Electrocaloric effects (ECE) in solid state materials, such as ferroelectric ceramics and ferroelectric polymers, have a great impact in developing cooling systems. Herein, we describe the ECE of a newly synthesized ferroelectric nematic liquid crystal compound at the isotropic-ferroelectric nematic (I-N) phase transition. While the Joule heat completely suppressed the ECE in a DC field, in an AC field with < 1.2 V μm and ≥ 40 Hz, an increase in optical transmittance was observed, which in comparison with a zero-field transmittance temperature plot indicated a shift in the transition temperature. These findings implied that one can induce the desired phase transition using an electric field ECE with an EC responsivity of ∼1.7 × 10 km V. Notably, the required electric field was two orders of magnitude smaller than the typical fields for other EC materials. EC effects observed under such low fields is a unique property of ferroelectric nematic liquid crystals. Furthermore, the specific EC energy could be increased considerably by reducing the ionic content, thus suppressing the Joule heat.
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http://dx.doi.org/10.1039/d4sm00979g | DOI Listing |
ChemSusChem
December 2024
North China Electric Power University, College of Environmental Science and Engineering, CHINA.
Although Pb-based metal halide perovskites (MHPs) have excellent photoelectric characteristics, their toxicity remains a limiting factor for their widespread application. In the paper, a series of CsCuClxBr3-x (x = 1, 2, 3) MHP microcrystals were developed and their hydrogen evolution performance in ethanol and HX (X = Cl, Br) was also studied. Among them, CsCuCl3 microcrystals exhibit high hydrogen evolution performance in both HX and ethanol, attributed to their longest average lifetime and suitable band structure.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
TU Berlin University: Technische Universitat Berlin, Fachbereich Keramische Werkstoffe, Hardenbergstr. 40, 10623, Berlin, GERMANY.
Carbon dioxide hydrogenation to methanol is a key chemical reaction to store energy in chemical bonds, using carbon dioxide as an energy sink. Indium oxide is amongst the most promising candidates for replacing the copper and zinc oxide catalyst, which is industrially applied for syngas mixtures but less idoneous for educts with carbon dioxide due to instability reasons. The polymorph of indium oxide and the operating conditions remain to be optimized for optimal and stable performance.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Ultrafast photoexcitation offers a novel approach to manipulating quantum materials. One of the long-standing goals in this field is to achieve optical control over topological properties. However, the impact on their electronic structures, which host gapless surface states, has yet to be directly observed.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Department of Physics and Astronomy, and Smalley-Curl Institute, Rice University, Houston, Texas 77251-1892, USA.
The hybrid quantum system of cold atomic gas and optical cavity can host many exotic phenomena including phase transitions and multistabilities. In this Letter, we investigate the effect of photon hopping between two Dicke cavities and show rich quantum phases for steady states and dynamic processes. Starting from a generic dimer system where the two cavities are not necessarily identical, we analytically obtain all possible steady-state phases and confirm their existence by numerical calculations.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
The dynamics of open quantum systems can be simulated by unraveling it into an ensemble of pure state trajectories undergoing nonunitary monitored evolution, which has recently been shown to undergo measurement-induced entanglement phase transition. Here, we show that, for an arbitrary decoherence channel, one can optimize the unraveling scheme to lower the threshold for entanglement phase transition, thereby enabling efficient classical simulation of the open dynamics for a broader range of decoherence rates. Taking noisy random unitary circuits as a paradigmatic example, we analytically derive the optimum unraveling basis that on average minimizes the threshold.
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