Mechanical and Electrical Characterization of Glassy Carbon Nanofibers

Open Access
Author:
Samuel, Benedict
Graduate Program:
Mechanical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
November 04, 2009
Committee Members:
  • Md Amanul Haque, Dissertation Advisor
  • Aman Haque, Committee Chair
  • Christopher Rahn, Committee Member
  • Melik C Demirel, Committee Member
  • Stephen Jacob Piazza, Committee Member
Keywords:
  • glassy carbon
  • MEMS mechanical testing
  • carbon nanofiber
  • carbon nanowire
Abstract:
One dimensional solids are systems where two dimensions of the solid (width, breadth) are constrained to the micrometer/nanometer range (in additional they also exhibit aspect ratios higher than 100). Various forms of one-dimensional solids such as nanowires, nanofibers, nanobelts, nanoribbons and nanotubes have become the focus of extensive research primarily because of their many unique/enhanced physical properties. Commercial application of nanoscale materials is burgeoning not only because of the cost and size benefits associated with miniaturization but also because of the technological advances resulting from novel properties of nanomaterials. In recent years, research in nanoscience has shown that physical properties, such as material strength, Young's modulus, electrical conductivity etc. may not be single-valued material constants but rather scale-dependent parameters, leading to a growth in literature in characterization experiments which contrast the anomalies between nanoscale and bulk material constants of the same material. Every physical phenomenon (mechanical strength, electrical conductance etc.) has a fundamental length-scale from which it originates, and many of these length-scales fall within the micro/nanoscale which makes defining and measuring material constants length scale-dependent. One dimensional solids are prime candidates for material testing at the nanoscale since they quite often form the transition regimes from the continuum "bulk" properties to quantum mechanical "nano" effects. This dissertation limits scientific study to the narrower focus of experimental mechanical and electrical property characterization of one dimensional materials. The absence of standardized testing tools or techniques coupled with the complexities of experimental testing at the nanoscale (especially for mechanical testing), has resulted in a dearth of experimental data within the published literature (especially when compared to the amount of available computational studies at the nanoscale). The main aim of this research is to create (Micro Electro Mechanical System (MEMS)-based) tools to reliably characterize the mechanical and electrical properties of nanoscale materials. Glassy carbon nanowires are chosen as the test material system because of its widespread use as electrode materials, filtration membranes, and in size-selective catalysis. However, in reality any one dimensional solid (any nanowire, nanofiber) can be experimentally characterized using the tools and techniques presented in this dissertation.