Thin-film piezoelectric-on-substrate resonators and narrowband filters

A new class of micromachined devices called thin-film piezoelectric-on-substrate (TPoS) resonators is introduced, and the performance of these devices in RF and sensor applications is studied. TPoS resonators benefit from high electromechanical coupling of piezoelectric transduction mechanism and superior acoustic properties of a substrate such as single crystal silicon. Therefore, the motional impedance of these resonators are significantly smaller compared to typical capacitively-transduced counterparts while they exhibit relatively high quality factor and power handling and can be operated in air. The combination of all these features suggests TPoS resonators as a viable alternative for current acoustic devices. In this thesis, design and fabrication methods to realize dispersed-frequency lateral-extensional TPoS resonators are discussed. TPoS devices are fabricated on both silicon-on-insulator and thin-film nanocrystalline diamond substrates. The performance of these resonators in simple and low-power oscillators is measured and compared. Furthermore, a unique coupling technique for implementation of high frequency filters is introduced in which dual resonance modes of a single resonant structure are coupled. The measured results of this work show that these filters are suitable candidates for single-chip implementation of multiple-frequency narrow-band filters with high out-of-band rejection in a small footprint.Ph.D.Committee Chair: Farrokh Ayazi; Committee Member: James D. Meindl; Committee Member: John D. Cressler; Committee Member: Nazanin Bassiri-Gharb; Committee Member: Oliver Bran

Micro-Resonators: The Quest for Superior Performance

Microelectromechanical resonators are no longer solely a subject of research in university and government labs; they have found a variety of applications at industrial scale, where their market is predicted to grow steadily. Nevertheless, many barriers to enhance their performance and further spread their application remain to be overcome. In this Special Issue, we will focus our attention to some of the persistent challenges of micro-/nano-resonators such as nonlinearity, temperature stability, acceleration sensitivity, limits of quality factor, and failure modes that require a more in-depth understanding of the physics of vibration at small scale. The goal is to seek innovative solutions that take advantage of unique material properties and original designs to push the performance of micro-resonators beyond what is conventionally achievable. Contributions from academia discussing less-known characteristics of micro-resonators and from industry depicting the challenges of large-scale implementation of resonators are encouraged with the hopes of further stimulating the growth of this field, which is rich with fascinating physics and challenging problems

Effect of antimony addition relative to microstructure and mechanical properties of continuous cast lead alloy

It is well documented that the addition of antimony in pure lead increases tensile strength and reduced elongation. The goal of the present work is to identify the cause of these phenomena by investigation of the effects of the addition of Sb (1.25 wt.%) on the structure of pure continuously cast lead and lead alloy rods. The microstructure and morphology of both pure lead and lead with 1.25 wt.% antimony were examined by digital optical microscope and scanning electron microscope respectively. Energy Dispersive X-ray Spectroscopy (EDX) was used to identify alloying elements. The results showed that the effect of additions of antimony on mechanical properties of lead-antimony alloys is mainly due to the solid solubility of the antimony. Distribution of the antimony results in a decrease in the grain size of the pure lead. These smaller grains mean higher strength so long as there is a homogeneous grain structure.</p

Analysis and quantification of mechanical properties of various DHP copper tubes manufacturing processes using drift expanding test

Deoxidized High Phosphorus (DHP) Copper tubes are frequently used in numerous industrial and household applications. To ensure the acceptability of DHP copper tubes prepared by various industrial processes, the quality of the DHP copper tubes must be evaluated. Drift expanding test is one of the best ways to do so is to examine the quality of tubes. In this paper the authors considered the mechanical properties of various DHP copper tubes manufacturing processes using drift expanding test. This paper concludes that there is a large difference in the mechanical properties of tubes with different manufacturing methods. Planetary rolling have a better expanding percentage than cast or extruded tube samples.</p

Influence of casting speed on the structure and mechanical properties of continuous cast DHP copper tube

DHP Copper tubes are frequently used in industrial applications with their unique characteristics such as high corrosion or excellent erosion resistance. Due to the requirement of good quality production, an excellent global factor is needed for the purpose of obtaining high mechanical properties. A mechanical properties has correlation with grain size and a high mechanical properties is achieved by small grain structure. There are three ways in which grain size can be altered: by thermal means, chemical means and by mechanical means. This paper looks at the first case, thermal means, which has very substantial cost benefits over the other two types of grain refinement in that it does not require large pieces of equipment that vibrate or mix and does not use any exotic metals as feed stock. Instead what thermal methods require is a change in parameters like: casting speed, liquid metal temperature or cooling water temperature. In this work, characterization of the influence of casting speed on the structure and mechanical properties of continuous cast DHP copper tube has been carried out by drift expanding test and grain size reading. A significant different based on grain structure has been investigated and it was also found that the casting speed could improve the elongation of samples from 29 % expanding to 36 % expanding