arXiv subjects

Swastik Mondal

Publications and source records attributed to Swastik Mondal.

3 recordsLinked to original sources

arXiv2024

Discovery of magnetic field line dependent anisotropic chemiresistive response in Magnetite: A new piece to the puzzle of magnetoreception

Chemiresistive materials, which alter their electrical resistance in response to interactions with surrounding chemicals, are valued for their robustness, rapid detection ability and high sensitivity. Recent research has revealed that the sensing performance of these materials can be enhanced by applying an external magnetic field. In this study, we report a novel finding in the chemiresistive behavior of magnetite (Fe3O4), where its response has been found to be modulated in an anisotropic manner when exposed to an external magnetic field, analogous to Earth's magnetic field. Remarkably, substantial variations have been observed in response to analytes naturally present in the atmosphere. This chemiresistive response exhibits a strong anisotropic dependence on the strength, direction and inclination of the magnetic field, suggesting that magnetite's electrical resistance dynamically adapts to both magnetic and chemical environmental changes. The observed behavior under Earth-like magnetic field closely mirrors the magnetoreception seen in migratory species that rely on magnetite for navigation. This finding may provide new insights into the mechanisms behind magnetite-based magnetoreception observed in various biological species.

physics.chem-ph↗

arXiv2022

High-resolution surface structure determination from bulk X-ray diffraction data

The key to most surface phenomenon lies with the surface structure. Particularly it is the charge density distribution over surface that primarily controls overall interaction of the material with external environment. It is generally accepted that surface structure cannot be deciphered from conventional bulk X-ray diffraction data. Thus, when we intend to delineate the surface structure in particular, we are technically compelled to resort to surface sensitive techniques like High Energy Surface X-ray Diffraction (HESXD), Low Energy Electron Diffraction (LEED), Scanning Transmission Electron Microscopy (STEM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS). In this work, using aspherical charge density models of crystal structures in different molecular and extended solids, we show a convenient and complementary way of determining high-resolution experimental surface charge density distribution from conventional bulk X-ray diffraction (XRD) data. The usefulness of our method has been validated on surface functionality of boron carbide. While certain surfaces in boron carbide show presence of substantial electron deficient centers, it is absent in others. Henceforth, a plausible correlation between the calculated surface structures and corresponding functional property has been identified.

cond-mat.mtrl-sci↗

arXiv2021

Material surface -- analyte interactions with similar energy rates vary as univariate quadratic function of topological polar surface area of analytes

Material surface - analyte interactions play important roles in numerous processes including gas sensing. However, the effects of topological polar surface area (TPSA) of analytes on surface interactions during gas sensing have been so far largely disregarded. In this work, based on experimental observations on changes in electrical resistance of cadmium sulphide (CdS) due to surface interactions during gas sensing, we found that unexpected univariate quadratic correlation exists between changes in resistance of CdS and TPSA of analytes. Further experiments on four other material systems showed the same trend, revealing a generalized picture of TPSA dependence of surface interactions.

physics.chem-ph↗