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In this work, we have analyzed key characteristics of nickel oxide (NiO) thin films using combined experimental and computational approaches for smart window applications. Thermo Gravimetric Analysis (TGA) depicts that nickel oxide films are stable beyond 275 °C.The XRD pattern revealed the single phase of the materials. FTIR studies confirm the stretching vibrational band of Ni−O. The current‐voltage analysis shows the semiconducting behavior of the materials. The synthesized NiO thin films have shown prominent electrochromic response with a wide linear range, better cyclic stability, high durability, and fast response time. The sample having concentration of 0.05 M/25 mL has best semi‐conductive response as rapid increase in current occurs above 0.8 V. Moreover, the electrochemical and optical properties have shown reversible redox behavior of the synthesized NiO thin films with changing their appearance from original greenish gray to the dark brown in the selected potential range. In addition, the computational study has also been performed for deep study of electronic charge conduction mechanism and photo response of NiO thin layer using Tran‐Blaha modified Becke Johnson (TB‐mBJ) approach. These fabricated NiO thin films have been utilized as an active electrode for electro chromic devices in smart window applications. [ABSTRACT FROM AUTHOR]

LiXH3 (X = Cr, Fe, Co, & Zn) hydride type perovskites have been studied by applying density functional theory (DFT), and their structural, optoelectronic, magnetic, hydrogen storage, and mechanical properties have been calculated. The results show that these materials are synthesizable for hydrogen storage applications. The energy band structures as well as total density of states (TDOS) and partial density of states (PDOS) unveil that LiCrH3, LiCoH3, and LiZnH3 possess metallic character, while LiFeH3 exhibits semiconducting behavior. The lattice constants are calculated by applying PBE + GGA functional which are listed as 3.4940, 3.1791, 3.6343, and 3.7132 Å for LiXH3 (X = Cr, Fe, Co, & Zn), respectively. In order to manage the restriction of PBE + GGA functional, the lattice constants are also calculated by applying hybrid HSE06 functional which are found to be 3.3126, 2.9675, 3.1531, and 3.4018 Å for LiCrH3, LiFeH3, LiCoH3, and LiZnH3, respectively. The elastic stiffness constants show that these materials are mechanically and elastically stable and are deemed suitable as transportation materials in hydrogen storage devices. Moreover, mechanical parameters such as Poisson coefficient, Cauchy pressure, melting temperature, Young, Bulk, and Shear moduli have been calculated. Dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function have been determined to seek an optical behavior of the considered perovskites for hydrogen storage applications. The present study is the first theoretical approach to the contribution for future exploration of these materials. [ABSTRACT FROM AUTHOR]

Resistive switching (RS) performances had prodigious attention due to their auspicious potential for data storage. Oxide-based devices with metal insulator metal (MIM) structure are more valuable for RS applications. In this study, we have studied the effect of divalent (nickel) as well as trivalent (aluminum) dopant without and with oxygen vacancy ( V o) in hafnia ( HfO 2) -based resistive random-access memory (RRAM) devices. All calculations are carried out within the full potential linearized augmented plane-wave (FP-LAPW) method based on the WIEN2k code by using generalized gradient approximation (GGA) and generalized gradient approximation with U Hubbard parameters (GGA+U) approach. The studies of the band structure, density of states and charge density reveal that HfNiO2+Vo are more appropriate dopant to enhance the conductivity for RRAM devices. [ABSTRACT FROM AUTHOR]

Abstract Phosphorene, a two-dimensional elemental material, has attracted increasing attention owing to its fascinating characteristics. In this work, all calculations have been performed with the help of density functional theory (DFT) based on generalized gradient approximation method. This work also includes the contributions of Hubbard (+U) potentials for determining the total density of states. This work explores the occurrence of magnetic moments in the non-magnetic phosphorene due to the substitution of Ce and Ti dopants in various configurations. In the presence of Ti impurity atom, phosphorene exhibits unique magnetic characteristics. The substitution of Ce Ce or Ti Ti couple in phosphorene layer has revealed ferromagnetic and half-metallic characteristics, whereas Ce and Ce Ti couple substitution has shown much weaker magnetic behavior. These findings provide a productive ground for future spintronics applications based on phosphorene. Highlights • The electronic and magnetic properties of Ti & Ce atom-decorated phosphorene explored using DFT method. • Occurrence of magnetic moments in the non-magnetic phosphorene due to the substitution of Ce and Ti dopants. • Phosphorene exhibits unique magnetic characteristics due to the presence of Ce and Ti impurity atoms along the zigzag direction. • The substitution of Ce Ce or Ti Ti couple in phosphorene has revealed ferromagnetic and half-metallic characteristics. • Ti and Ce atom-decorated phosphorene display fascinating magnetic properties, the exchange splitting of orbitals. [ABSTRACT FROM AUTHOR]

With a hexagonal (honeycomb) network of mono-layered carbon atoms, graphene has demonstrated outstanding electronic properties. This work describes the impact of deliberately introduced single, double and triple carbon vacancies in grapheme monolayer. In addition, these carbon vacancies were then substituted with gold atoms and their influence on the electronic properties of the two-dimensional (2D) graphene layers was investigated. In this regard, a first principle calculation was performed to examine electronic properties and formation energy of 2D graphene layer by applying density functional theory (DFT). Introduction of such defects appeared to increase the stability of the graphene sheet as confirmed by formation energy calculations. Moreover, decrease of formation energy was noticed to be significant with an increase in the number of defects. Band structure calculations described the shifting of localized states from valance to conduction bands which caused the transformation of semiconducting behavior into metallic one on the filling of carbon vacancies by gold atoms. Comparing this behavior with that of partial density of states (PDOS) it was noted that a lot of states existed in the valance band in the case of C-vacancies yielding charge free region around the vacancy. On the other hand, filling of C-vacancies by gold generated a large number of energy states in the conduction band illustrating the accumulation of charges near gold atom. Width of the peak across the Fermi level indicated the accumulative energy of electron to be almost 0.15 eV. These calculated DOS and PDOS demonstrated metallic like behavior of the graphene monolayer with typical defect states. [ABSTRACT FROM AUTHOR]

In the present work, first-principles calculations were performed to obtain the structural, electronic and optical properties of lithium niobate crystal using two exchange-correlation functionals (GGA-PBE and TB-mBJ). The calculated structural parameters were very close to the experimental values. TB-mBJ functional was found to be good when compared to LDA and GGA functionals in case of bandgap energy of 3.715 eV of lithium niobate. It was observed that the upper valence and lower conduction bands consist mainly the O-2p and Nb-4d states, respectively. Furthermore, calculations for real and imaginary parts of frequency-dependent dielectric function 𝜀(ω) of lithium niobate crystal were performed using TD-DFT method. The ordinary refractive index no(ω), extraordinary refractive index ne(ω), its birefringence and absorption peaks in imaginary dielectric function 𝜀2(ω) were also calculated. [ABSTRACT FROM AUTHOR]

This theoretical study examined the doping effects of alkali (K) and alkaline (Mg) earth metals on the structural, electronic, and optical properties of non-toxic, abundantly existing, and stable CuO and CuO 2 materials for optoelectronic device applications. This study elaborated on a light-dependent conducting filament-based resistive switching mechanism and confirmed that magnesium and potassium impurities enhance the dielectric properties of CuO and CuO 2 by generating conductive bridge filaments in their vicinity. The outcomes of this study showed that CuO–Mg is the most thermodynamically stable composite with the least formation energy. In addition, the response of CuO–Mg to the incident electromagnetic radiation energy suggests it is more effective for electronic and optoelectronic devices, including light-controlled resistive switching memory applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple hydrothermal route was adopted for the synthesis of doped Fe 3 O 4. • The optimum catalyst showed overpotential of 243 mV at 10 mAcm−2 and tafel slope of 54.84 mV dec-1. • DFT-based calculations revealed that less hydroxyl ions adhesion energy is very beneficial for the OER. • The material also showed good structural stability after 25 h continuous run. Herein, a simple hydrothermal approach has been used to synthesize nickel and cobalt co-doped ferric oxide (Ni-Co-Fe 3 O 4) nanospheres and tested for electrocatalytic oxygen evolution reaction (OER). The different characterization outcomes verify the successful co-doping of Ni and Co into Fe 3 O 4. The as-synthesized Ni-Co-Fe 3 O 4 nanospheres demonstrated better electrochemical properties as compared to its counterparts Fe 3 O 4 , Co-Fe 3 O 4 , and Ni-Fe 3 O 4. At a define current density of 10 mA cm−2, the Ni-Co-Fe 3 O 4 electrocatalyst obtained a smaller overpotential of 243 mV and the tafel value of about 54.84 mV dec-1. In addition, Ni-Co-Fe 3 O 4 acquired efficient electrochemical stability for 25 h duration reaching current density of 10 mA cm−2 in 1 M potassium hydroxide solution. Furthermore, it is determined that the outstanding electrocatalytic OER activity of the prepared material as a result of its distinct morphology. Analyses using the density functional theory revealed that less hydroxyl ions adhesion energy is very beneficial for the OER of crystalline Ni-Co-Fe 3 O 4 nanospheres. The least adhesive energy for adsorption of hydroxyl ion at the top of the Fe atom in Ni-Co-Fe 3 O 4 further confirmed their outstanding results in improving electrocatalytic OER performance. Our work gives a decent option for future transition metal oxides based electrode nanomaterials for water electrolysis applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal treatment was employed for the synthesis of ZrTe. • ZrTe deposited on carbon cloth (CC) perform well for OER. • ZrTe/CC exhibits lower overpotential of 294 mV and smaller Tafel slope of 71 mV dec-1. • The high performance of ZrTe/CC was also confirmed via the density functional theory (DFT). Next-generation fuels are produced via electrochemical water splitting technology, and energy conversion processes can be improved by fabricating high-performance oxygen evolution (OER) electrocatalysts. Among all types of electrocatalysts, alternative, cheap, and high-performance OER catalysts are the metal tellurides. Here in the present report, the novel ZrTe has directly grown on carbon cloth (CC) and outperforms OER due to its 3D shell-like structure, high conductivity, and porous nature. Hydrothermal conditions are employed to promote an anion-exchange process that leads to zirconium tellurium nanostructure from synthesized tellurium ions and hydroxide of the zirconium hexagonal nanosheets. The electrochemical measurements are performed using modified electrodes, and are tested in the alkaline environment using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and a constant potential chronoamperometry (CA). The ZrTe/CC resulted in a lower overpotential of 294 mV with a smaller Tafel slope of 71 mV dec−1 and high stability of 45 h towards OER because of its unique shape resulting in large electrochemical active zones and more active sites without any binding agent. Additionally, the present study also validates that ZrTe/CC hybrid is more active towards OER via the density functional theory (DFT) and theoretical calculations, as our findings show that it is possible to produce multi-metal telluride-based materials that can be exceptionally efficient and stable electrocatalyst for OER, and also in future applications. [ABSTRACT FROM AUTHOR]

The exploration of most suitable materials for optoelectronic applications is dire need of the current era of the Science and Technology. Here, we have discussed the structural parameters, optoelectronic and mechanical behavior of XLaS 2 (X Cu, Zn), monoclinic structures, for optoelectronic applications. The calculated lattice parameters for CuLaS 2 are found to be a = 6.551 Å, b = 7.218 Å, c = 6.852 Å with lattice angles α = 90°, β = 98° and γ = 90°, while for ZnLaS 2 these are a = 6.619 Å, b = 7.310 Å, c = 6.926 Å and α = 90°, β = 98° and γ = 90°. In addition, values of the energy band gap calculated for CuLaS 2 and ZnLaS 2 are 1.26 eV and 0.27 eV, respectively which reveal their semiconducting nature. The total density of states (TDOS) and partial density of states (PDOS) are determined using Perdew Burke Ernzerhof generalized gradient approximation (PBE-GGA). Moreover, dielectric function, absorption coefficient, refractive index, optical conductivity, reflectivity and energy loss function are evaluated with 0.5 eV smearing value for seeking their optical behavior. According to Born's criterion, CuLaS 2 is found brittle while ZnLaS 2 as ductile material for different mechanical applications. Moreover, both these materials can hold an anisotropic behavior. Both these materials are found to be good absorber of Ultraviolet rays from the electromagnetic radiations, this unique quality has compelled us to declare them very suitable materials for optoelectronic applications. • The studied compounds belong to semiconductor category. • PBE-GGA functional is used to seek electronic behavior. • Optical absorption is found in the ultraviolet region of electromagnetic waves. • CuLaS 2 is found brittle while ZnLaS 2 as ductile material. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, optical, vibrational, thermodynamic and mechanical properties of beryllium based perovskite type halides KBeBr 3 , RbBeBr 3 , and CsBeBr 3 in triclinic phase have been investigated by utilizing PBE + GGA functional based on density functional theory in CASTEP simulation code. The determined lattice constants for considered perovskite type halides are listed as 5.7125 Å, 5.7202 Å and 5.9533 Å for KBeBr 3 , RbBeBr 3 , and CsBeBr 3 , respectively. The electronic properties have been determined and it is observed that these materials show insulator type character. The observed energy band gaps are in the order of 4.0 eV, 4.2 eV, and 4.7 eV for KBeBr 3 , RbBeBr 3 , and CsBeBr 3 , respectively as calculated by hybrid HSE06 functional. The optical properties like dielectric function, absorption coefficient, conductivity, extinction coefficient etc. also predict that the studied perovskite type halides are the potential candidate for optoelectronic devices. Additionally, the dynamic vibrational stability has been calculated and the determined phonon energy dispersion curves predict that these compounds are dynamically stable. Also, the thermodynamic parameters including enthalpy, free energy and temperature time's entropy have been investigated. Moreover, the mechanical and elastic properties of considered materials are also calculated to check their reliability, stability and easy handling for optoelectronic applications. This first principle investigation of computational properties of the novel materials implement an advance route to the theorists and experimentalists for the new potential applications in the renewable and advanced optoelectronic devices. • Studied compounds are wide band gaps semiconductors. • The optical analysis predict the maximum absorption, minimum reflectivity and optical loss. • Antiferromagnetic behavior with zero magnetic diploe moment is observed in all cases. • The phonon energy dispersion curves revealed the dynamic stability with zero soft modes. [ABSTRACT FROM AUTHOR]

The structural, electronic, vibrational and optical properties of TbMn 2 O 5 and Tb 2 MnCoO 6 have been studied by using density functional implemented into CASTEP and GULP codes. The geometry optimization is achieved using PBE-functional in CASTEP code. So far as, the structure is optimized using Buckingham potential through GULP code. The calculated lattice constants for TbMn 2 O 5 and Tb 2 MnCoO 6 are found to be a = 6.973 Å, b = 8.638 Å, c = 6.097 Å and a = 5.559 Å, b = 7.415 Å, c = 5.182 Å, respectively in the orthorhombic phase of these crystal structures. The electronic band structure as well as density of states of both structures unveils that the studied materials belong to semi-metallic family. Force constant matrix related to force field methods is used to calculate the phonons of the studied materials. Phonon dispersion and vibrational density of states (VDOS) are plotted to calculate the vibrational modes. In addition, infrared and Raman spectroscopy have been performed to characterize modes of the vibrations. The calculated modes of vibrations of TbMn 2 O 5 demonstrate an excellent agreement with available experimental results. Finally, the optical behavior of TbMn 2 O 5 and Tb 2 MnCoO 6 has been investigated using Kramer-Kronig relations in terms of dielectric constant, reflectivity, absorption coefficient and refractive index in the frequency range 0–700 cm-1. • The studied compounds belong to semi-metallic category. • Optical behavior of studied compounds endorse their semi-metallic behavior. • Pseudo-states of TbMn 2 O 5 and Tb 2 MnCoO 6 have mainly contributed in conduction mechanism. • TbMn 2 O 5 has 96 modes of vibrations out of which 3 are acoustics and remaining are optical modes. [ABSTRACT FROM AUTHOR]

The structural, electronic and thermoelectric properties of AZr 1-x M x O 3 (A = Ba, Ca, Sr; M = Al, Cu, x = 0.25) without and with an oxygen vacancy (Vo) have been unveiled using the Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA) functional along with Tran-Blaha modified Becke-Jonhson (TB-mBJ)approximation based on Density Functional Theory (DFT) in the framework of WIEN2k code for memristors applications. Moreover, isosurface charge density plots have been calculated by using Vienna ab initio Simulation Package (VASP) simulation code. The analysis of structural parameters reveals that substituting Zr4+ with Al3+ and Cu2+ causes the lattice distortion which tends to increase in the presence of Vo along with dopant. The study of band structure, density of states (DOS) and isosurface charge density plots predict the enhanced charge conduction and formation of conducting filaments (CFs) for all composites with dopant and/or Vo. Moreover, spin polarized density of states for Cu doped composites has also been calculated to confirm the large exchange splitting of Cu-3d states. The thermoelectric characteristics of considered composites have also been explored using the Boltztrap code to better explain the semi-classical Boltzmann transport theory. Thermoelectric parameters confirm the semiconductor nature of all composites, ensuring the compatibility for memristors and thermoelectric devices applications. In addition to this spin polarized thermoelectric behavior of Cu doped composites that ensure the contribution of spin down (↓) states of Cu for charge transport mechanism. The SrZrCuO 3 +Vo composite is found most promising candidate followed by BaZrCuO 3 for memristors applications while, CaZrCuO 3 is found most suitable amongst studied composites for thermoelectric devices. The calculated isosurface charge density plots for (a) BaZrO 3 +Vo (b) BaZrAlO 3 (c) BaZrAlO 3 +Vo (d) BaZrCuO 3 and (e) BaZrCuO 3 +Vo.Whereas green, red, black, blue and brown balls represent Ba, O, Zr, Al, and Cu atoms in addition to cyan and yellow colors show charge depletion and accumulation respectively. Image 1 • We propose the electronic modification subsequently with the creation of the oxygen vacancy and metal ion dopant in AZr 1-x M x O 3 (A = Ba, Ca, Sr; M = Al, Cu, x = 0.25) have been investigated using density functional theory in depth which could support underlying mechanism of switching process. • Integrated charge density plots depicted charge transfer mechanism of AZr 1-x M x O 3 (A = Ba, Ca, Sr; M = Al, Cu, x = 0.25). • The conductivity of the phases increased with increasing the number of oxygen vacancies; and eventually resulted that the considered phase opted the low resistance state. • The spin polarized outcomes better elaborate the role of spin up (↑) and spin down (↓) channel electrons in charge conduction mechanism for memristor applications. • The results of seebeck coefficient, electrical conductivity, thermal conductivity and maximum power factor graded the CaZrCuO 3 as most emerging candidate amongst all studied composites for thermoelectric devices. [ABSTRACT FROM AUTHOR]

Hydrogen storage in current years has become significant and momentous for researcher's interest because hydrogen as an energy source can be utilized. In the current study, the structural, optoelectronic, magnetic, and thermodynamic properties along with bader charge density parameters of novel combinations of hydride perovskites such as CoCuH 3 , NiCuH 3 and ZnCuH 3 are investigated by first principles method in the frame work of density functional theory (DFT). The comprehensive investigations have been made while using three cations (Co, Ni and Zn) in ABH 3 cubical order of symmetry phases. The band structures are plotted along with partial density of states, which manifestly predict that XCuH 3 (X = Co, Ni and Zn) hydrides possess metallic behavior due to overlapping of conduction and valence bands. The lattice parameters of XCuH 3 (X = Co, Ni, Zn) are calculated on the basis of Generalized Gradient Approximations (GGA), which are indexed as 3.3287 Å, 3.3245 Å and 3.6129 Å for XCuH 3 (X = Co, Ni, Zn), respectively. However, to dominate the limitations of GGA functional, LDA + U (an effective Hubbard parameter) has been utilized and calculated improved lattice parameters are 3.4815 Å, 3.2838 Å and 3.4867 Å for XCuH 3 (X = Co, Ni, Zn), respectively. The dielectric function, refractive index, extinction coefficient, optical conductivity are calculated on the basis of Kramer-Kroing principle and their results show that NiCuH 3 is more appropriate material for hydrogen storage applications. The gravimetric ratio of hydrogen storage capacities are determined as 2.8 wt.%, 3.0 wt.%, and 2.7 wt.% for CoCuH 3 , NiCuH 3 and ZnCuH 3 , respectively. Antiferomagnetism is reported for NiCuH 3 and ZnCuH 3 , while magnetism has been observed for CoCuH 3 in line with the results calculated through DOS and PDOS for studied materials. The current study is the first computational attempt of XCuH 3 , which may contribute outstanding amelioration for future investigations in hydrogen storage applications. [ABSTRACT FROM AUTHOR]

In the present study, we have focused to investigate the structural, electronic and optical properties of transition metal (TM) doped HfO 2 i.e; Hf 1-x TM x O 2 (TM = Co, Ni, Zn, x = 12.5%) using the Full Potential Linearly Augmented Plane Wave (FP-LAPW) based on the density functional theory (DFT). Perdew-Burke-Ernzerhof - Generalized Gradient Approximation (PBE-GGA) has been used as an exchange correlation potential. In addition, Tran-Blaha modified Becke-Jahnson exchange potential approximation (TB-mBJ) has been employed to calculate improved electronic properties. The later approach better estimates the values of the electronic band gap much closer to the values of band gap calculated experimentally. The studies of the band structure, density of states and charge density reveal that Co-doped HfO 2 is more appropriate dopant to enhance the conductivity for resistive random accesses memory (ReRAM) devices. The results from partial density of states (PDOS) disclose the facts that localized energy states, i.e., TM-3 d and O-2 p have contributed mainly in increasing conductivity through hybridization. The optical analysis depicts that Hf 1-x Co x O 2 can absorb a wide ultra violet (UV) range of electromagnetic radiations in line with the electronic behavior which has been found a most suitable candidate for ReRAM/optoelectronic memristors and other allied devices. [ABSTRACT FROM AUTHOR]

• Structural and phonon stability of NdMn 2 O 5 and La 2 CoMnO 6 perovskites. • Calculated Band Gaps found to be suitable for optoelectronic applications. • Slater Modes of vibrations of single and double perovskites. The first principles simulation is performed to study the structural, electronic and dynamical properties of single perovskite NdMn 2 O 5 and double perovskite La 2 CoMnO 6. Their lattice constants for optimized orthorhombic phases are calculated from the structural properties using Conjugate Gradient method. The calculated electronic energy band gaps for NdMn 2 O 5 (1.07 eV) and La 2 CoMnO 6 (0.95 eV) are found to be suitable for optoelectronic applications. The vibrational properties are determined and compared using harmonic approximation for the supercell and semi empirical methods to explore stability of the compounds, and their modes of vibrations. The vibrational modes are characterized in infrared (IR) and Raman regions between the frequencies ranging 59 to 699 cm−1. These modes are discussed to analyze motion of the individual atom in complex structures of NdMn 2 O 5 and double perovskite La 2 CoMnO 6. Slater type stretching modes are observed at frequency 550 cm−1 and 512 cm−1 of NdMn 2 O 5 and La 2 CoMnO 6 , respectively. [ABSTRACT FROM AUTHOR]