BoltzTraP Code Research Articles

Investigating the Multifunctional Role of Sr2FeMnO6 Double Perovskite in Spintronic and Thermoelectric Properties

Herein, the double‐perovskite Sr2FeMnO6 is investigated using density functional theory to investigate its electronic, magnetic, thermoelectric, and thermodynamic properties. The Sr2FeMnO6 show the ferromagnetic phase stability with the formation energy of about −2.53 eV. Spin‐polarized band structure and density of states (DOS) calculations, performed using the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE‐GGA) and modified Becke–Johnson (GGA + mBJ) methods, confirm a half‐metallic nature. The system exhibits metallic behavior in the spin‐up channel, whereas the low‐spin counterpart demonstrates semiconducting characteristics with a bandgap of about 1.38 eV. A total magnetic moment of 7 μB per formula unit is observed, predominantly originating from Fe and Mn atoms, with induced magnetism in oxygen attributed to Mn‐3d, Fe‐3d, and O‐2p orbital interactions. The thermoelectric behavior of the system is studied by employing the semiclassical Boltzmann theory‐based BoltzTraP code for both spin channels, revealing zT values of 0.98 and 0.94 for spin‐down and spin‐up channels, respectively, with zT decreasing and the power factor increasing with temperature. These findings highlight Sr2FeMnO6 as a promising candidate for spintronics, spin dynamics, and energy‐harvesting applications, offering insights into its multifunctional potential.

DFT study of the binary intermetallic compound NdMn2 in different polytypic phases.

The structural stability, ground state magnetic order, electronic, elastic and thermoelectric properties of NdMn2 in the C15, C14 and C36 polytypic phases is investigated. The magnetic phase optimization and magnetic susceptibility reveal that NdMn2 is antiferromagnetic (AFM) in C36 phase; and paramagnetic (PM) in C14 and C15 phases respectively. The band profiles and electrical resistivity show the metallic nature in all these polytypic phases and reveal that the C36 phase possesses smaller resistivity. The presence of covalent bonds among Nd-Nd and Nd-Mn has been verified from the electron charge densities plots. The elastic constants calculated in different phases confirm the mechanical stability and are elastically anisotropic and incompressible in all phases. Due to large enough value of Young and Bulk moduli in C14 phase NdMn2 would be suitable candidate for applications that require high strength, stiffness and durability, as well as the ability to withstand extreme environments. The density functional theory (DFT) is used to investigate the physical properties of understudy binary intermetallic compounds NdMn2 in the C15, C14 and C36 polytypic phases. BoltzTraP code based on Boltzmann semi-classical transport theory is used to investigate magnetic susceptibility and electrical resistivities of the understudy compounds. The elastic constants are calculated with the help of IRELAST code embedded in WIEN2k software. Linux based xmgrace and origin software are used for plotting.

Study of Optical, Thermoelectric, and Mechanical Behaviors of Double PerovskitesCs2SnVX6(X = Cl, Br, I) for Renewable Energy

Abstract Double perovskites are emerging materials for solar cells and renewable energy applications. Here this research emphasizes the optical, transport, and mechanical characteristics of Cs2SnVX6 (X = Cl, Br, I) for renewable energy. The structural and dynamic stabilities of these double perovskites in the cubic phase have been ensured by the tolerance factor (0.94, 0.93, 0.91) and the Ab initio molecular dynamic (AIMD) simulation. Furthermore, formation energy and elastic constants have also been reported, which provide evidence of thermodynamic and mechanical stability. The band gaps analyzed by TB-mBJ potential are 1.48 eV, 1.29 eV, and 0.22 eV for the Cs2SnVCl6, Cs2SnVBr6, and Cs2SnVI6, respectively. The band gap of Cs2SnVBr6 is standard for solar cells. The absorption band exists in the visible to infrared zone, with minimal optical losses. The transport behavior has been addressed through the BoltztraP code, whose large thermoelectric performance has been confirmed by the figure of merit (1.10, 0.90, 0.65) at 300K, and ultralow lattice thermal conductivity. From mechanical analysis, it is assumed that Cs2SnVCl6 has a ductile nature (B/G = 2.0) while Cs2SnVBr6 and Cs2SnVI6 have a brittle nature (B/G = 1.26, 0.94). Moreover, their hardness, large Debye, and melting temperature are also important for device fabrication.

DFT-based computational investigation of the structural, electronic, and thermoelectric properties oftransition-metal hydride VH2.

Vanadium hydride is of significant interest because of its potential applications in thermoelectric materials and hydrogen storage technologies. Understanding its structural, electronic, and thermoelectric properties is crucial for optimizing its performance in these applications. This study investigates these properties via density functional theory (DFT), revealing key insights into its stability and efficiency as a thermoelectric material. In this work, the structural, electronic, and thermoelectric properties of cubic VH2 were investigated using the GGA approach within the framework of DFT. The band structure and density of states demonstrate the metallic nature of these compounds. Using the semi-empirical Boltzmann's approach implemented in the BoltzTraP code, transport parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit as a function of the chemical potential, are computed at a temperature gradient of 500K. For the VH2 compound, the thermal and electrical conductivities and Seebeck coefficient are greater for p-type doping and n-type doping. The moderate values of the figure of merit obtained for these materials indicate that these materials have applicability where small values of thermoelectric efficiency are required, and higher values can harm the process. The maximum values of the Seebeck coefficient for VH2 against chemical potential values ranging between 0.095 and - 0.095eV in the p-type region and n-type region are 2.28µV/K and - 2.27µV/K, respectively. The highest value of electrical conductivity per relaxation time in the chemical potential range between - 0.07 and 0.07eV in the p-type region is 5.3 × 10201/Ωms, and that in the n-type region is 1.97 × 10201/Ωms. The maximum dimensionless figure of merit value for VH2 is 0.020.

The Determination of the Mechanical, Optoelectronic, Structural and Transport Attributes of Double Perovskite A2InGaBr6 (A=K, Rb, Cs) Halides for Renewable Energies: A DFT Study.

Safer and more environmentally friendly alternatives to lead-based perovskites include lead-free halide perovskites, which retain good optoelectronic capabilities while reducing environmental toxicity. They also align better with ecological and regulatory standards for green technologies. In this manuscript, we have presented the first principles analysis of the physical traits of A2InGaBr6 (A=K, Rb, Cs). The exchange-correlation effects are treated with mBJ potential. The structural characteristic of A2InGaBr6 (A=K, Rb, Cs) was assessed through the volume optimization curves, formation energies and tolerance factor. The elastic properties of the studied halides are analyzed through elastic constants. The electronic band structures revealed indirect bandgaps for K2InGaBr6, Rb2InGaBr6, and Cs2InGaBr6. The optical properties indicate promising potential in the fabrication of optoelectronic devices for A2InGaBr6 (A=K, Rb, Cs). The transport properties for the studied halides are computed using the BoltzTraP code, which reveals that these halides are promising candidates for thermoelectricity.

Electronic Nature and Thermoelectric Characteristics of Cubic LaPb3 LaIn3 and LaTl3 Compounds: B3PW91 Approach

In this paper the structural, electronic and transport properties of the strongly correlated intermetallics LaX3 (X=Pb, In and Tl) in the space group Pm-3m (221) have been investigated using B3PW91 hybrid functional within the framework of density functional theory. These compounds have 4f orbitals and hence strong electron-electron correlation effect is expected, therefore, the electronic properties are also calculated with the B3PW91 hybrid functional and the effect of B3PW91 hybrid functional on the density of states is discussed in details. The band structure and density of states, demonstrate the metallic nature of these compounds. Using the semi-empirical Boltzmann’s approach implemented in the BoltzTraP code, the transport parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit as a function of the chemical potential are computed at a temperature gradient of 500 K. For all materials the thermal and electrical conductivities, and Seebeck coefficient has higher values for n-type doping in comparison with p-type doping. The moderate values of figure of merit obtained for these materials indicate that these materials have applicability where small values of thermoelectric efficiency are required and higher values can harm the process but need experimental verification. LaIn3 has the highest value of electrical conductivity per relaxation time and thermal conductivity per relaxation time are 9.43 x 1020 1/Ωms and 107.65 x 1014 W/mKs respectively. LaTl3 has the highest figure of merit among these materials.

An emerging aspirant for solar cell and non-conventional energy applications: Lead free fluoro-perovskites A2TlInF6 (A = K, Rb)

In the present work; structural, electronic, optical, and thermoelectric properties of double perovskites A2TlInF6 (A = K, Rb) have been studied using the ab-initio method in conjunction with full potential Linear Augmented Plane Wave (FP-LAPW) method and PBE-GGA potential. Structural properties, cohesive energy, and formation enthalpy collectively confirmed the stability of the halide perovskites in a cubic structure with Fm3m symmetry. Electronic properties revealed the p-type semiconductor nature of both materials. The indirect band gap values for K2TlInF6 and Rb2TlInF6 were found to be 3.489 eV and 3.591 eV, respectively, with PBE. With PBE + SOC, the values dropped to 3.445 eV and 3.546 eV, respectively. Optical properties such as Dielectric function εω, Refractive Index nω, Extinction Coefficient κω, Optical Conductivity σ(ω), Reflectivity R(ω), Electron Energy Loss Function L(ω), and Absorption Coefficient αω were determined using PBE-GGA potential. BoltzTraP code was used to determine thermoelectric properties, namely, Seebeck Coefficient (S), Electrical Conductivity (σ), Thermal Conductivity (K), Power Factor (PF), and Figure of merit (ZT) which were studied in detail. The study suggests halide-based double perovskites may have the potential for solar energy utilization due to their high absorption coefficient, large values of refractive index, and optimal values of the figure of merit.

First principles investigation of double perovskites Li2CuAsZ6 (Z = Cl, Br, I) as a suitable alternatives for energy conversion technologies

The present study employs density functional theory to examine the physical properties of halide double perovskites Li2CuAsZ6 (Z = Cl, Br, I). The stability of the phase has been confirmed by analyzing the cubic layout and the values of the octahedral and tolerance factors. The formation energies of all perovskites have been computed to guarantee thermodynamic stability. The detailed description of the electronic characteristics of Li2CuAsZ6 reveals its behavior as a semiconductor. Energy band gaps of 0.55 eV, 0.33 eV, and 0.088 eV for Li2CuAsCl6, Li2CuAsBr6, and Li2CuAsI6, respectively, are determined by our calculations. Additionally, we have investigated the optical properties of these materials with 0–4 eV energy span in detail, which are reported as strong candidates for use in optoelectronic systems. The BoltzTraP code is employed to evaluate the thermoelectric characteristics. The lower lattice thermal conductivity values for Li2CuAsCl6, Li2CuAsBr6, and Li2CuAsI6 suggest less contribution to thermoelectric functionality. Finally, this discussion indicates the suitability of studied perovskites for energy conversion systems; however, experimental confirmation is necessary before these perovskites may be used in thermoelectric and optoelectronic systems.

First principle study of physical aspects and hydrogen storage capacity of magnesium-based double perovskite hydrides Mg2XH6 (X = Cr, Mn)

Hydrogen's potential as a clean energy source has propelled hydrogen storage into a pivotal realm of contemporary research. Cutting-edge double perovskite compounds have become a central focus for exploring hydrogen storage applications. The aim is to scrutinize their structural, mechanical, electronic, magnetic, thermoelectric, and hydrogen storage properties. The negative value of enthalpy of formation and approaching value of tolerance factor confirm the thermodynamic and structural stability of studied compositions, leading to the calculation of ground state lattice parameters. The high value of Curie temperature (310 K), particularly for Cr-based composition, exhibits the viable application of this composition at room temperature. Metallic behavior in the spin-up channel and semiconducting nature in the spin-down channel are witnessed in the band structure that ascertains the half-metallic behavior of both compositions, ensuring 100% spin polarization, an essential feature for spintronic devices. Furthermore, employing the BoltzTraP code to analyze thermoelectric characteristics with heightened Seebeck coefficients and reduced thermal conductivity reveals their suitability for thermoelectric devices. Moreover, investigation into the hydrogen storage characteristics of Mg2XH6 (X = Cr, Mn) exhibits notable hydrogen storage capacities of 5.60 wt% for Mg2CrH6 and 5.51 wt % for Mg2MnH6. This study marks the pioneering examination of Mg2XH6 (X = Cr, Mn) double perovskite-type hydrides, promising significant contributions to future research endeavours in hydrogen storage applications.

Carbon monochalcogenides/graphene van der Waals heterostructures for sustainable energy harvesting

We constructed the van der Waals (vdW) heterostructures by stacking graphene (G) on top of carbon-based monochalcogenides (CX; X = S, Se, and Te) monolayer in two different patterns (I and II) and predicted various physical properties through first-principles calculations. Among the six heterostructures, three systems (CS/G in Pattern-I and II, and CSe/G in Pattern-II) were found to be most stable. Additionally, the calculated electronic properties confirmed that the CS/G and CSe/G heterostructures in Pattern II are indirect semiconductors with narrow band gap values of 0.49 and 0.30 eV, respectively. Notably, both heterostructures (CS/G and CSe/G) exhibit significantly larger electron carrier mobilities of 762.83 and 206.84 m2/Vs at room temperature, respectively. Furthermore, intrinsic and interface dipoles in both heterostructures were found to align along the +z axis, enhancing charge transfer at the interface and narrowing the band gap, particularly in CSe/G. This polarization effect contributes to the observed high electron mobility and thermoelectric performance. Electronic transport coefficients like the Seebeck coefficient, electrical conductivity, and thermoelectric power factor are predicted using the Boltzmann transport theory implemented in the BoltzTrap code. The highest power factor 249mW/mK2 was achieved for the CSe/G heterostructure at 300K, demonstrating its ability for good thermoelectric purposes. Besides, the computed optical properties revealed the potential of the CS/G heterostructure as a light absorber with an excellent solar light energy conversion efficiency (η) of 23.57 % for solar cell device applications. Our predictions show that the novel 2D CX/G vdW heterostructures could be promising candidates for designing new solar and heat energy harvesting devices.

Advancement in the thermoelectric performance of bulk SnSe: GGA+U approach for band gap calculation and strain induced thermal conductivity

The utilization of thermoelectric technology for harnessing electricity from waste heat has received considerable interest in recent years. Nevertheless, it is essential to develop high-performance thermoelectric materials that exhibit outstanding conversion efficiency to satisfy the world's energy needs. Density Functional Theory (DFT) techniques have gained wide spread recognition as computational simulation methods for determining electronic properties within materials science. The Boltzmann transport equation, used in conjunction with DFT, serves as a valuable tool for predicting the thermoelectric characteristics of various materials. In this investigation, we conducted a comprehensive analysis of the thermoelectric properties of SnSe using the Quantum Espresso software. Generalized gradient approximations were used as the exchange-correlation functional, which approximates the exchange and correlation energies between electrons in many-body problems. The investigation of core electrons employed ultrasoft pseudopotentials. Additionally, the Hubbard correction tool was applied for the final calculation of the band gap. The optimized structure used for the investigation of the thermoelectric properties of bulk SnSe was supported by the BoltzTraP code. Thermal conductivity studies were conducted using Slack's equation, which incorporates both elastic and lattice characteristics. The examination focused on assessing the impact of changes in lattice strain on lattice thermal conductivity. Notably, a significant alteration in the thermoelectric figure of merit was observed due to the applied lattice strain.

First‐Principles Study of Structural and Elastic, Electronic, and Thermoelectric Properties of PdSe2

The thermoelectric material in orthorhombic (Pbca) phase is studied with the help of density functional theory implemented in WIEN2k. The main properties of investigated are elastic, electronic, and thermoelectric properties. The anisotropy factors obtained with the elastic constants indicate that is strongly anisotropic. The Tran and Blaha‐modified Becke–Johnson exchange potential is used for bandgap calculations. The BoltzTraP code is used to find out the thermoelectric properties of . At 300 K, the maximum value of the Seebeck coefficient is 200 μV K−1 for the hole carrier concentration of 2.5 × 1019 cm−3 and is 241 μV K−1 for the electron carrier concentration of 1.2 × 1019 cm−3. The power factor (PF) and figure of merit (ZT) are calculated for different carrier concentrations and temperatures. The optimum value of ZT for bulk PdSe2 as calculated in this work is ≈0.6 for hole carrier concentration (p = 2.6 × 1020 cm−3) at 800 K, which suggests as a potential material in thermoelectric applications at higher temperatures.

First principles investigation of structural, electronic, optical, transport properties of double perovskites X2TaTbO6 (X= Ca, Sr, Ba) for optoelectronic and energy harvesting applications

Structural, electrical, optical, thermoelectric response of X2TaTbO6 (X = Ca, Sr, Ba) double perovskites oxides are studied by using WIEN2k that is based on quantum mechanical calculations employing PBE-GGA approximation under the framework of DFT. We present electronic attributes including band gaps and density of states, and explain the electronic properties of all three oxide double perovskite materials which proved that they belong to directly forbidden band gap materials family. The cubic compounds Ba2TaTbO6, Sr2TaTbO6, and Ca2TaTbO6 have respective direct band gaps of 2.35 eV, 2.15eV, and 2.25 eV. Optical conductivity σ(ω), reflection R(ω), complex dielectric constants, refractive index ƞ(ω), absorbance α(ω), loss parameter L(ω) and extinction coefficient K(ω) are all utilized to explore light dependent characteristics of studied compounds. Thermoelectric parameter like, Number of Seebeck effect (S), charge carrier (n), magnetic susceptibility, power factor (PF), electrical conductivity (σ/t), thermal conductivity K/t, and heat capacity are key characteristics for materials to study its ability of thermal behavior. These thermoelectric parameters were determined by using BoltzTraP code. By studying the numbers on various material properties, scientists are uncovering new possibilities for creating sustainable materials for sustainable gadgets.

First principle study of electronic, optoelectronic, and thermoelectric properties of zintl phase alloys BaAg2X2 (X = S, Se, Te) for renewable energy

Novel Zintl phases exhibiting promising thermoelectric properties have garnered considerable traction, largely attributed to the accuracy of computational estimates. In the present investigation, the density functional theory-based WIEN2k code is employed to analyze the structural, optoelectronic, and transport behavior of the BaAg2X2 (X = S, Se, Te) Zintl phase. All these compositions belong to the stable trigonal phase with nominal expansion in the unit cell with the replacement of S with Se and Te. A negative value of enthalpy of formation of −2.30, −2.0, and −1.80 for BaAg2S2, BaAg2Se2, and BaAg2Te2, respectively, assures their thermodynamic stability. These compositions demonstrate dynamic stability, as evidenced by the nonexistence of negative (-ve) frequency values in their phonon spectra. Increasing the size of chalcogens enhances the spin-orbit coupling and reduces the bandgap value from 2.10 to 1.55 eV. The examination of optical response suggests that studied compositions display high absorption and low energy loss in the visible range, rendering them suitable for optoelectronic devices. The temperature-dependent transport behavior is computed using BoltzTrap code, and the RT value of power factor is recorded as 0.89 × 1011, 0.65 × 1011, and 0.54 × 1011 Wm− 1K− 2 for BaAg2X2 (X = S, Se, Te). A high power factor value at elevated temperatures indicates the promising efficacy of studied compositions in thermoelectric device applications.

DFT-based Prediction of promising structural, elastic and Thermoelectronic properties in BaAgX3 (X= I, Br, and Cl) halide perovskites

The aim of this research is to explore the structural, electronic, elastic, mechanical and thermoelectric properties of inorganic halide perovskites BaAgX3 (X = I, Br, and Cl) through theoretical calculations guided by Density Functional Theory (DFT). We performed our computations using full potential linearized augmented plane wave (FP-LAPW) method, combined with the generalized gradient approximation (GGA-PBE) and Tran-Blaha modified Beck-Johnson (TB-mBJ) approximations to model the exchange-correlation potential as generated by the Wien2k code. The structural parameters, such as the lattice constant were calculated and found to be in excellent agreement with existing theoretical results, and the formation energy evaluation verifies the chemical stability of the compounds. Electronic properties derived from band structure and density of states for all compounds show a semiconducting behavior with an indirect band gap. Electron density mapping identifies covalent bonding in (Ag-X) and ionic bonding in (Ba-X). The elastic and mechanical properties were also computed, revealing that the compounds concerned are mechanically stable following Born stability criteria and exhibit both ductility and anisotropic character. Finally, the thermoelectric properties of halide perovskites were investigated using the BoltzTraP code. The analysis focused on key parameters like Seebeck coefficient, electrical conductivity, power factor, and figure of merit (ZT) across a temperature range of 300–1200 K. The results highlight the promising potential of these materials for both optoelectronic and thermoelectric applications due to their semiconductor and thermoelectric properties.

Unveiling half-metallic, thermoelectric and optoelectronic behavior of the new Heusler alloy RbCrZ (Z = Si, Ge): a DFT perspective

Abstract Utilizing the density functional theory (DFT) method, this study aims to predict with precision the structural, elastic, electronic, magnetic, thermoelectric, thermal, and optical properties of two recently discovered half-Heusler alloys, namely RbCrSi and RbCrGe. The exchange and correlation potential are accounted for using the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE) and the Tran–Blaha-modified Becke–Johnson exchange potential (TB-mBJ). Through structural analysis, it is observed that both RbCrSi and RbCrGe alloys exhibit energetic stability in a type-3 structure with a ferromagnetic (FM) state. Both alloys exhibit half-metallic properties and integer magnetic moments of 3 μB, following the Slater-Pauli rule. Additionally, elastic calculations confirm their mechanical stability and anisotropic ductile behavior. The quasi-harmonic Debye model (QHDM) is employed for calculating thermodynamic properties, while the BoltzTraP code, based on semi-classical Boltzmann theory (SCBT), is utilized for evaluating thermoelectric properties. Findings reveal that RbCrZ alloys (with Z = Si, Ge) exhibit high figure of merit (ZT) values nearing unity at highest temperature. Consequently, the newfound half-Heusler alloys RbCrSi and RbCrGe hold significant promise for applications in thermoelectricity and spintronic devices. This comprehensive analysis underscores the potential of these alloys in the realm of renewable energy applications.

Exploration of lead free half-metallic double perovskites Li2Mo(Cl/Br)6 for spintronic device: DFT-calculations

The intrinsic spin of electrons has revolutionized the various aspects in the field of electronics, like data storage and quantum computing. Magnetic, structural, mechanical, transport and thermoelectric aspects of the Li2Mo(Cl/Br)6 double perovskites have been examined using the Wein2k and BoltzTraP code. These compounds having cubic structure with negative enthalpy of formation confirms their thermodynamic stability. The energy versus volume optimization for both ferromagnetic (FM) and antiferromagnetic phases (AFM) indicate AFM state due to greater release of energy in this configuration. Double exchange model p-d hybridization for partial density of states (PDOS) is investigated in band structures and half-metallicity feature is reported. The spin–orbit interaction with hybridization in d states of Mo and integral magnetic moment reveals strong spin polarization. The thermoelectric features (Seebeck coefficient, power factor, and figure of merit, electrical and thermal conductivities) have also been evaluated for utilization of these compounds in spintronics appliances.

Enhancing thermoelectric and radiation shielding performance of novel LaFe0.8Mn0.2Sb12 skutterudites for energy applications

We explore the structural, optoelectronic, and thermoelectric properties of LaFe0.8Mn0.2Sb12 skutterudites using first-principles computations and semi-classical Boltzmann Transport equations. These materials are classified as semiconductors exhibiting band gaps of 0.55 eV and 1.8 eV for spin-up and down polarizations. Valence band maxima (VBM) and conduction band minima (CBM) lie on the gamma points, indicating direct band gaps for both spin channels. The band structure, density of states, and optical characteristics reveal that the material is a semiconductor. The optical reflectivity and complex dielectric function were calculated for a wide range of photon radiation to understand these compounds' optical properties. The transport parameters were investigated using electrical conductivity, thermal conductivity, the Seebeck coefficient, the power factor, the heat capacity, and the figure of merit determined using the Boltztrap code. The LaFe0.8Mn0.2Sb12 has a Seebeck coefficient of 5.77×10−6 V/K (Up), whereas the down channel has a 4.2×10−6 V/K. The highest figure of merit is 0.99, and as a result, the theoretical findings provide a robust foundation for upcoming experimental research. In this study, utilize the Phy-X program to evaluate the radiation shielding capabilities of LaFe0.8Mn0.2Sb12, focusing on critical parameters like mass attenuation coefficients (γmac) and half-value layers (γhvl), essential for optimizing protection against hazardous ionizing radiation. Computational study of energy-renewable and thermoelectric properties enables experimenters to investigate fresh applications for predicting photovoltaic materials with atomic-level accuracy.

Unveiling the recently synthesis noncentrosymmetric layered ASb3X2O12 (A = K, Rb, Cs, Tl; X = Se, Te) via first principles calculations

This study explores the structural, optical, and thermoelectric properties of non-centrosymmetric layered selenite and tellurite compounds KSb3Se2O12, RbSb3Se2O12, CsSb3Se2O12, TlSb3Se2O12, KSb3Te2O12, RbSb3Te2O12, CsSb3Te2O12, TlSb3Te2O12 to assess their potential for sustainable and renewable energy technologies. The selenite and tellurite compounds feature distinct non-centrosymmetric layered crystal structures, which are key to their unique optical and electronic properties. The materials display a layered structure without a center of symmetry, characterized by distinct atomic arrangements, and their band gaps vary depending on the constituent elements. For selenites, band gaps range from 2.97 eV to 3.19 eV, while for tellurites, they range from 2.75 eV to 3.02 eV, indicate their suitability for indirect semiconducting applications. The investigated materials exhibit high absorbance in the ultraviolet region, suggesting they are promising for solar cell applications. The energy loss function peaks at 14 eV, indicating minimal optical loss in the infrared and visible spectra. The static dielectric constants ε1(0) were calculated, showing variations based on the elemental composition. The response of ε2(ω) demonstrates strong interactions in the ultraviolet region, corresponding to electronic transitions from the valence to the conduction bands. Thermoelectric properties, evaluated with the BoltzTrap code using transport theory. The Seebeck coefficient of p-type semiconductors typically increases with temperature, but TlSb3Se2O12 shows an even greater increase, suggesting enhanced thermoelectric properties. Both selenites and tellurites have rising electrical conductivities, with ASb3Se2O12 peaking at 800 K. The Power Factor improves with temperature, reaching a peak for TlSb3Se2O12. These compounds exhibit favorable electrical conductivity and power factor, suggesting potential applications in thermoelectric systems. The figure of merit (ZT) values spanning from 0.90 to 1.51, with a maximum ZT value of 1.41 at 800 K, TlSb3Se2O12 shows great potential for high-temperature thermoelectric applications. These findings advance the understanding of non-centrosymmetric oxide materials and provide valuable insights for developing advanced materials for energy technologies.

A Comprehensive DFT Exploration of Physical Characteristics of Halide Double Perovskites Na2AgGa(Cl/Br)6: Environment-Friendly Alternatives for Renewable Energy Technologies

This work elucidates the comprehensive exploration of the stability, electronic aspects, and photovoltaic response and ability to utilize thermal energy of Na2AgGa(Cl/Br)6. The cubic phase and thermal stability are evaluated based on the depicted tolerance factor and formation enthalpy. The depicted electronic attributes comprehensively clarified the p-type nature of materials. The value of the obtained direct energy gap is reduced from 1.85 eV to 1.13 eV by replacing Na2AgGaCl6 with Na2AgGaBr6. The scrutiny of distributed states across bands is also explained by analyzing states’ partial and total density. Furthermore, the assessed optical properties indicate that these compounds exhibit considerable absorption values across the visible-ultraviolet spectrum. The optical characteristics suggest that these perovskites exhibit minimal loss of power and have an increased ability to capture light, making them well-suited for use in solar power generation. Using the BoltzTraP code, thermoelectric parameters have been scrutinized, uncovering a significant relationship between increased electrical conductivity and decreased heat transfer. The elastic properties are examined to ascertain the ductile characteristics, symmetry or asymmetry, and stability under applied stress. The combination of a higher absorption and ZT value indicates that these compounds have significant potential for generating power using light and dissipated heat.