We show anomalously strong shear piezoelectric activity in self-assembled diphenylalanine peptide nanotubes (PNTs), indicating electric polarization directed along the tube axis. Comparison with well-known piezoelectric LiNbO(3) and lateral signal calibration yields sufficiently high effective piezoelectric coefficient values of at least 60 pm/V (shear response for tubes of approximately 200 nm in diameter). PNTs demonstrate linear deformation without irreversible degradation in a broad range of driving voltages. The results open up a wide avenue for developing new generations of "green" piezoelectric materials and piezonanodevices based on bioactive tubular nanostructures potentially compatible with human tissue.

Piezoresponse force microscopy (PFM) has emerged as a powerful and versatile tool for probing nanoscale phenomena in ferroelectric materials on the nanometer and micrometer scales. In this review, we summarize the fundamentals and recent advances in PFM, and describe the nanoscale electromechanical properties of several important ferroelectric ceramic materials widely used in memory and microelectromechanical systems applications. Probing static and dynamic polarization behavior of individual grains in PZT films and ceramics is discussed. Switching spectroscopy PFM is introduced as a useful tool for studying defects and interfaces in ceramic materials. The results on local switching and domain pinning behavior, as well as nanoscale fatigue and imprint mapping are presented. Probing domain structures and polarization dynamics in polycrystalline relaxors (PMN‐PT, PLZT, doped BaTiO3) are briefly outlined. Finally, applications of PFM to dimensionally confined ferroelectrics are demonstrated. The potential of PFM for studying local electromechanical phenomena in polycrystalline ferroelectrics where defects and other inhomogeneities are essential for the interpretation of their macroscopic properties is illustrated.

We report hot filament thermal CVD (HFTCVD) as a new hybrid of hot filament and thermal CVD and demonstrate its feasibility by producing high quality large area strictly monolayer graphene films on Cu substrates. Gradient in gas composition and flow rate that arises due to smart placement of the substrate inside the Ta filament wound alumina tube accompanied by radical formation on Ta due to precracking coupled with substrate mediated physicochemical processes like diffusion, polymerization etc., led to graphene growth. We further confirmed our mechanistic hypothesis by depositing graphene on Ni and SiO2/Si substrates. HFTCVD can be further extended to dope graphene with various heteroatoms (H, N, and B, etc.,), combine with functional materials (diamond, carbon nanotubes etc.,) and can be extended to all other materials (Si, SiO2, SiC etc.,) and processes (initiator polymerization, TFT processing) possible by HFCVD and thermal CVD.

Ferroelectrics are multifunctional materials that reversibly change their polarization under an electric field. Recently, the search for new ferroelectrics has focused on organic and bio‐organic materials, where polarization switching is used to record/retrieve information in the form of ferroelectric domains. This progress has opened a new avenue for data storage, molecular recognition, and new self‐assembly routes. Crystalline glycine is the simplest amino acid and is widely used by living organisms to build proteins. Here, it is reported for the first time that γ‐glycine, which has been known to be piezoelectric since 1954, is also a ferroelectric, as evidenced by local electromechanical measurements and by the existence of as‐grown and switchable ferroelectric domains in microcrystals grown from the solution. The experimental results are rationalized by molecular simulations that establish that the polarization vector in γ‐glycine can be switched on the nanoscale level, opening a pathway to novel classes of bioelectronic logic and memory devices.

Diphenylalanine (FF) peptide nanotubes (PNTs) present a unique class of selfassembled functional biomaterials owing to a wide range of useful properties including nanostructural variability, mechanical rigidity, and chemical stability. In addition, a strong piezoelectric activity has been recently observed paving the way to their use as nanoscale sensors and actuators. In this work, we fabricated both horizontal and vertical FF PNTs and examined their optical second harmonic generation and local piezoresponse as a function of temperature. The measurements show gradual decrease of polarization with increasing temperature accompanied by irreversible phase transition into another crystalline phase at about 140-150 ºC. The results are corroborated by the molecular dynamic simulations predicting order-disorder phase transition into centrosymmetric (possibly, orthorhombic) phase with antiparallel polarization orientation in neighboring FF rings. Partial piezoresponse hysteresis indicates incomplete polarization switching due to high coercive field in FF PNTs.