Crystallography and Functional Evolution of Atomically Thin Confined Nanowires

Lead Research Organisation: University of Warwick
Department Name: Physics

Abstract

This project concerns the spatial and time resolved crystallography, structural refinement and functional evolution of one to four atom thick 1D 'Extreme Nanowires' formed inside single walled carbon nanotubes - atomically smooth templates that are thermally robust up to 1130 C. This project will also address the special case of nano-Confined Phase Change Materials, which have potential utility in Non-Volatile Memory and the development of thin film devices, both for fundamental properties evaluation - including several aspects of Novel Physics - but also for 'Proof of Principle' device creation for potential exploitation in thin film devices including solar cells, chemical sensors, fuel cells, batteries and catalysts, all of which may bring economic benefits.
Aims and objectives - it is expected that this project will combine many aspects of the following.
I. Synthesis and crystallography : the 3D crystallography of few-atom thick Extreme Nanowires (EN) 2-4 atoms in cross section in carbon nanotubes and also in boron nitride nanotubes will be investigated. The student will work on Ge2Sb2Te5 (GST) and some magnetic and ferroelectric formaulations.

II. 4D Crystallography : Resolving crystalline <=> glass transformations at the smallest volume scale ever attempted, establishing the lower size limit (~one nanometre cubed) at which Phase Change Materials (PCM) can be investigated and, in principle 'written'. The student will investigate the PCM GST in this context.

III. Refinement/Purification : Purification of Extreme Nanowire structures allowing the study of their functional evolution in unprecedented detail and the adaptation of their physical properties to a wide range of possible applications. The student will refine both carbon nanotube and boron nitride composites using these approaches.

IV. Thin Films/Trial Devices: Production and testing of thin films and trial devices in anisotropic films of encapsulated nanowires and nano-confined Phase Change Materials.The conductance switching characteristics will be tested in situ in a MEMS style heating/contacting TEM holders and these properties will also be tested 'ex situ' in simple in house fabricated devices for 'proof of principle' demonstrations.
All four aspects of this work will require optical testing and refinement of the host materials in collaboration with Dr. James Lloyd-Hughes
Novelty of the research methodology

This project will operate at the practical limit of scalable fabrication investigating 1D crystals as thin as a single atom in cross-section, a 'Final Frontier' of materials science and the next and ultimate lowest dimension relative to two-dimensional structures such as graphene or '2D' analogues.
Alignment to EPSRC's strategies and research areas (see https://www.epsrc.ac.uk/research/ourportfolio/themes/) Broadly speaking, this project addresses the EPSRC Grand Challenges 'Nanoscale Design of Functional Materials' but the quantum size scale and non-equilibrium architecture of these extreme objects will impact on other Grand Challenges, including 'Quantum Physics for New Quantum Technologies'and 'Emergence and Physics Far From Equilibrium.' This studentship was also awarded in by the Department of Physics in support of the awarded EPSRC funded project 'Crystallography and Functional Evolution of Atomically Thin Nanowires' awarded to Dr J Sloan in Warwick (i.e. EP/R019428/1)

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R513374/1 01/10/2018 30/09/2023
2270318 Studentship EP/R513374/1 30/09/2019 31/03/2023 Kiran Bal