| 1. |
- Schmidt, Falko, et al.
(författare)
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Dynamics of an active Nanoparticle in an optical trap
- 2021
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701.
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Konferensbidrag (refereegranskat)abstract
- We investigate a nanoparticle inside an optical trap and driven away from equilibrium by self-induced concentration gradients. We find that a nanoparticle performs fast orbital rotations and its probability density shifting away from equilibrium.
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| 2. |
- Schmidt, Falko, 1992, et al.
(författare)
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Non-equilibrium properties of an active nanoparticle in a harmonic potential
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 11926
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Tidskriftsartikel (refereegranskat)abstract
- Active particles break out of thermodynamic equilibrium thanks to their directed motion, which leads to complex and interesting behaviors in the presence of confining potentials. When dealing with active nanoparticles, however, the overwhelming presence of rotational diffusion hinders directed motion, leading to an increase of their effective temperature, but otherwise masking the effects of self-propulsion. Here, we demonstrate an experimental system where an active nanoparticle immersed in a critical solution and held in an optical harmonic potential features far-from-equilibrium behavior beyond an increase of its effective temperature. When increasing the laser power, we observe a cross-over from a Boltzmann distribution to a non-equilibrium state, where the particle performs fast orbital rotations about the beam axis. These findings are rationalized by solving the Fokker-Planck equation for the particle’s position and orientation in terms of a moment expansion. The proposed self-propulsion mechanism results from the particle’s non-sphericity and the lower critical point of the solution.
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| 3. |
- Sultana, Ayesha, et al.
(författare)
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The Origin of Thermal Gradient-Induced Voltage in Polyelectrolytes
- 2023
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Ingår i: Small. - : WILEY-V C H VERLAG GMBH. - 1613-6810 .- 1613-6829.
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Tidskriftsartikel (refereegranskat)abstract
- Ionic thermoelectric materials can generate large thermal voltages under temperature gradients while also being low-cost and environmentally friendly. Many electrolytes with large Seebeck coefficients are reported in recent years, however, the mechanism of the thermal voltage is remained elusive. In this work, three types of polyelectrolytes are studied with different cations and identified a significant contribution to their thermal voltage originating from a concentration gradient. This conclusion is based on studies of the loss and gain of water upon temperature changes, variations in conductivity with water content and temperature, and the voltages induced by changes in water content. The results are analyzed by the "hopping mode" dynamics of charge transport in electrolytes. The hydration of different cations influences the water concentration gradient, which affects the barrier height and ion-induced potential in the electrodes. This work shows that the hydro-voltage in ionic thermoelectric devices can be one order of magnitude larger than the contribution from thermodiffusion-induced potentials, and becomes the main contributor to energy harvesting when implemented into ionic thermoelectric supercapacitors. Together with the rationalized theoretical discussion, this work clarifies the mechanism of thermal voltages in electrolytes and provides a new path for the development of ionic thermoelectric materials. The thermal voltage of polyelectrolyte films largely depends on the water concentration gradient under a temperature difference, which can be optimized to promote the generated total voltage up to over 30 mV K-1.image
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| 4. |
- Zhao, Dan, et al.
(författare)
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Ionic thermoelectric materials and devices
- 2021
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Ingår i: Journal of Energy Challenges and Mechanics. - : ELSEVIER. - 2056-9386. ; 61, s. 88-103
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Forskningsöversikt (refereegranskat)abstract
- The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity. The main challenge in practical applications for thermoelectrics is the high cost from both materials and manufacturing. Recently, breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature gradient. The charging voltage is internally from the ionic Seebeck effect of the electrolyte between two electrodes. Hence electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric materials. Most ionic thermoelectric materials are composed of abundant elements, and they can generate hundreds of times larger thermal voltage than that of electronic materials. This emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices, and triggers a renewed interest for ionic thermodiffusion. In this review, we summarize the state of the art in the new field of ionic thermoelectrics, from the driving force of the ionic thermodiffusion to material and application developments. We present a general map of ionic thermoelectric materials, discuss the unique characters of each type of the reported electrolytes, and propose potential optimization and future topics of ionic thermoelectrics. (c) 2021 The Authors. Published by ELSEVIER B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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