arXiv subjects

Marcilei A. Guazzelli

Publications and source records attributed to Marcilei A. Guazzelli.

3 recordsLinked to original sources

arXiv2026

Resilience of the physicochemical properties of graphene-based materials for applications in harsh radiation environments

The development of radiation-tolerant materials capable of maintaining structural, electrical, and thermal stability in extreme, radiation-rich environments remains a critical challenge in materials science. In this work, the effects of 60 MeV 35Cl ion irradiation on highly oriented pyrolytic graphite (HOPG) and multilayer reduced graphene oxide (ML-rGO) were investigated. The samples were exposed to fluences of 5.11 x 10^9 and 1.3 x 10^10 ions/cm^2 and characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrical transport measurements. The results show that the irradiation response is strongly influenced by the initial structural organization of the material. In HOPG, ion exposure leads to a progressive loss of crystalline order, evidenced by XRD peak broadening and an increase in the Raman ID/IG ratio, accompanied by a reduction in electrical transport performance. In contrast, ML-rGO exhibits distinct behavior at higher fluences, suggesting partial structural reorganization. The appearance of more defined graphitic features in XRD and Raman analyses, along with changes in surface morphology and electrical response, suggests the formation of more ordered sp2 domains. These findings indicate that irradiation effects vary with the initial degree of order, providing useful insights for selecting carbon-based materials for devices operating under severe radiation conditions.

cond-mat.mtrl-sci↗

arXiv2025

Quantum Machine Learning Applied to the Sinking of the Titanic

This work investigates the performance of hybrid quantum-classical variational classifiers applied to a supervised learning task involving the titanic3 dataset. Quantum models were constructed using Pauli entangling and non-entangling expansion-based feature maps and the RealAmplitudes ansatz with up to 50 variational parameters. Model training employed the COBYLA gradient-free optimizer to minimize the cross-entropy loss, within an ideal statevector simulation framework. Comparative performance analysis reveals that the models based on the non-entangling feature map consistently outperformed the models based on the entangling features maps, achieving saturation of classification metrics (accuracy, balanced accuracy, and Youden's index) beyond 15 to 20 parameters. Further, two quantum models were benchmarked against a classical Support Vector Classifier (SVC). While both approaches yielded similar predictive performance across multiple training sizes, the classical model exhibited a performance collapse when trained with 90% of the dataset, a failure mode absent in the quantum classifiers. These results underscore the robustness and viability of variational quantum classifiers for binary classification tasks on classical datasets in the NISQ era.

quant-ph↗

arXiv2024

Effects of Neutron Radiation on the Thermal Conductivity of Highly Oriented Pyrolitic Graphite

Highly Ordered Pyrolytic Graphite (HOPG) has been extensively researched due to its chemical and physical properties that make it suitable for applications in several technologies. Its high thermal conductivity makes HOPG an excellent heat sink, a crucial characteristic for manufacturing targets used in nuclear reactions, such as those proposed by the NUMEN project. However, when subjected to different radiation sources, this material undergoes changes in its crystalline structure, which alters its intended functionality. This study examined HOPG sheets before and after exposure to a 14 MeV neutron beam. Morphological and crystallographic analyses reveal that even minor disruptions in the high atomic ordering result in modifications to its thermal properties. The results of this study are essential to establish the survival time of the HOPG used as thermal interface material to improve heat dissipation of a nuclear target to be bombarded by an intense high-energy heavy-ion beam.

cond-mat.mtrl-sci↗