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The present manuscript aims at the synthesis of cesium based halide perovskite nanostructures and the effect of cobalt doping on the structural, optical, lumnisent, charge storage and photocatalytic properties. In a very first attempt, we report the solvothermal synthesis of Co doped CsPbCl3 nanostructures under subcritical conditions. The structural features were demonstrated by X-ray diffraction (XRD) Surface morphology determined cubic shape of the synthesized particles. Doping is an excellent way to modify the properties of host material in particular to the electronic structure or optical properties. Incorporation of Co2+ ions in the perovskite structure tunes the optical properties of the nanostructures making this perovskite a visible light active material (Eg = 1.6 eV). This modification in the optical behaviour is the result of size effect, the crystallite size of the doped nanostructures increases with cobalt doping concentration. Photolumniscance (PL) study indicated that CsPbCl3 exhibited Blue emission. Thermogravametric analysis (TGA) revealed that the nanostructures are quite stable at elavated temperatures. The electrochemical performance depicts the pseudocapacative nature of the synthesized nanostructures and can used for charge storage devices. The charge storage capability showed direct proportionality with cobalt ion concentration. And Finally the photocatalytic performance of synthesized material shows superior catalytic ability degrading 90% of methylene blue (MB) dye in 180 min under visible light conditions.

We investigate the effects of pH and Fe doping on the size, structural and physical properties of Mg0.95Mn0.05-xFexO (x = 0, 0.04) nanoparticles. All the nanoparticles were synthesized by the sol-gel autocombustion method by varying the pH of the solution. Furthermore, the phase purity, size, and size distribution of the nanoparticles were studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Irrespective of the pH, Rietveld refinement analysis of the XRD data reveals single crystallographic cubic phases with MgO-type wurtzite structure (space group F m 3 ¯ m ) along with a lattice parameter of 4.2121(8) A for x = 0.0 and 4.2083(5) A for x = 0.04. This change in lattice parameter with Fe doping is due to the smaller size of Fe2+ (78 p.m.) compared with Mn2+ (83 p.m.). The size of the nanoparticles increases monotonically from approximately 10 nm to approximately 16 nm for x = 0.0 and from approximately 18 nm to approximately 23 nm for x = 0.04 with increasing pH. SEM micrographs of the powders show highly agglomerated nanoparticles with porous and irregular morphology. The TEM findings support the XRD results, showing that the nanoparticles increase in size with increase in pH. Because Raman modes should be absent in bulk MgO and present in MgO nanoparticles, the strong intensity of the three Raman modes at approximately 380 cm−1, 470 cm−1, and 608 cm−1 further supports the formation of small nanoparticles of Mg0.95Mn0.05-xFexO (x = 0, 0.04). The decrease in peak intensity with increase in pH suggests an increase in the size of the nanoparticles. The peak at 470 cm−1 corresponds to a transverse optical phonon, while the peak at 380 cm−1 corresponds to a transverse acoustic phonon.

DFT based structural optimizations and cohesive energies of novel Co-based Heusler compounds confirm the stability of these alloys in L21 phase (Cu2MnAl prototype). Later, the equilibrium lattice constants are predicted. While defining the electronic structure, the modified Beckhe Johnson scheme for exchange correlations predicted more efficient results than the generalized gradient approximation and onsite Hubbard approximation. Calculated band structure and densities of states together with spin magnetic moments designate the half-metallic character of these alloys. The elastic constants are calculated to define the mechanical stability and ductile nature of these alloys. The ferromagnetic spin moments amount to an integral value of 3μB for each system with a maximum contribution from transition metal cobalt atom. Present study opens a way out for the potential application of these alloys as spintronic materials.

In this report, we have applied the muffin tin orbital method within full-potential linearized augmented plane wave approximation to investigate the intricate details of the electronic structure, elastic properties and magnetism of antiperovskite compounds Co3XN with X = Rh, Pd and Sn. The detailed analysis of the electronic structure calculations using various chemical bonding indicators suggest the covalent hybridization of the electronic states associated with Co (the high valency transition element) and the X atom (low valency transition element) as the significant interaction liable for the exhibition of the octahedral symmetry by these alloys. The large magnetic moments of Co3RhN, Co3PdN and Co3PtN are observed to be 6.20 μB, 5.20 μB and 6.21 μB, respectively; with a net magnetic moment of around 4.7 μB contributed by Co atoms in each compound. The direct exchange between Co and X atoms and indirect interaction between Co and Co via N atoms is responsible for its ferromagnetic character. The influence of the strain on the overall magnetism and relative atomic moments in the unit cell is also investigated. The anisotropic nature of these alloys and the mechanical properties like ductility increases from Rh > Pd > Pt. Also, the Debye temperatures of Co3RhN, Co3PdN and Co3PtN are calculated to be 702 K, 689 K and 606 K, respectively.

Double perovskite La2NbMnO6 was systematically studied using the first-principles calculations. The structural, electronic, optical and transport properties of this compound were calculated. Spin resolved band structure predicted this material as a half-metal with an energy gap of 3.75 eV in spin down state. The optical coefficients including optical conductivity, reflectivity and electron energy loss are calculated for photon energy up to 30.00 eV to understand the optical response of this perovskite. The strong absorption of all the ultraviolet and infrared frequencies of the spectrum by this material may suggest the potential application of this material for the optoelectronic devices in ultraviolet and infra-red region. Also, the thermoelectric properties with a speculation from the half-metallic electronic structure are reported. Subsequently, the Seebeck coefficient, electrical and thermal conductivity coefficients are calculated to predict the thermoelectric figure of merit (zT), the maximum of which is found out to be 0.14 at 800 K.

We have computed the electronic structure and transport properties of Fe2TaZ (Z = Al, Ga, In) alloys by the full-potential linearized augmented plane wave (FPLAPW) method. The magnetic conduct in accordance with the Slater–Pauling rule classifies them as non-magnetic alloys with total zero magnetic moment. The semiconducting band profile and the density of states in the post DFT treatment are used to estimate the relations among various transport parameters such as Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit. The Seebeck coefficient variation and band profiles describe the p-type behavior of charge carriers. The electrical and thermal conductivity plots follow the semiconducting nature of bands along the Fermi level. The overall measurements show that semi-classical Boltzmann transport theory has well-behaved potential in predicting the transport properties of such functional materials, which may find the possibility of their experimental synthesis for future applications in thermoelectric technologies.

We hereby report the synthesis of Mg0.95Mn0.05O nanostructures using auto-combustion method. Effect of incorporation of different transition metal dopants (cobalt, nickel and copper) on structural, optical, morphological and dielectric properties of pristine Mg0.95Mn0.05O is investigated. X-ray diffraction plots confirm the cubic crystal structure of these samples. The crystallite size is found to be 78.2, 67.02, 78.11 and 64 nm for pure, Co, Cu and Ni doped MgMnO, respectively. Raman analysis clearly envisages the purity of the presently synthesized samples. Optical transmission spectrum shows that samples are highly transparent in the UV–Visible region. In addition, the FTIR results established the presence of magnesium oxide in all samples. Dielectric characterization depicts a reasonable decrease in the dielectric constant e′ as function of improving frequency, which in turn confirms its dispersive nature.

Solid state reaction synthesis of BaSn1-xMnxO3 (x = 0.0–0.3) nanostructures is presented in this article. Heavy transition metal doping in powdered BaSnO3 is accomplished to investigate the structural, morphological, chemical and dielectric properties of synthesized samples. Single phase, cubic crystal formations are revealed from the structural properties. Transmission electron micrographs (TEM) display the formation of polygonal discs with nanoscale (~50 nm) dimensions. Elemental composition of the synthesized samples has been confirmed from the x-ray photoelectron spectroscopy (XPS). Optical properties demonstrate the pristine BaSnO3 as an ultraviolet active material with a band gap of 3.2 eV. The enhancement in visible light active mode is achieved via band gap tuning by proportional Mn-doping in the parent material.

Here we discuss the electronic structure and optical properties of Yb based halide perovskites with keen interest on phonon and mechanical stability using the HSE06 approximated density functional theory calculations. The experimental structural parameters are exploited to calculate the semiconducting band structures with energy gap of 4.32 eV and 3.68 eV for CsYbCl3 and CsYbXBr3 alloys, respectively. Cubic phase stability is guaranteed by the phonon dynamics and machinability of these structures. The observed relaxed structural parameters are in accord with the previous experiments. We found that the present halide perovskite compounds are semiconductors with tuneable band gaps and the f-states of Yb element play a significant role in defining the electronic structure. In addition to this, the sound velocities accompanied by the Debye temperatures (181 K for Cl and 141 K for Br) are evaluated. Furthermore, the dielectric constant optical conductivity, electron loss function, refractive index provide a fundamental basis of the feasible optical characteristics suitable for optoelectronic devices and applications.

First principles calculations on the thermodynamic properties of PbTaO3 and SnAlO3 in a temperature range from 0 K to 800 K and pressure range from 0 GPa to 30 GPa have been carried out within the framework of density functional theory (DFT). The band structures of these oxides at different pressures display an increase in metallic character with a concomitant decrease in lattice constants, while the bulk modulus increases with increasing pressure. The thermal concert of these materials has been analyzed in terms of the temperature and pressure variation in Debye temperature, thermal expansion, entropy, and the Gruneisen parameter. Debye temperatures have been calculated from the elastic parameters as well as the quasi-harmonic Debye model, which are 339.07 GPa for PbTaO3 and 714.36 GPa for SnAlO3.

The structural and mechanical stability of Fe2TaAl and Fe2TaGa alloys along with the electronic properties are explored with the help of density functional theory. On applying different approximations, the enhancement of semiconducting gap follows the trend as GGA g = 1.80 eV for Fe2TaAl and 1.30 eV for Fe2TaGa. The elastic parameters are simulated to determine the strength and ductile nature of these materials. The phonon calculations determine the dynamical stability of all these materials because of the absence of any negative frequencies. Basic understandings of structural, elastic, mechanical and phonon properties of these alloys are studied first time in this report.

We conducted theoretical simulations for exploring the overall physical properties of the pristine SrFBiS2 as well as its derivative alloys (Sr1−x BaxFBiS2 (x = 0, 0.25, 0.5, 0.75, 1)) resulting from BiS2 layers via the compositional effect of substituting strontium with barium. In this respect, we computed the electronic and optical characteristics of Sr1−xBaxFBiS2 systems within the concentration limits of x varying from 0 to 1. Based on full-potential linear augmented plane wave scheme, we determined the structural properties of the Sr1−xBaxFBiS2 alloys, and the lattice parameter was found to increase with the augmentation of Ba concentration, which in turn agrees well with the available experimental works. The electronic band structures and density of states of Sr1−xBaxFBiS2 (0 ≤ x ≤ 1) alloys were also examined. According to our calculations, the parent compound SrFBiS2 has a semiconducting behavior and its energy gap is about 0.8 eV. The electronic band structures illustrated that the substitution of the divalent Ba+2 element instead of Sr+2 produces a semiconducting behavior for all Sr1−xBaxFBiS2 (0 ≤ x ≤ 1) alloys. When substituting Ba+2 with Sr+2, the acquired optical features, such as the dielectric function, refractive index, reflectivity, absorption coefficient, energy loss functions, and optical conductivity for Sr1−xBaxFBiS2 (0 ≤ x ≤ 1) alloys also exhibited a semiconducting nature. It is easily noticed that the maximum absorption coefficient changes with the variation of Ba concentration. Furthermore, a superior birefringence occurs in the concerned Sr1−xBaxFBiS2 alloys when the composition variation undergoes from x = 0 to 1. Intriguingly, the optical spectra for both parent compounds SrFBiS2 and BaFBiS2 and their ultimate Sr1−xBaxFBiS2 alloys displayed a high anisotropy. The viable significant role of the spin-orbit coupling in deciding the electronic structures and optical characteristics is due to the presence of heavy bismuth atoms. All our results determined for Sr1−xBaxFBiS2 systems are compared with the existing theoretical and experimental reports.

Antiperovskite materials display many fascinating properties like that of perovskites. We summed up the electronic, magnetic and mechanical properties of Ni3LiC compound in this work, via density functional theory calculations. The structural optimization via the Birch-Murnaghan approach supply the lattice parameters and ground state energy within the Fm-3m space group. Spin resolved band occupation and density of states define its metallic nature with a total ferromagnetic moment of 0.76 μB. The effect of uniform strain is analysed, which shows the increase in magnetic moment with the expansion of the lattice and vice versa. The speculated elastic constants and their different combinations conclude the mechanical strength and stability of this material. The large bulk modulus and B/G ratio claims its ductile and incompressible nature and the Zener's parameter reflects the exhibition of anisotropic properties.

Density functional theory (DFT)-based investigations have been put forward on the elastic, mechanical, and thermo-dynamical properties of BaPaO3. The pressure dependence of electronic band structure and other physical properties has been carefully analyzed. The increase in Bulk modulus and decrease in lattice constant is seen on going from 0 to 30 GPa. The predicted lattice constants describe this material as anisotropic and ductile in nature at ambient conditions. Post-DFT calculations using quasi-harmonic Debye model are employed to envisage the pressure-dependent thermodynamic properties like Debye temperature, specific heat capacity, Gruneisen parameter, thermal expansion, etc. Also, the computed Debye temperature and melting temperature of BaPaO3 at 0 K are 523 K and 1764.75 K, respectively.

Density functional theory (DFT)-based investigations have been put forward on the elastic, mechanical, and thermo-dynamical properties of BaPaO

Systemic investigation of structural parameters and electronic properties inclusive of band profiles for BaPaO3 and BaUO3 have been performed. The empirical as well as DFT calculated lattice constants are in agreement with the previously reported results. The critical energy values confirm that the BaPaO3 has lesser migration energy than BaUO3. Both, these materials show a semiconducting, direct band gap in the low spin state with 2.3 eV for BaUO3 and for BaPaO3, its value is 3.9 eV.

In this study, the CaMgSi and its subsequent doping by carbon atoms has been systematically studied using the first-principles calculations. Ground state properties focusing particularly on the structural, optical and transport coefficients of these alloys are discussed. Semi-metallic character is prominent from the observed band profiles when GGA scheme is utilized. The enhancement of thermoelectric properties with a speculation from the electronic structure is observed when doped with carbon. Also, the thermoelectric properties are envisaged within the specific transport constraints in order to figure out the dimensionless figure of merit (zT). The Seebeck, electrical and thermal conductivity coefficients are calculated and thereby utilized to find out the extremum of zT for both these alloys. The maximum zT for CaMgSi is found to be 0.4 at 400 K and for CaMgSiC, its value increases to 0.8 at 800 K. Thus, the later compound can be developed as a high temperature thermoelectric material. The optical considerations of such alloys are predicted from the calculated values of optical conductivity, reflectivity and electron energy loss within the range of 30.00 eV of incident photons. Likewise, the active region of these alloys for possible application in optoelectronic devices is ultraviolet region because the ultraviolet frequencies are strongly absorbed by these compounds.

In this work, Sn doped NiO nanoparticles were synthesized by co-precipitation route to explore the impact of doping on lattice structure, dielectric constant and magnetization. X-ray diffraction analysis confirmed cubic (Fd-3m) structure of Sn doped NiO. Average crystallite size decreases from 78.2 nm (Ni0.95Sn0.05O) to 64.23 nm (Ni0.8Sn0.2O). Scanning electron microscopy images confirm that nanocrystals have agglomerated spherical morphology. The Raman spectrum exhibits a strong, broad peak at 410 cm−1 and is attributed to the Ni-O stretching mode and doped samples show a blue shift. The dielectric constants at about 1 Hz are measured to be about 1.795, 1.030, 0.442, and 0.302 × 103 Ni1-xSnxO (x = 0.05, 0.1, 0.15, 0.2), respectively. The dielectric constant in nanoparticles of doped Ni1-xSnxO is three orders of magnitude higher as compared to pure NiO ceramics. The nature of magnetization - applied field (M-H) infers paramagnetic behaviour for Sn doped NiO nanoparticles.

Electronic structure, mechanical stability, magnetic and thermal properties of BaCfO3 perovskite have been investigated by density functional theory calculations using full potential linearized augmented plane wave method. The structural optimizations reveal the agreement of lattice parameter with the experimental data. The electronic structure and magnetic properties were precisely determined by generalized gradient approximation (GGA), and Hubbard approximation (GGA + U) methods. The electronic structure portrays the half-metallic nature for the compound in both the applied approximations. The total magnetic moment calculated via the above methods was found to be large and integral in nature (6 μB), which also is an indication of the half-metallic character of this material. The mechanical stability has been determined by the calculated elastic constants in addition to the preclusion of mechanical properties like the Young modulus (Y), Bulk modulus (B), the Shear modulus (G) and the Poisson ratio (ν). The observed data of B/G and Cauchy pressure (C12–C44) for the present material reveal its ductile nature. The thermodynamic parameters including heat capacity, thermal expansion, and Debye temperature and their variation w.r.t temperature and pressure (0 K to 500 K and 0 GPa to 40 GPa) has been examined. The melting temperature of 1791.94 ± 300 K for this material was also calculated.