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Dielectric, ferroelectric, and photovoltaic properties of La-doped Bi(Ni2/3Ta1/3)O3–PbTiO3 ceramics
摘要： Bi(Ni2/3Ta1/3)O3-PbTiO3 ceramics doped with different La contents were prepared using the conventional solid-state reaction route. The electric properties of La-doped Bi(Ni2/3Ta1/3)O3-PbTiO3 ceramics were compared with those of non-La ceramics. As the incorporated La content increased, the Curie temperature TC decreased linearly, whereas the dielectric constant ε'RT at room temperature increased. Although the remnant polarization Pr decreased, the bipolar strain S (%) increased as the La content increased, owing to phase transition from the ferroelectric phase to the paraelectric phase. The maximum bipolar strain S (0.42%) was observed in the Bi0.7La0.3(Ni2/3Ta1/3)O3-PbTiO3 ceramics. When the La content reached 50%, the ferroelectric performance deteriorated. After La was doped into the Bi(Ni2/3Ta1/3)O3-PbTiO3 ceramics, the photovoltages were markedly improved. The photovoltage (27 V) reached its maximum with 15% La content but was reduced to 0 V with 50% La doping content owing to a decline in ferroelectricity. The speed of the photovoltaic response to the incident light for this system was about 0.5 ms. Therefore, the strain and the photovoltaic properties of the La-doped Bi(Ni2/3Ta1/3)O3-PbTiO3 ceramics were markedly improved relative to those of undoped ceramics.
关键词： Ceramics,Ferroelectric,Dielectric,Photovoltaic
更新于2025-09-11 14:15:04
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Femtosecond laser microstructuring of alumina toughened zirconia for surface functionalization of dental implants
摘要： The continuous need for high-performance implants that can withstand mechanical loads while promoting implant integration into bone has focused recent research on the surface modification of hard ceramics. Their properties of biocompatibility, high mechanical and fatigue resistance and aesthetic color have contributed to its successful applications in dentistry. Alumina toughened Zirconia (ATZ) has been gaining attention as a material for dental implants applications due to its advanced mechanical properties and minimal degradation at body temperature. Still, in order to improve tissue response to this bioinert material, additional modifications are desirable. Improving the surface functionality of this ceramic could lead to enhanced implant-tissue interaction and subsequently, a successful implant integration. In this work, microtopographies were developed on the surface of Alumina toughened Zirconia using an ultrafast laser methodology, aiming at improving the cellular response to this ceramic. Microscale grooves and grid-like geometries were produced on ATZ ceramics by femtosecond laser ablation, with a pulse width of 150 fs, wavelength of 800 nm and repetition rate of 1 kHz. The variation of surface topography, roughness, chemistry and wettability with different laser processing parameters was examined. Cell-surface interactions were evaluated for 7 days on both microstructured surfaces and a non-treated control with pre-osteoblasts, MC3T3-E1 cells. Both surface topographies showed to improve cell response, with increased metabolic activity when compared to the untreated control and modulating cell morphology up to 7 days. The obtained results suggest that femtosecond laser texturing may be a suitable non-contact methodology for creating tunable micro-scale surface topography on ATZ ceramics to enhance the biological response.
关键词： Femtosecond laser microtexturing,Dental implants,Hard ceramics,Alumina toughened zirconia,Surface topography,Biological response
更新于2025-09-11 14:15:04
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Laser-stimulated piezo-optical and third harmonic generation studies for Na2O–Sb2O3 glass ceramics-influence of gold ions
摘要： Sodium antimonate glass ceramics with different concentrations of Au2O3 were synthesized. The prepared samples were characterized by XRD, XPS, SEM and TEM techniques. These studies have revealed that the samples consist of multiple crystalline phases composed of Sb3+, Sb5+, Au3+ ions, and Au0 particles; moreover these studies have indicated growing proportion of Au0 particles and Sb5+crystal phases (Na2Sb2O6) with increase of Au2O3 concentration. IR and Raman spectral studies have pointed out an increasing degree of polymerization of the glass network with increase of Au2O3 content while optical absorption studies indicated surface plasmon resonance effects. Nd: YAG laser (λ = 1320?nm and pulse width 8?ns) was used for inducing third harmonic generation (THG) signal. Later, THG signal intensity of Nd: YAG laser (λ = 1064?nm and pulse width of 20?ns) vs fundamental beam power density was recorded. The results indicated the maximum intensity for the samples containing a low concentration of Au2O3. For inducing piezo-optical effects, Nd: YAG laser (λ = 1064?nm) and its doubled frequency beam λ = 532?nm (with simultaneous mechanical pressure) were used. The cw He-Ne laser of 20?mW (with beam diameter about 0.5?mm) was used as probing beam for measuring the piezo-optical effects in the photo-polarized samples. The variation of the intensity of the THG beam and piezo-optical coefficients were found to be the maximal for the samples mixed with small quantities of Au2O3. The detailed analysis of XRD, SEM, EPR, IR, optical absorption spectral results suggested that concentrations of Na3SbO3 and also Au2O3 crystal phases are maximal in these?samples and are responsible for the maximal photoinduced effects, while the increasing presence of Na2Sb2O6 crystal phases and Au0 metallic particles are found to be hindrance for generation of third harmonic beams and also piezo-optical effects. Overall, the obtained results of nonlinear optical (NLO) and piezo-optical studies indicated that Na2O-Sb2O3 glass ceramics containing small traces of Au2O3 are useful for considering them for nonlinear optical triggering devices and piezo-electric devices.
关键词： Sodium antimonate glass ceramics,piezo-optical effects,Nd: YAG laser,Au2O3,third harmonic generation
更新于2025-09-11 14:15:04
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Improving Performance and Stability of Planar Perovskite Solar Cells through Grain Boundary Passivation with Block Copolymers
摘要： Al2O3–ZrO2 ceramic coatings were fabricated on titanium alloy substrate by ultrasonic assisted laser cladding. The effects of ultrasonic on the microstructure and mechanical properties of the coatings are investigated through experiments. A novel laser cladding method by ultrasonic assisted is used in this paper. In this method, ultrasonic waves are directly applied on the micro-zone of molten pool. Experimental results indicated that the grain size and mechanical properties of the coatings are improved with the ultrasonic assisted. The amount of coatings cracks are decreased due to the application of ultrasonic vibration in the laser cladding.
关键词： Al2O3–ZrO2 ceramics,ultrasonic,laser cladding,mechanical properties
更新于2025-09-11 14:15:04
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Alteration of fracture toughness (KIC) following laser shock peening of silicon nitride ceramics
摘要： This work focuses on the development in laser shock peening (LSP) Si3N4 ceramics with a view to first observe the general effects namely; the topography, hardness, flaw size, plane strain fracture toughness (KIc). Firstly, an LSP surface treatment was conducted to establish a crack-free surface treatment. This also established a parametric window and elucidated the feasibility of treating a brittle material such as Si3N4 with a high intensity/pressure surface treatment such as LSP. Upon comparing the as-received surface with the LSPned surface elucidated a natural increase in surface roughness from an average of 1.73μm to 4.79μm. This indicated some level of material removal. In addition, a decrease in hardness was found by 4.5% and an increase in the KIc by over 21.5% through a possible induction of plasticity within the Si3N4. The microstructure of the Si3N4 also showed considerable changes after LSP surface treatment and a possible α-beta transformation were introduced which indicated surface strengthening. The work undertaken herein have shown that with further refinement of the LSP parameters, this type of laser treatment could be beneficial for strengthening advanced ceramics, particularly, as the process offers a mechanism for enhancement in fracture toughness. An alteration of such an important property of a Si3N4 would open new avenues for its applications particularly where metals and alloys fail.
关键词： hardness,surface treatment,Laser shock peening,Si3N4 ceramics,fracture toughness
更新于2025-09-11 14:15:04
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Effects of laser-textured surface pattern on the wetting behavior and composition optimization of brazing filler: experimental study and numerical simulation
摘要： To reduce interface brittle compounds of brazed joints, laser-textured surface pattern was used instead of excessive active element to enhance the wetting behavior of brazing filler on Ti3SiC2 ceramic substrate. The cylindrical surface pattern was designed by theoretical calculation and examined by numerical simulation. The numerical simulation results showed that the cylindrical surface pattern can not only effectively reduce the wetting angle on the substrate surface, but also greatly accelerate the spreading process of brazing filler. The results of wetting experiment showed that the wettability of Ag–Cu–2Ti (wt.%) brazing filler on Ti3SiC2 with cylindrical surface pattern sufficiently increased compared with that on smooth surface, which were consistent with the theoretical calculation and numerical simulation results. The titanium content in Ag–Cu–Ti that suitable for the brazing of Ti3SiC2 even could be reduced from 4.5 to 2.0 wt.%. The novel method provides a feasible route for promoting the wetting behavior and achieving composition optimization of brazing filler.
关键词： Ceramics,Wetting,Composition optimization,Surface pattern
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Near-Infrared Wavelength Dependence of Verdet Constant in Tb <sub/>2</sub> Zr <sub/>2</sub> O <sub/>7</sub> Transparent Ceramics
摘要： Transparent ceramics are widely developing for optical windows, laser gain mediums, phosphors for the LED lighting, and magneto-optic (MO) applications. In particular, advantages from the glass material or the single crystal of MO ceramics are notable for the high-power lasers from the view point of the large size capability, good thermal properties, and superior magneto-optics properties. Now a day, ceramic technology can realize several kind of cubic oxide materials such as terbium gallium garnet (TGG) [1-4], terbium aluminium garnet (TAG) [5], and sesquioxides [6-8]. In addition of above materials, Tb2Zr2O7 (TZO) transparent ceramics is a new candidate material for the high-power laser application. TZO has a relatively high concentration of Tb3+ ion, a cubic pyrochlore structure, and no intrinsic absorption in the near infrared (NIR) region. To evaluate the potential of this material for the high-power laser application, we have evaluated the near-infrared (NIR) wavelength dependence of Verdet constant in TZO ceramics as the first time.
关键词： magneto-optic applications,transparent ceramics,Tb2Zr2O7,near-infrared,Verdet constant
更新于2025-09-11 14:15:04
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Construction of high <i>T</i> <sub/>c</sub> BiScO <sub/>3</sub> -BiFeO <sub/>3</sub> -PbTiO <sub/>3</sub> and its enhanced piezoelectric properties by sintering in oxygen atmosphere
摘要： The high-temperature piezoelectric ceramics 0.36[(1 ? x)BiScO3-xBiFeO3]-0.64PbTiO3 was constructed by introducing BiFeO3 with a high Curie temperature (Tc ～ 830 °C) in the 0.36BiScO3-0.64PbTiO3 binary system. In terms of microstructure, low-melting BiFeO3 plays a role as a sintering aid, lowering the sintering temperature of the ceramic and signi?cantly increasing the grain size. At the same time, the crystal structure shifts from the initial morphotropic phase boundary to the tetragonal phase side, and the Tc increased gradually with increasing BiFeO3 content. Under the conventional air atmosphere sintering conditions, the Tc of the sample with x = 0.3 can reach ～500 °C, and the piezoelectric constant d33 is 125 pC/N. Compared with that, the d33 of the same composition sample sintered in an oxygen atmosphere is increased to 165 pC/N, which is mainly due to the decrease in the content of oxygen vacancies that helps to increase poling electrical ?eld. Moreover, the oxygen-sintered specimen exhibits an excellent thermal stability in a wide temperature range from room temperature to 450 °C, indicating that it is a promising candidate for ultra-high-temperature piezoelectric devices applications.
关键词： high-temperature piezoelectric ceramics,thermal stability,BiScO3-BiFeO3-PbTiO3,sintering in oxygen atmosphere,piezoelectric properties
更新于2025-09-11 14:15:04
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Outstanding piezoelectric properties, phase transitions and domain configurations of 0.963(K0.48Na0.52)(Nb0.955Sb0.045)O3?0.037(Bi0.50Na0.50)HfO3 ceramics
摘要： Requirements for substituting the current lead-based piezoelectric materials with lead-free ones are becoming increasingly strong from environmental concerns. In this article, we report piezoelectric properties, phase transitions and domain configurations of a dense 0.963(K0.48Na0.52)(Nb0.955Sb0.045)O3?0.037(Bi0.50Na0.50)HfO3 lead-free ceramic prepared through solid-state reaction by two-step sintering. It has a large piezoelectric coefficient d33 = 512 pC/N and a planner eletromechanical coupling coefficient kp ≈ 0.54 at room temperature. Dielectric measurement indicates that rhombohedral-orthorhombic, orthorhombic-tetragonal, and tetragonal-cubic phase transitions upon heating process occur at ?30 °C, 57 °C and 238 °C, respectively. X-ray diffraction analysis shows that the crystalline structure is dominantly of orthorhombic phase at room temperature. Domain configurations were investigated by acid etching technique. The poled ceramic shows domain patterns of long parallel stripes with hierarchical nanodomain structure existing in some broad stripes. The observed outstanding piezoelectric properties are ascribed to the rhombohedral-orthorhombic and orthorhombic-tetragonal phase transitions, and to the characteristic domain structure.
关键词： Phase transitions,Piezoelectricity,Lead-free ceramics,Ceramics,Ferroelectrics,Domain structure
更新于2025-09-10 09:29:36
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Structure, dielectric behaviours, enhanced polarization responses and energy storage properties in (1???x)SrTiO3–xBi(Mg1/2Ti1/2)O3 ceramics
摘要： In this work, ceramics of (1 ? x)SrTiO3–xBi(Mg1/2Ti1/2)O3 (ST–BMT, x = 0.05–0.5) were successfully prepared. A single-phase perovskite structure is formed for all the compositions. The average structure is cubic at room temperature. The Raman analysis suggests that the 5 mol% BMT addition might cause the existence of the local tetragonal distortions at room temperature. All the compositions display a frequency-dependent and highly diffused dielectric anomaly. The BMT addition can effectively shift the freezing temperature (Tf), from ~ 32 K for x = 0.1 up to ~ 240 K for x = 0.5. The compositions with x = 0.4 and 0.5 show a small change in the relative permittivity (Δε′/??′373 K < ± 15% at 1 kHz) and keep low values of the dielectric loss (tanδ < 0.01 for x = 0.01 at 1 kHz) in the temperature range of 373–523 K. The BMT addition induces an enhancement of the polarization maxima. Among the compositions, 0.7ST–0.3BMT shows the optimum energy storage performance (Wrec, 0.78 J/cm3).
关键词： ceramics,energy storage,dielectric behaviour,SrTiO3,Bi(Mg1/2Ti1/2)O3
更新于2025-09-10 09:29:36