CuO nanostructures: Synthesis, characterization, growth mechanisms, fundamental properties, and applications

Owing to the unique mechanism of photoelectron storage and release, long persistent phosphorescence, also called long persistent luminescence or long lasting afterglow/phosphorescence, plays a pivotal role in the areas of spectroscopy, photochemistry, photonics and materials science. In recent years, more research has focused on the manipulation of the morphology, operational wavebands and persistent duration of long persistent phosphors (LPPs). These desired achievements stimulated the growing interest in designing bio-labels, photocatalysts, optical sensors, detectors and photonic devices. In this review, we present multidisciplinary research on synthetic methods, afterglow mechanisms, characterization techniques, materials system, and applications of LPPs. First, we introduce the recent developments in LPPs for the synthesis of nanoparticles from the aspects of particle sizes, monodispersity and homogeneity based on the urgent application of bio-imaging. In the later sections, we present the possible mechanisms, which involve the variation of trap distribution during the trapping and de-trapping process, complicated photo-ionization reaction of trap site levels and impurity centers together with their corresponding migration kinetics of carriers. Meanwhile, we emphasize the characterization techniques of defects, used to qualitatively or quantitatively describe the types, concentrations and depths of the traps. This review article also highlights the recent advances in suggested LPPs materials with a focus on the LPPs' hosts and optically active centers as well as their control, tuning and intrinsic links. We further discuss the classification of LPPs based on the different emission and excitation wavebands from the ultraviolet to the near-infrared region along with an overview of the activation mode of afterglow. Afterwards, we provide an exhibition of new products towards diverse application fields, including solar energy utilization, bio-imaging, diagnosis, and photocatalysts. Finally, we summarize the current achievements, discuss the problems and provide suggestions for potential future directions in the aforementioned parts.

Long persistent phosphors—from fundamentals to applications

The template carbonization method is a powerful tool for producing carbon materials with precisely controlled structures at the nanometer level. The resulting templated nanocarbons exhibit extraordinarily unique (often ordered) structures that could never be produced by any of the conventional methods for carbon production. This review summarizes recent publications about templated nanocarbons and their composites used for energy storage applications, including hydrogen storage, electrochemical capacitors, and lithium-ion batteries. The main objective of this review is to clarify the true significance of the templated nanocarbons for each application. For this purpose, the performance characteristics of almost all templated nanocarbons reported thus far are listed and compared with those of conventional materials, so that the advantages/disadvantages of the templated nanocarbons are elucidated. From the practical point of view, the high production cost and poor mass-producibility of the templated nanocarbons make them rather difficult to utilize; however, the study of their unique, specific, and ordered structures enables a deeper insight into energy storage mechanisms and the guidelines for developing energy storage materials. Thus, another important purpose of this work is to establish such general guidelines and to propose future strategies for the production of carbon materials with improved performance for energy storage applications.

Templated nanocarbons for energy storage.

A highly sensitive nonenzymatic glucose sensor based on CuO nanoparticles-modified carbon nanotube electrode.

High strain piezoelectric ceramics are the state-of-the-art materials for high precision, positioning devices. A comprehensive review of the latest developments of the various types of perovskite piezoelectric ceramic systems is presented herein, with special attention given to three promising families of lead-free perovskite ferroelectrics: the barium titanate, alkaline niobate and bismuth perovskites. Included in this review are details of phase transition behavior, strain enhancement approaches, material reliabilities as well as the status of some promising applications. This current review describes both compositional and structural engineering approaches that are intended to achieve enhanced strain properties in perovskite piezoelectric ceramics. The factors that affect the strain behavior of high-strain perovskite piezoelectric ceramics are addressed. The reliability characteristics of these high-strain ferroelectrics as well as the recent approaches to the long-term electrical, thermal and time-stability enhancement are summarized. Several promising applications of high-strain perovskite materials are introduced, which take advantages of their characteristics; examples include high-energy storage, pyroelectric and electro-caloric effect and luminescent properties.

Progress in high-strain perovskite piezoelectric ceramics

Electro‐Mechano‐Optical Conversions in Pr3+‐Doped BaTiO3–CaTiO3 Ceramics

One of the present intensive concerns about the high-temperature superconductors is whether charge stripes are a key to superconductivity. Here we report observation of charge stripes in the simplest copper oxide, CuO, by real-space images obtained by electron microscopy. Charge-ordered domains and normal-lattice domains exist alternatively in the vapor-grown single crystal of CuO. Since CuO consists of the Cu-O bonding, which is a basic material feature for high- ${T}_{c}$ cuprates, the discovery of charge stripes in this basic compound has important implications for discussing the mechanism of superconductivity in complex cuprates.

Observation of charge stripes in cupric oxide

The ferroelectricity of (Al1−xScx)N (x = 0–0.34) thin films with various thicknesses was investigated. (Al1−xScx)N films were prepared at 400 °C on (111)Pt/TiOx/SiO2/(001)Si substrates by the radio frequency dual-source reactive magnetron sputtering method using Al and Sc targets under pure N2 gas or a mixture of N2 and Ar gases. The film deposited under N2 gas showed larger remanent polarization than those under N2 + Ar mixture. Ferroelectricity was observed for films with x = 0.10–0.34 for about 140-nm-thick films deposited under N2 gas. The x = 0.22 films showed ferroelectricity down to 48 nm in thickness from the polarization–electric field curves and the positive-up-negative-down measurement. The ferroelectricity of the 9 nm-thick film also was ascertained from scanning nonlinear dielectric microscopy measurement. These results reveal that ferroelectric polarization can switch for films with much broader compositions and thicknesses than those in the previous study.

Effects of deposition conditions on the ferroelectric properties of (Al1−xScx)N thin films

Ultrasonic wave induced mechanoluminescence and its application for photocatalysis as ubiquitous light source

https://www.rsc.org/suppdata/cc/c1/c1cc11411e/c1cc11411e.pdf

Hiroshi Yamada

Papers

Electro‐Mechano‐Optical Conversions in Pr3+‐Doped BaTiO3–CaTiO3 Ceramics

Observation of charge stripes in cupric oxide

Effects of deposition conditions on the ferroelectric properties of (Al1−xScx)N thin films

Ultrasonic wave induced mechanoluminescence and its application for photocatalysis as ubiquitous light source

Mechanoluminescent light source for a fluorescent probe molecule