Microscopic Mechanism of the Large Electrocaloric Effect in Vinylidene Difluoride-Based Polymers

2021 ◽  
Author(s):  
Vadim I. Sultanov ◽  
Vadim V. Atrazhev ◽  
Dmitry V. Dmitriev ◽  
Nikolay S. Erikhman ◽  
David U. Furrer ◽  
...  
Keyword(s):  
Electrocaloric Effect ◽  
Microscopic Mechanism ◽  
Vinylidene Difluoride

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

scholarly journals The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the Associated Microscopic Mechanism

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1809
Author(s):  
Yongpeng Nie ◽  
Wankui Ni ◽  
Xiangning Li ◽  
Haiman Wang ◽  
Kangze Yuan ◽  
...  
Keyword(s):  
Filter Paper ◽  
Pore Diameter ◽  
Matric Suction ◽  
Microscopic Mechanism ◽  
Suction Stress ◽  
Dominant Soil ◽  
Before And After ◽  
Soil Pores ◽  
Paper Method ◽  
Compacted Loess

To better understand and analyze the unsaturated stability of loess filling body, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the SWCC of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the SEM and NMR. The results showed that the drying-wetting cycles had an important influence on the SSCC and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be well explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess’s SSCC, but it increased the porosity and the dominant pore diameter of loess, and reduced the suction stress under the same matric suction. The main significant change in suction stress with matric suction occurred within the range of the dominant soil pores. The larger the dominant pore diameter, the smaller the suction stress under the same matric suction. In addition, this study proposes a new method for calculating suction stress based on the PSD parameters.

Adjustable negative electrocaloric effect in Pb1+xZrO3 thin films

2021 ◽  
Author(s):  
Yi Ye ◽  
Fengzhen Huang ◽  
Lin Lei ◽  
Lin Liu ◽  
Shuo Yan ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrocaloric Effect

scholarly journals Gate Control of Superconductivity in Mesoscopic All-Metallic Devices

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1243
Author(s):  
Claudio Puglia ◽  
Giorgio De Simoni ◽  
Francesco Giazotto
Keyword(s):  
Probability Distributions ◽  
Superconducting Properties ◽  
Microscopic Mechanism ◽  
Technological Potential ◽  
Half Wave ◽  
Thermal Origin ◽  
Gate Control ◽  
Titanium Wire ◽  
Field Emission Of Electrons ◽  
Gating Effect

The possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen–Cooper–Schrieffer metals was recently demonstrated. Despite the extensive experimental evidence obtained on different materials and geometries, a description of the microscopic mechanism at the basis of such an unconventional effect has not been provided yet. This work discusses the technological potential of gate control of superconductivity in metallic superconductors and revises the experimental results, which provide information regarding a possible thermal origin of the effect: first, we review experiments performed on high-critical-temperature elemental superconductors (niobium and vanadium) and show how devices based on these materials can be exploited to realize basic electronic tools, such as a half-wave rectifier. Second, we discuss the origin of the gating effect by showing gate-driven suppression of the supercurrent in a suspended titanium wire and by providing a comparison between thermal and electric switching current probability distributions. Furthermore, we discuss the cold field-emission of electrons from the gate employing finite element simulations and compare the results with experimental data. In our view, the presented data provide a strong indication regarding the unlikelihood of the thermal origin of the gating effect.

scholarly journals A unified perturbative approach to electrocaloric effects

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Mónica Graf ◽  
Jorge Íñiguez
Keyword(s):  
External Field ◽  
Taylor Series ◽  
Physical Interpretation ◽  
Applied Field ◽  
Atomistic Simulations ◽  
Small Field ◽  
Electrocaloric Effect ◽  
Perturbative Approach ◽  
Similarities And Differences ◽  
Straightforward Interpretation

AbstractThe electrocaloric effect, that is, the temperature change experienced by an insulator upon application of an electric field, offers promising ecofriendly alternatives to refrigeration. However, the theoretical treatments of this response are mostly case specific and lack a unified picture revealing the similarities and differences among the various known effects. Here, we show that the electrocaloric effect lends itself to a straightforward interpretation when expressed as a Taylor series in the external field. Our formalism explains in a unified and simple way the most notable small-field effects reported in the literature, namely the so-called normal and inverse electrocaloric responses, corresponding to an increase or decrease of temperature under applied field, as usually found in ferroelectrics or antiferroelectrics, respectively. This helps us to clarify their physical interpretation. We then discuss in detail atomistic simulations for the prototype ferroelectric PbTiO3, explicitly evaluating subtle predictions of the theory, such as the occurrence of competing contributions to the electrocaloric response.

Room‐Temperature Symmetric Giant Positive and Negative Electrocaloric Effect in PbMg 0.5 W 0.5 O 3 Antiferroelectric Ceramic

2021 ◽  
pp. 2101176
Author(s):  
Junjie Li ◽  
Hong‐Hui Wu ◽  
Jianting Li ◽  
Xiaopo Su ◽  
Ruowei Yin ◽  
...  
Keyword(s):  
Room Temperature ◽  
Electrocaloric Effect
Sign in / Sign up

Export Citation Format

Share Document