Probing the opto-electronic, phonon spectrum, and thermoelectric properties of lead-free fluoride perovskites A2GeSnF6 (A = K, Rb, Cs) for energy harvesting devices.

The present work employs density functional theory to explore the structural, optoelectronic, and thermoelectric attributes of the halide-based double perovskite A2GeSnF6 (A = K, Rb, and Cs) compounds. The stable phonon dispersion spectrum affirms dynamical stability, whereas the enthalpy of formation and tolerance factor evaluated collectively verify structural stability. Considering the Tran Blaha modified Becke Johnson potentials (mBJ), the predicted direct band gaps along the symmetry point are 3.19 eV for K2GeSnF6, 3.16 eV for Rb2GeSnF6 and 3.12 eV Cs2GeSnF6. According to an in-depth examination of the optoelectronic features, A2GeSnF6 (A = K, Rb, and Cs), double perovskites are assuring contenders for optoelectronic devices due to their suitable bandgap. The extremely high figure of merit values (0.94-0.97) obtained from the numerical calculation of power factor and thermal conductivity suggest the intriguing prospects of these compositions for thermoelectric devices. These studies offer a perceptive comprehension of the materials for their potential applications in the future.

Exploring the multifaceted properties: electronic, magnetic, Curie temperature, elastic, thermal, and thermoelectric characteristics of gadolinium-filled PtSb3 skutterudite.

The investigation of binary and filled skutterudite structures, particularly PtSb3 and GdPt4Sb12, has gained significant attention, becoming a focal point in scientific research. This comprehensive report delves into the intrinsic characteristics of these structures using Density Functional Theory (DFT). Initially, we assess the structural stability of PtSb3 and GdPt4Sb12 by examining their total ground state energy and cohesive energy, employing the Brich Murnaghan equation of state to determine stability in various configurations. Further insights are gained by exploring second-order elastic constants (SOEC's) to extend our understanding of structural stability. The electronic structures are then meticulously defined through a quantum mechanical treatment, employing a combination of two distinct spin-polarized approximation schemes: Perdew-Burke-Ernzerhof Generalised Gradient Approximation (PBE-GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ). The resulting band structures reveal a symmetry in electronic behavior, showcasing spin-magnetic moments of 3 µB and 7.58 µB per formula unit, with the primary contributions emanating from the Pt 3d and Pt4+ 3d-transition elements. To gauge thermal stability, we evaluate the phonon-dependent Grüneisen parameter (γ) across specific temperature ranges. The study extends to exploring transport properties as a function of chemical potential (µ - EF) at various temperatures. The findings suggest that these designed materials hold substantial potential for diverse applications, particularly in conventional spin-based and thermoelectric technologies. The comprehensive insights obtained through this investigation pave the way for a deeper understanding and broader implications in various technological domains.

Exploring the structural, mechanical, magneto-electronic and thermophysical properties of f electron based XNpO3 perovskites (X = Na, Cs, Ca, Ra).

Here, we present systematic investigation of the structural and mechanical stability, electronic profile and thermophysical properties of f-electron based XNPO3 (X = Na, Cs, Ca, Ra) perovskites by first principles calculations. The structural optimization, tolerance factor criteria depicts the cubic structural stability of these alloys. Further, the stability of these materials is also determined by the cohesive and formation energy calculations along with mechanical stability criteria. The electronic structure is explored by calculating band structure and density of states which reveal the well-known half-metallic nature of the materials. Further, we have calculated different thermodynamic parameters including specific heat capacity, thermal expansion, Gruneisen parameter and their variation with temperature and pressure. The thermoelectric effectiveness of these materials is predicted in terms of Seebeck coefficient, electrical conductivity and power factor. All-inclusive we can say that calculated properties of these half-metallic materials extend their route in spintronics, thermoelectric and radioisotope generators device applications.

Holistic Exploration of Structural, Electronic, Magnetic, Transport, Mechanical, and Thermodynamic Characteristics, Including Curie Temperature Analysis.

Through intricate calculations, the density functional theory (DFT) implemented in the Wien2k code was employed to comprehensively investigate a wide range of material characteristics. Our study encompasses an exhaustive analysis of structural stability, electronic properties, magnetic behaviors, transport phenomena, mechanical responses, and thermodynamic profiles of two notable instances of filled Skutterudites, namely, CeNi4P12 and DyCo4Sb12, which have been thoroughly explored. These computations were performed using the WIEN 2K code, combining local orbitals and the full-potential linearized augmented plane-wave approach. The findings provided insight into the wide range of properties of these materials. In this methodology, the exchange-correlation potential relies on the local-density approximation. We conducted the calculations with and without incorporating spin-orbit interactions. The results obtained provide information about the lattice constant, bulk modulus, and pressure derivative. The stability, as indicated by the P-V graphical plot, suggests that there are no structural phase transitions from the cubic symmetry structure. Notably, our work includes an examination of Curie temperatures, which are pivotal in understanding magnetic phase transitions. The validated elastic properties further support the material's stability and corroborate its ductile nature. These alloys should be considered for spintronic and thermoelectric applications due to their estimated transport characteristics and the observed ductile nature. To enhance our understanding of the thermal stability of antimony-based compounds, we have made reliable estimations of the thermophysical characteristics. By integrating theoretical insights with practical implications, we bridge the gap between fundamental understanding and material design applications. Using DFT in the Wien2k framework, we discover connections and patterns among different properties, showing how to create materials with specific functions and better performance. This approach not only advances our fundamental comprehension of materials but also promises innovation across various technological domains.

Exploring the electronic structure, mechanical behaviour, thermal and high-temperature thermoelectric response of CoZrSi and CoZrGe Heusler alloys.

By using density functional theory, we have explored the structural, electro-mechanical, thermophysical and thermoelectric properties of CoZrSi and CoZrGe Heusler alloys. The ground state stability was determined by optimising the energy in various configurations like type I, II, and III. It was found that these alloys stabilized in the ferromagnetic phase in type I. We employed the Generalised Gradient Approximation and modified Becke-Johnson potentials to explore the electronic structure. The band structures of each of these Heusler alloys exhibit a half-metallic nature. Additionally, the computed second-order elastic parameters reveal their ductile nature of them. To understand the stability of the alloys at different pressures and temperatures, we investigated various thermodynamic parameters using the Quasi-Harmonic Debye model. We obtained the transport coefficients using the Boltzmann theory. Our findings indicate that these alloys can be used in spintronics and thermoelectric domains.

Correction: Theoretical exploration of inherent electronic, structural, mechanical, thermoelectric, and thermophysical response of KRu4Z12 (Z = As12, Sb12) filled skutterudite materials.

[This corrects the article DOI: 10.1039/D3RA05546A.].

Tailoring the intrinsic magneto-electronic, mechanical, thermo-physical and thermoelectric response of cobalt-based Heusler alloys: an ab initio insight.

We conducted a comprehensive analysis of the fundamental properties of CoHfSi and CoHfGe half-Heusler alloys using density functional theory simulations implemented in Wien2k. To begin, structural optimization revealed that both alloys effectively adopt a cubic C1b structure, with Y1 as the dominant ferromagnetic phase. Electronic properties were computed using various approximation schemes, including the Generalized Gradient Approximation and the modified Becke-Johnson potential. The examination of electronic band structures and their accompanying density of states using the modified Becke-Johnson functional approach unveiled their half-metallic nature. In this context, the spin-up channel exhibited semiconductor behaviour, while the spin-down channel displayed metallic characteristics. Additionally, the spin-splitting observed in their resulting band structures contributed to a net magnetism within their lattice structure, making them promising candidates for spintronic applications. We also scrutinized Seebeck coefficients, electrical conductivity, thermal conductivity, and power factor to gain a better understanding of their thermoelectric properties.

Understanding the computational insights of spin-polarised density functional theory into the newly half-metallic f electron-based actinide perovskites SrMO3 (M = Pa, Np, Cm, Bk).

Here, we investigated the structural, mechanical, electronic, magnetic, thermodynamic and thermoelectric properties of Strontium based simple perovskites SrMO3 (M = Pa, Np, Cm, Bk) by using density functional theory. First and foremost, the ground state stability of these perovskites was initially evaluated by optimizing their total ground state energies in distinct ferromagnetic and non-magnetic configurations. The structural stability in terms of their ground state energies defines that these alloys stabilize in ferromagnetic rather than competing non-magnetic phase. From the understandings of mechanical parameters these alloys are characterized to be ductile in nature. After that, two approximation schemes namely Generalized Gradient approximation and Tran-Blaha modified Becke-Johnson potential have been used to find their intimate electronic structures which displays the half-metallic nature of these alloys. Further, we have verified temperature and pressure effect on these alloys. Finally, the transport properties have been evaluated within the selected temperature range of 150-900 K. In view of this, the different transport parameters along with half-metallic nature advocate their possible applications in thermoelectric and spintronics devices.

Theoretical exploration of inherent electronic, structural, mechanical, thermoelectric, and thermophysical response of KRu4Z12 (Z = As12, Sb12) filled skutterudite materials.

Using the density functional theory methodology, we have thoroughly examined KRu4As12 and KRu4Sb12 skutterudites, including their structural, electronic, mechanical, transport, and thermodynamic properties. First and foremost, using the Birch-Murnaghan equation of state, the structural stability has been calculated in terms of their total ground state and cohesive energies. With the use of the approximation approaches GGA and GGA + mBJ, the electrical structure and density of the states reveal their metallic nature. This demonstration predicts the dominant ferromagnetic spin configuration of materials by considering their electronic behavior and magnetic interactions. The ductile behavior of these alloys is also addressed by their mechanical qualities, which indicate how they might be used in engineering and industrial settings. Moreover, the semi-classical Boltzmann transport theory has been employed to examine the Seebeck coefficient as well as the electric and thermal conductivities. The general tendency of these compounds demonstrates their various potential uses as electrode materials. The quasi-harmonic Debye approximation is a method used to analyze the stability of a system under high pressures and accounts for the temperature dependency of thermodynamics. It combines the quasi-harmonic approximation, which considers the anharmonicity of vibrations, with the Debye model, which describes the vibrational modes of a solid. This approach allows for a more accurate representation of the system's behavior at different temperatures and pressures. By implementing this approximation, researchers can gain insights into the stability and thermodynamic properties of materials under extreme conditions.

Exploring the half-metallic ferromagnetism, dynamical and mechanical stability, optoelectronic and thermoelectric properties of K2NaMI6 (M = Mn, Co, Ni) for spintronic applications.

The structural stability, optoelectronic and magnetic characteristics of K2NaMI6 (M = Mn, Co, and Ni) halide double perovskites have been demonstrated to be explained using density functional theory computations. The prominent generalized gradient approximation and integration of the mBJ potential are implemented to estimate the exchange-correlation potential, which is the only unidentified parameter in the state-of-the-art formulism. The structural optimization, mechanical stability criteria, and tolerance factor demonstrate the reliability of the double perovskites in a cubic structure with Fm3m symmetry. The elastic constants facilitated mechanical stability and revealed the brittle nature of these double perovskites. The spin-polarized electronic band profile and the behaviour of the dielectric constant and absorption coefficient in the spin-up and down channels show the presence of half-metallic nature in these materials. Additionally, we examined magnetism and the genesis of the half-metallic gap in this article. The half-metallic and magnetic properties are attributed to the unpaired electrons in the split d-orbitals of the M-sited elements in the crystal field. The Mn-, Co-, and Ni-based double perovskites were found to possess total magnetic moments of 4 µB, 4 µB, and 1 µB, respectively, with the transition metal atoms comprising up the majority of this magnetic moment. The Fermi level's perfect spin polarisation promotes the potential application of double perovskites in spintronic technology.

Probing the structural, mechanical, phonon, thermal, and transport properties of magnetic halide perovskites XTiBr3 (X = Rb, Cs) through ab-initio results.

Herein, we have first reported the intrinsic properties, including structural, mechanical, electronic, magnetic, thermal, and transport properties of XTiBr3 (X = Rb, Cs) halide perovskites within the simulation scheme of density functional theory as integrated into Wien2k. First and foremost, the structural stability in terms of their ground state energies has been keenly evaluated from their corresponding structural optimizations, which advocate that XTiBr3 (X = Rb, Cs) has a stable ferromagnetic rather than the competing non-magnetic phase. Later on, the electronic properties have been computed within the mix of two applied potential schemes like Generalized Gradient Approximation (GGA) along with Trans-Bhala modified Becke Johnson (TB-mBJ), which thoroughly addresses the half-metallic behaviour with spin-up as metallic and in contrast to opposite spin-down channel signatures the semiconducting behaviour. Furthermore, the spin-splitting seen from their corresponding spin-polarised band structures offers a net magnetism of 2 µB which lends their opportunities to unlock the application branch of spintronics. In addition, these alloys have been characterised to show their mechanical stability describing the ductile feature. Moreover, phonon dispersions decisively certify the dynamical stability within the density functional perturbation theory (DFPT) context. Finally, the transport and thermal properties predicted within their specified packages have also been forwarded in this report.

Tantalum half-Heusler alloys RbTaSi and RbTaGe: potential candidates for desirable thermoelectric and spintronic applications.

Heusler alloys have drawn the interest of researchers due to their possible technical significances and multifunctional use. Herein, a thorough theoretical analysis using "density functional theory (DFT)" is performed to investigate the general physical features of RbTaSi and RbTaGe alloys. The "generalised gradient approximation (GGA)" and "Tran-Blaha modified Becke-Johnson (TB-mBJ) potential" has been incorporated to model the electronic structures of RbTaSi and RbTaGe. The structural optimization results signify that these materials are stable in the ferromagnetic phase with a cubic F4̄3m structure, which is supported by the computed elastic parameters. In addition, cohesive energy and microhardness signify strong bonding. The spin-polarisation bands and density of states indicate the half-metallic nature of these materials. These materials have spin magnetic moment 2µB, thereby emphasizing the use of these alloys for spintronic applications. Transport and thermodynamic properties have been calculated, and their temperature dependence is illustrated. The behavior of transport coefficients with temperature futher implies the presence of half-metallic nature.

Scrutinized the inherent spin half-metallicity and thermoelectric response of f-electron-based RbMO3 (M = Np, Pu) perovskites: a computational assessment.

In the hunt for novel materials, we present self-consistent ab initio simulations of the structural stability, electronic profile, and transport properties of f-electron-based RbMO3 (M = Np, Pu) perovskites within the context of density functional theory. The structural stability and thermodynamic concerns are fixed by relaxing the crystal structure and computing the energy of formation, respectively. Furthermore, the decisive physical features of given materials have been outlined using the optimised lattice constant retrieved from structural optimizations. The ground state magnetic phase stability is ascertained by minimizing Birch Murnaghan's equation of state in distinct magnetic phases, upholding the ferromagnetic phase (FM) as the ground state magnetic phase, which is further backed by positive Curie Wiess constant values. To specify the electronic structure, a mix of the two approximations GGA and GGA + mBJ has been executed, both of which assert the half-metallic character, culminating in 100% spin polarisation at the Fermi level. The study of the magnetic moment and Curie temperature of each material has further been assessed in the present study. Apart from half-metallicity, the thermoelectric response of the present materials is quantified by exploring the chemical potential dependency of several transport parameters like Seebeck coefficient, electrical and thermal conductivity, power factor, etc. Moreover, the thermoelectric competence has been tested using a zT calculation, adapting values of 1.01 and 0.987 at 300 K for RbNpO3 and RbPuO3, respectively. The high electronic zT at encompassing temperatures uncovers the significant utility of these materials in both low-and high-temperature thermoelectric device applications. In essence, the comprehensive survey of these alloys could certainly open up their possibilities in spintronics, thermoelectric, and solid-state (RTG) device applications.

DFT analogue of prospecting the spin-polarised properties of layered perovskites Ba2ErNbO6 and Ba2TmNbO6 influenced by electronic structure.

Since the unexpected accelerated discovery of half-metallic perovskites is continuously on the rise both from basic sciences and application-oriented sides. Herein, for the first time in this carried research work, we significantly delivered a detailed analysis on one of experimentally synthesized perovskite structure Ba2ErNbO6 and in related to Ba2TmNbO6 within the realm of unified density functional theory. Initially, the structural stability of two molecular perovskite structures were critically established interms of their total ground state and cohesive energies by the expendition of Brich Murnaghan equation of state. Also, the tolerance factor (τ) oversees the cubic structural stability without possessing any geometrical strains. More likely, the density functional perturbation theory (DFPT) has been calibrated to perceive the dynamical context of these layered structures. Also, from the understandings of second order elastic and mechanical parameters adresses their suitable ductile characteristics. The quantum mechanical refinement of their intrinsic electronic structures were systematically tuned by the exploitation of Generalised gradient approximation (GGA), on-site Hubbard scheme (GGA + U) selected to the strongly correlated electrons of particular angular momentum and modified Becke-Johnson (mBJ) potential. Moreover, the two-dimensional representation of asymmetric density of states (DOS) pinned around the Fermi-level (EF) and the interpretation linked to their corresponding spin-polarised band structures signatures the well-known half-metallic nature. Subsequently, the transport properties especially the value of figure of merit (ZT) equals to unity (1) along the selected chemical potential range at different temperatures. The summed-up properties and the overall tendency triggers the possibility of these materials to register their extending applications in spintronics, thermoelectrics, nanoengineering, and radioisotope generator perspectives.

Potential lead-free small band gap halide double perovskites Cs2CuMCl6 (M = Sb, Bi) for green technology.

Explorations of stable lead-free perovskites have currently achieved substantial interest to overcome the instability and avoid toxicity related issue faced with the lead-based perovskites. In this study, we have comprehensively studied the stability, nature and origin of electronic, transport and optical properties of inorganic halide double perovskites, which could provide a better understanding of their possible potential applications. The density functional theory is used to investigate the different physical properties of these materials. The stability of these cubic materials is validated by optimizing the structure, tolerance factor, mechanical stability test. The materials are small band gap semiconductors with outshining optoelectronic performance. Due to high optical absorption, high conductivity and low reflectivity they have great potential to be used for optoelectronic application purpose. Because of small band gap we have also investigated the variation of various transport parameters with chemical potential. The semiconducting nature of materials results in ZT close to unity predicting its excellent application in thermoelectric technology.

Scrutinizing the stability and exploring the dependence of thermoelectric properties on band structure of 3d-3d metal-based double perovskites Ba2FeNiO6 and Ba2CoNiO6.

Through the conventional DFT computation, we have designed new oxide double perovskites Ba2FeNiO6 and Ba2CoNiO6. The structural and thermodynamic stabilities are predicted by optimizing the crystal structure and evaluation of enthalpy of formation, respectively. Then by using the optimized lattice constant, we have explored the different physical properties. The GGA + mBJ electronic band-structure illustrates Ba2FeNiO6 is a half-metal with 100% spin polarization at the Fermi level. While Ba2CoNiO6 shows a ferromagnetic semiconducting nature. The change in the electronic structure when Fe is replaced by Co is explained with the help of the orbital diagram and exchange interaction. The eg-eg hybridization that happens via O-p states is strong because Fe-O-Ni and Co-O-Ni bond angles are strictly 180°. The narrow bandgaps in the semiconducting channels prompted us to analyze the applicability of these materials towards thermoelectric technology. Besides this, we have investigated the dependency of transport properties on electronic band structure. The semiconducting nature in Ba2CoNiO6 results in a significant ZT around 0.8 at room temperature makes it suitable for wasted-energy regeneration.

Analysing cation-modified magnetic perovskites A2SnFeO6 (A = Ca, Ba): a DFT study.

Self-consistent DFT-based structural optimizations for understanding the cation effect on various properties of A2SnFeO6 (A = Ca, Ba) perovskites have been figured out in this study. The two-dimensional spin-polarized band structures, along with their corresponding density of states within the mix of two calculation schemes Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA) and Hubbard correlation correction (PBE + U), strongly appeals its half-metallic nature, which has been discussed in detail. The perfect occurrence of the half-metallic nature with high-spin subsystem corresponds to a metal-type spectrum and in contrast to the opposite-spin claims semiconducting behaviour. The effect of significant spin-polarisation creates a ferromagnetism of total 4 (µ B) mostly arising at (Fe). The induced magnetism of oxygen atoms is due to the overlapping between Fe-3d-O-2p orbitals. The mechanical strength is characterized from cubic elastic parameters that decide the capability of these materials against various external distortion forces displaying brittle nature. Apart from this, the semi-classical Boltzmann transport theory embedded in BoltzTraP package has been keenly addressed to turn out Seebeck coefficients, electrical and lattice thermal conductivities. The overall study creates a significant momentum in connection with the development of unlocking spintronics, spin dynamics and energy harvesting applications.

New ferromagnetic half-metallic perovskites for spintronic applications: BaMO3 (M = Mg and Ca).

Herein, first principles computer-based simulations were performed to predict the ground-state structure, mechanical stability, and magneto-electronic properties of BaMO3 (M = Mg and Ca) perovskites, which have not been experimentally synthesized to date. Structural optimization authenticate the stability in the cubic structure for BaMO3 perovskites having symmetry of the Pm3m space group. The tolerance factor and cohesive energy further validate the stability of BaMO3 in the cubic phase. Moreover, mechanical stability was confirmed by the positive elastic constants, satisfying the necessary stability conditions. The band structure and density of states at the optimized lattice constants revealed the ferromagnetic half-metallic character of BaMO3 materials, with O-p states playing a prominent role. The half-metallic character originates from the partial filling of the O-p states in the spin-down channel. Spatial charge distribution indicated the dominant ionic character of bonding. No change in the magnetic moment of perovskites was observed upon changing the M-site atoms. Various elastic parameters suggested that these perovskites are ductile in nature with highly anisotropic character. The three-dimensional graphical representation of different elastic moduli revealed that the linear compressibility is isotropic, whereas the shear modulus, Young's modulus, and Poisson's ratio of these perovskites are highly anisotropic. The results obtained in this study are in agreement with those reported in the literature for other similar perovskites.

Comprehensive DFT investigation of transition-metal-based new quaternary Heusler alloys CoNbMnZ (Z = Ge, Sn): compatible for spin-dependent and thermoelectric applications.

The hunt for high spin polarization and efficient thermoelectric materials has endured for decades. In this paper, we have explored the structural, mechanical stability, magneto-electronic, and thermoelectric properties of two new quaternary Heusler alloys, CoNbMnZ (Z = Ge, Sn), using first-principles simulation methods. The alloys are stable, showing a Y1-type phase and ferromagnetic nature. Based on a generalized gradient approximation method, the alloys exhibit metallic nature; upon employing a modified version of the Becke-Johnson potential, both alloys demonstrate half-metallic nature, with gaps of 0.43 and 0.45 eV, which is a precursor for high spin polarization in these alloys. The alloys also follow the necessary Slater-Pauling rule condition M T = Z T - 24 for half-metallicity and they have a total magnetic moment of 1 µ B. Elastic parameters convey the mechanical stabilities of these alloys, with Debye temperatures of 518 K and 445 K. These materials act as anisotropic media with respect to longitudinal and transverse sound velocities. Possible energy efficiency and thermoelectric applications were scrutinized via computing Seebeck coefficients, electrical and electronic lattice thermal conductivities, and, lastly, power factors. The highest S values for Ge- and Sn-based alloys are 60.43 and 68.2 µV K-1, respectively, and the highest power factors are 32 and 35 µW K-2 cm-1, respectively, suggesting potential efficient applications in thermoelectric power generation.

Systematic investigation of the magneto-electronic structure and optical properties of new halide double perovskites Cs2NaMCl6 (M = Mn, Co and Ni) by spin polarized calculations.

A cohesive study using density functional theory simulations is performed to reveal and understand the structural stability, optoelectronic and magnetic properties of Cs2NaMCl6 (M = Mn, Co and Ni) halide double perovskites. The exchange-correlation potential, which is the only unknown parameter in the state-of-the-art formulism is determined through the well-known generalized gradient approximation and integration of the mBJ potential to it. The structural optimization, mechanical stability criteria and tolerance factor confirmed the stability of the double perovskites in a cubic structure with Fm3̄m symmetry. The elastic constants endorsed the mechanical stability and justify the brittle character of these double perovskites. The spin polarized electronic band profile and behaviour of the dielectric constant and absorption coefficient in the spin up and down channels revealed the presence of half-metallic nature in these materials. Moreover, herein, we have discussed the origin of the half-metallic gap and magnetism. The unpaired electrons in the crystal field splitted d-orbitals of the M-sited constituents are responsible for the half-metallic and magnetic character. The total magnetic moment was determined to be 4µ B, 4µ B and 1µ B for the Mn-, Co- and Ni-based double perovskites, respectively, with main contributions solely coming from the transition metal atoms. The perfect spin polarization at the Fermi level suggests the application of double perovskites in spintronic technology.