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Using the Full Potential Linearized Augmented Plane Wave FP-LAPW, as implemented in the Wien2k package. The structural, electronic, magnetic and elastic properties of the Half Heusler (HH) RhNbGe and RhNbSn were investigated. The Generalized Gradient Approximation (GGA) and the Tran-Blaha-modified Becke-Johnson exchange potential method (TB-mBJ) was applied to model the exchange correlation potential. Our results show that the both compounds studied are mechanically stable. Moreover, RhNbZ (Z:Ge,Sn) presents a semiconductor behavior obeying the Slater-Pauling rule. The thermodynamic properties, in particular the Bulk modulus, the heat capacity, the Debye temperature and the thermal expansion coefficients of the two alloys are investigated using the quasi-harmonic Debye model. The semi-classical Boltzmann theory, as implemented in the BoltzTraP code, is used to study thermoelectric properties. The high values obtained figures of merit ZT of RhNbGe and RhNbSn compounds make them promising candidates for thermoelectric applications at low and high temperatures.

To date, ideal topological nodal line semimetal (TNLS) candidates in high dynamically stable and high thermally stable two-dimensional (2D) materials are still extremely scarce. Herein, by performing first-principles calculations, on the one hand, we found that three-dimensional Nb3GeTe6 bulk possesses a single closed TNL in the kx = 0 plane and a fourfold TNL in the S–R direction without considering spin–orbit coupling (SOC). Under the SOC effect, a new topological signature, i.e., hourglass-like Dirac nodal line, occurs in Nb3GeTe6 bulk. On the other hand, we found that the 2D Nb3GeTe6 monolayer features a doubly degenerate TNL along surface X–S paths. Importantly, this monolayer enjoys the following advantages: (i) it has high thermal stability at room temperature and above; (ii) its TNL is nearly flat in energy and is very close to the Fermi level (EF), which provides a fantastic maximum value platform of the thermoelectric power factor around the EF; and (iii) no extraneous bands are close to the TNL, near the Fermi level. Moreover, we explore the entanglement between the topological states and thermolectric properties for the 2D Nb3GeTe6 monolayer. Our work not only reports the discovery of a novel TNL material, but also builds the link between the TNL and thermoelectric properties.

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.

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 hereby discuss the structural stability of Fe2CrSb via energetic considerations, phonon dynamics and mechanical aspects. Later, the electronic, magnetic and thermoelectric properties are discussed in order to reach out the possible explanations of the observed half-metallic bandgap and other physical properties. Phonon dispersion of Fe2CrSb with positive-only frequencies accompanied by the observed elastic parameters indicate the dynamic stability and mechaneablity of this alloy. The relaxed and optimized structural calculations predict the ferromagnetic Cu2MnAl-type L21 phase as the stable one. This compound has a half-metallic ferromagnetic character with an integer magnetic moment of 3 μB, which is in good agreement with the Slater–Pauling (SP) rule. Finally, we have pronounced the thermoelectric performance against the temperature range of 50–800 K using Boltzman transport theory. The room temperature Figure of merit (0.54) reaches to maximum of 0.67 at 800 K, indicating that Fe2CrSb can work at low as well as high temperature thermoelectric devices operations.

In the last few decades, varieties of semiconductors have been explored for electronic and thermoelectric applications. As a result of these motivations, the current research work investigates the structural, electronic, vibrational, elastic, mechanical, thermodynamic, and thermoelectric properties of two quaternary Heuslers (QHs), namely LiHfCoGe and LiHfCoSn (both of which are semiconducting in nature), within the computational framework of DensityFunctional Theory (DFT) and Boltzmann transport equations. Both alloys display the p-type semiconductivity, dynamical stability and crystallize in the FCC cubic structure within F-43 m space group. The high Seebeck coefficient values pronounce an excellent and fundamental thermoelectric character. The large melting points expose their scope in the high-temperature regions. However, all of the thermoelectric characteristics are also measured in terms of the estimated relaxation time using deformation potential theory. Even though the figure of merit (ZT) is in the middle of the pack yet better than many compounds of the same sort. The impact of spin–orbit coupling on the thermoelectric characteristics is also examined. The practical utilization of the materials can be evaluated from the elastic and mechanical properties that are favorable in manufacturing efficient and reliable Thermoelectric Modules at high-temperatures.

The relativistic effects and compositional dependence on the electronic and optical properties of Cd1-xHgxTe alloys are reported by employing ab-initio self-consistent calculations based on full potential linear augmented plane-wave method (FP-LAPW) within the generalized gradient approximation (GGA). The electronic and optical characteristics are explored using the GGA combined with the modified Becke–Johnson (mBJ) potential, and spin-orbit coupling (SOC) is also incorporated. The mBJ-GGA + SOC scheme reveals the ability to alter the energy gap for Cd1-xHgxTe alloys by manipulating the Hg composition. The alloy undergoes a change from semimetal to semiconducting behavior. An accurate knowledge of the electronic band parameters is crucial in these mixed ternary alloys. For Hg-rich content of 75%, a band gap was found at around 0.15 eV. The direct energy band gap and significant absorption between the infrared and ultraviolet spans would suggest prominent optical activity in these promising systems.

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 low dimensional materials, the conversion of thermal to electrical energy via thermoelectric devices gained much more attention when a ZT > 5 was reported in metastable Fe2V0.8W0.2Al thin film (2019 Nature 576 85). In this brief review, we tried to describe the underlying physics of nanostructured thermoelectric materials accompanied by the introduction to enhance the efficiency of energy conversion from one form to another. From this determination, we select the two dimensional (AB type) materials such as ScX (X = P, As), SiX (X = S, Se, N, P, As, Sb, Bi), GeX (X = S, Se, Te), SnX (X = S, Se, Te) and BX (X = S, Se, Te) etc. Different theoretical methods have also been mentioned to study the intrinsic thermoelectric properties which might help in searching experimentally the new and promising thermoelectric materials. We explore the thermoelectric parameters such as Seebeck coefficient, electrical conductivity and thermal conductivity by using density functional theory, Boltzmann transport theory with constant relaxation time approximation and non-equilibrium Green’s function approach. Reduced dimensions potentially expand the thermoelectric efficiency by enhancing the Seebeck coefficient and decrease the thermal conductivity. Theoretical calculations thus recommend the stimulation of the two-dimensional (2D) materials with experimental capabilities in designing and improving the thermoelectric performances.

In the present work we explore the electronic, vibrational and thermoelectric properties of new Li based quaternary Heusler compound LiYNiSn that is recently proposed by Jiangang He et.al. [Chem. Mater. 30 (2018) 4978] which is based on the 18-electron rule. Here the theoretical calculations are performed within the approach of density functional theory and semi classical Boltzmann transport equations with the constant relaxation time approximation. The band gap of the proposed compound is 0.38 eV that is in agreement with the available results in literature. The Seebeck coefficient and the Figure of Merit (ZT) are calculated at the three different temperatures (300K, 600K and 700K) with respect to the chemical potential (μ). The maximum ZT recorded is 0.14 at 700 K temperature. The compound is reported first time as the thermoelectric material and can be beneficial in the experimental research of thermoelectrical materials.

In this study, the structural stability, optoelectronic, and magnetic characteristics of lead-free halide double perovskites Cs 2 KXCl 6 : X = Co and Ni were revealed and understood utilizing a rigorous and systematic investigation employing the density functional theory adopted in WIEN2k simulation software. The given double perovskites are stable in cubic structure having Fm-3 m symmetry, this stability was confirmed by optimized structural, satisfying criteria of mechanical stability and tolerance factor. The half-metallic ferromagnetic feature of materials is caused by unpaired electrons in the crystal field splitted d-orbitals of Co and Ni. The total magnetic moments of these double perovskites were computed, and the calculated results were 4 μ B for Cs 2 KCoCl 6 and 1 μ B for Cs 2 KNiCl 6 , with the transition metal atoms contributing the most. The fact that these double perovskites exhibit 100% spin polarization at the Fermi level suggests that they might be used in spintronics.

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.

First principles calculations on structural, electronic, magnetic and thermoelectric properties of newly synthesized perovskite Sr2HoNbO6 are carried out at the behest of much reliable density functional theory (DFT). The equilibrium lattice parameters at the cost of structural optimizations are observed to agree with the available experimental data. Three different methods for exchange correlations are utilized to investigate the electronic structure of this oxide. Spin polarized band structure calculations predict the semiconducting nature of this compound along with a large energy gap of 3.6 eV. Ferromagnetic interactions among the constituent atomic spin moments determine the total magnetic moment μ = 4.0 μB for this material with a maximum contribution from μHo = 3.95 μB. In addition, the temperature dependent thermoelectric properties based on the electronic results of Sr2HoNbO6 in temperature range from 50 to 1000 K are investigated. The total negative Seebeck coefficient signifies the p-type conduction or holes as charge carriers along the selected temperature range. The outcome of this study specifies the maximum value of dimensionless figure of merit zT ≈ 0.97 at room temperature.

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.

The structural, electronic, elastic, thermodynamic and thermoelectric properties of RhTaZ (Z = Si, Ge and Sn) half-Heusler materials have been studied using density functional theory. We have found that the compounds studied can be experimentally synthesized. Also, RhTaZ (Z = Si, Ge and Sn) alloys exhibit a semiconductor behavior following the Slater–Pauling rule. The elastic properties calculated confirm that our compounds are mechanically stable. Using Debye’s quasi-harmonic model, the thermodynamic properties of these half-Heusler alloys were investigated. For the study of thermoelectric properties, the semi-classical Boltzmann theory, as implemented in the BoltzTraP code, has been used. The high values obtained from the figure of merit for RhTaZ (Z = Si, Ge and Sn) compounds suggest that they are promising candidates for thermoelectric applications at low and high temperatures.

We have studied the origin of the semimetallic pseudo gap and the role of site preference in the L21-type Heusler compound Ru2TaGa. A detailed account of the structural stability, phonon-dependent properties, electronic structure, and thermoelectric properties of the host compound is presented herein. Stability assessments have been made on the basis of phonon band structure, formation energy, mechanical criteria, and hull energy calculations. From the calculated density of states (DOS) and band structure, a semimetallic scenario is evident, with the Fermi level trapped in the pseudo gap. HSE calculations provide a decisive picture, with an indirect overlap between electron and hole pockets near the Fermi level of Ru2TaGa being responsible for the formation of a negative or pseudo gap. Comparison of the Ru eg and Ta t2g states reveals the role of d-d hybridization in pseudo gap formation in Ru2TaGa-like compounds. Additionally, we endeavor to discuss the transport coefficients of Ru2TaGa. The room temperature Seebeck coefficient calculated for Ru2TaGa is 66.42 μV/K, considerably larger than those of other semimetallic compounds of the same family. Considering the lattice thermal conductivity (κL = 2.5 W/mK) at 800 K, we obtain a significant figure of merit of ZT = 0.025 in Ru2TaGa. Although the absolute thermoelectric figure of merit (0.002) is relatively low in Ru2TaGa, it is still the highest among the non-doped full Heuslers of the same family hitherto reported.

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.

First principles calculations on structural, electronic, magnetic and elastic properties of BaNpO 3 oxide are reported using full potential augmented plane wave method. To achieve the optimized lattice parameters, the local density approximation (LDA) and generalized gradient approximation (GGA) have been used. The calculated values of lattice constant and bulk modulus are found to be in agreement with experimental and other reported results. In addition, Hubbard approximation potential (GGA + U) and modified Becke Johnson approximation (mBJ) are also engaged for the exact prediction of band structure. Half-metallicity along with 100% spin polarization is reflected from the spin resolved band structures as well as densities of states. The ferromagnetic stable configuration of BaNpO 3 perovskite is observed from the double cell optimization method as well as the spin-magnetic moment calculations. In addition, elastic constants have been calculated to envisage the mechanical response of this material. From these mechanical parameters, the ductile nature of the material is observed along with a Debye temperature of 356 K and melting temperature of 1968.71 K.

An extensive study of rare-earth perovskite BaPaO3 and BaNpO3 has been performed by first-principles tactics based on density functional theory (DFT), because the delocalized f-electrons play an important role in the band structure formation, to reveal their impact on the overall physical and chemical properties; it has turned out to be an interesting theme. Along with critical radii and thermoelectric properties, two different theories are employed to calculate the structural properties. The DFT and empirically calculated lattice constants are in rational accord with the experimental results. The critical radius calculations show that the BaPaO3 lattice has a smaller oxygen migration activation energy than the BaNpO3. In addition, we discuss the band profile and magnetic moments for these materials, which demonstrate the half-metallic ferromagnetism with a direct energy gap of 3.91 eV for BaPaO3 and an indirect gap of 3.79 eV for BaNpO3. More interestingly, the integral magnetic moments are in accordance with the Slater–Pauling rule.

The structural, electronic, mechanical and thermodynamic properties of the perovskite oxide BaAmO3 have been predicted using the full-potential linearized augmented plane wave (FP-LAPW) method. The equilibrium lattice constant, bulk modulus and pressure derivative were computed using different exchange correlations. The optimization of structure was carried out in ferromagnetic, anti-ferromagnetic and non-magnetic states, and the compound was found to be stable in the ferromagnetic state. A systematic study on the band structure and density of states was accomplished using generalized gradient approximation (GGA), Hubbard approximation (GGA + U) and modified Becke–Johnson exchange potential (mBJ),and the compound was found to have a half-metallic nature in all the approximations. The calculated total spin magnetic moment was found to be 5 μ B in all the approximations used. The second-order elastic constants, Young modulus, shear modulus, Poisson ratio and anisotropic factor have also been calculated. In order to have a complete understanding of BaAmO3, the thermodynamic properties were studied in the pressure range of 0 to 40 GPa and the temperature range extending from 0 to 600 K.

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 present our work on the rapid hydrothermal synthesis of highly crystalline 2D SnS nanostructures. An innovative idea is used in which thioglycolic acid is the sulfur precursor source. Structural studies indicate the material has grown in a single-phase orthorhombic structure. The single-phase formation of the material is also confirmed from the rietveld refinement of the experimental XRD data and by raman spectroscopic analysis. Morphological studies show the formation of 2D sheets having thickness in the nanoscale (100–150 nm) dimensions. Optical absorbance studies show the material is visible-light active exhibiting an indirect bandgap of 1.1 eV and direct band gap ∼1.7 eV. Density functional theory calculations support the experimental bandgap results. Photocatalytic activity of the nanosheets was investigated against methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes employing a solar simulator as the source of photons (light source). The nanosheets were found to photodegrade 80% of MB, 77% of RhB and 60% of MO in 120 min of light illumination. Reusability and post catalytic properties affirm the durability and stability of the nanosheets, which is very important in the context of waste water treatment considering the toxic nature of the effluents from dye industries.

Half-Heuslers (HH) have found ever-increasing popularity as high temperature thermoelectric (TE) materials. In this paper, the electron and phonon transport equations are solved to understand the thermoelectric character of the PtXSn (X = Zr, Hf) compounds. Here, we have elucidated the phonon stability, electronic properties, thermoelectric response from lattice thermal conductivity, and phonon dependent parameters. The PtXSn compounds reveal an indirect bandgap semiconducting nature with a gap of 1.23 eV and 0.94 eV for PtZrSn and PtHfSn, respectively. At room temperature, a low magnitude of lattice thermal conductivity (κl) for PtZrSn (16.96 W/mK) and PtHfSn (10.04 W/mK) compounds is observed. The calculated maximum value of ZT is 0.57 and 0.24 observed for PtHfSn and 0.24 PtZrSn, respectively. Our present investigation demonstrate that the PtHfSn compound is potentially a favorable candidate for high-temperature power generation.

We thoroughly inspected the strain induced electronic properties, phonon dynamics and thermoelectric performance of ZrRhSb compound via density functional theory calculations. The optimized lattice parameters are in accord with the experimental observations. The equilibrium lattice constant is utilized to predict the p-type semiconducting and indirect energy gap of 1.15 eV between the X and Γ symmetry points. The application of strain widens the band gap up to 1.5 eV at 10% of compressive strain keeping the indirect nature consistent. Phonon studies display positive frequencies up to 5% of expansion and 25% of compression and thus confirm the dynamic stability of ZrRhSb under strain. Machineability and elastic properties, evidenced from elastic constants and Pugh’s parameter characterize it as a ductile alloy while maintaining its Debye temperature to 333 K. Herein, using ab initio quantum mechanical calculations and Boltzmann theory, optimization of thermoelectric performances in strained and robust ZrRhSb phase was performed. Starting from 300 K, it displays satisfactory thermoelectric performances, namely figure of merit ZTe > 0.65 and Seebeck coefficient >190 μV/K. Better performances via strain engineering were obtained at room temperature, where ZTe values reach 0.81 with a minimal fluctuation over broad temperature spectrum. The optimal strain conditions are achieved at 10% compression, where the S = 426 μV/K and figure of merit reaches up to a maximum of 0.91 at 800 K, which signifies the possible exploitation of ZrRhSb for thermoelectric applications.

Systematic investigation of the ground state structure, which includes elastic and transport properties, of perovskite oxides REMnO3 (RE = Ce and Pr) has been carried out by first principles calculations. We present the analytical as well as DFT calculated equilibrium lattice constants which show good agreement with experimental data. Three independent elastic constants are emphasised to yield the corresponding mechanical properties, including the elastic moduli (B, G and Y), Poisson's ratio (ν), anisotropy factor (A) and Pugh ratio B/G, for these compounds. These calculations predict the brittle PrMnO3 as a less hard material than the ductile CeMnO3 oxide. Post DFT treatment involving Boltzmann's theory is conveniently employed to investigate the thermoelectric properties of these compounds. The analysis of the thermal transport properties specifies the dimensionless figure of merit of 0.24 and 0.19 at room temperature for PrMnO3 and CeMnO3, respectively. Their half-metallic nature with efficient thermoelectric parameters, including electrical conductivity, Seebeck coefficient and thermal conductivity, suggest the likelihood of these materials to have a potential application in the design of shape memory devices and imminent thermoelectric materials.

Self-consistent ab initio calculations with highly precise spin-polarised, density functional theory (DFT) have been performed for the first time, to study the structural stability, mechanical and magneto-electronic properties of cubic perovskite PbTaO3. The DFT as well as the analytically calculated values of tolerance factor, in addition to stable-phase optimization, mechanical and elastic properties show stability of the present material in the cubic phase with a reasonably stiff nature and ductile properties. The symmetric spin-polarised band structure of both the spin (up and down) channels reveals zero spin polarisation at the Fermi level. Moreover, the insignificant total and individual spin magnetic moments of adjacent atoms and magnetic susceptibility calculations via the post-DFT treatment predict the paramagnetic nature of the material. Based on results of the present study, the paramagnetic metal PbTaO3 material is considered a promising candidate in designing new electrode materials.