Local Piezoelectric Properties of Doped Biomolecular Crystals

Piezoelectricity is the ability of certain crystals to generate mechanical strain proportional to an external electric field. Though many biomolecular crystals contain polar molecules, they are frequently centrosymmetric, signifying that the dipole moments of constituent molecules cancel each other. However, piezoelectricity can be induced by stereospecific doping leading to symme-try reduction. Here, we applied piezoresponse force microscopy (PFM), highly sensitive to local piezoelectricity, to characterize( 010) faces of a popular biomolecular material, α-glycine, doped with other amino acids such as L-alanine and L-threonine as well as co-doped with both. We show that, while apparent vertical piezoresponse is prone to parasitic electrostatic effects, shear piezoelectric activity is strongly affected by doping. Undoped α-glycine shows no shear piezoelectric response at all. The shear response of the L-alanine doped crystals is much larger than those of the L-threonine doped crystals and co-doped crystals. These observations are rationalized in terms of host–guest molecule interactions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported by the collaborative program of the Israeli Ministry of Science with the Russian Foundation for Basic Research (RFBR), grant № 3-16492, and directly by the RFBR (grant № 19-52-06004 MNTI_a). The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. A.K. acknowledges the Ministry of Science and Higher Education of the Russian Federation for the support under the project № 075-15-2021-588 from 1.06.2021. The work was also developed within the scope of the project CICECO at the Aveiro Institute of Materials, refs. UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. I.L. expresses his gratitude to the Estate of Olga Klein–Astrachan fund, grant № 721977

Piezoelectic properties of DL-alanine single crystals

The study was carried out using the equipment of UCSU "Modern Nanotechnology" UrFU with the financial support of the Government of the Russian Federation (Act 211, contract 02.A03.21.0006)

Surface piezoelectricity and pyroelectricity in centrosymmetric materials: A case of α-glycine

Surface pyroelectricity and piezoelectricity induced by water incorporation during growth in α-glycine were investigated. Using the periodic temperature change technique, we have determined the thickness (~280 µm) of the near surface layer (NSL) and its pyroelectric coefficient (160 pC/(K × cm2) at 23◦C) independently. The thickness of NSL remains nearly constant till 60◦C and the pyroelectric effect vanishes abruptly by 70◦C. The piezoelectric effect, 0.1 pm/V at 23◦C measured with an interferometer, followed the same temperature dependence as the pyroelectric effect. Abrupt disappearance of both effects at 70◦C is irreversible and suggests that water incorporation to α-glycine forms a well defined near surface phase, which is different form α-glycine because it is polar but it too close to α-glycine to be distinguished by X-ray diffraction (XRD). The secondary pyroelectric effect was found to be <14% of the total, which is unexpectedly small for a material with a large thermal expansion coefficient. This implies that water incorporation infers minimal distortions in the host lattice. This finding suggests a path for the control of the piezoelectric and pyroelectric effects of the crystals using stereospecific incorporation of the guest molecules. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.This work was supported by the collaborative program of the Israeli Ministry of Science with the Russian Foundation for Basic Research, grant № 3-16492. This research was made possible in part by RFBR (Grant No. 19-52-06004 MNTI_a), and the Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006). The work has been supported in part by the Ministry of Science and Higher Education of the Russian Federation under Project № 3.9534.2017/8.9. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, refs. UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. I.L. expresses his gratitude to Estate of Olga Klein–Astrachan fund, grant № 721977

Piezoelectric properties of α-glycine and DL-alanine single crystals

We present the results of studying piezoelectric properties in pure DL-alanine and α-glycine crystals doped with amino acids: L-alanine, L-serine, and phase transformations in pure DL-alanine crystals. Crystals were provided by Weizmann Institute of Science. Piezoelectric properties have been measured with high spatial resolution by piezoresponse force microscopy (PFM) using Asylum MFP 3D (Asylum Research, USA). Phase transformation was visualized by PFM

Electrostriction measurements in gadolinium doped cerium oxide

The equipment of the Ural Center for Shared Use “Modern nanotechnology” UrFU was used. The research was made possible with the financial support of Russian Foundation for Basic Research grant (15-52-06006-MNTI_a)

Uncovering the origin of local electrochemical response in Ce1.9Gd0.1O2

Cerium oxide (CeO) has a wide range of different applications such as gas sensing, water splitting and others. CeO is an attractive alternative to yttria-stabilized zirconia as an electrolyte for low-temperature fuel cells because of its high ionic conductivity, low reactivity and good chemical compatibility with many mixed conducting cathode materials [1].The equipment of the Ural Center for Shared Use"Modern nanotechnology" UrFU was used. This research was made possible in part by RFBR (Grant No. 15-52-06006 MNTI_a). This work was supported by the Israeli Ministry of Science and Technology within the program of Israel Russian Federation Scientific Collaboration, Grant No. 12421-3. A.L.K. and A.T. acknowledge the CICECO– Aveiro Institute of Materials POCI-01-0145-FEDER-007679 (Ref. FCT UID /CTM /50011/2013), financed by national funds through the FCT/MEC and when applicable co- financed by FEDER under the PT2020 Partnership Agreement. This work has been supported in part by the Ministry of Education and Science of the Russian Federation under Project No. 3.9534.2017/BP

Modeling of space-charge effects in nanocrystalline ceramics: The influence of geometry

The distribution of mobile charge carriers in the space-charge regions at grain boundaries of ceramic materials was modeled. Delocalization effects are neglected, i.e., we consider ionic defects or polarons. The calculations were performed for cubic- shaped grains of equal size. When considering the size dependence, the standard free chemical potentials of the defects rather than the specific grain-boundary charge density or the defects' boundary concentration were set to be constant in accordance with the core space-charge model. Although specific edge and corner effects are neglected in the present analysis and hence the structural potentials are invariant along grain boundaries, the accumulation or depletion of charge carriers turns out to be inhomogeneous along the grain boundary and to be particularly pronounced near grain edges and grain corners if the grain size was smaller than four Debye lengths. Especially the accumulation near grain edges can have a strong influence on the effective conductivity (though being a purely geometric effect). The modeling also predicts that a contact of two grains that differ only in size, leads to a redistribution of mobile ions between grains, provided that either one or both grain sizes are smaller than the double width of space-charge layers. Such a charge transfer between the grains can be viewed as a "heterosize charging." (C) 2002 American Institute of Physics