We propose a mechanism, a piezoelectrochemical effect for the direct conversion of mechanical energy to chemical energy. This phenomenon is further applied for generating hydrogen and oxygen via direct water decomposition by means of as-synthesized piezoelectric ZnO microfibers and BaTiO3 microdendrites. Fibers and dendrites are vibrated with ultrasonic waves leading to a strain-induced electric charge development on their surface. With sufficient electric potential, strained piezoelectric fibers (and dendrites) in water triggered the redox reaction of water to produce hydrogen and oxygen gases. ZnO fibers under ultrasonic vibrations showed a stoichiometric ratio of H2/O2 (2:1) initial gas production from pure water. This study provides a simple and cost-effective technology for direct water splitting that may generate hydrogen fuels by scavenging energy wastes such as noise or stray vibrations from the environment. This new discovery may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.

Ceramic of ZrB2 and its composite of the ceramics with SiC are used for ultrahigh temperature protection coatings in re-entry space vehicles because of high melting temperature of ZrB2 (3245°C). Chemical composition and microstructure of the ceramics are critical to thennal shock properties of the ceramics. Especially oxidation of boron and formation of boron oxide will degrade property of thermal resistance. Conventional TEM with Energy dispersive X-ray spectroscopy (EDS) is unable to study light elements like boron. However, parallel-recorded electron energy-loss spectroscopy (EELS) and energy-filtering GIF system associated with field-emission gun (FEG) TEM are able to carry out chemical imaging and chemical information of light elements. Bonding structure and oxidation states of an element (such as B) can be obtained by using EELS.Figure A is a zero-loss bright-field TEM image showing an interface between ZrB2 and SiC. Figure B is a Plasmon-loss filtered TEM image of the same area. A plasmon peak at about 20 eV was used for this image.

Advanced ceramics have been increasingly used for various manufacturing processes. The current sensors used in ceramic tools are difficult to reliably provide thermomechanical measurements in or near the ceramic tool–workpiece interface. Thin film micro sensors could be embedded—thus avoiding direct contact with workpieces—at critical locations without interfering with normal manufacturing operation of the ceramic tool. However, little research has been conducted in embedding of thin film sensors in ceramic materials. To initiate the study on ceramic embedded thin film sensors, palladium-13 wt% chromium (PdCr) material was used to fabricate thin film strain gauges (TFSGs) on sapphire substrates and a diffusion bonding process was used to embed the TFSGs into sapphire. The interface between the sapphire and embedded sensors was characterized by high-resolution TEM (HRTEM). The results clearly indicated a good chemical bonding between the host sapphire and embedded thin films with no inter-diffusion. Moreover, TEM images showed there were local stresses at the interface due to the chemical bonding. The functionality of the embedded micro TFSGs into sapphire was successfully characterized. This study clearly demonstrates the feasibility of fabricating and embedding micro thin film sensors for potential use in ceramic tools for various applications.

No abstract