No description available.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 155-159). Available also in a digital version from Dissertation Abstracts.

Zinc oxide (ZnO) crystal with a direct wide band gap (3.37 eV) and large excition binding energy (60 meV) is one of the most potential semiconductors in numerous application fields such as room-temperature UV-Iaser, light-emitting- diode (LED), photocatalyst, gas sensor, solar cell, piezoelectric device, etc. In past decades, different methods have been investigated to produce a variety of different shapes of nano and submicron ZnO nanostructures. Among them, the ZnO nanobelts (NBs) with a rectangular cross section have unique optoelectronic properties due to its unusual shape and structure. It is well demonstrated by recent success in field-effect transistor, nanoresonator, and spintronics applications of the ZnO NBs. Two-dimensional (2D) nanostructures such as nanosheets (NSs) and thin films have also great potential for unique purposes where a large uniform coverage at nanoscale is essential. One of the conventional methods for synthesis of the ZnO nanostructures is vapour transport and condensation process at high temperature, in some cases up to 1400°C. Such an extreme condition for vaporization of precursor could induce many oxygen defects on surface of the ZnO nanobelts. These specific defects hinder progress to the applications of ZnO in optoelectronic and lasing devices. In this respect, mild processing is strongly demanded for the synthesis of the ZnO nanoparticles. In terms of low energy consumption and simplicity, soft- solution process based on hydrothermal reactions at low temperature (under 100°C) is a green chemical procedure. However, there are only few reports on the synthesis of the ZnO NBs and NSs due to their unusual growth habit against typical growth rate of the ZnO crystal. Here we are reporting a developed simple, low cost and high yield hydrothermal technique to synthesis layered basic zinc acetate (LBZA) NBs and also a novel rapid microwave-assisted hydrothermal technique to grow LBZA NSs only in 2 minutes. Growth procedures are followed by pyrolytic decomposition to produce nanocrystalline NBs and NSs. SEM and AFM results revealed that the morphology and quantity of the nanobelts and nanosheets are strongly temperature and pH dependent. In addition, results showed that as-grown LBZA nanostructures could be easily transformed to corresponding ZnO nanostructures through pyrolytic decomposition without.

Magister Scientiae - MSc / The objective of this research was to develop highly efficient and yet effective MnO2 electrode materials for supercapacitors applications. Most attention had focussed on MnO2 as a candidate for pseudo-capacitor, due to the low cost of the raw material and the fact that manganese is more environmental friendly than any other transition metal oxide system. The surface area and pore distribution of MnO2 can be controlled by adjusting the reaction time. The MnO2 synthesised under optimum conditions display high capacitance, and exhibit good cycle profile. This work investigates the ways in which different morphological structures and pore sizes can affect the effective capacitance. Various -MnO2 were successfully synthesised under low temperature conditions of 70 oC and hydrothermal conditions at 120 oC. The reaction time was varied from 1 to 6 hours to optimise the conditions. KMnO4 was reduced by MnCl.H2O under low temperature, whereas MnSO4.4H2O, (NH4)2S2O8 and (NH4)2SO4 were co-precipitated under hydrothermal conditions in a taflon autoclave to synthesise various -MnO2 nano-structures. / South Africa

No description available.

The objective of this thesis is to present a modelling and simulation study for the mechanics of PNs with an emphasis placed on the unique features of PNs due to the piezoelectric and small scale effects.

Thesis (Ph.D.)--Victoria University of Wellington, 2007. / Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 150-153).

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy