• The Korean Journal of Ceramics
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• 제6권4호
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• pp.348-353
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• 2000

The effects of MnO$_2$ and Fe$_2$O$_3$ on the piezoelectric properties of 0.05PMN-0.451PT-0.499PZ ceramics were investigated. The addition of MnO$_2$ increased mechanical quality factor (Q$_m$) but decreased the dielectric constant (K$^{T}_{33}$) and compliance (S$^{E}_{11}$) of the specimens. These results indicated that MnO$_2$ behaves as an acceptor in 0.05MN-0.451PT-0.499PZ ceramics. The electromecanical coupling coefficient (K$_P$) of 0.05PMN-0.451PT-0.499PZ ceramics slightly increased with the addition of MnO$_2$ however, the enhancement of $K_P$ was insignificant. A small amount of Fe$_2$O$_3$ was added to enhance the $K_P$ of the 0.05PMN-0.451PT-0.499PZ + 0.5 wt% MnO$_2$ ceramics. The addition of Fe$_2$O$_3$ largely increased $K_P$ through the increase of the K$^{T}_{33}$ and the polarization. The mechanical quality factor of the specimens decreased with the addition of Fe$_2$O$_3$however, the reduction was negligible.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.627-631
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• 2011

[ $[Li_{0.04}(Na_{0.54}K_{0.46})_{0.96}](Nb_{1-0.04-X}TaxSb_{0.04})O_3$ ]lead-free piezoelectric ceramics have been prepared by normal sintering at $1,100^{\circ}C$ for 5 h. X-ray diffraction analysis indicated that specimens demonstrate orthorhombic symmetry when $Ta\leq5$ mol%. While transforming into tetragonal symmetry when $x\geq20$ mol%. These suggest that the orthorhombic and tetragonal phases co-exist in the ceramics with 5 mol% $cm^3$. As the result of SEM images, the grain growth was decreased with the increase of Ta substitution. The ceramics become 'softening', leading to improvements in $k_p$, $\varepsilon_r$ and $d_{33}$, but a decrease in $Q_m$. Excellent properties of $k_p$= 0.46, $d_{33}$= 293 pC/N, ${\varepsilon}_r$= 1,583 and Tc= $340^{\circ}C$ were obtained when Ta= 15 mol%.

• 센서학회지
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• 제6권5호
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• pp.392-399
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• 1997

본 연구에서는 $0.125Pb(Mg_{1/2}Nb_{2/3})O_{3}-0.435PbTiO_{3}-0.44PbZrO_{3}$의 조성을 갖는 hard계 압전 재료에 0.5 wt%의 $MnO_{2}$를 첨가하였으며, 이 시편으로 초음파 전동기를 제작하고자, 소결 온도에 따른 시편의 유전 및 압전특성에 대하여 연구하였다. 실험 결과, $1270^{\circ}C$의 소결 온도에서 다음과 같이 가장 우수한 압전특성을 나타냈다. 즉 시편의 밀도는 $7.72\;g/cm^{3}$ 유전상수는 570, 유전손실은 0.82 %f, 잔류분극 Pr은 $19.18{\mu}C/cm^{2}$ 항전계 Ec는 9.63 kW/cm, 전기기계 결합계수 kp는 55.1%, 기계적 품질계수 Qm은 886이 되었다. 또한 $1270^{\circ}C$ 에서 소결된 시편의 유전상수 및 유전손실을 주파수 변화와 온도 변화에 따라 조사하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.282-283
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• 2006

본 연구에서는 분말입자의 미립화에 따른 $(K,Na)NbO_3$(KNN) 세라믹스의 소결밀도와 압전특성을 평가하였다. 먼저 입자를 미립화 시키기 위해 planetary milling machine을 이용하였으며, 소결밀도 및 압전 특성을 측정하였다. Ball milling을 24~72시간동안 한 결과 particle size는 730~490nm 정도였다. Milling 시간이 증가할수록 입자크기는 감소하였고, 소결밀도는 particle size가 작을수록 증가하였고, $4.50g/cm^3$으로 가장 높은 밀도를 나타냈다. 또한 소결 밀도가 증가함에 따라 기계적 품질 계수(Qm) 역시 증가한 반면, particle size가 작아짐에 따라 전기기계 결합계수(Kp)는 감소하는 경황을 보였다.

• 한국재료학회지
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• 제16권11호
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• pp.705-709
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• 2006

Nb was doped to Pb-free $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) by a solid state mixing process to form $(Bi_{0.5}Na_{0.5})Ti_{1-x}Nb_xO_3\;(x=0{\sim}0.05)$ (BNTNb) and its doping effects on ferroelectric and piezoelctric properties of BNT were investigated. The BNTNb solid solutions were formed up to x=0.01 with no apparent second phases while grain sizes decreased. As x increased, coercive field ($E_c$) and mechanical quality factor ($Q_m$) decreased but piezoelectric constant ($d_{33}$) increased, which indicates Nb acts as a donor for BNT.

• 한국음향학회지
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• 제26권2호
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• pp.80-86
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• 2007

본 연구에서는 압전세라믹과 고분자재료를 사용하여 다이스와 필 방법으로 2-2형 압전복합재료를 제작하고 이것을 이용하며 초음파 센서를 설계하고 제작하여 전기적 및 음향 특성을 조사하였다. 제작된 시편의 공진특성은 유한요소 해석 결과와 임피던스 분석기(HP4194A)를 이용하여 실제로 측정한 결과와 유사하게 나타났다. 2-2형 압전복합재료의 고유음향 임피던스는 PZT의 부피분율이 감소함에 따라 선형적으로 감소하였다. 이것을 이용하여 제작된 초음파 센서의 공진특성 및 전기기계결합계수는 PZT의 부피분율이 0.6일 때 가장 우수하였다. 또한, 이것의 음향특성을 측정한 결과 PZT 부피분율이 0.6일때 진폭, 주파수 대역폭, 울림감쇠 특성 등이 가장 우수하게 나타났으며, 단일 압전세라믹으로 제작된 센서에 비하여 상당히 우수한 감도 특성을 나타내었다.

• 한국세라믹학회지
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• 제50권1호
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• pp.82-86
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• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.690-695
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• 2005

We have investigated on the development of 2-2 mode piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the electrical properties and acoustic impedance of 2-2 mode piezocomposite which were fabricated using the dice-and-fill technique for the different volume fractions of PZT The volume shrinkage of polymer is an important factor in 2-2 mode piezocomposites fabrication. The thickness mode electromechanical coupling factor($\kappa_t$) of PZT was compared with that of piezocomposites. It was shown that the 2-2 mode piezocomposites were much better than the PZT only. The acoustic impedance of 2-2 mode piezocomposites decreased linearly when PZT volume fraction was decreased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.192-195
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• 1995

PZT powders were prepared by the molten salt synthesis method. The porous PZT was prepared from a mixture of PZT an polyvinylacohol(PVA) powders by BURPS(Burnout Plastic Sphere) technique. The piezolectirc and acoustic properties with various PVA wt% were studied, Piezoelectric coefficient d$\sub$33/ of porous PZT ceramics was almost same to that of single phase PZT ceramics, The thickness mode coupling factor k$\sub$t/ was 0.53~0.59 in comparable with the single phase PZT ceramics(k$\sub$t/=0.7)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.690-693
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• 2002

This paper is concerned on method of simultaneous force(stress) and temperature sensing with PVDF film. PVDF film has piezoelectric and pyroelectric properties. Therefore, it senses changes of stress and temperature. But it's output is affected with two properties. Using different medium in a sensing element, this problem is solved. Two structures induce different equations that its solutions are changes of stress and temperature. This method and result is applicable in skin sensor that has complexity of material and structure.