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Finely depressed dielectric loss and conductivity achieved in high-kappa stannic oxide/polymer nanocomposites from surfactant-assisted electric percolation
摘要： During past decades, both of interface polarization and electric percolation mechanisms have been found to have a significant influence on the dielectric and conductive properties of polymer based nanocomposites bearing electrically conducting nanoparticles. Although the significantly elevated high dielectric constant of composites has gained great success, the finely balanced high dielectric constant, depressed dielectric loss and low conductivity have been faced with a huge challenge. Instead of the high-cost organic modification onto the surfaces of inorganic conductive nanofiller, in current work, a small quantity of polyvinylpyrrolidone surfactant was introduced to prepare the ternary polymer based nanocomposite films bearing stannic oxide nanoparticles. Their dielectric and conductive performances were compared with that of the corresponding binary composites without bearing that surfactant. The positive influence of that surfactant on the finely balanced high comprehensive electric properties of composites namely high dielectric constant and depressed loss/conductivity was confirmed due to the improving of interface compatibility and depressing of interface air voids. The ternary nanocomposite bearing 10 vol% filler could have a dielectric constant of ca. 175, loss of ca. 0.35 and conductivity of ca. 1.8 × 10?5 S cm?1 at 1 kHz under 1 V bias voltage. This work might open the door to the large-scale fabrication of promising composite dielectrics materials by facilely introducing the third surfactant component.
关键词： surfactant,stannic oxide,dielectric properties,polymer nanocomposites,electric percolation
更新于2025-09-23 15:19:57
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Preparation, structural and functional properties of PbTiO3-δ ceramics
摘要： In the present study, oxygen deficient PbTiO3-d ceramics were prepared by solid state-reaction method. The formation of the pure perovskite phase with tetragonal structure was confirmed for the 800°C/2h calcined sample by using X-ray diffraction analysis at room temperature. Energy dispersive X-ray spectroscopy analyses confirm the creation of oxygen vacancies in the system for charge compensations, as demonstrated by the percentage of O atoms of ~53%. The complex impedance data reveals important contributions of the oxygen vacancies to the total dielectric response that are homogeneous distributed within the sample. The room temperature magnetic properties show a weak ferromagnetic character in all the samples that might be attributed to the oxygen vacancies defects and to surface effects.
关键词： oxygen vacancies,EDX spectra,magnetic properties,ceramics,dielectric properties
更新于2025-09-19 17:15:36
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Piezoelectric and Dielectric Properties of ((K0.475Na0.495Li0.03)NbO3-0.003ZrO2)/PVDF Composites
摘要： The (K0.475Na0.495Li0.03) NbO3-0.003ZrO2 (KNNL-Z) ceramic was synthesized by the conventional solid-state reaction and (KNNL-Z)/PVDF composites were fabricated by hot-pressing process using polyvinylidene fluoride (PVDF) and KNNL-Z ceramic. The effects of the ceramic content on the crystalline structures, morphology, densities, dielectric and piezoelectric properties of (KNNL-Z)/PVDF 0–3 composites were systemically studied. The KNNL-Z ceramic possesses a perovskite phase with orthorhombic symmetry and the PVDF polymer mainly possesses a, b and c phases. Interestingly, the incorporation of the ceramic particles can decrease the crystallite size of the PVDF matrix. In addition, the b phase content increases and the a phase decreases when the ceramic particles are added. When the ceramic content increases from 40 wt.% to 80 wt.%, the relative fraction of b phase increases from 47.7% to 53.8%. Successful incorporation of ZrO2 into the KNN ceramic has been demonstrated by energy-dispersive x-ray spectroscopy and the most elements are homogeneously distributed in the composites. The dielectric and piezoelectric properties are found to be improved with the increase of KNNL-Z content. When 80 wt.% KNNL-Z is added, the dielectric permittivity reaches the value of 272 (100 Hz) at room temperature and the piezoelectric coefficient is 39 pC/N. After 30 days of aging, it is obvious that all the composites present a good stability of their piezoelectric property.
关键词： PVDF,0–3 composite,KNNL-Z,dielectric properties,piezoelectric properties
更新于2025-09-19 17:15:36
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Synthesis, and spectroscopic, thermal and dielectric properties of phosphazene based ionic liquids: OFET application and tribological behavior
摘要： Mono(4-fluorobenzyl)cyclotriphosphazene derivatives with (dimethylamino)ethoxy (Pz1a–2a) and (dimethylamino)propoxy (Pz1b–2b) chains were synthesized. The chain nitrogen atoms of fully substituted cyclotriphosphazene compounds were quaternized by treatment with CH3I to give phosphazene based ionic liquids (PzILs), PzIL1–PzIL4. Subsequent metathesis with LiN(SO2CF3)2 gave the salts, PzIL1a–PzIL4a. The structures of the PzILs were confirmed by elemental analyses, FTIR and 1H, 13C{1H}, and 31P{1H} NMR techniques. The thermal properties of all compounds were described using thermogravimetric analysis (TGA). These newly synthesized PzILs were used as the dielectric layer in organic field effect transistors (OFETs). Both dielectric and OFET characterization were performed. Because of the high dielectric effect of the PzILs, the fabricated OFETs operated in the low voltage range. Furthermore, a sliding wear test was conducted at room temperature using an AA7075 disc specimen against a stationary 100Cr6 steel ball. The wear protection of the PzILs and 15W40 engine oil was determined by considering the volume loss of AA7075. The lowest coefficient of friction (COF) and wear loss were obtained with PzIL4a.
关键词： ionic liquids,dielectric properties,phosphazene,OFET,tribology,synthesis
更新于2025-09-19 17:15:36
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Optical band gap and dielectric abnormality in (Sr, Ce, Zr)TiO3 composite ceramics sintered in nitrogen
摘要： The crystal-chemical structure, band gap-grain structure and dielectric properties of (1?x)SrTiO3-xCe0.95Zr0.05O2 [(Sr,Ce,Zr) TiO3, for x = 0.0, 0.3 and 0.4] ceramics were investigated. Samples with 0.3 ≤ x ≤ 0.4 appeared cubic by X-ray diffraction (XRD), however, splitting of the peaks along with Rietveld refinement indicated tetragonal structure. The change in the band gap energy with Ce(x) have been investigated and are related to variation in the grain size, activation energy and octahedral tilting. The reduction in band gap energy with Ce0.95Zr0.05O2 ions (x = 0.4) is attributed to the widening of conduction band with octahedral tilting. The absence of TO2 (175 cm?1) mode while the existence of TO4 (521.72 cm?1) mode has been considered as sign of relaxor-like-dielectric behavior. The ε′?T curve and the P–E loop analysis confirms that there is no signature of the ferroelectric phase in all samples. Base on the X-ray photoelectrons spectroscopy (XPS) and high temperature ac conductivity analysis, the dielectric anomalies were due to the formation of lattice defects and defect dipoles ( Ti4+ ? e? ? V ?? o ) generated by the Ti3+ ions and ionized oxygen vacancies.
关键词： Crystal-band gap structure,Dielectric properties,Oxygen vacancies
更新于2025-09-19 17:15:36
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Effects of substrate bias and temperature on the structure and dielectric properties of Ti Zr1?N ternary nitride thin films
摘要： Transition metal nitrides have become a kind of promising alternative plasmonic materials. TixZr1?xNy ternary nitride ?lms were prepared by magnetron co-sputtering method, and the e?ects of bias voltage and temperature on the structure and dielectric properties of the ?lms were investigated. The experimental results show that all the ?lms are fcc-structured, and high substrate bias and temperature can signi?cantly improve the N and Ti content. Increasing substrate bias voltage or temperature can reduce the crossover frequency ωc at which the ?lms transit from dielectric to metallic phase. Also, a high bias can greatly in?uence the energy loss of the ?lms. Furthermore, the plasmonic quality factor can be e?ectively tailored by bias and temperature. Increasing bias can decrease the quality factor while high temperature (600 °C) can enhance the quality factor signi?cantly. The study demonstrates that the TixZr1?xNy ?lms, as one kind of alternative plamonic materials, have considerable performances, and their dielectric and plasmonic properties can be modulated by varying the bias voltage and temperature in a wide range.
关键词： Bias,Temperature,Dielectric properties,Thin ?lm,Nitride
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - High-Volume Production and Non-Destructive Piezo-Property Mapping of 33% SC Doped Aluminium Nitride Thin Films
摘要： Scandium-doped aluminum nitride (ScAlN) thin films with 22% scandium content (Sc0.22Al0.78N) were deposited on a 100-mm sapphire substrate using a sputtering tool. The films exhibit enhanced piezoelectric properties compared to pure AlN, making them promising for microelectromechanical systems (MEMS) applications. The dielectric constant and loss tangent were measured at 100-mm and 20-mm wavelengths, showing values of εr ≈ 11.7 ± 0.2 and tanδ ≈ 0.002 ± 0.001, respectively. These results indicate high potential for voltage manufacturing and sensing devices.
关键词： dielectric properties,piezoelectric,sputtering,ScAlN,thin films,MEMS
更新于2025-09-19 17:15:36
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Dielectric and photoluminescence properties of fine-grained BaTiO <sub/>3</sub> ceramics co-doped with amphoteric Sm and valence-variable Cr
摘要： Dielectric and photoluminescence properties of fine-grained BaTiO3 ceramics co-doped with amphoteric Sm and valence-variable Cr (Ba1-xSmx)(Ti1-xCrx)O3 (BSTC) and (Ba1-xSmx)(Ti1-(x-0.01)Crx-0.01)O3 (BSTC1) ceramics with a single-phase perovskite structure were prepared using a traditional solid state based method. The structure, microstructure, site occupations, valence states of Cr, photoluminescence, and dielectric properties of these ceramics were investigated using XRD, SEM, EDXS, RS, EPR, XPS, and dielectric measurements. All ceramics exhibit a fine-grained microstructure (0.7 mm). Three valence states of Cr ions were confirmed and Cr predominates as Cr3+ enter the Ti4+ sites with a stronger EPR signal (1.974). The RS bands of high-wavenumber were attributed to photoluminescence from Sm3+ ions. The formation of SmBa?-CrTi' defect complexes play leading roles in the removal of VO??, prevent the grain growth, and photoluminescence quenching. (Ba1-xSmx)(Ti1-(x-0.01)Crx-0.01)O3 (BSTC1) ceramics with amphoteric Sm3+ ions exhibit a regular diffuse phase transition behavior, rapid Tm-shifting rate of -24.3 °C/at% (Sm/Cr), higher εRT; lower tan δ and x = 0.04 and 0.05 met the EIA Y5V specification.
关键词： Sm and Cr doping,BaTiO3 ceramics,photoluminescence,dielectric properties,co-doping
更新于2025-09-19 17:15:36
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Enhanced dielectric and piezoelectric properties in the [001]-poled 0.25Pb(In <sub/>1/2</sub> Nb <sub/>1/2</sub> )O <sub/>3</sub> -0.43Pb(Mg <sub/>1/3</sub> Nb <sub/>2/3</sub> )O <sub/>3</sub> -0.32PbTiO <sub/>3</sub> single crystal near morphotropic phase boundary by alternating current treatment
摘要： In this paper, temperature dependance of induced dielectric and piezoelectric properties in the [001]-oriented predirect current poling (DCP) of the 0.25Pb(In1/2Nb1/2)O3-0.43Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (0.25PIN-0.43PMN-0.32PT) single crystals near morphotropic phase boundary was investigated using the alternating current treatment (ACT). By the optimized ACT conditions of 1 kV/mm at 50 Hz over 20 cycles, the dielectric permittivity (ε0) and piezoelectric coefficient (d33) at room temperature of the DCP-ACT crystal were improved to be 7120 and 2610 pC/N, which were 48% and 54% higher than that of the DCP crystal (ε0 = 4800, d33 = 1700 pC/N). Based on the temperature dependence of dielectric permittivity and dielectric loss of the DCP-ACT crystal, the induced monoclinic phases (MA and MC) were involved in the phase transition process from a rhombohedral phase to a tetragonal phase. The phase transition temperatures TR-MA of 116 °C of the DCP-ACT crystal showed about 10 °C higher than that of DCP. Meanwhile, ε0 of the DCP-ACT crystal at TR-MA and in the tetragonal phase region, at around 110 °C and 130 °C, were 160% and 390% higher than those of the DCP crystal, respectively. The ultrahigh ε0 = 17 000 of the DCP-ACT crystal at 130 °C may relate to the nanoscale heterogeneous polar-regions induced by ACT. The ACT is a promising way to enhance the dielectric and piezoelectric performance of the pre-DCP 0.25PIN-0.43PMN-0.32PT single crystals with broadened temperature range for device applications.
关键词： single crystal,piezoelectric properties,morphotropic phase boundary,alternating current treatment,dielectric properties
更新于2025-09-19 17:13:59
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Dielectric and electrical properties of annealed ZnS thin films. The appearance of the OLPT conduction mechanism in chalcogenides
摘要： The annealing temperature (Ta) dependence of the structural, morphological, electrical and dielectric properties of ZnS thin films was investigated. In this work, we consider the as-deposited and annealed ZnS thin films at different temperatures. The as-deposited films were amorphous in nature. However, the films annealed at Ta ≥ 673 K, exhibited a hexagonal structure with (002) preferential orientation. The post annealing caused an improvement in crystallinity. The best one was observed at Ta = 723 K. Grain size increased from 7 nm to 25 nm as annealing temperature was increased from 673 K to 723 K. The surface of annealed samples is homogenous and uniform and the rms roughness is dependent on the annealing temperature: it increases with temperature within the range 5–50 nm. The film electrical conductance is found to be dependent on frequency measurement and annealing temperature: the dc conductance exhibits semi-conductor behavior for all ZnS films over the explored range of temperature and the conductance was found to enhance with increasing annealing temperature up to 623 K. In addition, it was observed that the highest conductance and lowest activation energy of ZnS films were obtained at an annealing temperature of 623 K. The mechanism of alternating current ac conductance can be reasonably explained in terms of the overlapping-large polaron tunnelling (OLPT) model for samples annealed at 623 K and 673 K. To our knowledge, this conduction mechanism was rarely found in chalcogenide materials. A significant change of Nyquist plot with annealing temperature was noted permitting the correlation between the microstructure and its electrical properties. The impedance analysis investigated that the relaxation process is well pronounced for the both annealed films at 623 K and 673 K. The dielectric behavior was associated to the polarization effect, an improvement on the dielectric constant 30 and dielectric loss 300 with annealing was noticed.
关键词： electrical properties,dielectric properties,annealing temperature,OLPT conduction mechanism,ZnS thin films
更新于2025-09-16 10:30:52