You are cordially invited to the Ph.D. Thesis Defense Presentation
“Discovery of Low-Dimensional Solid-State Ionic Conductors”
Amir Parsi, Ph.D. Student in Materials Science and Nanotechnology Graduate Program
Abstract: Understanding intrinsic ion transport in solids is essential for developing next-generation energy, memory, and neuromorphic technologies. However, grain boundaries and structural disorder in conventional materials often obscure the underlying mechanisms. This dissertation addresses this challenge by investigating cation-driven phase transitions in low-dimensional single crystals. Using a custom-built real-time optical chemical vapor deposition (RTO-CVD) platform, four model systems—AgI, Na-MnO2, KxWO3, and Cu2-xSe—are studied to reveal how confined ionic motion enables reversible and tunable transformations.
In this thesis, I demonstrate the growth of single-crystalline β-AgI nanoflakes exhibiting superionic conductivity and filamentary memristive switching driven by Ag+ migration. I further show that intrinsically Na+-intercalated δ-MnO2 nanosheets display moisture-sensitive ionic transport and reversible structural transformations that enable neuromorphic behavior. Through studies of single-crystalline KxWO3 nanobelts, I reveal how electric-field-driven K+ redistribution within one-dimensional tunnels gives rise to bipolar resistive switching and analog conductance modulation. Finally, I investigate Cu2-xSe crystals, where liquid-like Cu+ mobility produces an ion-mediated insulator–metal transition and contact-dependent photothermal responses linked to vacancy ordering and interfacial effects.
Taken together, the results presented in this thesis provide experimental insight into ion-mediated transformations in low-dimensional materials and highlight the unique advantages of single-crystal platforms for studying intrinsic ionic processes. The findings establish a foundation for the design of future ionic and mixed ionic–electronic devices, including solid-state memristors, neuromorphic systems, and reconfigurable optoelectronic technologies.
Keywords: Solid-State Ionics, Real-Time Optical Chemical Vapor Deposition (RTO-CVD), Single-Crystalline AgI Nanoflakes, Intrinsically Intercalated Na–MnO2 Nanosheets, Single-Crystalline KxWO3 Nanobelts, Cu2-xSe Mixed Ionic–Electronic Conductor
Supervisor: Dr. Aykut Erbaş
Co-Supervisor: Dr. T. Serkan Kasırga
Date: Thursday, June 25, 2026
Time: 13:00
This is an online seminar. To request event details please send a message to department.