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Piezoresponse force microscopy (PFM) has been widely used for the nanoscale analysis of piezoelectric properties and ferroelectric domains. Although PFM is useful because of its simple and nondestructive features, PFM measurements can be obscured by non-piezoelectric effects that could affect the PFM signals or lead to ferroelectric-like behaviors in non-ferroelectric materials. Many research studies have addressed related technical issues, but they have primarily focused on vertical PFM. Here, we investigate significant discrepancies in lateral PFM signals between the trace and the retrace scans, which are proportional to the scan angle and the cantilever lateral tilting discrepancy. The discrepancies in PFM signals are analyzed based on intrinsic and extrinsic components, including out-of-plane piezoresponse, electrostatic force, and other factors. Our research will contribute to the accurate PFM measurements for the visualization of ferroelectric in-plane polarization distributions. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp), a main constituent of the cortical bone, retains a large surface charge that plays a critical role in the regeneration of bones, whose source remains an enigma. Here, we used multi-eigenmode piezoresponse force microscopy via Pearson correlation and conducted multiscale material analysis to independently measure the piezoelectric coefficient and the surface charge density of HAp. Quantitative comparison was conducted between the measured surface charge density and the conceptual values computed for all possible candidates of the surface charging such as piezoelectricity, chemically induced surface charging, flexoelectricity, and defect dipole moment. The results presented Ca2+ ions released during local calcium orthophosphate phase transition at the surface as the main source of the surface charging. Further analysis showed that the ion concentration was modulable using a charged conductive tip, implying that the interstitial ions are mobile within the HAp matrix. In this work, we developed a novel method to measure the effective surface charge density of arbitrary material systems, thereby facilitating the investigation of biophysical phenomena related to surface electromechanics. Most importantly, the research promotes a new understanding of the origin of osteoconduction observed in past works conducted on HAp. [ABSTRACT FROM AUTHOR]

Piezoresponse force microscopy (PFM) uses a cantilever arm to track the electromechanical motion of the electric dipole moment to visualize the ferroelectric domain structure, which provides an important insight into the physics of switchable electric polarization—especially for memory devices and integrated microelectronics. Here, I provide a tutorial on single frequency vertical PFM, the most basic mode of PFM. I will start with the basic components of atomic force microscopy (AFM), including tip, cantilever, X–Y stage, Z actuator, and lock-in amplifier. Contact mode AFM will be briefly explained and discussed, where you can find two modes: constant deflection and constant height modes. Single-frequency vertical PFM splits the frequency domain of tip vibration into low and high frequencies and uses a low-pass filter to nullify any motion caused by topography (constant deflection). In contrast, the lock-in amplifier will pinpoint the vibration induced by the vertical piezoelectric strain along the sample's surface normal (constant height). This tutorial will provide an overall and detailed step by step instruction to conduct PFM imaging and piezoresponse hysteresis loop measurement using atomic force microscopy and a lock-in amplifier and teach how to interpret the PFM images and the piezoresponse hysteresis loops for various applications. [ABSTRACT FROM AUTHOR]

Section VI, page 7, paragraph 1, "...we get SB 0 sb = 587.1 I i C/cm SP 2 sp , which is remarkably close to the surface charge density given by our measurement = 530.2 ± 26.5 I i C/cm SP 2 sp ." should be changed to "we get SB 0 sb = 581.4 I i C/cm SP 2 sp , which is precisely within range of the surface charge density given by our measurement = 602.5 ± 37.7 I i C/cm SP 2 sp ." As such, the following change must be made to all related values: Section VI, page 7, paragraph 1, "L SB P sb = 14.97 nm" should be changed to "L SB P sb = 14.73 nm." Section VII, page 8, paragraph 2, " L SB P sb /L SB 0 sb = 0.6202" should be changed to " L SB P sb / L SB 0 sb = 0.6105.". [Extracted from the article]

(c) A simple topography composed of two sinusoidal components where the red curve represents the high frequency variation in topography whereas the blue curve represents the low frequency one. (b) The temporal evolution of AFM tip vibration during the scan shown in (a). (d) Temporal evolution plots of AFM tip vibration for low-frequency and high-frequency components. [Extracted from the article]

Here, we demonstrate a novel process to convert TiO2 nanotubes into ferroelectric nanohoneycombs, comprised of vertically aligned PbTiO3 nanotubes. Tube bottom opening process enabled effective infiltration of lead acetate precursor into the nanotubes. Nanohoneycombs, which were converted via additional lead supplement process, showed uniform conversion and well-defined ferroelectric properties with the effective piezoelectric coefficient of approximately 20 pm/V, which was measured by piezoresponse force microscopy. [ABSTRACT FROM AUTHOR]

ABSTRACT We have fabricated vertically aligned ferroelectric PVDF mesoscale rod arrays comprising β and γ phases using a 200 nm diameter anodized aluminum oxide (AAO) as the porous template. We could synthesize the ferroelectric phase in mesoscale rod forms by combining the well-established recipe for crystallizing the β phase using dimethyl sulfoxide (DMSO) at low temperature and template-guided infiltration processing for the rods using AAO. We measured the dimensions of the PVDF rods by scanning electron microscopy and identified the polymorph phases by X-ray diffraction and Fourier transform infrared spectroscopy. The length of the rods varied from 3.82 μm to 1.09 μm and the diameter from 232 nm to 287 nm when the volume ratio between DMSO and acetone changed from 5 : 5 to 10 : 0. We obtained well-defined piezoresponse hysteresis loops for all rods with remnant piezoresponse ranging from 2.12 pm/V to 5.04 pm/V and coercive voltage ranging from 2.29 V to 2.71 V using piezoresponse force microscopy. Our results serve as a processing platform for flexible electronic devices that need high capacitance and piezoelectric functionalities such as flexible memory devices or body energy harvesting devices for intelligent systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3842-3848, 2013 [ABSTRACT FROM AUTHOR]

A simple quantitative measurement procedure of in-plane cantilever torsion for calibrating lateral piezoresponse force microscopy is presented. This technique enables one to determine the corresponding lateral inverse optical lever sensitivity (LIOLS) of the cantilever on the given sample. Piezoelectric coefficient, d31 of BaTiO3 single crystal (-81.62 ± 40.22 pm/V) which was calculated using the estimated LIOLS was in good agreement with the reported value in literature. [ABSTRACT FROM AUTHOR]

The dielectric gap between the scanning probe microscopy (SPM) tip and the surface of a ferroelectric using conductive atomic force microscopy and piezoresponse force microscopy (PFM) is investigated. While the gap functions as a dielectric layer, it also allows tunneling current to inject charges into the ferroelectric when a critical loading force between 10–20 µN is applied to a tip with a radius of 25 nm under a bias voltage of 0.5 V. It is observed that the permittivity of the dielectric gap determines the coercive voltage measured by the piezoresponse hysteresis loop. While such studies done in air often produce coercive voltages much larger than those studied for the same materials in capacitor‐based studies, the use of high permittivity media such as water (ɛr = 79) or silicone oil (ɛr = 2.1‐2.8) produces coercive fields that more closely match those measured in conventional capacitor‐based polarization hysteresis loop measurements. Furthermore, using water as a dielectric medium in PFM imaging enhances the accuracy in extracting the amplitude and phase data from periodically poled lithium niobate crystals. These findings provide insight into the nanoscale phenomena of polarization switching instigated by the SPM tip and provide a pathway to improved quantitative studies. [ABSTRACT FROM AUTHOR]

Piezoelectric materials are suitable for haptic technology as they can convert mechanical stimuli into electrical signals and vice-versa. However, owing to their disadvantageous mechanical properties such as brittleness (in ceramics) and a low piezoelectric coefficient (in polymers), their application in haptic technology remains challenging. In this paper, we introduce a truss-like 3D hollow nanostructure using zinc oxide (ZnO) that exhibits a drastically improved elastic strain limit while maintaining a piezoelectric coefficient similar to that of single-crystal ZnO. The ZnO hollow nanostructure was fabricated using proximity field nanopatterning (PnP) and atomic layer deposition (ALD) at four different processing temperatures. The piezoelectric characteristics were analyzed through dual AC resonance tracking piezoresponse force microscopy (PFM), and the piezoelectric coefficient was measured to be up to 9.2 pm/V. The nanopillar compression test result showed that the measured elastic strain limit of approximately 10% was at least 3 times greater than the previously reported value. The extended elastic limit of the 3D hollow structure was further supported by finite element simulations. The ZnO hollow nanostructure shows excellent potential for its application to enhanced haptic devices, which mimic the human sense of touch. A 3D ZnO hollow nanostructure exhibits an improved elastic strain limit while maintaining a piezoelectric coefficient similar to that of single-crystal ZnO. This nanostructure is fabricated using atomic layer deposition at four different temperatures. The piezoelectric coefficient of ≈ 9.2 pm/V and elastic strain limit of ≈ 10% are measured by piezoresponse force microscopy and nanopillar compression test, respectively. Image 1 • We developed a 3D ZnO hollow nanostructure through atomic layer deposition and 3D nanolithography. • The effective piezoelectric coefficient of 3D ZnO hollow nanostructure is close to that of a single-crystal bulk ZnO. • The 3D ZnO hollow nanostructure has a high elastic strain limit of 10% which is 3 times greater than the bulk ZnO value. • Our 3D hollow nanostructure can be used in enhanced haptic devices, which mimic the human sense of touch. [ABSTRACT FROM AUTHOR]

We report visualization of three-dimensional domain structures in ferroelectric PbTiO3 (PTO) nanotubes (NTs) using piezoresponse force microscopy (PFM). The domain distributions of the x, y, and z-axes in PTO NTs were separately measured out-of and in-planes at angles of 0° and 90° by vertical and lateral PFM. The separately obtained PFM images were combined to reconstruct the complex domain structures based on some basic assumptions and finite element modeling. The cross-sectional domain configurations of the PTO NTs were visualized by the proposed approach. The results can provide insight into complex domain configurations of ferroelectric nanostructures. [ABSTRACT FROM AUTHOR]

A correction to the article "Direct observation of fatigue in epitaxially grown Pb(Zr, Ti)O3 thin films using second harmonic piezoresponse force microscopy," that was published in the 2010 issue is presented.

We have performed a piezoresponse force microscopy (PFM) study on methylammonium lead iodide (MAPbI 3 ) thin films in normal (non-resonance, non-band-excitation) contact mode. In contrast to the ferroelectric Pb 0.76 Ca 0.24 TiO 3 (PCT) control sample, a typical ferroelectric response was not observed. However, a nonlinear electric field dependence of the local PFM amplitude was found in MAPbI 3 , similar to PCT. An analysis combining results on structure, dielectric dispersion, and weak ferroelectricity demonstrates that MAPbI 3 is actually a re-entrant relaxor ferroelectric which, upon cooling, enters into a relaxor phase below its ferroelectric phase transition at ∼327 K, due to the balance between the long range ferroelectric order and structural methylammonium group orientational disorder. The ferroelectricity at room temperature is compromised due to the re-entrant relaxor behavior, causing the poor polarization retention or weak ferroelectricity. Our findings essentially conciliate the conflicting experimental results on MAPbI 3 's ferroelectricity and are beneficial both for basic understanding as well as for device applications. [ABSTRACT FROM AUTHOR]