계 압전 세라믹스의 압전　특성과 비교하여 여전히 낮은 값(d33=100∼200pC/N)을 나타낸다.
Liu와 Ren에 의해 새로이 발견된 BCTZ((Ba,Ca)(Ti,Zr)O3)계 무연 압전 세라믹 재료는, 페로브스카이트 구조를 가지며, 비교적 높은 전기 기계 변환 상수(kp)와 압전 전하 상수(d33)를 나타내는 BCTZ계 무연 압전 세라믹스에 관한 연구가 최근 활발히 이루어지고 있다　
본 발명은 압전 특성이 개선된, BCTZ계 무연 압전 세라믹 조성물 및 BCTZ계 무연 압전 세라믹의 제조 방법을 제공하기 위한 것이다.
특히, 본 발명은 고주파 대역에서 초고음질을 제공할 수 있는 스피커를 위한 무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법을 제공하기 위한 것이다.
상기한 목적을 달성하기 위한 본 발명의 일 실시예에 따르면, BCTZ계 모재료에 산화 구리가 첨가된 혼합물을 제조하는 단계; 및 1300도(℃) 내지 1600도(℃)의 온도에서, 1시간 내지 5시간동안 상기 혼합물을 소결하는 단계를 포함하며, 상기 혼합물에서 상기 산화 구리의 중량비는 0.6wt%인 무연 압전 세라믹의 제조 방법을 제공한다.
또한 상기한 목적을 달성하기 위한 본 발명의 다른 실시예에 따르면, BCTZ계 모재료 및 산화구리(CuO)를 포함하며, 무연 압전 세라믹 조성물에서, 상기 산화구리의 중량비는 0.6 wt%인 무연 압전 세라믹 조성물을 제공한다.
본 발명의 일실시예에 따르면, BCTZ계 무연 압전 세라믹 조성물의 압전 특성이 개선될 수 있다.
또한 본 발명의 일실시예에 따르면, 고주파 대역에서 높은 이득을 제공하는 스피커를 제공할 수 있다.
도 1은 소결 온도에 따른 무연 압전 세라믹의 전계방출형 주사전자현미경(FE-SEM) 이미지를 나타내는 도면이다.
도 2는 소결 온도에 따른 무연 압전 세라믹의 XRD 그래프를 나타내는 도면이다.
본 발명은 다양한 변경을 가할 수 있고 여러 가지 실시예를 가질 수 있는 바, 특정 실시예들을 도면에 예시하고 상세한 설명에 상세하게 설명하고자 한다. 그러나, 이는 본 발명을 특정한 실시 형태에 대해 한정하려는 것이 아니며, 본 발명의 사상 및 기술 범위에 포함되는 모든 변경, 균등물 내지 대체물을 포함하는 것으로 이해되어야 한다. 각 도면을 설명하면서 유사한 참조부호를 유사한 구성요소에 대해 사용하였다.
이하에서, 본 발명에 따른 실시예들을 상세하게 설명한다.
무연 압전 세라믹 조성물
본 발명에 따른 무연 압전 세라믹 조성물은, 개선된 압전 특성을 제공하며, 고주파 대역에서 높은 이득을 제공할 수 있는 BCTZ계 무연 압전 세라믹 조성물로서, BCTZ계 모재료 및 산화구리(CuO)를 포함한다.
본 발명의 일실시예에 따른 무연 압전 세라믹 조성물은, BCTZ계 모재료 (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3에, 부재료로서 산화구리가 첨가된 조성물이다. 산화구리는, 무연 압전 세라믹 조성물에서, 산화구리의 중량비가 0.6wt%가 되도록, 첨가될 수 있다.
본 발명의 일실시예에 따른 무연 압전 세라믹 조성물은 10kHz의 고주파 대역에서 높은 이득을 제공하는 스피커 특성을 나타내기 때문에, 고주파 대역에서 초고음질을 제공하는 스피커 특히, 이어폰 등에 활용될 수 있다.
스피커, 이어폰 등에는 이미, 고주파에서 높은 이득을 제공하는 부품이 사용되고 있지만, 대부분의 부품은 납이 포함된 압전 세라믹 조성물로 구성된 부품이다. 본 발명의 일실시예에 따르면, 납이 포함되지 않음에도 우수한 스피커 특성을 제공하는 환경친화적 무연 압전 세라믹 조성물이 제공될 수 있다.
본 발명의 일실시예에 따른 무연 압전 세라믹 조성물의 압전 특성 및 스피커 특성은 아래에서 자세히 후술된다.
무연 압전 세라믹 제조 방법
도 1 및 도 2는 본 발명의 일실시예에 따른 무연 압전 세라믹의 제조 방법을 설명하기 위한 도면으로서, 도 1은 소결 온도에 따른 무연 압전 세라믹의 전계방출형 주사전자현미경(FE-SEM) 이미지를 나타내는 도면이며, 도 2는 소결 온도에 따른 무연 압전 세라믹의 XRD 그래프를 나타내는 도면이다. 도 2에서 x축은 2θ, y축은 세기(intensity)를 나타낸다.
본 발명에 따른 무연 압전 세라믹 제조 방법은, BCTZ계 모재료에 산화 구리가 첨가된 혼합물을 제조하고, 혼합물을 소결하는 과정을 포함한다.
일실시예로서, BCTZ계 모재료로 (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3가 이용되며, 혼합물에서의 산화구리의 중량비가 0.6wt%가 되도록, 산화구리가 첨가된 혼합물이 제조될 수 있다. 그리고 BaCO3(바륨 카보네이트) 및 CaCO3(칼슘 카보네이트)를 몰비 0.85:0.15, TiO2(이산화 타이타늄) 및 ZrO2(지르코늄 다이옥사이드)를 몰비 0.9:0.1 비율로 혼합 및 분쇄하여 (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3를 마련할 수 있다.
이러한 혼합물이 1300도(℃) 내지 1600도(℃)의 소결 온도에서, 1시간 내지 5시간동안 소결됨으로써, 무연 압전 세라믹이 제조될 수 있으며, 1550도의 온도에서 2시간 동안 소결될 경우, 보다 우수한 압전 특성과 스피커 특성을 나타내는 무연 압전 세라믹이 제조될 수 있다.
도 1, 도 2 및 [표 1]은, 산화구리가 중량비 0.6 wt%인 BCTZ계 무연 압전 세라믹 조성물을 1300도(℃) ~ 1600도(℃) 범위에서 50도(℃)씩 조절된 온도에서 소결하여 제조한, 무연 압전 세라믹의 특성을 나타낸다. 여기서 소결 시간(sintering time)은 2시간이며, BaCO3 1259.62g, CaCO3 112.47g, TiO2 538.58g, ZrO2 92.3112g, CuO 6g이 사용되었다. 그리고 도 1의 7개 이미지들은, 도 1의 좌측 상단 첫번째 이미지에서 우측 하단 마지막 이미지의 순서로, 소결 온도 1600도, 1550도, 1500도, 1450도, 1400도, 1350도, 1300도에 대한 FE-SEM 이미지를 나타낸다.
도 1을 참조하면, 1300도에서 1550도까지 소결 온도가 증가될수록 무연 압전 세라믹의 그레인 사이즈는 증가되는 반면, 1600도에서 소결될 경우, 그레인 사이즈가 작아지고 무연 압전 세라믹의 표면이 녹는 현상이 관찰되었다. 또한 도 2를 참조하면, 1300도에서 1550도까지 소결 온도가 증가될수록 Tetragonal 상이 뚜렷하게 나타나지만, 1600도에서 소결될 경우 Tetragonal 상이 사라지는 현상이 관찰되었다.
이를 통해 1300도에서 1550도까지 소결 온도(sintering temperature)가 높아질수록 압전 특성이 향상되고, 1600도에서 소결될 경우 압전 특성이 나빠짐을 예측할 수 있으며, 압전 특성의 향상과 함께 스피커 특성 역시 향상될 것으로 예측할 수 있다. 그리고 이러한 예측 결과는 [표 1]에 나타난 압전 특성과 일치함을 알 수 있다.
[표 1]은 무연 압전 세라믹의 압전 특성과 스피커 특성을 나타낸다. 압전 특성 및 스피커 특성의 측정을 위해, 본 발명의 일실시예에 따른 무연 압전 세라믹 조성물이 적층된 시트를 1cm2 크기로 자르고, 2시간 동안 소결한 후, 은(Ag) 전극을 650도에서 소부한 무연 압전 세라믹 샘플이 이용되었다. 무연 압전 세라믹 샘플에는 스피커 특성 측정을 위해, 10kHz의 주파수로 8Vp-p 전압이 인가되었다.
Figure PCTKR2022002209-appb-img-000001
압전 특성을 나타내는 파라미터로서, 압전 전압 상수(g33), 압전 전하 상수(d33), 압전 변환 상수(d33g33)가 있으며, 값이 클수록 높은 압전 특성을 나타낸다. 또한 스피커 특성을 나타내는 이득값 역시, 클수록 높은 스피커 특성을 나타낸다.
[표 1]을 살펴보면, 압전 전압 상수, 압전 전하 상수, 압전 변환 상수는, 소결 온도가 1300도에서 증가될수록 증가하며, 1550도의 소결 온도에서 가장 높은 값을 나타냄을 알 수 있다. 즉, 1550도의 소결 온도에서 2시간 동안 소결될 경우, 가장 우수한 압전 특성을 나타낸다. 그리고 1550도보다 높은 소결 온도인 1600도에서는 압전 전압 상수, 압전 전하 상수, 압전 변환 상수가 모두 급격히 낮아짐을 알 수 있다.
또한 스피커 특성을 나타내는 이득값(db) 역시 소결 온도가 1300도에서 증가될수록 증가하여, 1550도의 소결 온도에서 가장 높은 값을 나타냄을 알 수 있다. 그리고 1550도보다 높은 소결 온도인 1600도에서는 이득값이 급격히 낮아짐을 알 수 있다.
한편, [표 2]는 1500도의 소결 온도에서 1시간 내지 5시간동안 소결한 무연 압전 세라믹의 특성을 나타낸다. 1500도에서 소결이 이루어질 경우, 3시간 동안 소결할 때 가장 우수한 압전 특성이 나타남을 알 수 있으며, 3시간보다 길거나 짧게 소결이 이루어진 경우 압전 특성이 떨어짐을 알 수 있다.
Figure PCTKR2022002209-appb-img-000002
이상과 같이 본 발명에서는 구체적인 구성 요소 등과 같은 특정 사항들과 한정된 실시예 및 도면에 의해 설명되었으나 이는 본 발명의 보다 전반적인 이해를 돕기 위해서 제공된 것일 뿐, 본 발명은 상기의 실시예에 한정되는 것은 아니며, 본 발명이 속하는 분야에서 통상적인 지식을 가진 자라면 이러한 기재로부터 다양한 수정 및 변형이 가능하다. 따라서, 본 발명의 사상은 설명된 실시예에 국한되어 정해져서는 아니되며, 후술하는 특허청구범위뿐 아니라 이 특허청구범위와 균등하거나 등가적 변형이 있는 모든 것들은 본 발명 사상의 범주에 속한다고 할 것이다.

Claims (8)

  1. BCTZ계 모재료에 산화 구리가 첨가된 혼합물을 제조하는 단계; 및
    1300도(℃) 내지 1600도(℃)의 온도에서, 1시간 내지 5시간동안 상기 혼합물을 소결하는 단계를 포함하며,
    상기 혼합물에서 상기 산화 구리의 중량비는 0. 6wt%인
    무연 압전 세라믹의 제조 방법.
  2. 제 1항에 있어서,
    상기 혼합물을 소결하는 단계는
    1550도의 온도에서 2시간동안 상기 혼합물을 소결하는
    무연 압전 세라믹의 제조 방법.
  3. 제 1항에 있어서,
    상기 혼합물을 소결하는 단계는
    1500도의 온도에서 3시간동안 상기 혼합물을 소결하는
    무연 압전 세라믹의 제조 방법.
  4. 제 1항에 있어서,
    상기 BCTZ계 모재료는
    (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3인
    무연 압전 세라믹의 제조 방법.
  5. 제 1항에 있어서,
    상기 무연 압전 세라믹은
    스피커를 위한 무연 압전 세라믹인
    무연 압전 세라믹의 제조 방법.
  6. 무연 압전 세라믹 조성물에 있어서,
    BCTZ계 모재료 및 산화구리(CuO)를 포함하며,
    상기 무연 압전 세라믹 조성물에서, 상기 산화구리의 중량비는 0.6 wt%인
    무연 압전 세라믹 조성물.
  7. 제 6항에 있어서,
    상기 BCTZ계 모재료는
    (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3인
    무연 압전 세라믹 조성물.
  8. 제 6항에 있어서,
    상기 무연 압전 세라믹 조성물은
    스피커를 위한 무연 압전 세라믹 조성물인
    무연 압전 세라믹 조성물.
PCT/KR2022/002209 2021-02-16 2022-02-15 무연 압전 세라믹 조성물 및 무연 압전 세라믹 제조 방법 WO2022177262A1 (ko)

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