Piezoelectric actuation of graphene-based polar structures: frequency and geometry effects

The work was financially supported by the Russian Foundation for Basic Research within the project 16-29-14050 ofr. The equipment of the Ural Center for Shared Use “Modern nanotechnology” of UrFU was used

Piezoelectric Actuation of Graphene-Coated Polar Structures

Ferroelectric materials based on lead zirconate titanate (PZT) are widely used as sensors and actuators because of their strong piezoelectric activity. However, their application is limited because of the high processing temperature, brittleness, lack of conformal deposition, and a limited possibility to be integrated with the microelectromechanical systems (MEMS). Recent studies on the piezoelectricity in the 2-D materials have demonstrated their potential in these applications, essentially due to their flexibility and integrability with the MEMS. In this work, we deposited a few layer graphene (FLG) on the amorphous oxidized Si3N4 membranes and studied their piezoelectric response by sensitive laser interferometry and rigorous finite-element modeling (FEM) analysis. Modal analysis by FEM and comparison with the experimental results show that the driving force for the piezoelectric-like response can be a polar interface layer formed between the residual oxygen in Si3N4 and the FLG. The response was about 14 nm/V at resonance and could be further enhanced by adjusting the geometry of the device. These phenomena are fully consistent with the earlier piezoresponse force microscopy (PFM) observations of the piezoelectricity of the graphene on SiO2 and open up an avenue for using graphene-coated structures in the MEMS. © 1986-2012 IEEE.This work was supported in part by the Russian Foundation or Fundamental Research under Grant 16-29-14050, in part by the Ministry of Education and Science of the Russian Federation in the framework of the Increase Competitiveness Program of MISiS under Grant K2-2019-015, in part by the Project CICECO-Aveiro Institute of Materials financed by national funds through the Portuguese Foundation for Science and Technology/MCTES under Grants UIDB/50011/2020 and UIDP/50011/2020, and in part by the Center for Nanophase Materials Sciences, which is a Department of Energy Office of Science User Facility. The work was also supported by Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006) and by the Ministry of Science and Higher Education of the Russian Federation (state task FEUZ-2020-0054). The equipment of the Ural Center for Shared Use “Modern nanotechnology” UrFU was used. The work of Yakov Kopelevich was supported in part by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and in part by the Fundação de Amparo à Pesquisa do Estado de S. Paulo (FAPESP) (Brazil)

THERMALLY ASSISTED GROWTH OF BULK DOMAINS CREATED BY FEMTOSECOND LASER IN MAGNESIUM DOPED LITHIUM NIOBATE

The domain growth to the polar surfaces from the tracks created by focused NIR femtosecond pulses in the bulk of MgO-doped lithium niobate plate has been studied. The tracks have been imaged by optical and Cherenkov-type second harmonic generation microscopy. The domain appearance at the irradiated

Reactions of Sulfur- and Phosphorus-Substituted Fluoroalkylating Silicon Reagents with Imines and Enamines under Acidic Conditions

Nucleophilic fluoroalkylation reactions of imines and enamines with α-phenylthio, α-phenylsulfonyl, and α-diethylphosphoryl substituted fluorinated silanes have been investigated. The reactions are promoted by hydrofluoric acid generated <i>in situ</i> from potassium hydrodifluoride and trifluoroacetic acid. Sulfur reagents worked well with both imines and enamines, whereas phosphorus reagent efficiently coupled only with enamines

Geminal Silicon/Zinc Reagent as an Equivalent of Difluoromethylene Bis-carbanion

A new difluorinated reagent, [difluoro­(trimethylsilyl)­methyl]­zinc bromide, bearing C–Zn and C–Si bonds is described. The reagent is conveniently prepared by cobalt-catalyzed halogen/zinc exchange. It can be coupled with two different C-electrophiles in a stepwise manner (with allylic halides for C–Zn bond and aldehydes for C–Si bond) affording products containing a difluoromethylene fragment