Methodology of ZnO Based 1D Microstructures : from Synthesis to Application
ZnO is among the most studied materials in the past decades. A large number of synthesis routes and a unique combination of properties offer a wide range of possible applications. This work focuses on the development of applications using 1D ZnO micro- and nanostructures. The development starts with the introduction of a new synthesis process, flame transport synthesis (FTS). The FTS allows the fabrication of various metal oxide micro- and nanostructures. Depending on the used parameter set the structural type can be modified leading to different morphologies, e.g., interconnected net- works, core spike particles or large 1D single crystals. These resulting structures were characterized by state of the art methods to determine their crystalline, electric and piezoelectric properties. X-ray diffraction analysis revealed excellent crystalline properties and the absence of pre-strain in 1D ZnO microrods. TEM investigations showed the existence of twin boundaries in the spikes of core spike particles. Electromechanical measurements were used to demonstrate the pre- strain in ZnO microrods when attached to a plane substrate. Electromechanical measurements inside SEM allowed the precise measurement of the piezoresistive properties of individual ZnO microrods. The hydrophobic and hydrophilic wetting states of ZnO are discussed and a theoretical model is introduced which expands the common wetting theory and explains the wetting of superhydrophobic surfaces. Magnetoelectric sensors based on ZnO microrods are realized and investigated. The new concept of piezotronic measurements is applied for the sensors and is compared to the classical piezoelectric measurement concept. The comparison revealed a lower limit of detection for the piezotronic sensor, which makes it a promising candidate for new applications.