In this Review, we aim to provide an updated summary of the research related to hollow micro- and nanostructures, covering both their synthesis and their applications. After a brief introduction to the definition and classification of the hollow micro-/nanostructures, we discuss various synthetic strategies that can be grouped into three major categories, including hard templating, soft templating, and self-templating synthesis. For both hard and soft templating strategies, we focus on how different types of templates are generated and then used for creating hollow structures. At the end of each section, the structural and morphological control over the product is discussed. For the self-templating strategy, we survey a number of unconventional synthetic methods, such as surface-protected etching, Ostwald ripening, the Kirkendall effect, and galvanic replacement. We then discuss the unique properties and niche applications of the hollow structures in diverse fields, including micro-/nanocontainers and rea...

Synthesis, Properties, and Applications of Hollow Micro-/Nanostructures

A humidity sensor based on a single SnO2 nanowire was fabricated. This sensor has fast and sensitive response to relative humidity (RH) in air from a wide range of atmospheres at 30 °C. The response sensitivity of the sensor to RH is linear to 90%.

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High-Sensitivity Humidity Sensor Based on a Single SnO2 Nanowire

Diameter-controlled Growth of Single-crystalline In2O3 Nanowires and Their Electronic Properties

Book reviewsComposite materials: fatigue and fracture: Edited by: H.T. Hahn ASTM STP 907, 1986 (£64.00)

Laser peening without protective coating (LPPC) has been applied to water-immersed SUS304 (Type 304) and SUS316L (Type 316L) austenitic stainless steels. The surface residual stress of both materials was converted from tensile to compressive of several hundreds of megapascals by LPPC with a Q-switched and frequency-doubled Nd:YAG laser. The depth of the compressive residual stresses after LPPC exceeded 1 mm from the surface. Accelerating stress corrosion cracking (SCC) tests in a high-temperature and corrosive-water environment showed that LPPC completely prevented the SCC initiation of sensitized SUS304. SCC tests of pre-cracked samples were also performed for SUS304, which indicated that LPPC inhibits the propagation of the small pre-cracks. Rotating bending tests demonstrated that the fatigue strength of SUS316L with LPPC is enhanced by 1.4–1.7 times compared to that of the reference material at 108 cycles.

Retardation of crack initiation and growth in austenitic stainless steels by laser peening without protective coating

The effect of laser shock peening on the fatigue behavior of 2024-T3 aluminum alloy with a fastener hole, multiple crack stopholes and single-edge notch was investigated. Laser shock peening (LSP) was performed under a ‘confined ablation mode’ using a Nd:glass laser at a laser power density of 5 GW cm−2. The fatigue crack initiation life and fatigue crack growth rates of the Al alloy, with different preexisting notch configurations, were characterized and compared with those of the unpeened material. The results clearly show that LSP is an effective surface treatment technique for improving the fatigue performance of Al alloys having various preexisting notch configurations.

Laser shock peening on fatigue behavior of 2024-T3 Al alloy with fastener holes and stopholes

Large-scale SnO2 nanoblades have been synthesized on a glass substrate covered with a 100-nm-thick SnO2 buffer layer in a controlled aqueous solution at temperatures below 100°C. Typical widths of the nanoblades were about 100–300nm and the lengths were up to 10μm, depending on the growth temperature. The thicknesses were about a few tens of nanometers. Transmission electron microscopy data, x-ray diffraction patterns, and x-ray photoelectron spectroscopy spectral analyses confirmed that the as-grown nanoblades had the phase structure of the rutile form of SnO2 growing along the [110] direction. No other impurities, such as elemental Sn and tin oxides, were detected. An intense blue luminescence centered at a wavelength of 445nm with a full width at half maximum of 75nm was observed in the as-grown SnO2 nanoblades, which is different from the yellow-red light emission observed in SnO2 nanostructures prepared by other methods. It is believed that the strong blue luminescence from the as-grown SnO2 nanoblad...

http://web.nchu.edu.tw/pweb/users/ycho22081/research/5069.pdf

Low-temperature growth and blue luminescence of SnO2 nanoblades

One-dimensional (1D) crystalline/amorphous WO3 core–shell heterostructures were synthesized by a simple, two-step hydrothermal process. Single-crystalline hexagonal WO3 (h-WO3) nanorod cores with diameters of about 200 nm and lengths of 6–7 μm were obtained in the first step. Amorphous WOx (a-WOx) shells with thicknesses ranging from 8 to 40 nm were grown on the h-WO3 cores in the second step. The electrochromic properties of the devices based on the h-WO3/a-WOx core–shell heterostructures were measured and compared with those based on the bare a-WOx and h-WO3 nanorods. The optical modulation of coloration/bleaching at λ = 550 nm was measured to be 44% after coloration at −3.0 V for 180 s and bleaching at +2.0 V for 90 s. The coloration and bleaching times were found to be 41 s and 6 s, respectively, and the coloration efficiency was 82 cm2 C−1. After cyclic stability tests for 1000 cycles, the transmittance changes compared with the initial stage at the colored and bleached states are only 2.6 and 3.4%, respectively. It appears that the h-WO3/a-WOx core/shell heterostructures combine the assets of the constituent phases and exhibit highly improved and balanced electrochromic properties.

Facile synthesis of one-dimensional crystalline/amorphous tungsten oxide core/shell heterostructures with balanced electrochromic properties

Adding specific foreign elements into the eutectic Sb70Te30 fast-growth material is expected to be an effective way to increase its thermal stability for blue laser recording. We have studied the effects of Ag and In addition on the optical properties and crystallization kinetics of the eutectic Sb70Te30 recording film. The results showed that the addition of Ag and In increased the refractive index and decreased the extinction coefficient of amorphous Sb70Te30 film and decreased both the refractive index and extinction coefficient of crystalline Sb70Te30 film. The archival stability of the eutectic SbTe alloy could be effectively improved by adding Ag and In elements, however, the addition of Ag and In also made the initialization of the as-deposited eutectic SbTe film more difficult. During the isothermal crystallization process, the incubation time was extended, crystallization speed was reduced, and the crystallization process became more grain-growth dominated as Ag and In were added. All these effec...

http://web.nchu.edu.tw/pweb/users/ycho22081/research/5058.pdf

Effects of ag and in addition on the optical properties and crystallization kinetics of eutectic Sb70Te30 phase-change recording film

We have synthesized brushlike p-Te/n-SnO2 hierarchical heterostructures by a two-step thermal vapor transport process. The morphologies of the branched Te nanostructures can be manipulated by adjusting the source temperature or the argon flow rate. The growth of the branched Te nanotubes on the SnO2 nanowire backbones can be ascribed to the vapor–solid (VS) growth mechanism, in which the inherent anisotropic nature of Te lattice and/or dislocations lying along the Te nanotubes axis should play critical roles. When exposed to CO and NO2 gases at room temperature, Te/SnO2 hierarchical heterostructures changed the resistance in the same trend and exhibited much higher responses and faster response speeds than the Te nanotube counterparts. The enhancement in gas sensing performance can be ascribed to the higher specific surface areas and formations of numerous Te/Te or TeO2/TeO2 bridging point contacts and additional p-Te/n-SnO2 heterojunctions.

Yung-Chiun Her

Papers

Laser shock peening on fatigue behavior of 2024-T3 Al alloy with fastener holes and stopholes

Low-temperature growth and blue luminescence of SnO2 nanoblades

Facile synthesis of one-dimensional crystalline/amorphous tungsten oxide core/shell heterostructures with balanced electrochromic properties

Effects of ag and in addition on the optical properties and crystallization kinetics of eutectic Sb70Te30 phase-change recording film

Vapor-solid growth of p-Te/n-SnO2 hierarchical heterostructures and their enhanced room-temperature gas sensing properties.