2025-04

Transactions on Electrical and Electronic Materials

This study investigates the structural, electronic, and optical properties of tetragonal-phase RbGeA2X (A = Br, Cl; X = Br, I) lead-free mixed halide perovskites using density functional theory (DFT) with PBE-GGA for exchange-correlation energy. These perovskites show enhanced properties, including high charge carrier mobility, tunable direct band gaps, and strong ultra-violet (UV) absorption. Band structure and density of states (DOS) analyses highlight their suitability for optoelectronic applications. Optical studies of the dielectric function and absorption coefficient of the studied structures confirm their ability to absorb electromagnetic radiation beyond the visible spectrum, making them promising candidates for advanced (UV)-range optoelectronic devices.

2025-02

PloS one (Issue : 2) (Volume : 20)

In this study, the structural, electronic and optical properties of cubic lead-free halide perovskites LiSnX₃ (X = Br and Cl) under hydrostatic pressure are investigated. The first-principle approach based on density functional theory (DFT) is employed. The exchange-correlation functional is treated using the generalized gradient approximation (GGA), specifically a variant of the Perdew–Burke–Ernzerhof (PBE) method. The aim of the study is to understand the effect of pressure on the properties of LiSnX₃ (X = Br and Cl), with a maximum pressure limit of 6 GPa. The results show a decreasing tendency in the energy band gap as pressure increases. In addition, a prominent reduction in the energy band gap is observed when the halogen atom is changed from Cl to Br under constant pressure. The calculations also investigate the density of states (DOS), showing variations in energy levels near the Fermi level under different pressures. For optical properties, density functional perturbation theory (DFPT) is used in conjunction with the Kramers-Kronig relation. Optical parameters such as the real and imaginary parts of the dielectric constant, refractive index, absorption coefficient, and wavelength are computed under different pressures to understand the optical response of the perovskites to the electromagnetic spectrum. The insights from this study highlight the fundamental properties of LiSnX₃ (X = Br and Cl) under different pressures, which could influence advancements in optoelectronic devices, photonic applications, and solar cell technologies. Moreover, this research contributes to the growing body of knowledge on lead-free halide perovskites

2024-12

Journal of Sensor and Actuator Networks (Issue : 6) (Volume : 13)

In spite of the development in technology and the recent innovations in dentistry, dental anxiety remains a common issue, and accurately assessing it is challenging due to reliance on patients’ self-reports, which are often biased. Hence, this study was undertaken to determine whether dental anxiety can be quantified objectively using the EDA parameters. EDA (skin conductance (SC), skin susceptance (SS), and skin potential (SP)) parameters and heart rate (HR) were recorded from 40 participants during two different sessions (baseline and anxiety). In addition, the Modified Dental Anxiety Scale (MDAS) scale was also used to record the level of anxiety. The physiological data from EDA and HR were compared with the subjective self-reports of anxiety provided on the MDAS to show whether higher EDA and HR readings correspond to higher scores on the MDAS. To elicit dental anxiety, participants were exposed to several film clips associated with dental treatment. EDA signals were compared between the two sessions for all clips and all EDA scores. SC and HR significantly (p < 0.05) increased during the anxiety session compared to the baseline session. The number of fluctuations per minute in the SC, SS, and SP notably increased during the anxiety session. The MDAS results revealed that the participants had dental anxiety when they were exposed to video clips of dental procedures. The study results imply that EDA parameters could be used as a useful tool to monitor dental anxiety, in particular in young children and non-verbal patients or those with intellectual disabilities, which may aid the dentist in the successful management of dental

2024-12

Semiconductor Physics, Quantum Electronics & Optoelectronics (Issue : 4) (Volume : 27)

Pseudopotentials and density functional theory (DFT) implemented in the ABINIT code were used to study the properties of the GaSb cubic alloy zinc-blende structure. Both the local density approximation and the generalized gradient approximation were used for the exchange-correlation (XC) potential calculation. The calculated lattice parameter aligns well with available experimental and theoretical results. Elastic constants, Young’s modulus, shear modulus, and anisotropy factor were determined, and the pressure dependence of elastic constants was investigated. Band gaps were initially calculated but showed discrepancies with experimental values due to the known band gap problem of DFT. To enhance accuracy, the Green function and screened Coulomb interaction approximation were introduced. The impact of thermal effects on compound properties was investigated using the quasi-harmonic Debye …

2023-09

Sensors (Issue : 19) (Volume : 23)

Electrodermal activity (EDA) usually relates to variations in the electrical properties of palmar or plantar skin sites. EDA responses, namely skin conductance responses (SCRs), skin potential responses (SPRs) and skin susceptance responses (SSRs) are shown to be sensitive indexes of sympathetic nervous system activation and are studied in many research projects. However, the association between EDA responses and the five basic human senses has not been investigated yet. Our study aimed to explore the relationship between the three EDA responses (SCRs, SSRs and SPRs) and the five basic human senses. These three EDA responses were measured simultaneously at the same skin site on each of the 38 volunteers. The tested five senses were sight, hearing, touch, taste and smell. The results showed that the different tested senses led to different degrees of EDA responses due to activation of the sympathetic nervous system and corresponding secretion of sweat. Although a controlled study on the degree of EDA as a function of the strength of each stimulus was not performed, we noted that the largest EDA responses were typically associated with the smell sense test. We conclude that EDA responses could be utilized as measures for examining the sensitivity of the human senses. Hence, EDA devices may have important roles in sensory systems for future clinical applications.

2023-01

Science Journal of University of Zakho (Issue : 1) (Volume : 11)

The Successive Ionic Layer Adsorption and Reduction (SILAR) method was utilized to produce nanostructured silver thin films on a glass substrate. Ag nanoparticles were grown using SILAR parameters such as silver nitrate (AgNO 3), reduction time, reduction agent in an aqueous solution of hydrazine hydrate with various concentrations, and growth cycles. In this study, X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible-NIR absorption spectroscopy techniques were used to assess the produced silver thin film nanostructure. The size and spreading of the formed silver nanoparticles are observed to grow with the reducing agent and eventually saturate for constant growth cycles. As a result, the size and the distribution of the produced Ag nanoparticles grow uniformly. Higher growth cycles, however, caused Ag nanoparticles to lose their homogeneity and change into gravel-shaped particles. Therefore, silver nanoparticles that have been produced with the ideal SILAR conditions can be employed as an extremely sensitive, repeatable substrate with an exceptionally efficient factor. Moreover, the Effect of the concentration of HyH on the properties of SILAR-grown silver thin films has been extensively studied.

2014-07

Eastern Mediterranean University (EMU)-Doğu Akdeniz Üniversitesi (DAÜ) (Issue : 11) (Volume : 4)

In this study we consider two different and particular quantum systems. The first system is a one-dimensional particle confined within an infinite well with the left wall at rest and the right wall moving with or without acceleration. This is a quantum configuration with time-dependent Hamiltonian where the conservation of energy does not hold anymore. Our task in this problem is to solve the correspondence time dependent Schrödinger equation and find the energy eigenvalues and eigenfunctions. The second system is a particle which undergoes a modified radial attraction force in two dimensions. The modification is such that the corresponding potential depends on not only the radial coordinate but also the polar angle. We find the energy spectrum of the particle and using the concept of coherent states, we show that the classical trajectory of a classical particle directed by a similar radial potential is almost the same as the predicted probability density of the quantum particle by the coherent states. Keywords: One-dimensional infinite well, Time-dependent potential, Exact solution, Coherent state.