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Structural Differences of BaTiO3 Ceramics Modified by Ultrasonic and Mechanochemical Methods
摘要： Barium titanate powders were synthesized by the modified solid-state method with ultrasonic (5 min) and mechanochemical (12 h) deagglomeration methods. The structure of the samples was verified using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). Scanning electron microscopy (SEM) analysis of the powders showed that using ultrasonic deagglomeration significantly decreased the particle size with perfect homogeneity in the shortest time. The particle size of the powders was calculated as 44.7 nm and 80.4 nm for ultrasonic and mechanochemical deagglomeration, respectively. The sintered pellet by ultrasonic method had no abnormal grain growth, and the grain sizes were between 10 and 30 μm. The pellet by mechanochemical method had an abnormal grain growth, and the grain sizes were between 10 and 100 μm. The results showed that ultrasonication remarkably improved the structure of the samples in the shortest time.
关键词： deagglomeration,grain size,milling,ultrasonication,BaTiO3
更新于2025-09-10 09:29:36
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Large-scale uniform fabrication and morphology control of ultrafine perovskite nanocrystals
摘要： Nanomaterials are playing more and more important roles in modern industry, while the large-scale fabrication and dispersibility still need to be addressed. This report explores the uniform fabrication and morphology control of ultrafine BaTiO3 (BT) nanocrystals using a "TEG-sol" method. By varying the reactant concentration, the obtained product sols, Ba/Ti ratios, structure and morphology of the nanocrystals are investigated. The results reveal that under low concentrations (0.4 - 0.8 mol/L), transparent sols with uniform BT nanocrystals are obtained. Increasing the concentration to higher than 1.0 mol/L, BT precipitates with abnormal large crystals are obtained. Moreover, the Ba/Ti ratio variation further reveals that the surface organics are critical to the control of crystal size and morphology. This investigation is potential to be extended to the synthesis of various perovskite nanocrystals.
关键词： morphology control,Nanomaterials,BaTiO3,TEG-sol method,perovskite nanocrystals
更新于2025-09-10 09:29:36
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Meso-kinetics of one time relaxation electrical processes in BaTiO <sub/>3</sub> ceramics—modified Boltzmann-Poisson model
摘要： This paper is focused on the research an improved version of the Boltzmann-Poisson model for BaTiO3-ceramics. In the approximation of one relaxation time, for constant external electrical field, this approach included correct quadratic relation for varistor effect in the case of the Heywang model. Within meso-kinetics, quantum corrected Boltzmann-Poisson model, contains space-time correlations for the probability distribution density function f(r, k, t), fractional relaxation velocity description. These new results corresponds to our other research based on electronic particles Brownian motion within its fractal nature.
关键词： Brownian motion,BaTiO3-ceramics,fractals,Heywang model,Boltzmann-Poisson model,dielectrics
更新于2025-09-10 09:29:36
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Resistive switching effect enhanced by light irradiation in C/BaTiO <sub/>3</sub> /C memory structure
摘要： The Ta/[C/BaTiO3/C]/Si device was obtained. The resistive switching (RS) behaviors of the Ta/[C/BaTiO3/C]/Si device are studied in the dark and under white-light illumination with various power densities. The results show that the device displays bipolar RS effect, which can be modulated by the white light. And the RS memory device shows biggish resistance ratio, which is more than 105 under white-light irradiation with a power density of 40 mW/cm2, and the ratio can stabilize at nearly 71 cycles. This work is helpful for the optical control non-volatile memory.
关键词： C/BaTiO3/C,memory device,Resistive switching,white light
更新于2025-09-10 09:29:36
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A Comparative Analysis of BaTiO3/(Ba,Sr)TiO3 and BaTiO3/(Ba,Sr)TiO3/SrTiO3 Artificial Superlattices via Raman Spectroscopy
摘要： BaTiO3/Ba50Sr50TiO3 and BaTiO3/Ba50Sr50TiO3/SrTiO3 superlattices are characterized via Raman spectroscopy. Special attention is paid to a comprehensive analysis of their polarized Raman spectra, especially, within a soft mode (E(1TO)) range. The shift of E(1TO) soft mode is found to be more pronounced for BaTiO3/Ba50Sr50TiO3/SrTiO3 sample than for BaTiO3/Ba50Sr50TiO3, presumably owing to stronger 2D compression of BT layers and abruptly increased temperature of transition from ferroelectric to paraelectric phase.
关键词： BaTiO3/Ba50Sr50TiO3/SrTiO3 ferroelectric superlattices,Raman spectroscopy,soft mode,strain,BaTiO3/Ba50Sr50TiO3
更新于2025-09-09 09:28:46
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Magnetoelectric effect in self-bias gradient structure CoFe <sub/>2</sub> O <sub/>4</sub> /Ni/BaTiO <sub/>3</sub> with 0-3 connectivity
摘要： The paper is devoted to the study of mechanism of internal magnetic fields occurrence in the magnetostrictive-piezoelectric gradient structure CoFe2O4/Ni/BaTiO3. The insertions of CoFe2O4 and Ni in this gradient structure in the matrix BaTiO3 is located. The connectivity type of this composite is 0-3 and a modified model of the cell in the form of a parallelepiped is used. This parallelepiped consists of two cubic cells of BaTiO3 matrix. One cubic cell contains of CoFe2O4 insertion and another cell contains of Ni one. The corresponding magnetic circuit by using the magnetostatics equations was considered. Internal magnetic fields which arise in sublattices of CoFe2O4 and Ni, taking into account the known parameters of their magnetization curves were found and equal of 860 Oe and of 50 Oe for CoFe2O4 and Ni, respectively. Further, the pseudo-piezomagnetic constants that correspond to the resulting internal magnetic fields were found by using of the existing dependencies of the pseudo-piezomagnetic coefficients of CoFe2O4 and Ni on the bias magnetic field. The effective parameters of the structure in the form of a parallelepiped was found.
关键词： internal magnetic fields,CoFe2O4/Ni/BaTiO3,magnetoelectric effect,gradient structure,0-3 connectivity
更新于2025-09-09 09:28:46
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Influence of Ba/Ti ratio on PTCR effect of Bam(Ti1?xNbx)O <sub/>3</sub> ceramics prepared by the reduction sintering-reoxidation method
摘要： In this work, we investigate the influences of Ba/Ti ratio and sintering conditions on the characteristics of positive temperature coefficient of resistance (PTCR) and electrical properties of Bam(Ti1?xNbx)O3 (BTN) ceramics. The ceramics were fired at 1190?C for 0.5–6.0 h in a reducing atmosphere and then reoxidized at 600–650?C for 0–8 h. The Ba/Ti ratio (m) affected the electrical properties and PTCR effect of the BTN specimens. The room-temperature (RT) resistance of the BTN samples initially decreased (0.994 < m < 1.006) and then increased (1.006 < m < 1.018) as the Ba/Ti ratio increased. Moreover, BTN ceramics exhibit a pronounced PTCR effect, with a resistance jump greater by 3.0 orders of magnitude and a low 0.1 ? RT resistance at a low reoxidation temperature of 600?C after sintering under a reducing atmosphere. Furthermore, the average sample grain size increased along with the Ba/Ti ratio. In addition, the influence of the sintering time and the reoxidation time on the electrical properties and the PTCR effect were also investigated.
关键词： PTC effect,Nb2O5-dopant,Ba/Ti ratio,BaTiO3
更新于2025-09-09 09:28:46
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1D Piezoelectric BaTiO3 Polycrystal of Topochemical Mesocrystal Conversion from Layered H2Ti4O9?H2O Single Crystal
摘要： A 1D piezoelectric BaTiO3 (BT) polycrystal with a tetragonal system was controllably prepared using a one-step hydrothermal soft chemical process. A layered H2Ti4O9·H2O (HTO) single crystal was used as the precursor. Interestingly, the obtained polycrystalline BT constructed from oriented BT nanoparticles shows a set of single-crystalline diffraction points, implying that the BT polycrystal is a mesocrystal. The [010] and [001] directions of the obtained mesocrystalline BT correspond to the [001] and [010] directions of the original HTO crystal, respectively, and the [010] direction of the mesocrystalline BT corresponds to the direction along the length of a 1D rod matrix. An in situ topochemical mesocrystal conversion of mesocrystalline BT grown on the HTO substrate occurred not only on the substrate surface but also in the interlayers owing to the unique TiO6 octahedral layers of HTO. In addition, the piezoelectric response of 1D mesocrystal was captured for the first time. The piezoelectric property of BT mesocrystals hinges on its nanostructure. It is a challenge to develop a special process to prepare highly 1D anisotropic perovskite titanate polycrystals with high crystallinity and piezoelectric response. This novel strategy can be utilized to develop piezoelectric mesocrystalline materials.
关键词： layered H2Ti4O9·H2O single crystal,1D piezoelectric BaTiO3,piezoelectric response,hydrothermal soft chemical process,topochemical mesocrystal conversion
更新于2025-09-09 09:28:46
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Asymmetric Resistive Switching Dynamics in BaTiO <sub/>3</sub> Tunnel Junctions
摘要： The resistive switching associated with polarization reversal is studied in detail in ferroelectric BaTiO3 tunnel junctions, with focus on the dynamics of the ferroelectric domain switching. It is observed that the transition between the high-resistance state (HRS) and the low-resistance state (LRS) is largely asymmetric being smooth from LRS to HRS, but proceeds via avalanches in the HRS-to-LRS transitions. It is shown that this distinct behavior is related to the presence of an imprint field in the junction and has important consequences on the junction’s performance.
关键词： ferroelectric tunnel junctions,ferroelectric dynamics,neuromorphic computing,BaTiO3 films,memristors
更新于2025-09-09 09:28:46
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Influence of Sm and Nb on the structural, electric, magnetic and magneto-electric properties of BaTiO3-Li0.5Fe2.5O4 composite ceramics grown by the conventional solid state technique
摘要： The Sm and Nb doped BaTiO3-Li0.5Fe2.5O4 composite ceramics having chemical formulae (90)BaTi(1?2x)NbxSmxO3 + (10) Li0.5Fe2.5O4 (x = 0, 0.05 and 0.1) were synthesized using conventional solid state technique. The structural, morphological, magnetic, dielectric, ferroelectric and magneto-electric properties of composites have been studied. The XRD measurement reveals the absence of peaks pertaining to impurities and strongly confirms the high crystalline nature of all the composites. From FESEM images, the average grain size of composites increases with increase in the concentration of Nb and Sm. The VSM studies confirm the soft magnetic nature of all the composites. The dielectric measurements confirm the increase in the transition temperature (Tc) of the BTL composite with an increase in the concentration of Nb and Sm. The P–E studies confirm that the ferroelectric nature of the BTL composite softens after doping Nb and Sm in it. The ME voltage coefficient value confirms the uniform growth of grains in all the composites and reveals a strong interaction between ferroelectric and magnetic orders.
关键词： magneto-electric properties,BaTiO3-Li0.5Fe2.5O4,electric properties,magnetic properties,composite ceramics,Sm and Nb doping,structural properties
更新于2025-09-09 09:28:46