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Mechanical, spin-polarized electronic, and transport characteristics of rare-earth-based MgSm 2 Y 4 (Y S, Se) spinels are investigated using first-principle calculations. In contrast to the anti-ferromagnetic and nonmagnetic states of MgSm 2 Y 4 (Y S, Se), the optimization study reveals that ferromagnetic states release more energy, and optimized lattice constants in ferromagnetic states are comparable to existing values. Phonon dispersion and formation energy are also calculated to confirm the dynamical stability stability. The ductile character is confirmed by investigating the Poisson's and Pugh ratios, and the values of other elastic parameters show their importance for the manufacturing of devices. Heisenberg model and the density of electron states at the Fermi level report the Curie temperature and the spin polarization. Spin-polarized electronic properties indicate half-metallic ferromagnetic because the spin-down reflects a semiconductor nature, whereas the metallic nature manifests the spin-up. The total magnetic moments are generated through hybridization of chalcogenide 2p-states and the Sm f-states. We found that the studied spinels may be used in thermoelectric devices by examining transport characteristics such as electronic and phononic thermal conductivity, Seebeck co-efficient, and figures of merit (ZT). Our results indicate that the ZT for MgSm 2 S 4 is almost three times the ZT obtained for MgSm 2 Se 4. • Half-metallic ferromagentic spinels MgSm 2 Y 4 (Y S, Se). • Phonon dispersion are investigated for dynamical stability. • Electronic and magnetic properties for spintronic applications. • Magnetic moments are discussed for both spinels. • The ZT for MgSm 2 S 4 is almost three times the ZT obtained for MgSm 2 Se 4. [ABSTRACT FROM AUTHOR]

• Theoretically examined the physical features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). • Elastic properties are investigated for structural stability. • Electronic and optical properties for solar applications. • The dispersion of light is explained by ε 1 (ω). • Due to its higher Seebeck coefficient, Li 2 CuBiCl 6 possessed a larger power factor than Li 2 CuBiBr 6 and Li 2 CuBiI 6. Due to their potential applications for optoelectronic and thermoelectric devices, Li-based double perovskites (DPs) have been widely investigated. In current article, we theoretically examined the mechanical, optoelectronic and thermoelectric features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). We employ the generalized gradient approximation (PBEsol) for examining the structural and elastic characteristics of these compounds, while the modified Becke-Johnson (mBJ) functional is used for obtaining an improved accord of the thermoelectric and electronic characteristics with experimental observations. For the stability of all DPs, the Born Criteria and formation energy are investigated. The cubic symmetry's elastic constants are examined to determine the difference between ductile and brittle nature, anisotropy, and Debye temperatures. The bandgaps are 2.0 eV, 1.7 eV, and 1.3 eV, for Li 2 CuBiCl 6 , Li 2 CuBiBr 6, and Li 2 CuBiI 6 , respectively, as determined by the mBJ potential. All DPs were also examined regarding optical absorption, refractive index, and dielectric constants for the energy range 0–10 eV, ensuring the absorption among visible regions. Furthermore, all DPs are appropriate candidates for thermoelectric applications due to the lower lattice thermal, higher Seebeck coefficient, thermal conductivity, and Figure of merit (ZT), which are all elucidated by Boltzmann classical theory. [ABSTRACT FROM AUTHOR]

Methods based on density functional theory are used to evaluate the thermodynamic, mechanical, optoelectronic and thermoelectric properties of the alkali metal-based iodides: XGeI 3 (X = K, Rb and Cs). The thermodynamic stability of these compounds is checked by negative formation energy, and mechanical stability tested through tensor analysis of Chapin's method. For optoelectronic and thermoelectric properties, the recently developed modified Becke–Johnson potential is applied for accurate analysis of bandgap values. The optical properties are explored in terms of dielectric constants and refraction, while thermoelectric properties are explained by electrical and thermal conductivities, Seebeck coefficient, power factor and figure of merit scale. The narrow bandgap, high value of light absorption in the visible region and thermoelectric efficiency make XGeI 3 prospective materials for renewable energy applications. • We elucidate physical properties of alkali metal-based iodides [XGeI 3 (X = K, Rb, and Cs)]. • We confirm thermodynamic stability of studied compounds by enthalpy of formation. • Thermoelectric properties of spinel oxides determined using BoltzTraP code. • Narrow bandgap and thermoelectric efficiency give XGeI 3 potential in renewable energy applications. • These materials are suitable for use in thermoelectric devices. [ABSTRACT FROM AUTHOR]

For leading spintronic technology, the significance of rare earth in the spinels chalcogenide MgCe 2 Z 4 (Z = S, Se) has been investigated. Wein2K and BoltzTraP program packages are used to calculate the magnetic and transport characteristics of the spinels. While comparing the energies within the ferromagnetic and nonmagnetic states, the ferromagnetic state stability in the ground state is examined. The formation energy, phonon dispersion curve, and mechanical stability conditions help clarify the issue of stability in the cubic ferromagnetic phase. Poisson's and Pugh's ratios are employed to ensure the brittle characteristics. To explore the electronic properties, modified Becke and Johnson (mBJ) potential are utilized to investigate both spinels' direct narrow bandgap (spin up channel) nature. Chalcogenide's 2p produces the total magnetic moments- and rare-earth metals' f-states, which result in significant hybridization around the Fermi level. The computed total magnetic moment integer values and polarization are used to demonstrate spin polarisation. Finally, the Seebeck coefficient, thermal-to-electrical conductivity ratio, and power factor are used to evaluate thermoelectric properties. [ABSTRACT FROM AUTHOR]

The spin-dependent magnetic, thermoelectric, and electronic characteristics of Mg-based spinels MgGd 2 X 4 (X = S, Se) are investigated using density functional theory (DFT) calculations. The modified Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol-GGA) is utilized to compute the structural and elastic characteristics. In addition, the magnetic, thermoelectric, and electronic characteristics are explored employing the modified-Becke and Johnson (mBJ) potential. After the energy difference calculations among the ferromagnetic (FM) and nonmagnetic (NM) phases, the stability of the structures is confirmed in the FM phase. Further, thermodynamic stability is determined by calculating formation energies and phonon dispersion spectra. The Charpin method is used to analyze elastic characteristics in detail. The total magnetic moments are produced by 2p-states of chalcogenides and f-states of Gd atoms, which result in substantial hybridization at the Fermi level. Finally, electronic-thermal coefficients, such as the power factor, Seebeck coefficient, and thermal and electrical conductivity, are investigated, concluding that investigated spinels can be used in thermoelectric devices. [ABSTRACT FROM AUTHOR]

To probe the applications in spintronics and sustainable energy devices of ZnMn 2 X 4 (X=S, Se, Te) spinels, their structural, elastic, electronic and thermoelectric properties have been studied in the present work. Structural properties reveal stability of ferromagnetic (FM) phase in these spinels which is further confirmed by computing the heat of formation for these compounds. The mechanical properties of the ZnMn 2 X 4 spinels have been investigated by computing their elastic constants, which show that all these spinels exhibit a brittle character. Moreover, electronic band structure and density of states reveal a half-metallic FM structure in all these spinels. Analysis of the band structure of these materials reveals a semiconducting nature in the spin down channel. Exchange constants (N 0 α and N 0 β) have been computed to directly probe the state splitting and our results large splitting of Mn 3d-states by N 0 β owing to its larger negative value as compared to N 0 α. The strong p-d hybridization is found to make exchange field dominant to crystal field which consequently induces ferromagnetism. In addition, the p-d hybridization reduces the magnetic moment of Mn ions by inducing traces of magnetic moments at non-magnetic sites. The observation of thermoelectric behavior within temperature range 200K–800K reveals positive Seeback coefficient indicating holes as majority charge carriers. Although the power factor is found to increase on going from ZnMn 2 S 4 to ZnMn 2 Te 4 , our results clearly show improvement of power factor with increasing temperature. Image 1 • Density functional theory calculations are performed for ZnMn 2 X 4 (X = S, Se, Te). • Structural analysis depict FM stability of ZnMn 2 X 4 (X = S, Se, Te). • The band structures analysis show their half-metallic nature of ZnMn 2 X 4 (X = S, Se, Te). • The computed magnetic parameters indicate potential spintronic devices applications. • The temperature effect on thermoelectric properties indicate that the material can be used even at elevated temperatures. [ABSTRACT FROM AUTHOR]

Intense research has been done to build materials that are potential candidates for energy storage applications. Spinels are of great interest in this respect because they have vast potential to be used in Mg-based batteries. To explore their energy storage as well as transport response, we calculate Mg-based spinels, namely MgLu 2 Z 4 (Z S, Se). The full potential linearized augmented plane wave method has been used to examine their optoelectronic and transport response. An increase in the lattice constant has been observed by replacing S with Se, and our calculated values are in good agreement with those obtained experimentally. The Tran-Blaha modified Becke-Johnson exchange potential (TB-mBJ), has been used to study the optoelectronic and thermoelectric characteristics of the respective spinels. The dependence of these properties on the bandgap has also been observed. Replacing S with Se resulted in the transformation of the electronic bandgap from near-infrared to the visible region (MgLu 2 S 4 : 2.60 eV and MgLu 2 Se 4 : 2.00 eV). These results showed that these materials have the potential to be used in optoelectronic devices. The optical properties are discussed as a function of energy. Besides, the thermal transports are discussed with the help of Seebeck coefficient and figure of merit as a function of chemical potential and temperature. [ABSTRACT FROM AUTHOR]

• Double perovskites halides K 2 AgBiX 6 (X = Cl, Br) are executed in terms of density functional theory. • Structural and thermodynamic investigation depict structural stability of K 2 AgBiX 6 in cubic phase. • The electronic band structures and optical analysis show both halides are strong candidate for the fabrication of solar cell devices. • Calculated thermoelectric parameters indicate that the both halides can be used even at elevated temperatures. Lead-free double-perovskites (DPs) K 2 AgBiX 6 (X = Cl, Br) has been executed as well as examined by ab-initio computations for solar cell energy sources. Improved and latest Becke and Johnson potential (TB-mBJ) has been suggested to calculate optoelectronics characteristics. The lattice constants reported theoretical and computed values using Perdew-Burke-Ernzerhof's generalized-gradient-approximation (PBEsol-GGA) had been determined in good agreement. The calculated bandgap 2.3 eV (K 2 AgBiCl 6) and 1.5 eV (K 2 AgBiBr 6) disclosed their indirect nature, which showed that these are suitable potential candidates for visible light solar-cell (SC). Optical ranges explain the dielectric-constant, light absorption and reflection, and refractive index. The maximum absorption band has been noted within the wavelength of 620–310 nm. In addition, the BoltzTraP (BT) Code has been determined thermoelectric characteristics that result in higher value Seebeck coefficient and lower thermal conductivity. Hence, executed theoretical calculation proposed that examined material has potential application in renewable energy fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halide based double perovskites Na 2 AgTlZ 6 (Z = Cl, Br, I) have been explored for their optoelectronic and thermoelectric properties. • Lattice parameter, bulk modulus, and mechanical properties varied with substitution at halide side. • Study of optical, electronic and thermoelectric properties highlighted the importance of these materials for optoelectronic and thermoelectric applications. The bandgap engineering and deliberate band edge manipulation of perovskites make them potential candidates for the photovoltaic industry. Here we theoretically investigate the structure, density of states, and photovoltaic and thermoelectric characteristics of Na 2 AgTlZ 6 (Z = Cl, Br, I) using WIEN2k code. The incorporation of Br and I at the Cl site caused the increase in lattice constant which leads to the decrease in bulk modulus and Debye temperature. The computed values of Poisson (<0.26) and Pugh (<1.75) ratio verified their brittle nature. The bandgap analysis reveals direct bandgap nature and bandgap value lie in the visible region for parent composition and infrared and far infrared when Cl is replaced with Br and I. The density of state plots uncovers the shifting of energy states in valence and conduction bands towards the Fermi level with the increasing number of electrons in the halogens. The increase in the value of dielectric constant, refractive index, and shifting of peaks towards lower energy value is witnessed with atomic number of halogen atoms. The viability of these compositions for thermoelectric devices is further confirmed when electrical conductivity and Seebeck coefficient dependent Figure of merit and power factor are evaluated in the temperature range of 200–800 K. In addition, the anisotropic nature of studied compositions is explored through the computation of the modulus of elasticity including Young's modulus, Shear modulus in addition to compressibility, and Poisson's ratio. [ABSTRACT FROM AUTHOR]

Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs 2 YCuX 6 (X = Cl, Br, I) DPHs. The examined DPHs indicate low thermal conductivity scales and high Seebeck coefficient significantly increased the figure of merit (ZT). The examined ZT∼1 at room temperature against temperature and chemical potential makes them appropriate for thermoelectric devices. [Display omitted] Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs 2 YCuX 6 (X = Cl, Br, I) DPHs. The elastic constants and phonon dispersion curves reveal ductile nature and mechanical and thermodynamic stability of the examined materials. The Born stability criteria ensures structural stability, while the formation energy ranging from −2.28 to −1.68 eV signifies thermodynamic viability. Furthermore, the thermodynamic stability of investigated double perovskites Cu 2 YCuX 6 (X = Cl, Br, I) have been verified by performing ab-initio finite temperature molecular dynamics (MD) simulation. The examination of mechanical characteristics affirms the ductile nature of the material, and its substantial anisotropic factor enhance its significance for device fabrication. The band gaps calculated at 2.65 eV, 2.55 eV, and 2.45 eV from band structures, highlight the significance of the studied double perovskites (DPs) for optoelectronic applications. Optical parameters yield information on minimal dispersion and expansive absorption band. Additionally, transport characteristics are analyzed through parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity, and the Figure of merit (ZT). [ABSTRACT FROM AUTHOR]

The toxicity and instability of lead-based perovskites have been replaced with newly investigated stable lead-free inorganic perovskites. The current study included the comprehensive analysis of electronic behavior, elastic, optical, and transport characteristics of lead-free inorganic double perovskites (DPs) Rb 2 KTlX 6 (X = Cl, Br) halides for possible uses. These physical characteristics were revealed using density functional theory (DFT) based Wien2k code. Using the energy optimization process, we have computed structural parameters comparable to existing data using generalized gradient approximation (PBEsol-GGA). In addition, the elastic parameters, formation energy (−1.94 eV and −1.39 eV), and tolerance factor (0.98 and 0.97) endorsed the cubic stability of both halides. Further, we employed modified Becke-Johnson (mBJ) potential to an accurate value of direct bandgaps of both halides reveal that changing the anions from Cl to Br leads to significant adjustment in the band gap, transitioning from the visible to the IR spectrum, with energy levels ranging from 2.08 to 1.2 eV. Our calculated results of optical parameters indicate that both halides with remarkable optoelectronic working due to low reflectivity, high optical absorption, and conductivity. The study reveals that electronic transport factors are associated with temperature due to small bandgap of the materials. The observed figure of merit near unity indicates the semiconducting behavior of these materials that can be useful in thermoelectric tools. • First-principle calculations of DPs Rb 2 KTlX 6 (X = Cl, Br). • Direct bandgap semiconductor. • Optical characteristics for optoelectronic devices. • Transport characteristics are discussed in details for thermoelectric devices. [ABSTRACT FROM AUTHOR]

Spintronics is an emerging field that has the potential to replace conventional electronics due to their comparatively high speed, low power consumption, and infinite endurance. The phenomena of ferromagnetism with high spin polarization in double perovskites make them the desired materials for spintronics. In the present work, the structure of Cs 2 CuCrX 6 (X = Cl and Br) and their magnetic and optoelectronic properties were studied by utilizing density functional theory (DFT). For the calculations of exchange-correlation potential, PBE-sol approximation was utilized while for the accurate measurement of electronic band structure and density of states (DOS), we employed mBJ potential. Both materials exhibit cubic structure and are thermodynamically stable as confirmed by volume optimization and negative formation energy respectively. Spin-based energy-volume optimization and values of exchange constants reveal the ferromagnetic nature of materials. It has been observed that 3-d states of Cr are responsible for ferromagnetism and have the major contribution to the net magnetic moment caused by exchange splitting. Furthermore, investigations of band structure and electronic density of states showed that both Cs 2 CuCrCl 6 and Cs 2 CuCrBr 6 were indirect bandgap (E g) semiconductors with the E g values of 1.2 eV and 0.33 eV respectively. The optical spectra of materials showed strong absorption in the ultraviolet region. Lastly, the transport and thermoelectric properties (TE) of materials were investigated in the range of temperature 300 K–800 K by using the BoltzTrap code. The transport parameter which included the electrical conductivity (σ/τ) and thermal conductivity (κ e /τ) of the materials showed a decreasing trend with temperature whereas the Seebeck coefficient (S) and Power factor (P.F) showed an increasing trend for Cs 2 CuCrCl 6 while decreases in case of Cs 2 CuCrBr 6. Furthermore, a high figure of merit (ZT) with values of 0.75 and 0.64 was obtained for Cs 2 CuCrCl 6 and Cs 2 CuCrBr 6 respectively. The results of this work are encouraging and show the capabilities of the discussed materials in the fields of spintronics, thermoelectric, and optoelectronics. [Display omitted] • This manuscript presents a comprehensive theoretical investigation into the magnetic, optoelectronic, and thermoelectric properties of Cs 2 CuCrX 6 (X = Cl and Br) double perovskites. • Through rigorous theoretical analysis, the manuscript unveils the spintronic potential of Cs 2 CuCrX 6 double perovskites, shedding light on their intrinsic magnetic properties and their suitability for spin-based electronic applications. This insight opens avenues for innovative spintronics device designs. • Delving into the optoelectronic characteristics, the manuscript elucidates the optical properties of Cs 2 CuCrX 6 double perovskites, offering valuable insights into their light-matter interaction mechanisms. • By examining the thermoelectric properties of Cs 2 CuCrX 6 double perovskites, the manuscript assesses their potential for thermoelectric applications, highlighting their ability to efficiently convert heat into electrical energy. This exploration paves the way for dual-functionality devices coupling data storage with energy harvesting capabilities. [ABSTRACT FROM AUTHOR]

Lead free double perovkistes is an emerging class of optoelectronic material which have a huge potential for futuristic electronic industry. In present communication, we theoretically studied the structural, optoelectronic, and thermoelectric properties of Li 2 AgTlCl 6 and Li 2 AgTlBr 6 using WIEN2k software. The permissible values of tolerance factor and enthalpy of formation ensure the structural and thermodynamic stability of these compositions. The substitution of halides increase the lattice constant from 10.52 to 11.11 Å and reduce the bulk modulus from 33.38 to 26.20 GPa. The calculation of Poisons and Pugh ratios ensures their ductile nature, whereas the examination of band structure indicates exposed the bansgap value of 2.0 and 1.2 eV for Li 2 AgTlCl 6 and Li 2 AgTlBr 6 , respectively. A remarkable increase in optical parameters like static dielectric constant, refractive index, and shifting of peaks towards lower energy values is observed the replacement of Cl with Br. This substitution increased the electrical conductivity, specific heat at constant volume, Seebeck coefficient, and figure of merit that showed the feasibility of these compositions for photovoltaic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halide based double perovskites K 2 ScAuX 6 (X = Br, I) have been theoretically investigated using WEIN2k software. • Structural parameters were optimized using Perdew–Burke–Ernzerhof generized gradient approximation (PBEsol-GGA) • Investgation of mechanical response of these materials revealed their ductile nature. • Indirect band gap nature with bang gap values of 2.20 eV and 1.90 eV were estimated using mBJ potential. • Electronic transport properties in a wide range of temperature has been evaluated. Here we report a theoretical analysis of various technologically important physical properties of double perovskites K 2 ScAuX 6 (X = Cl, Br) including thansport, optoelecronic, and strucutral. The computation of tolerance factor and estimation of entahly of formation remained key indicators to ensure the srucutal and thermodynamic stability of these compositions. The substitution of Br at Cl site increased the lattice parameter and reduced the bulk modulus. The computation of elastic constants-based modulus of elasticity revealed their ductile nature. The analysis of electronic band structure unveiled their indirect bandgap nature. Polarizability of material is accessed by computing the dielectric constant, scattering by extinction coefficient, absorption by refractive index, in addition to electrical and thermal conductivity and the Seebeck coefficient, highlighted their suitability for advanced technologically important applications in optoelectronic and thermoelectric industry. [ABSTRACT FROM AUTHOR]

Double perovskite halides are a potential candidate for the applications of the solar cell, photovoltaic and thermoelectric, due to their non-toxicity and environmental stability. The density functional theory (DFT) calculation investigates the details physical properties of halides Rb 2 ScAgX 6 (X = Cl, Br, I) that can be useful for applications like thermoelectric and solar cells. The structural and thermodynamics stability is endorsed by the formation energy, tolerance factor, and Born stability criteria. The calculated indirect band gaps of 1.95 eV, 1.85, and 1.60 eV for Rb 2 ScAgCl 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgI 6 respectively, ensure the light absorption in the region of visible range. Therefore, all studied halides are widely used in optoelectronic devices like solar cells. In addition, thermoelectric properties are examined through thermal conductivity, electrical conductivity, and the Seebeck coefficient. ZT values of 0.74, 0.71, and 0.72 for Rb 2 ScAgI 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgCl 6 double perovskites are recorded, which spotlight their significance for the applications of thermoelectric. [ABSTRACT FROM AUTHOR]