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Preparation of high-quality stress-free (001) aluminum nitride thin film using a dual Kaufman ion-beam source setup
摘要： We proposed and demonstrated a preparation method of (001) preferentially oriented stress-free AlN piezoelectric thin films. The AlN thin films were deposited by a reactive sputtering technique at substrate temperatures up to 330 °C using a dual Kaufman ion-beam source setup. We deposited the AlN on Si (100), Si (111), amorphous SiO2, and a (001) preferentially oriented Ti thin film and compared their crystallographic, optical, and piezoelectric properties. The AlN thin films deposited on the (001) preferentially oriented Ti thin films have the highest crystallographic quality. The stress-free AlN reached a high value of the piezoelectric coefficient d33 = (7.33 ± 0.08) pC·N?1. The properties of the AlN thin film prepared at such low temperatures are suitable for numerous microelectromechanical systems, piezoelectric sensors, and actuators monolithically integrated with complementary metal-oxide-semiconductor signal-processing circuits.
关键词： Ellipsometry,Aluminum nitride thin film,Optical properties,d33 piezoelectric coefficient,Kaufman ion-beam source,Ion-beam sputtering deposition,(001) preferential orientation,X-ray diffraction
更新于2025-09-23 15:23:52
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Prediction of Strong Piezoelectricity in 3R-MoS2 Multilayer Structures
摘要： We present the first calculation of piezoelectric constants of 3R-MoS2 which is one of three known polytypes of MoS2. We demonstrate that the 3R-MoS2 structure with 5 layers has the highest reported piezoelectric constant of all MoS2 multilayer structures. The maximum piezoelectric constant is approximately 13% above the monolayer value. Also 3R-MoS2 structures with 4 and 6 layers have a larger piezoelectric coefficient compared to monolayer MoS2. Results are obtained using the molecular dynamics computational package LAMMPS subject to room temperature simulations. Our results indicate strong potential for multilayer 3R-MoS2 structures in nanosensor and nanogenerator applications.
关键词： Piezoelectric coefficient,3R-MoS2,Multilayers,Molecular dynamics
更新于2025-09-23 15:21:21
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Improved upconversion photoluminescence properties of 0.965K0.4Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with balanced piezoelectric coefficient and Curie temperature
摘要： A series of erbium- and indium-doped 0.965K0.40Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with upconversion photoluminescence (UCPL) properties were prepared by the conventional solid state reaction. A systematical investigation into the effects of In3+ doping on the structural, dielectric, ferroelectric, piezoelectric, and UCPL properties of the ceramics was carried out. The distribution of Er3+-sites could be modified by In3+ doping according to the analysis of UV–Vis-NIR absorption cross-section, resulting in improved piezoelectric and photoluminescence properties of the ceramics. The optimized comprehensive properties are performed by the x = 0.25% samples of which the piezoelectric coefficient d33 ~ 257 pC/N, Curie temperature TC ~ 273 °C, remanent polarization Pr ~ 12.5 μC/cm2, dielectric constant εr ~ 1551, and d33 ~ 257 pC/N which is the supreme piezoelectric coefficient achieved in KNN-based UCPL ceramics as of now. The results demonstrate that erbium and indium co-doped KNN-based ceramics may have potential applications in electro-optical devices.
关键词： Upconversion photoluminescence,Erbium and indium co-doping,Piezoelectric coefficient,Lead-free piezoelectric ceramics,Curie temperature
更新于2025-09-23 15:21:01
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Improved piezoelectric and strain performance of Na2B4O7-doped (Li,K,Na)NbO3 lead-free piezoceramics
摘要： A polymorphic phase transition effect has been employed to regulate the piezoelectric property of lead-free (K,Na)NbO3-based materials, which intrinsically bear the disadvantage of the evident temperature sensitivity. In this research, Li0.04[(K0.49Na0.51)]0.96NbO3–xNa2B4O7 piezoceramics were prepared through a conventional solid-state reaction. A piezoelectric coefficient d33 of about 285 pC/N and a unipolar strain of 0.14%@5 kV/mm were achieved in the ceramics with x = 0.5%. These improved properties can be ascribed to the coexistence of orthorhombic and tetragonal phase structure around room temperature. Besides, the field-induced unipolar strain varied less than 15% in the temperature region from room temperature to 180 °C. The stability of strain property could be rationally interpreted by a quantitative approach of electrostrictive coupling to the polarization amplitude.
关键词： Piezoelectric coefficient,Lead-free piezoceramics,Temperature stability,Na2B4O7 doping,Polymorphic phase transition
更新于2025-09-23 15:21:01
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Ferroelectric properties and phase transitions of high performance vertically aligned KNN nanowire-arrays grown by pulsed laser deposition
摘要： Pulsed laser deposition (PLD) was used to synthesize piezoelectric nanowire-arrays of K0.5Na0.5NbO3 (KNN) on Pt/TiO2/SiO2/Si substrates. These arrays were successfully prepared by using two different deposition conditions than the previously reported for KNN. KNN with orthorhombic structure and minority secondary phases were identified by XRD. Ferroelectric and Piezoelectric properties were confirmed by piezoresponse force microscopy, and showed that nanowire-arrays have an improvement in their effective piezoelectric coefficient of d33eff = 94.6 pm/V and 133.6 pm/V, higher than previously reported coefficients. Pulsed laser photoacoustic technique was used to analyze the phase transition temperatures and they showed a phase transition (O-T) at ～170 ?C and a phase transition (T-C) at ～360 ?C, lower temperatures than those found for bulk ceramics. Furthermore, it was identified the presence of minor amount of secondary ferroelectric phase (K4Nb6O17).
关键词： Phase transitions,KNN nanowire-arrays,Ferroelectric properties,Pulsed laser deposition,Piezoelectric coefficient
更新于2025-09-23 15:19:57
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Dielectric and Piezoelectric Properties of Composite Poly(vinylidene fluoride-trifluoroethylene) Copolymer with Carbon Nanotubes
摘要： Film samples of poly(vinylidene fluoride-trifluoroethylene) copolymer containing 2% of carbon nanotubes were synthesized. The temperatures of the ferroelectric phase transition and the value of permittivity at the frequency of 1 MHz were determined. The surface was visualized using scanning probe microscopy; the values of the effective piezoelectric coefficient were obtained. It was shown that incorporation of carbon nanotubes into the polymer matrix improves the values of the permittivity and piezoelectric coefficient of the polymer.
关键词： permittivity,copolymer,piezoelectric coefficient,carbon nanotubes
更新于2025-09-19 17:15:36
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Model Calculation of the Piezoelectric Coefficient of Hexagonal 2D Materials
摘要： A quantum-mechanical microscopic model of the piezoelectric e?ect in 2D materials is developed. The piezoelectric coe?cient requires the calculation of an internal atomic displacement and an e?ective piezoelectric charge. The internal displacement is obtained from minimizing the strain energy given by a Keating-like model, while the e?ective charge takes into account the atomic displacements and also a redistribution of the electronic charge; a bond-orbital model is used to compute the latter. The ?nal theory only requires atomic energies and the elasticity constants of the materials as input parameters. The piezoelectric coe?cients of a number of II-VI, III-V and IV-IV materials that could stably form in the planar hexagonal structure are computed; results for the IV-IV materials are obtained for the ?rst time.
关键词： piezoelectric coefficient,electronic structure,2D materials,bond-orbital model
更新于2025-09-04 15:30:14