arXiv subjects

Ihsan Caha

Publications and source records attributed to Ihsan Caha.

3 recordsLinked to original sources

arXiv2026

Chemical transformation of MgH2/V2O5 composite to Mg-V-O rock salt and its influence on the electrochemical Li conversion and hydrogen storage characteristics of MgH2

This study investigates the lithium conversion behavior of a hydrogen storage material based on vanadium oxide added magnesium hydride. To understand the chemical interaction between vanadium oxide and magnesium hydride, detailed X ray diffraction and X ray photoelectron spectroscopy analyses were performed on ball milled composites with varying compositions. The results confirm the formation of a combined magnesium vanadium oxide with a rock salt structure, indicating strong chemical interaction between the components. It is further shown that the presence of a small amount of this oxide additive significantly influences the lithium reaction with magnesium hydride, leading to a high initial discharge capacity and limited recharge capacity in lithium ion coin cells. Post use analyses confirm the presence of magnesium hydride, suggesting that volume expansion is not responsible for the observed irreversibility. Electrochemical impedance spectroscopy using differential function of relaxation times indicates that electrolyte degradation is not a major issue. Instead, slow charge transfer processes are identified as the limiting factor, and these are sensitive to the composition of the additive. These findings highlight that improving electrode and electrolyte compatibility is essential for enhancing performance in this system.

cond-mat.mtrl-sci↗

arXiv2025

Confinement-Controlled Morphology and Stability of One-Dimensional CrI3 Nanotubes

Integrating monolayers derived from 2D van der Waals (vdW) magnetic materials into next-generation technological applications remains a significant challenge due to their structural and magnetic instability issues. Template-assisted encapsulation is a potential route for the growth of stable 2D monolayers aimed at designing novel 1D heterostructures, opening new avenues for studying low-dimensional quantum effects and spin-related phenomena. In this study, we explored the diameter-dependent encapsulation of 2D CrI3 crystals using multi-walled carbon nanotubes as nanoscale host templates. Advanced microscopic analysis revealed distinct structural transitions, ranging from internal nanorod encapsulation to external shell formation, directly influenced by the host nanotube diameter. Furthermore, statistical analysis of structural morphologies indicates that CrI3 nanorods preferentially form within MWCNTs with inner diameters up to 5 nm, while single-walled CrI3 nanotubes are stabilized in CNTs with diameters up to 8 nm. For host CNTs exceeding 10 nm in diameter, CrI3 predominantly forms surface coatings rather than confined one-dimensional structures. In situ electron beam irradiation demonstrates the superior structural stability of single-walled CrI3 confined within MWCNTs, while externally coated CrI3 undergoes decomposition into metallic Cr clusters. Prolonged irradiation induces a morphological transformation of CrI3 nanotubes into nanorods. These insights lay the groundwork for engineering robust, tunable 1D magnetic heterostructures of CrI3 for spintronic and data storage applications.

cond-mat.mtrl-sci↗

arXiv2024

Magnetic single wall CrI3 nanotubes encapsulated within multiwall Carbon Nanotubes

CrI3 is a layered ferromagnetic insulator that has recently attracted enormous interest as it was the first example of a stand-alone monolayer ferromagnet, paving the way towards the study of two-dimensional magnetic materials and their use as building blocks of hybrid van der Waals layered heterostructures. Here we go one step down in the dimensionality ladder and report the synthesis and characterization of a tubular one-dimensional van der Waals heterostructure where CrI3 nanotubes are encapsulated within multiwall carbon nanotubes, integrating a magnetic insulator and a conductor. By means of the capillary filling of multi-wall carbon nanotubes (MWCNT), we obtained single-wall CrI3 nanotubes with diameters ranging between 2 nm and 10 nm, with an average of 5.3 nm. Using aberration corrected electron microscopy in combination with spectroscopic techniques we confirm the structure and chemical composition of the nanotubes. SQUID measurements, combined with element-specific X-ray magnetic circular dichroism (XMCD) indicate unequivocally that the Cr atoms in encapsulated CrI3 nanotubes are magnetic with a collective state compatible with a radial magnetization state predicted both by first-principles calculations and a model Hamiltonian. Our results represent a step forward in establishing 1D van der Waals heterostructures as a playground for the exploration of non-collinear magnetic states arising from the interplay between magnetic anisotropy and curvature in tubular geometries.

cond-mat.mtrl-sci↗