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2. Synergetic boost of functional properties near critical end points in antiferroelectric systemsVida Jurečič, Lovro Fulanović, Jurij Koruza, Vid Bobnar, Nikola Novak, 2023, izvirni znanstveni članek Povzetek: The increase of the dielectric permittivity with an electric field and enhanced energy storage properties make antiferroelectrics very attractive for high-power electronic applications needed in emerging green energy technologies and neuromorphic computing platforms. Their exceptional functional properties are closely related to the electric field-induced antiferroelectric↔ferroelectric phase transition, which can be driven toward a critical end point by manipulation with an external electric field. The critical fluctuation of physical properties at the critical end point in ferroelectrics is a promising approach to improve their functional properties. Here, we demonstrate the existence of two critical end points in antiferroelectric ceramics with a ferroelectric-antiferroelectric-paraelectric phase sequence, using the model system Pb 0.99 Nb 0.02 [ ( Zr 0.57 Sn 0.43 ) 0.92 Ti 0.08 ] 0.98 O 3 . The critical fluctuation of the dielectric permittivity in the proximity of the antiferroelectric-to-paraelectric critical end point is responsible for the strong enhancement of the dielectric tunability (by a factor of > 2 ) measured at ≈ 395 K. The enhancement of the energy storage density at ≈ 370 K is related to the proximity of the ferroelectric-to-antiferroelectric critical end point. These findings open possibilities for material design and pave the way for the next generation of high-energy storage materials.
Ključne besede: electronic applications, high-power electronic, green energy, electric field
Objavljeno v DiRROS: 10.07.2024; Ogledov: 146; Prenosov: 96
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3. An experimental study of liquid micro-jets produced with a gas dynamic virtual nozzle under the influence of an electric fieldBor Zupan, Gisel Esperanza Peña-Murillo, Rizwan Zahoor, Jurij Gregorc, Božidar Šarler, Juraj Knoška, Alfonso M. Gañán-Calvo, Henry N. Chapman, Saša Bajt, 2023, izvirni znanstveni članek Povzetek: The results of an experimental study of micro-jets produced with a gas dynamic virtual nozzle (GDVN) under the influence of an electric field are provided and discussed for the first time. The experimental study is performed with a 50% volume mixture of water and ethanol, and nitrogen focusing gas. The liquid sample and gas Reynolds numbers range from 0.09–5.4 and 0–190, respectively. The external electrode was positioned 400–500 μm downstream of the nozzle tip and an effect of electric potential between the electrode and the sample liquid from 0–7 kV was investigated. The jetting parametric space is examined as a function of operating gas and liquid flow rates, outlet chamber pressure, and an external electric field. The experimentally observed jet diameter, length and velocity ranged from 1–25 μm, 50–500 μm and 0.5–10 m/s, respectively. The jetting shape snapshots were processed automatically using purposely developed computer vision software. The velocity of the jet was calculated from the measured jet diameter and the sample flow rate. It is found that micro-jets accelerate in the direction of the applied electric field in the downstream direction at a constant acceleration as opposed to the standard GDVNs. New jetting modes were observed, where either the focusing gas or the electric forces dominate, encouraging further theoretical and numerical studies towards optimized system design. The study shows the potential to unlock a new generation of low background sample delivery for serial diffraction measurements of weakly scattering objects.
Ključne besede: micro jet, electric field, experimental study, flow focusing, Taylor cone, gas dynamic virtual nozzles
Objavljeno v DiRROS: 07.02.2024; Ogledov: 480; Prenosov: 176
Celotno besedilo (1,94 MB)
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