Fig 31 - uploaded by Konstantin Astafiev
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Dielectric constant of ferroelectric-dielectric composite material as a function of weight concentration of the dielectric inclusions in the mixture for (a)—Ba 0.45 Sr 0.55 TiO 3 /oxide, (b)—Ba 0.50 Sr 0.50 TiO 3 /oxide, (c)—Ba 0.55 Sr 0.45 TiO 3 /oxide, (d)—Ba 0.60 Sr 0.40 TiO 3 /oxide material compositions. The black triangles are the experimental data, and the solid curves correspond to Eq. (3.24a) ε mix (q) = ε f (1 − 3 2 q) with recalculated values of the concentration of dielectric inclusions q from the volume values into the percents by weight Wt(%). RT data.
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![Fig. 2. Sketch of ferroelectric lens antenna [18].](profile/Konstantin-Astafiev/publication/37437677/figure/fig43/AS:668543246934018@1536404539183/Sketch-of-ferroelectric-lens-antenna-18_Q320.jpg)
A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured pro...
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The temperature dependences of the dielectric permittivity and dielectric loss tangent in the ferroelectric ceramic Ba0.8Sr0.2TiO3 have been studied at frequencies from 25 Hz to 120 Hz. It was found that the phase transition at the Curie point (ТС ≈ 338 K) is diffused in the temperature range of ∼ 30 K. The temperature dependence of the local order...
Citations
... Ion doping is a well-established approach for decreasing T c over a wide temperature range. In the case of pyroelectric materials, strontium-doped barium titanate Ba 1− x Sr x TiO 3 (SBT) has garnered significant attention for this purpose [160,161]. The best pyroelectric signal is observed at a Sr content of x = 0.30 [162]. ...
The focus on sustainable energy sources is intensifying as they present a viable alternative to conventional fossil fuels. The emergence of clean and renewable hydrogen fuel marks a significant technological shift toward decarbonizing the environment. Harnessing mechanical and thermal energy through piezoelectric and pyro-electric catalysis has emerged as an effective strategy for producing hydrogen and contributing to reducing dependence on carbon-based fuels. In this regard, this review presents recent advances in piezoelectric and pyroelectric catalysis induced by mechanical and thermal excitations, respectively, towards hydrogen generation via the water splitting process. A thorough description of the fundamental principles underlying the piezoelectric and pyroelectric effects is provided, complemented by an analysis of the catalytic processes induced by these effects. Subsequently, these effects are examined to propose the prerequisites needed for such catalysts to achieve water splitting reaction and hydrogen generation. Special attention is devoted to identifying the various strategies adopted to enhance hydrogen production in order to provide new paths for increased efficiency.
... Because of their superior piezoelectric, pyroelectric, electro-optic, and dielectric features, piezoceramics materials have extensive applications in electronics, optics, sensors, and actuators [1][2][3][4]. Most piezoelectric devices available today contain high levels of lead due to its high performance and unique crystal chemistry of Pb 2+ ion. ...
Barium titanate (BaTiO3) is a potential material for producing lead-free piezoceramics-based electronic devices. Microstructural engineering improves ceramic materials’ dielectric, ferroelectric, and piezoelectric characteristics. This research aims to investigate the impacts of the sintering process and Ca²⁺ substitution on microstructure and electromechanical performance of the Ba0.46Sr0.54TiO3 (BST) and Ba0.46Sr0.27Ca0.27TiO3 (BSCT) samples. The Ba0.46Sr0.54TiO3 and Ba0.46Sr0.27Ca0.27TiO3 powders were synthesized using a solid-state reaction technique. X-ray diffraction indicated the presence of tetragonal and cubic phases in a single-phase powder. The sintering condition influences grain size and density; as the sintering temperature rises, grain size reduces and density increases. We measured grain sizes in the range of 0.89 to 2.14 µm, and densities between 82% and 93.5% of the theoretical density, along with dielectric constants between ~ 250 and ~ 6000 at 5 kHz. A relation between grain sizes, dielectric constants, and polarization behaviors in response to temperature and electric field were all evaluated. The giant impact was observed in by the inclusion of Ca²⁺ in recoverable energy densities and efficiency from 1.21 J/cm³ (BST@1250 °C at 20 kV/cm) to 1.76 J/cm³ (BSCT@1250 °C at 20 kV/cm) and 21.48 to 51.50 %, respectively, in prepared piezoceramics.
... The most interesting materials for tunable ferroelectric applications are the paraelectric phases of displacive ferroelectrics (or incipient ferroelectrics) due to their high values of dielectric permittivity and tunability even far above the Curie temperature, reduced sensitivity of the permittivity to temperature changes and the low loss level caused by the absence of ferroelectric domains [26]. The Curie point of BaxSr1−xTiO3 can be controlled by varying the amount of Sr substitution, and the material can be brought into the paraelectric phase at room temperature. ...
In the present paper, composite thin films of barium strontium titanate (BaxSr1−xTiO3) with an acceptor modifier (magnesium oxide—MgO) were deposited on metal substrates (stainless steel type) using the sol–gel method. The composite thin films feature BaxSr1−xTiO3 ferroelectric solid solution as the matrix and MgO linear dielectric as the reinforcement, with MgO concentrations ranging from 1 to 5 mol%. Following thermal treatment at 650 °C, the films were analyzed for their impedance response. Experimental impedance spectra were modeled using the Kohlrausch–Williams–Watts function, revealing stretching parameters (β) in the range of approximately 0.78 to 0.89 and 0.56 to 0.90 for impedance and electric modulus formalisms, respectively. Notably, films modified with 3 mol% MgO exhibited the least stretched relaxation function. Employing the electric equivalent circuit method for data analysis, the “circle fit” analysis demonstrated an increase in capacitance from 2.97 × 10−12 F to 5.78 × 10−10 F with the incorporation of 3 mol% MgO into BST-based thin films. Further analysis based on Voigt, Maxwell, and ladder circuits revealed trends in resistance and capacitance components with varying MgO contents, suggesting non-Debye-type relaxation phenomena across all tested samples.
... Dielectric materials exhibiting significant dielectric nonlinearity are increasingly explored for high-frequency tunable devices, including filters and phase shifters [1][2][3][4][5]. This nonlinearity is typically measured by the tunability (n), defined as: (1) where ε(0) and ε(E) represent the dielectric permittivity at zero bias electric field and under a specific field, respectively. ...
... Composite materials, formed by combining two or more components with distinct chemical compositions, structures, and physicochemical characteristics, are of significant scientific and practical interest [1][2][3][4]. These materials exhibit new properties that are not characteristic of individual phases, particularly in the ability to control electrophysical properties in the microwave range via an electric or magnetic field [5][6][7]. ...
... The barium hexaferrite nanoparticles corresponding to the formula BaFe 11.6 O 19±γ were synthesized by one-stage and two-stage precipitation from aqueous solutions. In a one-stage synthesis, a mixture of aqueous solutions of Fe(NO 3 ) 3 and BaCl 2 salts was precipitated with an aqueous ammonia solution at pH 9. In a two-stage synthesis, iron (III) hydroxide was first precipitated at pH 4-4.5, and then barium carbonate was precipitated on the pre-precipitated iron hydroxide using an ammonium carbonate solution as a precipitant at pH 9. The precipitates prepared by two methods were washed with distilled water until they were free of NO 3− and Cl − ions, dried in air at 291 K and in a drying cabinet at 353 K, and then calcined in a muffle furnace at 973 -1373 K for 2 h. ...
... After heat treatment at temperatures ≥ 1273 K, these precipitates form highly agglomerated crystalline particles (Fig. 1a) that are difficult to separate and use in practice. However, when precipitation is carried out in two stages, with iron hydroxide Fe(OH) 3 precipitated at pH ~ 4-4.5 in the first stage and barium carbonate BaCO 3 precipitated on the iron hydroxide precipitate at pH ~ 9 in the second stage, soft particles with sizes of 60-65 nm are formed after hightemperature treatment. These particles correspond to single domains (Fig. 1b) and do not require significant mechanical grinding. ...
... tunneling probability of the device with steep SS. CMOS compatible silicon-doped hafnium oxide material (Si:HfO2) is reported as a ferroelectric material for nanoscale devices [43]. Hence, Si:HfO2 is chosen as the ferroelectric material in the device architecture. ...
The self-heating effect of the silicon-on-insulator (SOI)-raised-buried-oxide (RBOX) ferroelectric tunnel field effect transistor is explored in this article. Proposed device reliability issues have been examined by activating the acceptor and donor uniform and Gaussian interface trap concentrations (ITCs). The proposed TFET is designed to diminish the ambipolar current, intensify on-state current and to improve subthreshold slope. The device performance for Analog/RF applicability is also tested by calculating the capacitances (Cgg–3.6 × 10⁻¹⁶ F/µm), transconductance in the order of 7.3 × 10⁻³S/µm, the cutoff frequency of 71 THz, and further transistor frequency product of 3.1 × 10¹⁵ Hz/V, transit time (1.4 × 10⁻¹⁵ s), and gain–bandwidth product of 12 THz are determined. All these parameter variations are investigated by changing the temperature and trap concentrations. The parameters have been compared with the room temperature and noticed an improved performance in terms of Analog/RF applicability. In addition, the introduction of the trap concentrations at the interfaces such as front gate oxide/silicon and the silicon/buried oxide is compared with no trap concentrations. It is proven that for Analog/RF applications, the proposed SOI-RBOX-ferroelectric-TFET exhibits the prominent behavior.
... The advantages of film FE materials for microwaves include low losses, fast dielectric response, low power consumption, high operating power, and low manufacturing cost. It is possible to implement electrically tunable capacitors, phase shifters, delay lines, and other microwave elements using the dielectric nonlinearity of ferroelectric thin films [3][4][5]. ...
... The only characteristic by which STO films were inferior to BST films was nonlinearity. The substitution of Sr by Ba in a solid solution led to an increase in the dielectric constant and, consequently, tunability [4,9,13,32]. ...
Thin films of strontium titanate, which have nonlinear properties that are promising for microwave applications, were grown on a polycrystalline aluminum oxide substrate using magnetron sputtering and high-temperature annealing. It was shown that the improvement of the film structure with an increase in the deposition temperature was clearly correlated with both an increase in nonlinearity and an improvement in the loss level. A capacitor based on an SrTiO3 film deposited at a deposition temperature of 900 °C and subjected to annealing demonstrated a tunability of 46% with a loss tangent of 0.009–0.014 at a frequency of 2 GHz. This was the first successful attempt to form a planar SrTiO3 capacitor on an alumina substrate, which exhibited a commutation quality factor of above 3000 in the microwave range.
... Ferroelectric materials exhibit a notable nonlinear behavior in their dielectric constant ε in response to an applied E 0 , which can be described by a parameter called tunability (n). 40 It is defined as the ratio of the dielectric constant when no E 0 is applied to its minimum dielectric constant when subjected to a nonzero E 0 , mathematically expressed as ...
... The ε (0) shows a turning point at about 150 • C, which is in line with the results previously reported by Liu et al. 13,14 and Cai et al. 22,41 In addition, the relative tunability (n r ) experiences an increase from 5.5% to 7.3%, followed by a decrease with increasing temperature, corresponding exactly to the general trend in ferroelectric materials that "the higher the dielectric constant of a material, the higher its tunability will be." 40 This trend can not only explain the increase in tunability observed in the current study but also explain why the tunability of Sr 3 Sn 2 O 7 ceramic is lower compared to BaTiO 3 or other perovskite materials. 19 Moreover, the presence of the small ε (0) unequivocally substantiates the genuineness of improper ferroelectricity. ...
The quasi‐two‐dimensional Ruddlesden–Popper material, Sr3Sn2O7 with hybrid improper ferroelectricity, has gained significant scientific interest owing to its unique ferroelectric phase transition mechanism. However, its electrical behaviors near the phase transition temperature necessitate further investigation. In this study, high‐quality Sr3Sn2O7 ceramic was successfully prepared, and its temperature‐dependent electrical properties were systematically studied. The phase transition from ferroelectric to paraelectric of Sr3Sn2O7 ceramic near 160°C was evidenced by the varying electrical properties dependence of temperature. It is found that the space‐charge‐limited bulk conduction with deep traps is identified as dominant conduction mechanism for Sr3Sn2O7 ceramic that has high resistivity. An abnormal increasing trend of coercive field with temperature was observed and is discussed with trap‐filling process and octahedral rotation distortion. Interestingly, Sr3Sn2O7 ceramic exhibits negative piezoelectric effect and negative electrostriction responded to biased electric field, which is dramatically influenced by ferroelectric polarization. Overall, this study serves as a reference for exploring the electrical properties of other hybrid improper ferroelectrics, particularly near their Curie temperature.
... Ferroelectric materials are a class of materials that exhibit a unique property known as ferroelectricity whereby the spontaneous electric polarization can be reversed by applying an external electric field [6]. Due to this versatility of ferroelectric materials, they are utilized in diverse fields such as energy storage, energyharvesting systems, actuators, sensors, ultrasound transducers, energy conversion, human health treatment, neuromorphic devices, etc. [7][8][9][10][11][12][13][14]. ...
Ferroelectric materials are known to possess multicatalytic abilities that are nowadays utilized for removing organic pollutants from water via piezocatalysis, photocatalysis, piezo-photocatalysis, and pyrocatalysis processes. The Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) ceramic is one such ferroelectric composition that has been extensively studied for electrical and electronic applications. Furthermore, the BCZTO ceramic has also shown remarkable multicatalytic performance in water-cleaning applications. The present review explores the potentiality of BCZTO for water-cleaning and bacterial-killing applications. It also highlights the fundamentals of ferroelectric ceramics, the importance of electric poling, and the principles underlying piezocatalysis, photocatalysis, and pyrocatalysis processes in addition to the multicatalytic capability of ferroelectric BCZTO ceramic.
... According to LG theory, the dielectric response for ferroelectric material can be expressed as a function of temperature [17,18]. As per this theory, the first two terms of Helmholtz free energy F can be expressed as the function of macroscopic polarization (P) as, ...
Power consumption of the device enhances as temperature rises, degrading the performance of conventional MOSFET. In the present paper the performance parameters of proposed (NC-FinFET) device has been found to be improved with the rise in temperature compared to baseline FinFET. The simulation is carried out in Sentaurus TCAD and several electrical characteristics are extracted. The results are explained on the basis of Landau theory, with the incorporation of 5 nm FE layer in the gate stack. Mathematical modeling of electrical parameters like drain current (Ids), threshold voltage (Vth), transconductance (gm) and subthreshold swing (SS) has been done to incorporate the effect of temperature considering the ferro and paraelectric phase. The said parameters have been investigated for temperature variations from 250 to 500 K, in ferroelectric and paraelectric phases that are distinguished through the Curie temperature (Tc = 460 ± 10 K). The Vth and SS show a non linear nature at T < Tc and linear behavior T > Tc. The transconductance shows peak value at Tc. Finally, the proposed NC-FINFET is utilized to realize an inverter. The proposed inverter design shows a better performance matrix interms of average propagation delay (tp) as compared to baseline Complementary FINFET inverter.
