Icing temperature measurements of water on pyroelectric single crystals: Impact of experimental methods on the degree of supercooling

Goldberg, P.Y.; Apelt, Sabine; Spitzner, Dirk; Boucher, R.; Mehner, Erik; Stöcker, Hartmut; Meyer, Dirk C.; Benke, Annegret; Bergmann, Ute

doi:10.1016/j.coldregions.2018.02.008

Cited by 10 publications

(4 citation statements)

References 90 publications

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“…Goldberg et al reported a similar elevation of the icing temperature of SCW at the positively charged surfaces of the following pyroelectric crystals: LiNbO 3 , SrBaNbO 3 , and LiTaO 3. However, they measured smaller differences in the icing temperatures between the positively and the negatively charged faces in comparison to our results reported on the LiTaO 3 crystals. After our recent finding that the icing temperature of SCW is triggered by atmospheric CO 2 (see below), it is suggested that those differences might arise as a result of different environmental conditions present in the two laboratories.…”

Section: Introductionmentioning

confidence: 99%

Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces

et al. 2022

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Conspectus The ability to control the icing temperature of supercooled water (SCW) is of supreme importance in subfields of pure and applied sciences. The ice freezing of SCW can be influenced heterogeneously by electric effects, a process known as electrofreezing. This effect was first discovered during the 19th century; however, its mechanism is still under debate. In this Account we demonstrate, by capitalizing on the properties of polar crystals, that heterogeneous electrofreezing of SCW is a chemical process influenced by an electric field and specific ions. Polar crystals possess a net dipole moment. In addition, they are pyroelectric, displaying short-lived surface charges at their hemihedral faces at the two poles of the crystals as a result of temperature changes. Accordingly, during cooling or heating, an electric field is created, which is negated by the attraction of compensating charges from the environment. This process had an impact in the following experiments. The icing temperatures of SCW within crevices of polar crystals are higher in comparison to icing temperatures within crevices of nonpolar analogs. The role played by the electric effect was extricated from other effects by the performance of icing experiments on the surfaces of pyroelectric quasi-amorphous SrTiO 3 . During those studies it was found that on positively charged surfaces the icing temperature of SCW is elevated, whereas on negatively charged surfaces it is reduced. Following investigations discovered that the icing temperature of SCW is impacted by an ionic current created within a hydrated layer on top of hydrophilic faces residing parallel to the polar axes of the crystals. In the absence of such current on analogous hydrophobic surfaces, the pyroelectric effect does not influence the icing temperature of SCW. Those results implied that electrofreezing of SCW is a process influenced by specific compensating ions attracted by the pyroelectric field from the aqueous solution. When freezing experiments are performed in an open atmosphere, bicarbonate and hydronium ions, created by the dissolution of atmospheric CO 2 in water, influence the icing temperature. The bicarbonate ions, when attracted by positively charged pyroelectric surfaces, elevate the icing temperature, whereas their counterparts, hydronium ions, when attracted by the negatively charged surfaces reduce the icing temperature. Molecular dynamic simulations suggested that bicarbonate ions, concentrated within the near positively charged interfacial layer, self-assemble with water molecules to create stabilized slightly distorted “ice-like” hexagonal assemblies which mimic the hexagons of the crystals of ice. This occurs by replacing, within those ice-like hexagons, two hydrogen bonds of water by C–O bonds of the HCO 3 – ion. On the basis of these simulations, it was predicted and experimentally confirmed that other trigonal planar ions such as NO 3 ...

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Section: Introductionmentioning

confidence: 99%

Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces

et al. 2022

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“…IRRAS, gracing incidence infrared reflection absorption spectroscopy; MEK, butan-2-one; n, number of independent droplets; PMMA, polymethylmethacrylate; P(VDF-TrFE), poly(vinylidene fluoride-co-trifluoroethylene); P s , spontaneous polarisation; p, pyroelectric coefficient; R a , arithmetic average of the roughness profile; SC, spin-coating; T, temperature; T c , Curie temperature; T m , melting temperature; THF, tetrahydrofuran; 2D-GIWAXS, two-dimensional gracing incidence wide angle X-ray spectroscopy face chemistry. 1,2 Using P(VDF-TrFE) thin films as active materials in aqueous environments is expected to enable new applications, such as passive anti-ice surfaces, [3][4][5] pyrocatalytic materials, 6 and materials affecting cell proliferation. 7 The surface charge generated by the pyroelectric effect during a temperature change might postpone the freezing of water droplets on technical surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…It is assumed that the surface charges generated due to the combination of the pyroelectric effect and a temperature change can influence processes in the electrochemical double layer (EDL) (Figure 1) and, therefore, result in thermally switchable surface chemistry 1,2 . Using P(VDF‐TrFE) thin films as active materials in aqueous environments is expected to enable new applications, such as passive anti‐ice surfaces, 3–5 pyrocatalytic materials, 6 and materials affecting cell proliferation 7 . The surface charge generated by the pyroelectric effect during a temperature change might postpone the freezing of water droplets on technical surfaces.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous freezing on pyroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) thin films

Apelt

Höhne

Uhlmann

et al. 2020

Surface & Interface Analysis

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Active deicing of technical surfaces, such as for wind turbines and heat exchangers, currently requires the usage of heat or chemicals. Passive coating strategies that postpone the freezing of covering water would be beneficial in order to save costs and energy. One hypothesis is that pyroelectric active materials can achieve this because of the surface charges generated on these materials when they are subject to a temperature change. High-quality poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) thin films with a high crystallinity, prefererd edge-on orientation, low surface roughness, and comprised of the-analogous ferroelectric phase were deposited by spin-coating. Freezing experiments with a cooling rate of 1 K min −1 were made on P(VDF-TrFE) coatings in order to separate the effect of different parameters such as the poling direction, film thickness, used solvent, deposition process, underlying substrate, and annealing temperature on the achievable supercooling. The topography and the underlying substrate significantly changed the distribution of freezing temperatures of water droplets in contact with these thin films. In contrast, no significant effect of the thickness, morphology, or pyroelectric effect of the as-prepared domain-state on the freezing temperatures was found.

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“…Despite comprehensive investigations during the years, the mechanism of this electrofreezing is still under debate. Some reports deny the existence of the effect, , whereas others maintain that electric fields can either reduce or elevate the icing temperature of SCW. − In order to gain additional insight into the electrofreezing mechanism, in particular, to disentangle electric and geometric effects, we capitalized on the unique properties of polar crystals. − Such crystals exhibit pyroelectricity, the derivative of the spontaneous polarization with temperature, and develop positive and negative charges at opposite hemihedral surfaces during a temperature change.…”

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confidence: 99%

Biguanide, an Efficient Electrofreezing “Ice-maker” Ion of Supercooled Water

Javitt

Weissbuch

Ehre

et al. 2021

Crystal Growth & Design

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Following our previous investigations on the electrofreezing mechanism of supercooled water on pyroelectric crystal surfaces, we discovered that electrofreezing is a process involving the attraction and arrangement of specific ionic charges by an electric field. We found two classes of ions: the trigonal planar ions that raise the icing temperature, or “ice-makers”, and ions of different structures that reduce the icing temperature, or “ice-breakers”. In the search for more efficient promoters for electrofreezing, we anticipated that molecules that have the propensity to self-assemble with water to form hexagonal clusters might be better ice nucleators. Through icing experiments performed directly on the hemihedral faces of pyroelectric crystals of LiTaO3, we found that ions of biguanide elevate the icing temperature of supercooled water when concentrated near the negatively charged crystal’s interfacial water layer, either upon cooling or upon heating. On the other hand, the analogous guanylurea ions, which presumably assume configurations with deviations from planarity, operate as “ice-breakers”.

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Icing temperature measurements of water on pyroelectric single crystals: Impact of experimental methods on the degree of supercooling

Cited by 10 publications

References 90 publications

Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces

Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces

Heterogeneous freezing on pyroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) thin films

Biguanide, an Efficient Electrofreezing “Ice-maker” Ion of Supercooled Water

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