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Evolving antiferroelectric stability and phase transition behavior in NaNbO3-BaZrO3-CaZrO3 lead-free ceramics
摘要： The stability of antiferroelectricity in NaNbO3 ceramics was found to evolve with co-doping x mol% CaZrO3 and 6 mol% BaZrO3, from a dominant ferroelectric (FE) orthorhombic Q phase (x=0) to a gradually stabilized antiferroelectric (AFE) orthorhombic P phase owing to different ionic radii of Ba and Ca ions. Although a complete AFE P phase appears at x=0.5, the field induced AFE-FE phase transformation is irreversible at first, and then becomes partially reversible at x=1 and finally completely reversible at x=3. The above-mentioned change process proves to be associated with the enhancing stability of antiferroelectricity with x, as evidenced by means of dielectric, polarization and strain properties as well as in/ex-situ synchrotron x-ray diffraction and Raman spectra. A composition-field phase diagram for the NN-based lead-free AFE ceramic was constructed on basis of the phase structural change, which would provide a clear understanding of how ion doping influences its antiferroelectricity.
关键词： lead-free ceramics,Antiferroelectricity,phase transition,NaNbO3
更新于2025-11-14 17:28:48
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Effect of NaNbO <sub/>3</sub> Crystals on the Electrical Properties of Na <sub/>0.47</sub> K <sub/>0.47</sub> Li <sub/>0.06</sub> NbO <sub/>3</sub> Ceramics Synthesised by Seed Induced Method
摘要： In this work, we investigated the influence of crystalline NaNbO3 on the electrical properties of Na0.47K0.47Li0.06NbO3 (NKLN) ceramics. Preparation by the conventional method for the upcoming phase of random elements did not control the properties. For this reason, we studied the electrical properties and phase formation that occurred with the addition of NaNbO3 crystals, used at the initial phase of the reaction, in order to modify the electrical properties of NKLN ceramics. We synthesized lead-free piezoelectric ceramics by the seed-induced method. We prepared the NaNbO3 crystals used as seeds by molten salt synthesis (MSS). We mixed the powder oxides of Na2CO3 and Nb2O5 with NaCl oxides-salt ratio 1:6. The seeds varied in content from 0 to 20 mol%. The calcination temperature of NKLN was from 800 to 900 °C for 10 h, using two-step sintering (TSS) techniques. Our investigation further reported on the microstructure and the electrical properties. The results showed high Curie temperature of about 480 °C, while the effect of the seed crystal improved the piezoelectric properties of the samples, compared with the conventional mixed-oxide.
关键词： Seed-Induced Method,NKLN,Lead-Free Ceramic,NaNbO3
更新于2025-11-14 17:28:48
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Effects of raw materials on NaNbO <sub/>3</sub> nanocube synthesis via the solvothermal method
摘要： A nanocube is a single nanoscale crystal with a cubic shape. Raw materials are an important factor in determining the synthesis of nanocubes. In this study, we investigated various niobium compounds that serve as raw materials, each inducing different effects during nanocube synthesis. NaNbO3 nanocubes were synthesized using a two-step process. The first step in this process, synthesis of the raw materials, was followed by solvothermal synthesis of NaNbO3 nanocubes. The raw material for the first step was obtained by applying heat treatment to a precursor following Nb hydrolysis. The heat treatment was performed at temperatures of 300°C to 1000°C. Nb2O5 was obtained after heat treatment of its precursor, during which its crystalline system morphed into hexagonal, orthorhombic, and monoclinic systems with respective increases in temperature. For the second step, we obtained various NaNbO3 morphologies via the solvothermal method using water, methanol, or ethanol as a reaction medium. NaNbO3 nanocubes were formed by applying the solvothermal method to the synthesized precursor during heat treatment at 800°C. Solvothermal synthesis was performed with methanol as the reaction medium at 200°C, which resulted in the formation of NaNbO3 nanocubes.
关键词： Raw material,Solvothermal method,Nanocube,NaNbO3
更新于2025-09-23 15:23:52
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Enhanced photoelectrochemical performance of plasmonic Ag nanoparticles grafted ternary Ag/PaNi/NaNbO3 nanocomposite photoanode for photoelectrochemical water splitting
摘要： In this work, we have successfully synthesized silver nanoparticles (Ag-NPs) decorated binary PaNi/NBO nanocomposite by facile chemisorption route and demonstrated enhanced photoelectrochemical (PEC) water splitting activity. The ternary Ag/PaNi/NBO nanocomposite photoanode exhibits ~5 fold higher current density than pristine NaNbO3 nanofibers (NBO-NFs). The ternary Ag/PaNi/NBO photoanode exhibits a current density of 5.93 mA/cm2 at 0.9 V with respect to Ag/AgCl, whereas the pristine NBO-NFs photoanode exhibits only 0.85 mA/cm2 at 0.9 V. The improved performance is correlated to the high surface area, formation of the type-II heterojunction among PaNi and NBO-NFs and the introduction of the plasmonic behaviour of Ag-NPs as it expands the absorption of the visible part of the solar spectrum, which together decreases the recombination of charges with strong redox capability. Furthermore, the ternary Ag/PaNi/NBO photoanode showed lower charge transfer resistance (Rct) in the EIS measurements and improved incident photon to current efficiency (IPCE) of ~31.3% which is ~23% higher to the IPCE of bare NBO-NFs photoanode. Thus, these results suggest that the ternary Ag/PaNi/NBO nanocomposite is a promising material for PEC activity and wide practical applications.
关键词： Water Splitting,Silver nanoparticle,PaNi,NaNbO3,Ag/PaNi/NBO
更新于2025-09-23 15:19:57
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An urchin-like SnO2/NaNbO3 nanocomposite with stable humidity-sensing properties at room temperature
摘要： An urchin-like nano-composite of SnO2/NaNbO3 was fabricated by the hydrothermal method and the influence of the Sn/Nb ratio in the samples on their humidity-sensing properties was investigated. The phases and morphologies of these composites and their elemental distributions were analyzed by X-ray diffraction scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The sensor based on the optimum Sn/Nb ratio of 1:0.4 exhibited remarkable humidity-sensing properties, including a good response (S = 4823.8) that was 8.72 times higher than that of the pure SnO2 sensor (S = 553.01). The composites showed rapid response and recovery times (3/9 s), as well as good stability, linearity, and excellent selectivity. The fabrication and humidity-sensing mechanisms were systematically analyzed using analog computations and Nyquist diagrams, respectively. Compared with pure NaNbO3 and SnO2 sensors, our easily prepared SnO2/NaNbO3 sensor demonstrates good sensing properties and holds great promise for use in humidity-sensing applications.
关键词： Humidity,SnO2,Urchin-like structure,NaNbO3,Hydrothermal method
更新于2025-09-19 17:15:36
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Enhanced photoelectrochemical performance of NaNbO3 nanofibers photoanode coupled with visible-light active g-C3N4 nanosheets for water splitting
摘要： Sodium niobate nanofibers (NaNbO3-NF) have been synthesized by hydrothermal technique and further coupled with visible light responsive graphitic carbon nitride (g-C3N4) nanosheets in the different concentration ratio of 2:1 (2-CN), 4:1 (4-CN) and 8:1 (8-CN). A significant improvement in the photoelectrochemical (PEC) performance of g-C3N4/NaNbO3-NF (4-CN) nanostructured photoanode as compared to bare NaNbO3 photoanode is observed. A current density of 12.55 mA cm?2 at 1 V with respect to Ag/AgCl reference electrode is achieved for g-C3N4/NaNbO3-NF (4-CN) photoanode which is ~3 times higher than the NaNbO3-NF photoanode. Also, as compared to NaNbO3-NF, g-C3N4/NaNbO3-NF (4-CN) nanocomposite photoanode showed ~3 times improvement in the incident photon-to-current conversion efficiency. The improvement in the PEC performance of visible light active g-C3N4/NaNbO3-NF (4-CN) nanocomposite is attributed to the improved photoresponse of NaNbO3-NF due to the coupling of g-C3N4 and formation of type-II heterojunction between them leading to the enhanced separation of the photogenerated charge carriers. A possible reaction mechanism for the improved photoelectrochemical water splitting performance has been proposed for g-C3N4/NaNbO3-NF (4-CN) photoanode.
关键词： Photoelectrode,Nanocomposite,Heterojunction,g-C3N4/NaNbO3-NF,PEC Water Splitting
更新于2025-09-12 10:27:22
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Design and Comparative Studies of Z-Scheme and Type II Based Heterostructures of NaNbO <sub/>3</sub> /CuInS <sub/>2</sub> /In <sub/>2</sub> S <sub/>3</sub> for Efficient Photoelectrochemical Applications
摘要： Here, we report the fabrication of a new Z-scheme based core/shell/shell heterostructure of NaNbO3/CuInS2/In2S3 (core/shell/shell) for photoelectrochemical (PEC) water splitting and also for degradation of organic pollutants. We have also performed a comparative study with a modified heterostructure of NaNbO3/In2S3/CuInS2 having Type II band alignment. The PEC measurements under visible light irradiation show increased photocatalytic performance for the NaNbO3/CuInS2/In2S3 heterostructures as revealed by a high current density of ～6.72 mA/cm2 at ?1.0 V versus Ag/AgCl and low photocurrent onset potential of ～?110 mV in comparison to the Type II system (～1.63 mA/cm2 and ?180 mV vs Ag/AgCl). Mott?Schottky plots confirmed the n?p?n type heterojunction formation in the NaNbO3/CuInS2/In2S3 heterostructure which reduces the charge carrier recombination (revealed by PL intensity and short lifetime). The Z-scheme based system also exhibits excellent degradation efficiency (～99.6%) of organic pollutants. This work shows that the Z-scheme charge separation mechanism in NaNbO3/CuInS2/In2S3 nanostructures is more efficient than the Type II based on NaNbO3/In2S3/CuInS2.
关键词： core/shell/shell heterostructure,photoelectrochemical water splitting,Type II band alignment,organic pollutants degradation,Z-scheme,NaNbO3/CuInS2/In2S3
更新于2025-09-09 09:28:46