Papers by Ali Hossain
Materials Science in Semiconductor Processing, 2021
This report aims to demonstrate the plane wave pseudopotential approached ab initio computation b... more This report aims to demonstrate the plane wave pseudopotential approached ab initio computation based on density functional method integrated within semi-classical Boltzmann transport theory to investigate the pressure induced electronic, optical and thermoelectric properties of LiAeH 3 (Ae = Ca, Sr, Ba) perovskite hydrides. The computed electronic structures of these compounds possess indirect band gaps with mixed covalent and ionic bonding in the whole range of studied pressure (0-50 GPa) in which the band gaps of LiCaH 3 decrease while those of LiSrH 3 and LiBaH 3 increase as the pressure increases. The rational analyses of optical spectra devote these perovskites to optoelectronic applications. For instance, the investigated hydrides reveal plasmonic excitation owing to their unique loss spectra, which are significant in optical sensing devices. The estimated electronic and optical parameters are compared, whenever possible, to the available results and found a reasonable agreement among them. To further assess physical behavior, the pressure and temperature dependent thermoelectric properties in terms of Seebeck coefficients, thermal conductivities, electrical conductivities, power factors and figure of merits are carried out first time as implemented in the BoltzTraP code. The estimated positive Seebeck coefficients of the studied perovskites exhibit p-type semiconducting nature, and thus holes are the majority charge carriers for conduction rather than electrons. The large figure of merits and small thermal to electrical conductivity ratios disclose their suitability in thermoelectric device applications.
Results in Chemistry, 2025
Borazine and its derivatives have significant appeal due to their utility as precursors for synth... more Borazine and its derivatives have significant appeal due to their utility as precursors for synthesizing hexagonal boron nitride sheets, which are isostructural to graphene with a wide bandgap, making them promising materials for advanced technological applications. This report demonstrates the electronic structures, reactivity, and thermodynamic properties of borazine and its derivatives utilizing the density functional theory. Borazine and its alkyl- and halide-substituted derivatives, trichloroborazine, trifluoroborazine, trimethylborazine, and triethylborazine, have been thoroughly investigated. The molecular geometries have been optimized, satisfying the convergence criteria and frequency calculations to assess their stability. No imaginary frequencies are found, confirming the stable structure of these molecules. The electronic structures and chemical reactivity are analyzed by examining their frontier molecular orbitals. Halide-substituted derivatives exhibit higher stability than alkyl-substituted ones, while reactivity follows an inverse trend. Additionally, the thermodynamic parameters have been computed over the temperature range of 100–1000 K. All thermodynamic parameters increase with increasing temperature, except Helmholtz free energy change, which decreases with increasing temperature. The change in Helmholtz free energy is found to be positive at low temperatures and becomes negative at higher temperatures in some instances, suggesting the shift of reaction kinetics from non-spontaneous to spontaneous at higher temperatures. The findings will be valuable for understanding the reaction kinetics and for advancing knowledge in developing synthetic routes for boron nitride-based nanostructures and devices.
Computational Condensed Matter, 2023
A systematic ab initio study within the density functional theory is employed to investigate the ... more A systematic ab initio study within the density functional theory is employed to investigate the structural, mechanical, elasto-acoustic, and anisotropic properties of AePdH3 (Ae = Ca, Sr, Ba) perovskites. A close agreement is found, while comparing the calculated ground state structural parameters with available results. The estimated results of formation and cohesive energy indicate that the presented hydrides are energetically stable and synthesizable. The pressure induced elastic stiffness constants revealed that the studied hydrides are mechanically stable with satisfying the Born stability criteria. The pressurized mechanical properties are evaluated in estimating the elastic constants by the stress-strain method formulating the Voigt-Reuss-Hill approximation. In view of Poisson's ratio, Pugh's ratio, and Cauchy pressure, all perovskites behave as ductile and soft manner. Utilizing elastic moduli, Debye temperatures along with isotropic acoustic velocities as a function of pressure are discussed in depth. The anisotropy is explained by means of elastic anisotropy factors, three-dimensional (3D) elastic moduli, acoustic sound velocities, and minimum thermal conductivities. According to all indexes, all perovskites are exhibited anisotropic nature except 3D contour plots of linear compressions, isotropic instead, and the maximum anisotropy is achieved in BaPdH3 hydrides.
Journal of Physics: Materials, 2024
Atomic layer deposition (ALD) based on polymer-derived ceramics (PDCs) chemistry is used for the ... more Atomic layer deposition (ALD) based on polymer-derived ceramics (PDCs) chemistry is used for the fabrication of boron nitride thin films from reaction between trichloroborazine and hexamethyldisilazane. The transposition of the PDCs route to ALD is highly appealing for depositing ceramics, especially non-oxide ones, as it offers various molecular precursors. From a two-step approach composed of an ALD process forming a so-called preceramic film and its subsequent ceramization, conformal and homogenous BN layers are successfully synthesized on various inorganic substrates. In the first stage, smooth polyborazine coatings are obtained at a temperature as low as 90 °C. The saturation and self-limitation of the ALD gas-surface reactions are verified. Intriguingly, three ALD windows seem to exist and are attributed to change in ligand exchange. After the ceramization stage using a heat treatment, conformal near-stoichiometric BN layers are obtained. Their structure in terms of crystallinity can be adjusted from amorphous to well-crystalline sp2 phase by controlling the treatment temperature. In particular, a crystallization onset occurs at 1000 °C and well defined sp2 crystalline planes oriented parallel to the surface are noted after ceramization at 1350 °C. Finally, side-modification of the substrate surface induced by the thermal treatment appears to impact on the final BN topography and defect generation.
Materials Science And Engineering: B, Mar 1, 2020
This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of... more This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of spinel CoFe 2 O 4 using generalized gradient approximation (GGA). Both the spin and non-spin polarized density functional theory (DFT) have been used to study the influence of spin interactions on electronic structures, spin magnetic moments, and optical properties. The calculated magnetic moments of CoFe 2 O 4 from spin density of states are 6.98 μ B per formula unit. The Fe and Co ions prefer high spin orientations owing to the cationic polarization because of crystal field strength and intra-atomic exchange interactions, which induces large spin magnetic moments. The high values of spin magnetic moments confirm strong spin orbit coupling due to strong electron-electron interactions and can be a promising for spintronic application. Moreover, the calculated high reflectivity of CoFe 2 O 4 material (~100%) in the Infrared-Visible-Ultraviolet region up to~30 eV, which suggesting that the CoFe 2 O 4 can also be a good candidate for solar reflector.
Journal of Physics: Conference Series, 2018
View the article online for updates and enhancements. You may also like Facile synthesis and char... more View the article online for updates and enhancements. You may also like Facile synthesis and characterisations of cobalt ferrite-silver-graphene oxide nanocomposite in enhancing electrochemical response capacity
Applied Physics A, Aug 13, 2018
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Engineering Physics, 2019
The ground state electronic structures and optical properties of FeCo alloy have been reported us... more The ground state electronic structures and optical properties of FeCo alloy have been reported using plane wave ultrasoft pseudopotential based on spin polarized density functional theory through first principles study. The crystallographic structure of FeCo consists with body-centered cubic lattice that is described in space group Im-3m (229). The geometry is optimized with zero applied pressure and the optimized lattice constant is found to be 2.854Å. The electronic energy bands represent the overlapped between valence and conductance electronic states and confirm zero forbidden gaps i.e. metallic nature of the FeCo alloy. The Fermi surfaces manifest the anisotropic features of electronic energy dispersion along the high symmetry directions (X-R-M-G-R) of the Brillouin zone. The total density of states arises from the contribution of the electronic states of Co and Fe atoms. The calculated spin magnetic moments of FeCo alloy is 1.26µ B. The spin magnetic moments mainly come from the exchange interactions among electronic spins, which confirms the strong electron-electron interactions. Moreover, the optical properties are computed which also attest the metallic behavior of the material. The optical measurements indicate that FeCo alloy is an optically anisotropic material. The obtained loss spectrum reveals the plasmonic excitations that is important for many magneto-optical applications.
OSA Continuum, 2019
The nonlinear optical properties of Rh-Pd and Rh-Pt solid-solution alloy nanoparticles (NPs) were... more The nonlinear optical properties of Rh-Pd and Rh-Pt solid-solution alloy nanoparticles (NPs) were experimentally investigated by means of the z-scan technique. The open aperture (OA) measurement showed a reverse saturable behavior, whereas the closed aperture (CA) measurement showed a peak-and valley-shape. Both the Rh-Pd and Rh-Pt NPs exhibited a positive nonlinear optical index of refraction at 800 nm relating to the self-focusing phenomenon. In addition, the nonlinear absorption of the Rh-Pt NPs (4.39 × 10 −12 cm/W) was higher than that of the Rh-Pd NPs (1.63 × 10 −12 cm/W) due to the small interval between the occupied and unoccupied density of states (DOS) of Rh-Pt than Rh-Pd. The nonlinear responses of the Rh-Pd and Rh-Pt NPs was attributed to the hot electron contribution and the reverse saturation of intraband and interband transitions.
Micro-Raman Investigations with Surface Mapping of CVD Grown Graphene on Different Substrates
Solid State Communications, 2021
Density functional theory based first-principles investigation on structural, elastic, ultrasonic... more Density functional theory based first-principles investigation on structural, elastic, ultrasonic and thermodynamic properties of cubic perovskite hydrides XLiH3 (X = Ba, Sr, Ca) at ambient and high pressures is reported in this study. The evaluated structural parameters of the titled hydrides are in agreement with available experimental and theoretical results. The influences of hydrostatic pressure on single-crystal and subsequent polycrystalline elastic parameters along with different mechanical properties are discussed in detail. The calculated ultrasonic velocities, Debye temperatures (ΘD) and minimum thermal conductivities (κmin) increase monotonically with increasing pressure for each hydride. The increase of both ΘD and κmin along BaLiH3→SrLiH3→CaLiH3, and the estimated Vickers hardness indicate that CaLiH3 is the hardest among these hydrides. The relatively low values of κmin in the ground state suggest that these compounds are promising to be used as thermal insulators. Various macroscopic thermodynamic parameters such as bulk modulus, heat capacity, thermal expansion coefficient and entropy as a function of temperature and pressure are also predicted using the quasi-harmonic Debye model and their implications are elucidated.
Journal of Physics Communications, 2020
This report demonstrates the systematic study of electronic, mechanical, and optical properties o... more This report demonstrates the systematic study of electronic, mechanical, and optical properties of Fe 1−x Co x alloy (x=0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) using plane wave ultrasoft pseudopotential based on spin-polarized density functional theory. The upshots expose overlapped of valence and conductance states and confirms electronic bands polarization. The energy bands are significantly shifted with increasing Co atoms. The dispersion energies reveal anisotropic behavior of electronic energy levels. The density of states manifests strong electronic interaction between Co and Fe atoms. The spin polarization is mainly attributed from the exchange interactions among electronic spins, which confirms the strong electron-electron interactions. Subsequently, spin polarization induces spin magnetic moments. Minority spin states are dominant for Fe 1−x Co x alloy, which significantly changed the electronic properties. Moreover, Elastic constants confirm that all the phases of Fe 1−x Co x alloy are mechanically stable, and the higher elastic modulus manifests better performance of the resistance to shape change and against uniaxial tensions. The optical properties of FeCo alloy exhibit strong interrelation with atomic composition of Fe and Co. The loss spectra reveal high plasmonic resonance that can be chemically tuned through atomic composition. The spin magnetic moments and high plasmonic resonance make the Fe 1−x Co x alloys as the prominent mechanically stable materials for magneto-optical applications.
Materials Science and Engineering B , 2020
This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of... more This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of spinel CoFe2O4
using generalized gradient approximation (GGA). Both the spin and non-spin polarized density functional theory
(DFT) have been used to study the influence of spin interactions on electronic structures, spin magnetic mo-
ments, and optical properties. The calculated magnetic moments of CoFe2O4 from spin density of states are 6.98
μB per formula unit. The Fe and Co ions prefer high spin orientations owing to the cationic polarization because
of crystal field strength and intra-atomic exchange interactions, which induces large spin magnetic moments.
The high values of spin magnetic moments confirm strong spin orbit coupling due to strong electron-electron
interactions and can be a promising for spintronic application. Moreover, the calculated high reflectivity of
CoFe2O4 material (~100%) in the Infrared-Visible-Ultraviolet region up to ~30 eV, which suggesting that the
CoFe2O4 can also be a good candidate for solar reflector.
OSA Continuum, 2019
The nonlinear optical properties of Rh-Pd and Rh-Pt solid-solution alloy nanopar-ticles (NPs) wer... more The nonlinear optical properties of Rh-Pd and Rh-Pt solid-solution alloy nanopar-ticles (NPs) were experimentally investigated by means of the z-scan technique. The open aperture (OA) measurement showed a reverse saturable behavior, whereas the closed aperture (CA) measurement showed a peak-and valley-shape. Both the Rh-Pd and Rh-Pt NPs exhibited a positive nonlinear optical index of refraction at 800 nm relating to the self-focusing phenomenon. In addition, the nonlinear absorption of the Rh-Pt NPs (4.39 × 10 −12 cm/W) was higher than that of the Rh-Pd NPs (1.63 × 10 −12 cm/W) due to the small interval between the occupied and unoccupied density of states (DOS) of Rh-Pt than Rh-Pd. The nonlinear responses of the Rh-Pd and Rh-Pt NPs was attributed to the hot electron contribution and the reverse saturation of intraband and interband transitions.
Journal of Physics: Conference Series , 2018
CoFe 2 O 4 nanomaterials have been synthesized through conventional sol-gel process by using CoCl... more CoFe 2 O 4 nanomaterials have been synthesized through conventional sol-gel process by using CoCl 2 .6H 2 O and FeCl 3 as precursors and citric acid is used as a capping agent. The as synthesized nanomaterials have been investigated thoroughly using x-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and an impedance analyzer. The XRD patterns indicate the formation of body centered cubic spinel CoFe 2 O 4 having cell constant 8.403 Å and the corresponding space group is Fd-3m, in which the Fe 3+ and Co 2+ ions occupied in octahedral and tetrahedral sites in the crystallographic orientations. The average crystallite size was found to be 30 nm. The SEM micrographs reveal that the synthesized nanomaterials (NMs) formed as octahedron and tetrahedron and the particles are well dispersed and contain some pores. We found 17.5% porosity of the nanomaterials that plays an important role in technological applications, e.g. water and chemical filtration related to bio-medical applications. Measurement of the AC electrical properties shows that dielectric constant increases up to 5.13 for 0.3 MHz and then it decreases with increasing applied frequency. Lower dielectric constant at high frequency region appears due to decreasing interfacial polarization and limiting grain boundary effect.
This work reports the synthesis and studies of semi-soft ferrimagnetic CoFe 2 O 4 nanoparticles u... more This work reports the synthesis and studies of semi-soft ferrimagnetic CoFe 2 O 4 nanoparticles using sol–gel method. The X-ray diffraction patterns confirm the formation of cubic spinel CoFe 2 O 4 nanoparticles. The average crystallite size was found from XRD data is about 30 nm. The high resolution transmission electron microscopy analysis shows that nanoparticles are highly crystalline. The magnetic properties reveal that the particles are ferrimagnetically ordered soft magnetic materials with coercive field of 620 Oe and saturation magnetization M s = 60 emug − 1. The higher value of saturation magnetization is due to the ordered single-domains magnetic nanoparticles and lower magnitude of coercivity is attributed to the decrease of inter-particle interactions and magneto-elastic anisotropy. The value of remanence ratio R < 0.5 is responsible for magnetostatic interactions of the particles. The nanoparticles possess low values of dielectric constant which decreased with increasing frequency. The low dielectric constant makes the nanoparticles as a promising candidate for high frequency magnetic devices.
Conference Presentations by Ali Hossain
PhoBiA Annual Nanophotonics International Conference, 2019
This report demonstrates the magnetic properties of cobalt ferrite nanoparticles (NPs) fabricated... more This report demonstrates the magnetic properties of cobalt ferrite nanoparticles (NPs) fabricated using sol-gel process. The cobalt ferrite manifests the semi-soft ferrimagnetic properties and high saturation magnetization with lower coercivity. The low coercive field confirms that the fabricated NPs are magnetically ordered and highly crystalline. The high saturation magnetization attributed the single domain ordered distribution to the efforts of the lower inter particle interactions due to limiting size effect. The magnetization arises due to net spin contribution of the d-electronic states of Fe and Co atoms. The electronic structures have been computed through general gradient approximation plane wave ultra-soft pseudopotential approached. The spin density of states confirms the polarization of electronic states due to strong exchange interaction that leads the formation of spin magnetic moment.
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Papers by Ali Hossain
using generalized gradient approximation (GGA). Both the spin and non-spin polarized density functional theory
(DFT) have been used to study the influence of spin interactions on electronic structures, spin magnetic mo-
ments, and optical properties. The calculated magnetic moments of CoFe2O4 from spin density of states are 6.98
μB per formula unit. The Fe and Co ions prefer high spin orientations owing to the cationic polarization because
of crystal field strength and intra-atomic exchange interactions, which induces large spin magnetic moments.
The high values of spin magnetic moments confirm strong spin orbit coupling due to strong electron-electron
interactions and can be a promising for spintronic application. Moreover, the calculated high reflectivity of
CoFe2O4 material (~100%) in the Infrared-Visible-Ultraviolet region up to ~30 eV, which suggesting that the
CoFe2O4 can also be a good candidate for solar reflector.
Conference Presentations by Ali Hossain