NOVEL SYNTHETIC METHODS AND CHARACTERIZATION STUDIES OF NIOBIUM-DISULFIDE IN MULTIPLE GEOMETRIES
Open Access
- Author:
- Cooper, Brian C
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 05, 2016
- Committee Members:
- Mauricio Terrones, Dissertation Advisor/Co-Advisor
Mauricio Terrones, Committee Chair/Co-Chair
Jorge Osvaldo Sofo, Committee Member
Nitin Samarth, Committee Member
Thomas E Mallouk, Outside Member - Keywords:
- NbS2
Layered Transition Metal Dichalcogenide - Abstract:
- Since the discovery of graphene, there has been a marked uptick in the rate of research conducted on layered 2D systems. Although much of this work has focused on understanding the properties of the semiconducting members of this group, earnest efforts towards gaining further insight into the physical properties of the non-semiconducting members has also been made. NbS2, a member of the latter group, offers wide spectrum of physical behavior for study as it undergoes multiple phase transitions from a metal at room temperature to a dual-band superconductor a very. At room temperature this material exhibits metallic character, while at lower temperatures in the range of 30K it undergoes a phase transition to a charge density wave state. It , and that is a undergoes several state transitions within certain temperature regimes Though the effects that quantum constraints impose on Cooper pairs limited to planar transport have been a long established area of research, it has only been in recent years that strides have been made into understanding the nature of quantum confinement on dual-band superconductors. In the contents of this thesis, I provide a thorough account of the development for a novel technique for the synthesis of NbS2 and this technique’s evolution through the careful characterization studies performed on the materials resulting from each successive trial. The thesis opens with a brief introduction and relevant historical account of the study of graphene and other 2D layered materials to provide the context from which the reader will understand the motivation for this work. Protocols and parameters developed from the first set of successful experiments, provided the backbone for a reliable synthetic technique for growth of polycrystalline NbS2. The 3R polytype of NbS2 was the overwhelmingly dominant phase within the resultant materials grown during the first trials, but the desire to produce results rich in the 2H-NbS2 polytype prompted a series of optimising experiments. The results of those optimizing trials, lead to the development of a highly reliable and robust method for the synthesis of the compound. I shall also report how these small variations to the basic experimental canon, lead to a adaptations which could produce not only materials rich in the 2H phase of NbS2, but also NbS2 crystals exhibiting various geometries.