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In this study, with the motivation of developing low temperature sintered Pb-free ceramics for use in piezoelectric actuators, 0.97(Na0.52K0.443Li0.037)(Nb0.923Sb0.04Ta0.037)O3 − 0.03 (Bi0.5Na0.5)0.9 (Sr)0.1ZrO3 ceramics were manufactured and their piezoelectric properties analyzed. All specimens doped with boron oxide showed a typical pure perovskite structure. The ceramics with x = 0.1 composition showed a co-existence of R-T phases. When boron oxide is doped at 0.1 wt%, excellent physical properties of d33 = 270 pC/N εr = 1386, kp = 0.416, and Qm = 130 were obtained making the ceramic ideal for use in piezoelectric actuators.

Monitoring biosignals at the skin interface is necessary to suppress the potential for decubitus ulcers in immobile patients confined to bed. We develop conformally contacted, disposable, and breathable fabric-based electronic devices to detect skin impedance, applied pressure, and temperature, simultaneously. Based on the experimental evaluation of the multifunctional sensors, a combination of robust AgNW electrodes, soft ionogel capacitive pressure sensor, and resistive temperature sensor on fabric provides alarmed the initiation of early-stage decubitus ulcers without signal distortion under the external stimulus. For clinical verification, an animal model is established with a pair of magnets to mimic a human decubitus ulcers model in murine in vivo. The evidence of pressure-induced ischemic injury is confirmed with the naked eye and histological and molecular biomarker analyses. Our multifunctional integrated sensor detects the critical time for early-stage decubitus ulcer, establishing a robust correlation with the biophysical parameters of skin ischemia and integrity, including temperature and impedance.

In this study, for developing the multilayer piezoelectric actuator, the (Na,K)(Nb,Sb)O3–(Bi,Na)ZrO3 ceramics were manufactured and their dielectric and piezoelectric properties were investigated. The manufactured ceramics showed the excellent physical properties: density = 4.56 g/cm2, kp = 0.47, Qm = 50, er = 1944, and d33 = 313 pC/N, suitable for piezoelectric actuator. The properties of the piezoelectric actuators are as follows: at the average size of 30.47 mm $$\times$$ 17.92 mm $$\times$$ 1.0 mm, resonance frequency fr = 69.87 kHz, anti-resonance frequency fa = 71.20 kHz, kp = 0.22, d33 = 1120 pC/N were appeared, respectively. The three piezoelectric actuators connected in parallel showed the high vibration acceleration of 2.0G at 580 Hz under 70 V, suitable for the force feedback actuator.

Nowadays, piezoelectric speakers have been actively studied for the applications to smartphone, TV monitor, and car audio system. Accordingly, for developing the piezoelectric speaker composition c...

In this study, 1, 2, 3, 4, 5, and 6 layer ceramic piezoelectric actuator were designed and simulated according to the variations of ceramic layer by ATILA software in order to develop the f...

In this study, (Na,K,Li)(Nb,Sb,Ta)O3 ceramics substituted with (Sr,Ca)ZrO3 by conventional solid state method were manufactured and their dielectric and piezoelectric properties were investigated. ...

(1 − x)(NKL)(NST)O3 − x(Ba0.90Ca0.1)ZrO3 ceramics with (Ba0.90Ca0.1)ZrO3 substitution were synthesized and their physical characteristics were systematically analyzed. All specimens showed typical perovskite structure and no second phase was found according to (Ba0.90Ca0.1)ZrO3 substitution. When Ba0.90Ca0.1)ZrO3 substitution x = 0.02, the highest piezoelectric characteristics of d33 = 260 pC/N, er = 1904, kp = 0.4102, Qm = 106 were found for piezoelectric devices such as actuators and ultrasonic sensors.

In this study, 0.97(Na0.52K0.443Li0.037)(Nb0.96-xSb0.04Tax)O3–0.03(Bi0.5Na0.5)0.9(Sr)0.1ZrO3 ceramics were fabricated as a function of Ta substitution by conventional solid state method in order to develop the excellent composition ceramics for piezoelectric actuator, and their dielectric and piezoelectric properties were investigated. As the chemical composition results of 0.97(Na0.52K0.443Li0.037)(Nb0.96-xSb0.04Tax)O3–0.03(Bi0.5Na0.5)0.9(Sr)0.1ZrO3 system, we obtained the following results: When Ta was substituted for the ceramics, all the ceramics possessed a perovskite structure. When the substitution of Ta was 0, 0.01 and 0.02, Morphotropic phase boundary (MPB) region, which is coexist with rhombodedral phase and tetragonal phase was appeared. With further increasing the Ta substitution, the ceramics showed the strengthened tetragonal phase together with the coexistence of rhombodedral phase and tetragonal phase. The NKN-BNZ ceramics with x = 0.02 showed excellent piezoelectric properties. The density (ρ), piezoelectric constant (d33), planar piezoelectric coupling coefficient (kp), mechanical quality factor (Qm), and dielectric constant (er) were optimized as 4.456 (g/cm3), 269 (pC/N), 0.419, 51, 1644, respectively.

In this works, in order to develop the composition ceramics for a capacitor with the excellent dielectric properties, (Ba0.86Ca0.14) (Ti0.85Zr0.12Sn0.03) O3(abbreviated as BCTZ) ceramics were fabricated with the amount of Bi2O3. All specimens showed a typical perovskite structure. As the Bi2O3 addition was increased, secondary phase was found. When x = 0.006, the maximum value of er = 6043 was shown at 0 °C. At the 0.003 mol Bi2O3, the most excellent dielectric and TCC properties were obtained. Namely, the dielectric constant (er), the range of TCC from − 20 to 80 °C, Curie temperature were 5015, − 2 to + 48%, and 40 °C, respectively.

In this paper, in order to develop the composition ceramics with the high piezoelectric properties for ultrasonic transducer, Pb[(Mn1/3Nb2/3)x(Ni1/3Nb2/3)0.10(Zr0.48Ti0.52)0.90−x]O3 ceramics were fabricated with the variation of Pb(Mn1/3Nb2/3)O3. The effects of Pb(Mn1/3Nb2/3)O3 (abbreviated as PMN) on their microstructure and piezoelectric properties were systematically investigated. The tetragonality was decreased in the ceramics with the increase of Pb(Mn1/3Nb2/3)O3. When Pb(Mn1/3Nb2/3)O3 and sintering temperature were 8 mol%, 940 °C, respectively, the excellent physical properties of d33 = 302 pC/N, er = 1390, kp = 0.542, Qm = 1378 were obtained in the specimens for ultrasonic transducer.

In this paper, in order to develop the composition ceramics for piezoelectric actuator. (1 − x)(Na0.52K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 − x(Sr0.95Ca0.05)ZrO3 ceramics were sintered at 1020 °C by the conventional solid-state method. The effects of (Sr0.95Ca0.05)ZrO3 substitution on their microstructure and piezoelectric properties were systematically investigated. The orthorhombic-tetragonal coexistence phase has been found in the ceramics with x = 0.01, 0.015 and x = 0.02. The maximum value of d33 was 322 pC/N at x = 0.025 composition ceramics with the rhombohedral phase. The (Sr0.95Ca0.05)ZrO3 substitution increased the density and then aided the grain growth of specimens. When x = 0.01, the optimal physical properties of d33 = 254 pC/N, er = 1096, kp = 0.46, and Qm = 156 were obtained, respectively, for piezoelectric actuator application.

In this study, in order to develop relaxor ferroelectric ceramics with large electrocaloric effect, (Pb0.88La0.08)(Zr0.65Ti0.35)O3 ceramics were manufactured using conventional solid-state reaction...

Polyethylene/carbon black(PE/CB) composites have been widely used in various application devices such as heating element, temperature sensor and current limiter due to its positive temperature coef...

In this study, in order to develop the composition ceramics for ultrasonic sensor application, Pb0.985Bi0.01(Co1/2W1/2)0.03(Ni1/3Nb2/3)0.09(ZrxTi1-x)0.88O3+0.25wt% CuO (abbreviated as PCW-PNN-PZT) system ceramics were prepared with the variations of x and then their phase microstructure, piezoelectric and dielectric characteristics were investigated with the variations of x. The compositions near the morphotropic phase boundary (MPB) appeared when x = 0.495. Moreover, the PCW-PNN-PZT ceramics could be sintered at low temperature of 920°C by adding sintering aids CuO. At sintering temperature of 920°C and x = 0.495 specimen, the density (ρ), electromechanical coupling factor(kp), dielectric constant (ϵr), mechanical quality (Qm) and piezoelectric constant (d33) piezoelectric figure of merit (d33·g33) indicated the optimal value of 7.94 g/cm3. 0.65, 1959, 356, 486 pC/N, and 15.56 [pm2/N], respectively, suitable for ultrasonic sensor application. The CuO was proved to lower the sintering temperature ...

In this study, in order to develop piezoelectric ceramics with high piezoelectric d 31 coefficient and high Curie temperature (Tc), Pb(Mg 1/2 W 1/2 ) 0.03 (Ni 1/3 Nb 2/3 ) 0.09 (Zr 0.5 Ti 0.5 ) 0.88 O 3 ceramics doped with sintering aids were fabricated using a columbite precursor method. The crystal structure, dielectric and piezoelectric properties were investigated as a function of calcination temperature. At the sintering temperature of 920 °C, the optimal values of density = 7.83(g/cm 3 ), piezoelectric coefficient(d 31 ) = 263pC/N, piezoelectric coefficient(d 33 ) = 620pC/N, planar electromechanical coupling coefficient (k p ) = 0.689, mechanical quality factor (Q m ) = 100, dielectric constant(e r ) = 2524 and Curie temperature (Tc) = 340 °C were obtained from the ceramics with the two step calcination temperature of 1st = 1130 °C, 2nd = 780 °C, respectively, for haptic actuator application.

In this work, in order to develop lead-free piezoelectric ceramics with excellent dielectric and piezoelectric properties, (1−x)(Na 0.52 K 0.443 Li 0.037 )(Nb 0.883 Sb 0.08 Ta 0.037 )O 3 +x(Sr 0.95 Ca 0.05 )TiO 3 ceramics were fabricated as a function of (Sr, Ca)TiO 3 substitution using a conventional mixed oxide method. The microstructure, dielectric and piezoelectric properties were systematically investigated as a function of amount of the (Sr, Ca)TiO 3 substitution. A morphotropic phase boundary(MPB) between orthorhombic and tetragonal ferroelectric phases has been identified in the composition range of 0.005 33 )=310pC/N, planar piezoelectric coupling coefficient(k p )=0.44, mechanical quality factor (Q m )=98 and dielectric constant(e r )=1687, were obtained from the ceramics substituted with x=0.01, respectively.

Self-powered sensors have attracted significant interest for individual wearable device operation. Here, transparent and wearable single-electrode triboelectric nanogenerators (SETENGs) with high power generation are created using electrospun Ag nanowires (AgNWs)/poly(vinylidenefluoride-cotrifluoroethylene) [P(VDF-TrFE)] composite nanofibers (NFs). The SETENGs generate an output power density of up to 217 W/m

The degree of transformation from mechanical to electrical energy by flexible piezoelectric nanogenerators (f-PNGs) to power wearable electronics can be significantly enhanced through the synergy between piezoelectric ceramic nanoparticles (PCNPs) and flexible piezoelectric polymers. In this study, we investigated the mechanical and piezoelectric properties of composite nanofibers (c-NFs) of lead-free (Na, K)(Nb, Sb)O3-BaZnO3-(Bi, K)ZrO3 (NKNS-BZ-BKZ) PCNPs embedded in a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) matrix. A significant reduction in the agglomerate size of the PCNPs and their enhanced interfacial adhesion with the P(VDF-TrFE) matrix were achieved through a tetradecylphosphonic acid (TDPA) surface treatment of the PCNPs. The uniform distribution of the embedded PCNPs made the web of c-NFs have a highly negative relative surface potential and a high effective modulus of approximately 170 MPa. Consequently, the f-PNG with the TDPA surface-treated PCNPs maintained an open-circuit voltage, a high maximum generated power, and an output voltage of approximately 12.2 V, 33.2 nW, and 1.25 V, respectively, despite being bent for 10,000 cycles at a bending radius (r) of 15 mm.

In this paper, piezoelectric ceramics with the composition of (Na0.525K0.4425Li0.0375)(Nb0.8975Sb0.065Ta0.0375)O3 + 0.3 wt% CoO + x CuO (0.005≤x≤0.025) (abbreviated to NKL-NST) were fabricated for ultrasonic sensor application. The effects of CuO addition and sintering on the microstructure and the piezoelectric properties of the NKL-NST ceramics were systematically studied. Excellent piezoelectric properties such as electromchanical coupling factor(kp) = 0.415, piezoelectric constant (d33) =166 pC/N and piezoelectric figure of merit d33*g33= 5.47 pm/N were obtained from the 2.5 mol% CuO doped NKL-NST+0.3 wt%CoO ceramics sintered at 1,000°C for 3 h.

In this study, in order to develop relaxor ferroelectric ceramics for refrigeration device application with large electrocaloric effect, PLZT(8/65/35) composition was fabricated using conventional solid-state method. The Curi temperature of this composition PLZT ceramics was , and the P-E hysteresis loops of the PLZT ceramics as a fuction of temperature became slim by degrees with higher temperatures. The maximum value of of in ambient temperature of with 30 kV/cm was appeared. It is considered that PLZT ceramics possess the possibility of refrigeration device application.

In this study, boost DC-DC converter was designed and manufactured in order to light Light Emitting Diode (abbreviated as LED) using piezoelectric energy harvesting device. Piezoelectric energy harvesting device was fabricated using PMW-PNN-PZT ceramics with excellent piezoelectric properties of kp = 0.60, d33 = 518 (pC/N), g33 = 25.9 (×10−3Vm/N), and d33.g33 = 13.416(pm2/N). Cantilever type with the dimension of 80 × 12× 1.5mm3 was used to generate the power. Piezoelectric energy harvesting device generated an AC 2.19V at the driving frequency of 139 Hz under 3.5G. Output voltage of the piezoelectric energy harvesting device was rectified as DC 1.46V, and then charged on the capacitors. The DC 1.46V was used as the input voltage of the boost DC-DC converter. Output voltage of boost DC-DC converter exhibited DC 5.01V, indicating the sufficient value for lightening LED.

In this paper, in order to develop excellent Pb-free composition ceramics for ultrasonic sensor. The -doped ()(abbreviated as NKL-NST) ceramics have been synthesized using the ordinary solid state reaction method. The effect of -doping on their dielectric and piezoelectric properties was investigated. The ceramics doped with 0 wt% have the optimum values of piezoelectric constant(), piezoelectric figure of merit(), planar piezoelectric coupling coefficient() and density : , , . suitable for duplex ultrasonic sensor application.

In this paper, in order to develop the composition ceramics with the outstanding piezoelectric properties, ceramics substituted with were prepared by the conventional solid-state reaction method. The addition of small amount of and as sintering aids decreased the sintering temperature of the ceramics. The effects of substitution on their piezoelectric and dielectric properties were investigated. when 0.015 mol was substituted, the optimal physical properties of $d_{33}

In this paper, the (Ba0.85Ca0.15)(Ti0.915Zr0.085)O3+0.004CuO lead-free piezoelectric ceramics have been fabricated using the conventional ceramics processing in air and the effect of B2O3 addition on their phase structure, microstructure, and piezoelectric properties of (Ba0.85Ca0.15)(Ti0.915Zr0.085)O3+0.004CuO+xB2O3 ceramics were systematically investigated. The B2O3 diffuses into the BCTZ lattice to form a stable soild solution, rhombohedral and tetragonal phase coexistence is observed in the ceramics with the 1.0

The particle sizes of 0.95(K0.5Na0.5)NbO3-0.05BaTiO3 powder were controlled by secondary milling time after calcination. The average particle sizes, Dmean, of 0.95(K0.5Na0.5)NbO3-0.05BaTiO3 powders were critically changed from 14.31 μm to 0.91 μm by secondary milling time. The dielectric and piezoelectric properties of 0.95(K0.5Na0.5)NbO3-0.05BaTiO3 ceramics depended on the particle sizes of powders after calcination and the secondary milling process. As secondary milling times after calcination were increased to more than 48 hr, the dielectric and piezoelectric properties of 0.95(K0.5Na0.5)NbO3-0.05BaTiO3 ceramics were deteriorated.

In this study, in order to develop the composition ceramics with the excellent electrocaloric properties, (Pb 0.88 La 0.08 )(Zr 0.65 Ti 0.35 )O 3 ceramics were fabricated by the conventional solid-state method. Electrocaloric effects of (Pb 0.88 La 0.08 )(Zr 0.65 Ti 0.35 )O 3 ferroelectric ceramics were investigated and discussed using the characteristics of P-E hysteresis loops at wide temperature range from room temperature to 220. The temperature change ΔT due to the electrocaloric effect was calculated by Maxwell’s relations, and reached the maximum of 0.19 at 190under applied electric field of 30 kV/cm. Keywords: Electrocaloric effects, Ceramics, PLZT, Ferroelectric1. 서 론 effect)는 많은 연구자들의 관심을 받고 있다. 전기열 현재 지구온난화에 따라 지구의 온도는 점점 올라가고 있다. 그로 인해 냉장고와 에어컨 등의 사용빈도가 높아지고 있으며, 각종 냉각장치에 냉매제로 사용되는 프레온 가스 또한 사용량이 늘어나고 있는 추세이다. 프레온 가스는 오존층의 파괴와 온실효과를 일으키는 주요 원인으로 잘 알려져 있다. 지구환경을 보호하기 위해서 프레온 가스를 대체할 물질을 개발하는 것이 시급하다 [1]. 그러나 현재까지도 프레온 가스를 완벽하게 대체할 물질을 찾지 못하고 있는 것이 현실이다. 새로운 냉각기술로서 전기열량 효과 (electrocaloric

Lead-free (Ba0.85Ca0.15)(Ti0.915Zr0.085)O3 + x wt%ZnO piezoelectric ceramics were synthesized using a conventional solid state sintering method and the effect of ZnO addition on their piezoelectric and dielectric properties was investigated. The X-ray diffraction date exhibited that ZnO diffuses into the lattice of (Ba0.85Ca0.15)(Ti0.915Zr0.085)O3 (abbreviated as BCTZ) and pure perovskite structure phase was formed at all the specimens, And no secondary phases are observed in the measurement range of XRD. In addition, all the specimens showed tetragonal phase structure. The Curie temperature of BCTZ ceramics decreases with increasing the ZnO content. At the 0.2 wt% ZnO added (Ba0.85Ca0.15)(Ti0.915Zr0.085)O3 ceramics sintered at 1360°C, the optimized piezoelectric properties were obtained; piezoelectric constant(d33) = 348 [pC/N], dielectric constant(ϵr) = 3263, mechanical quality factor(Qm) = 267, electromechanical coupling factor(kp) = 0.41, respectively.

In this paper, in order to develop outstanding Pb-free piezoelectric composition ceramics, the (x

In this paper, in order to develop the composition ceramics with the excellent dielectric properties, Pb(Mg 1/2 W 1/2 ) 0.03 (Ni 1/3 Nb 2/3 ) 0.09 (Zr 0.5 Ti 0.5 ) 0.88 O 3 ceramics were fabricated by the conventional solid-state method. The effects of ZnO addition on their microstructure and piezoelectric properties were systematically investigated. The rhombohedral-tetragonal phase coexistence has been found in the ceramics without ZnO content and then with further increasing ZnO content, specimens exhibited tetragonal phase. The optimized ZnO content formed liquid phase and aided the grain growth of specimens. When 0.4 wt% ZnO was added, the optimal physical properties (d 33 = 422 pC/N, d 31 = 161 pC/N, e r = 1,905, k p = 0.55, Q m = 160) were obtained. Keywords : ZnO addition, Ceramic, PMW-PNN-PZT, Dielectric properties 1. 서 론 물에 대한 연구가 진행되어졌으며, 그로 인해 PbTiO Pb(Zr,Ti)O

(Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 + x wt% ZnO-B2O3 (NKLNST + x ZnO-B2O3) lead-free piezoelectric ceramics were prepared via a conventional solid-state reaction for various values of x = {0, 0.3, 0.6, 0.9, 1.2}; then, the dielectric and the piezoelectric properties of these ceramics were investigated. A pure perovskite structure and a small secondary phase were observed in the X-ray diffraction patterns. For the 0.3-wt% ZnO-B2O3 specimen, a density of ρ = 4.537 g/cm3, an electromechanical coupling factor of k P = 0.432, a mechanical quality factor of Q m = 96, and piezoelectric constant of d 33 = 209 pC/N were found to be optimal. These results indicate that the material with this composition is a promising candidate for use in a lead-free piezoelectric device.

In this study, in order to develop lead-free composition for piezoelectric actuator applications, (Na0.525K0.48-x)(Nb0.92-xSb0.08)O3 + 0.25wt%Bi2O3 + xLiTaO3 (x = 0.036, 0.037, 0.038, 0.039, 0.040) composition ceramics were fabricated by the normal sintering technique. The piezoelectric properties of resultant ceramics were studied with a special emphasis on the varying of LiTaO3. The structure of the specimen exhibits an orthorhombic perovskite structure. The grain size of the specimen increased with increasing the content of LiTaO3 substitution. High physical properties of the piezoelectric constant d33 = 317 pC/N, electromechanical coupling factor kp = 0.466, dielectric constant ϵr = 1913, and density ρ = 4.527 g/cm3 were obtained from the composition ceramics with x = 0.037. Also, at this composition, Δkp/kp20°C and Δfr/fr20°C showed the maximum value of −0.041 and −0.022 at −20°C and 50°C, respectively. Accordingly, it is considered that the temperature stability of x = 0.037 composition ceramics is ...

Na0.525K0.4425Li0.0375)(Nb0.9975Sb0.065Ta0.0375)O3 + 0.3 wt%CoO ceramics were fabricated as a function of CuO addition by traditional solid state sintering process in order to develop excellent lead-free piezoelectric ceramics composition. The addition of CuO in the LNKNTS composition ceramics can effectively enhance the densification of the ceramics, resulting in the oxygen vacancies as hardening effect. The excellent piezoelectric properties of electromechanical coupling factor(kP) of 0.378, piezoelectric constant(d33) of 152 pC/N were obtained from the 1.0 mol% CuO doped LNKNTS ceramics sintered at 1,020℃ for 3 h.