A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Methylammonium Chloride Induces Intermediate Phase Stabilization for Efficient Perovskite Solar Cells

Ferroelectrics are essential components in a wide range of applications, including ultrasonic transducers, sensors, and actuators. In the single crystal form, relaxor-PbTiO3 (PT) piezoelectric materials have been extensively studied due to their ultrahigh piezoelectric and electromechanical properties. In this article, a perspective and future development of relaxor-PT crystals are given. Initially, various techniques for the growth of relaxor-PT crystals are reviewed, with crystals up to 100 mm in diameter and 200 mm in length being readily achievable using the Bridgman technique. Second, the characterizations of dielectric and electromechanical properties are surveyed. Boundary conditions, including temperature, electric field, and stress, are discussed in relation to device limitations. Third, the physical origins of the high piezoelectric properties and unique loss characteristics in relaxor-PT crystals are discussed with respect to their crystal structure, phase, engineered domain configuration, macr...

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High performance ferroelectric relaxor-PbTiO3 single crystals: Status and perspective

Advantages and Challenges of Relaxor-PbTiO3 Ferroelectric Crystals for Electroacoustic Transducers- A Review.

Organic–inorganic halide perovskite solar cells have recently attracted much attention due to their low-cost fabrication, flexibility, and high efficiency The power conversion efficiency achieved with such cells was over 22% in 2016 from an initial 381% in 2009, highlighting how the cells are now benefiting from the highly optimized morphology of perovskite films To date, a great number of approaches have been done to improve the morphology of perovskite films, in which additives play an important role in perovskite crystal growth and in the dynamics of the crystallinity, and thus the performance of perovskite solar cells Herein, we review the recent progress on additives, such as polymers, fullerene, metal halide salts, organic halide salts, inorganic acids, solvents, and nanoparticles, in improving the morphology of perovskite films in terms of the crystal growth, crystallization kinetics, and device performance We also discuss the importance of further understanding the fundamental homogeneous nucleation process by the use of additives Further innovation in terms of the additives could help to further develop high-performance devices with long-term stability for future practical applications of perovskite solar cells

Additive engineering for highly efficient organic–inorganic halide perovskite solar cells: recent advances and perspectives

Chemical solution deposition (CSD) provides a low-cost, versatile approach for processing of thin and ultrathin ferroelectric films, as well as short and high aspect ratio ferroelectric nanostructures. This review discusses the state of the art in the processing of ferroelectric oxide thin films and nanostructures by CSD, with special emphasis on nucleation and growth phenomena. The effects of choice of precursor solution, substrate and bottom electrode stack, and thermal treatment conditions on the nucleation and growth are examined. Furthermore, methods to control ferroelectric thin film's microstructure, including phase content, texture, grain size and chemical homogeneity, are reviewed. Lastly, current CSD-based methods for processing of ferroelectric oxide nanostructures are presented with special consideration of the structural development, as well as advantages and shortcomings associated with each method. Lead zirconate-titanate, Pb(ZrxTi1−x)O3 (PZT), and barium titanate, BaTiO3 (BT), are used throughout the discussion, as specific examples for CSD processing of perovskite ferroelectrics.

Chemical solution growth of ferroelectric oxide thin films and nanostructures

A new nano-manufacturing method for the creation of high aspect-ratio ferroelectric (PbZr0.52Ti0.48O3) nanostructures by use of polymeric templates is presented. The ferroelectric response is characterized by band-excitation PFM, supporting the high quality of the nanostructures. Piezoelectric size effects for ferroelectric materials are reported for the first time in nanotube configuration (critical thickness ∼15 nm) and compared to thin films' response.

Free‐Standing Ferroelectric Nanotubes Processed via Soft‐Template Infiltration

The dielectric response of (1−x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-x%PT,4.5≤x≤12) single crystals is reported for ac field amplitudes up to ∼2 kV/cm at 1 kHz. The Rayleigh law is used to study the dielectric nonlinear response. It is found that the extrinsic contributions are extremely anisotropic. Rhombohedral crystals poled along [001]C showed enhanced extrinsic contributions to their dielectric response with respect to those poled along [111]C, while in tetragonal crystals, the enhancement was observed for poling along [111]C rather than along [001]C. This is attributed to “domain engineering” or higher domain wall concentrations in ferroelectric crystals poled along nonpolar axes.

Effects of orientation and composition on the extrinsic contributions to the dielectric response of relaxor-ferroelectric single crystals

Helping Undergraduate Students of any Engineering Discipline Develop a Systems Perspective

Testing with lateral and radial shears is becoming standard in optical shops. Of late, holographic optical elements have proven to be easy and simple to set up, and can be used in both a collimated and convergent beam. However, there is very little work on making quantitative measurements using a symmetric radial shear. We demonstrate a simple method of obtaining both asymmetric and symmetric radial shears, and use the inherent tilt in the wavefronts to perform spatial Fourier transformation to extract phase maps. This radial shear interferometer is also suitable for static and dynamic situations.

Ashley Bernal

Papers

Chemical solution growth of ferroelectric oxide thin films and nanostructures

Free‐Standing Ferroelectric Nanotubes Processed via Soft‐Template Infiltration

Effects of orientation and composition on the extrinsic contributions to the dielectric response of relaxor-ferroelectric single crystals

Helping Undergraduate Students of any Engineering Discipline Develop a Systems Perspective

Radial shear interferometer with holographic lenses coupled with a spatial Fourier transform method suitable for static and dynamic measurements