Semi-classical Boltzmann Theory Research Articles

Robust chiral spin transport in the antiferromagnetic iron oxide/heavy metal bilayers

We have observed robust chiral spin torques and non-reciprocal charge transport behaviors in the α-Fe2O3/Pt bilayers through a combination of magnetic field and current-dependent second longitudinal harmonic resistance measurements. The interfacial Dzyaloshinskii–Moriya interaction induced magnetic chirality has been predicted to account for the sign reversal characteristic of the second longitudinal harmonic resistance with increasing the current amplitude. A physical model that considers the chirality dependence of both the asymmetric scattering and the giant Rashba spin–orbit coupling has been set up to uncover the microscopic interactions between charge, spin, and magnetic chirality. Our comprehensive approach leverages the semiclassical Boltzmann theory to validate the consistency between this model and our experimental findings. Through our investigation, we have established the pivotal role of interfacial magnetic chirality in determining both charge and spin transport behaviors within antiferromagnetic insulator/heavy metal bilayer systems. Our work not only enhances the comprehension of spin–orbit torques and non-reciprocal charge transport but also contributes to the broader understanding of these phenomena. The outcomes of this study have broader implications for the advancement of spintronics and related fields.

Comprehensive investigation of half Heusler alloy: Unveiling structural, electronic, magnetic, mechanical, thermodynamic, and transport properties

This study employs density functional theory (DFT) using Wien2k to comprehensively analyze the essential properties of two half-Heusler alloys, KCrSi and KCrGe. Our findings demonstrate that the ferromagnetic Type 2 configuration exhibits superior stability over non-magnetic and antiferromagnetic states for all KCrZ (Z = Si, Ge) alloys. These alloys exhibit complete spin polarization and half-metallic character, with calculated magnetic moments of 3 μB for both KCrSi and KCrGe. The Curie temperature (TC) is determined using the mean field approximation. Mechanical stability is assessed through second-order elastic constants (SOECs), and electronic properties are analyzed using local spin density approximation (LSDA), Perdew-Burke Generalized Gradient Approximation (PBE-GGA), and Tran-Blaha modified Becke-Johnson (TB-mBJ) schemes, confirming the retention of the half-metallic nature. The negative enthalpy of formation (ΔH) suggests material stability. The use of semi-classical Boltzmann theory, incorporated through the sophisticated scheme of BoltzTraP, explores transport coefficients. High pressures and temperature discrepancies in thermodynamics are considered by implementing the quasi-harmonic Debye approximation to illustrate stability. Finally, optical properties are summarized to assess the applicability of this alloy for optoelectronic applications. The overall characteristics of these particular alloys suggest potential applications in sustainable thermoelectric and optoelectronic features.

A DFT approach to explore the structural, optoelectronic, mechanical, and thermoelectric attributes of lead-free RbInX3 (X = I, Br, Cl) halide perovskites for renewable energy applications

Halide perovskites are significant due to their versatility and high performance in optoelectronics and green technologies. This paper thoroughly investigates the structural, elastic, optoelectronic and transport characteristics of RbInX3 (X = I, Br, Cl) perovskites using density functional theory (DFT) embedded in Wein2K. Modified Becke Johnson as an exchange correlation potential is used to evaluate the physical characteristics. Structural stability is achieved with the tolerance factor and octahedral tilting along with the optimization curves. A metallic character is detected in RbInI3. However, the replacement of I with Br and Cl atoms results in an indirect band gap of 0.9 eV and 1.95 eV at (L-X) symmetry points, respectively. The elastic constants are utilized to determine the elastic parameters that ensure the structural stability of perovskites. Cauchy pressure and Poisson’s ratio indicate the ductile nature of all studied phases. The thermal behavior is evaluated through the computation of Debye temperature. Furthermore, an insight into the material’s interaction with electromagnetic radiation is accessed through the optical parameters. A high absorption at 1.49 eV for RbInI3, 1.65 for RbInBr3 and 2.57 for RbInCl3 show their potential for light emitting devices. The semi-classical Boltzmann theory is employed to compute thermoelectric properties, which show RbInI3, RbInBr3 and RbInCl3 possess high electrical conductivities of 3.068 ×1019 S m–1, 1.88 ×1019 S m–1 and 1.76 ×1019 S m–1 at 1200 K, respectively. The ZT value for RbInBr3 is 0.74 and RbInCl3 is 0.73, while RbInI3 exhibit the lowest ZT of 0.04 at 1200 K. The examined characteristics indicate that RbInBr3 and RbInCl3 possess promising potential for renewable energy applications.

Investigation of AcXO3 (X = Al, Ga) perovskites for energy harvesting applications: a DFT approach

Full potential linearized augmented plane wave (FP-LAPW) based computational study is presented for AcAlO3 and AcGaO3. Tolerance factor (τG) is 0.93 for AcAlO3 and 0.90 for AcGaO3 which reveal the stability of proposed perovskite oxides in cubic phase. The calculated band structures for both materials reveal the nonmagnetic semiconductive nature with energy band gaps of 3.98 and 2.75 eV for respective Al and Ga based perovskites. Total, and partial density of states (DOS) are computed for meaningful understanding of semiconducting behavior of the proposed perovskites. The partially filled O-2p and Ac-6d states are observed to lie in the vicinity of Fermi level. Furthermore, various parameters of optical spectra have also been computed to study the light matter interaction. Moreover, thermoelectric (TE) properties of both materials have been investigated by using semiclassical Boltzmann theory with constant relaxation time approximation. Calculated figure of merit (ZT) values for AcAlO3 and AcGaO3 are 0.23 and 0.20 at 800 K, respectively. Overall, computational study for titled perovskites indicate that these materials have application in UV sensors, photovoltaic and thermoelectric devices.

Investigation of optoelectronic and thermoelectric properties of novel BaCd2X2 (X = P, As, Sb) Zintl-phase for energy harvesting applications

The quest for new Zintl phases with promising thermoelectric properties has gained significant momentum recognitions to the precision of computational predictions. Our study presents an in-depth investigation of fundamental characteristics like structural, optoelectronic, optical, and transport aspects of BaCd2X2 (X = P, As, Sb) Zintl compounds. The stability of all compounds is firmly established through their optimized negative (-ve) formation energies and phonon dispersion spectra. Our findings affirm their robust structural integrity. Notably, we observe a semiconductor nature in these compounds, with calculated bandgap values of 1.35 eV for BaCd2P2, 0.85 eV for BaCd2As2, and 0.23 eV for BaCd2Sb2. Probing into optical properties, we uncover their potential utility in optoelectronic devices, as indicated by the optical response of these phases. We employ semi-classical Boltzmann theory, executed via BoltzTraP code, to explore their thermal behavior. Impressively higher values of Seebeck are attained, both at RT and elevated temperatures. Furthermore, the power factor exhibits an increasing trend with increasing temperature. Crucially, the analysis of the figure of merit (ZT) reveals promising values, 0.90, 0.81, and 0.72 for BaCd2X2 (X = P, As, Sb) at 300 K, respectively. These favorable optical and thermoelectric characteristics position these phases as attractive candidates for applications in optoelectronics and thermoelectric systems.

Tuning the thermoelectric and optoelectronic attributes of lead-free novel fluoroperovskites Cs2BB'F6 (B = Rb, In, Na and B'=Ir, As, Rh): A first-principles investigation

Cesium-based double perovskite materials have generated significant interest because of their fascinating prospects in various optoelectronic and thermoelectric uses. In this manuscript, the physical characteristics of Cs2BB'F6 (B = Rb, In, Na and B' = Ir, As, Rh) are investigated in detail. Volume optimization curves, negative formation energies, tolerance factor and octahedral tilting are used to evaluate the structural stability. Pugh's ratio, Cauchy pressure and Poisson's ratio endorses the ductile character of all studied perovskites. Debye temperature shows that Cs2NaRhF6 is a stiffer material in comparison to Cs2InAsF6 and Cs2RbIrF6. The electronic bandgap and total density of states of Cs2InAsF6, Cs2RbIrF6, and Cs2NaRhF6 reveal a direct band gap of 2.76 eV, 3.78 eV and 3.6 eV, respectively. Furthermore, Kramer-Kronig equations are used to examine the interaction of studied double perovskites with electromagnetic radiation. The optical parameters reveal the absorption in UV region, which show their potential for laser and UV-shields applications. In Addition, thermoelectric characteristics are calculated using the semi-classical Boltzmann theory, extending the investigation up to 800 K. The large ZT value of 0.92 is achieved for Cs2RbIrF6 at 800K, while Cs2InAsF6 and Cs2NaRhF6 exhibit 0.76 and 0.82 at 800K, respectively. Their high ZT values and electrical conductivity enhance their suitability for use in renewable energy devices.

Investigation of electronic, elastic, dynamical, thermodynamic and thermoelectric properties of Cobalt based half-Heusler compounds

Heusler compounds have attracted remarkable attention from scientists over the year by virtue of their peculiarity and suitability in multi-functional applications. In the current study, the structural, elastic, dynamical, thermodynamic and thermoelectric properties of CoMSb (M = V, Nb and Ta) half-Heusler compounds were computed. Projector augmented-wave (PAW) pseudopotentials with PBE exchange correlation functional have been used to obtain the results for the studied compounds. The computed elastic constants satisfy the general stability condition based on the cubic symmetry and endorse the ductile nature of the compounds. The CoVSb compound is predicted to be ferromagnetic half-metallic compound while CoNbSb and CoTaSb are non-magnetic compounds. The dynamical properties revealed the dynamical stability in CoVSb and CoTaSb compounds while the imaginary frequency observed at W⟶L⟶Γ predicts instability in CoNbSb compound. The thermodynamic properties for the compounds were reported. The thermoelectric properties were calculated based on the results obtained from electronic structure using semi-classical Boltzmann theory. The ductile nature and the figure of merit computed predict CoMSb (M = V, Nb and Ta) are relatively good for thermoelectric application.

Significantly enhanced thermoelectric performance of interstitial N-doped graphene: A density functional theory study

The thermoelectric characteristics of interstitial nitrogen (N)-doped graphene have been studied using the first principles calculations combined with the semi-classical Boltzmann theory. We found that the Seebeck coefficient of N-doped graphene is 3 and 5.5 times higher compared to pristine graphene, along with ZT values. At room temperature, for pristine graphene, the ZT value stands at 0.81, whereas it rises to 0.98 and 1.00 for N-doped graphene with 6.25 % and 50 % nitrogen doping, respectively. The increase in the Seebeck coefficient of N-doped graphene is due to the increase in the effective mass band as the chemical potential rises above the conduction band minimum. We observed that N-doped graphene exhibits the highest ZT value in the positive energy range, indicating a p-type character. Our findings suggest that N-doped graphene has promising potential for thermoelectric applications and provides insights into the underlying physics governing the thermoelectric properties of doped graphene materials.

Sensing behavior of pentagonal two-dimensional noble-metal dichalcogenide PdSeS for NO2 gas: DFT and semiclassical studies

The gas sensing performance of the pentagonal two-dimensional noble-metal dichalcogenide PdSeS for NO2 gas detection has been extensively studied using DFT, the nudged elastic band (NEB) model, and the semiclassical Boltzmann theory. The NEB calculations indicate a highly effective physical NO2 adsorption, implying the potential of the PdSeS monolayer as an excellent material for creating efficient and reusable gas sensors. Additionally, the PdSeS monolayer, characterized as a semiconductor with a band gap of 1.34 eV, demonstrates the emergence of a deep trap in the band structure following the adsorption of NO2 gas. Subsequently, the values of σxx and σyy decrease significantly from 11.41 and 42.82 S/cm to 2.24 and 0.99 S/cm, respectively. The decrease in conductivity can be attributed to several factors, including an increase in effective mass, the formation of deep traps, and a reduction in the number of charge carriers. Furthermore, our calculations demonstrate the potential use of the PdSeS monolayer in work function (WF) type sensors. Consequently, the pentagonal two-dimensional PdSeS monolayer fulfills the demands of portable, affordable, and reusable NO2 gas sensors by exhibiting remarkable sensitivity and short recovery time.

A Delicate Balance Between Spin-Wave Mediated Weak Localization and Electron-Phonon Scattering in the Design of Zero Temperature Coefficient of Resistivity.

Zero thermal coefficients of resistivity (ZTCR) materials exhibit minimal changes in resistance with temperature variations, making them essential in modern advanced technologies. The current ZTCR materials, which are based on the resistivity saturation effect of heavy metals, tend to function at elevated temperatures because the mean free path approaches the lower limit of the semiclassical Boltzmann theory when the temperature is sufficiently high. ZTCR materials working at low-temperatures are difficult to achieve due to electron-phonon scattering, which results in increased resistivity according to Bloch's theory. In this work, the ZTCR behavior at low-temperatures is realized in pre-microstrained Mn3NiN. The delicate balance between the resistivity contribution from electron-phonon scattering and spin-wave mediated weak localization is well revealed. A remarkable temperature coefficient of resistivity (TCR) value as low as 1.9ppmK-1 (50K≤T≤200K) is obtained, which is significantly superior to the threshold value of ZTCR behavior and the application standard of commercial ZTCR materials. The demonstration provides a unique paradigm in the design of ZTCR materials through the contraction effects of two opposite conductance mechanisms with positive and negative thermal coefficients of resistivity.

Mechanical, magneto-electronic and thermoelectric properties of Ba2MgReO6 and Ba2YMoO6 based cubic double perovskites: an ab initio study

We report an analysis of the structural, electronic, mechanical, and thermoelectric properties of oxide double perovskite structures, specifically the compounds Ba2MgReO6 and Ba2YMoO6. Our study employs first-principles density functional theory (DFT) as the investigative methodology. The electronic attributes of the examined compounds are explained by investigating their energy bands, as well as the total and partial density of states. The computational evaluation of the electronic band structure reveals that both compounds exhibit an indirect band gap semiconductor behavior in the spin-down channel, while demonstrating metallic properties in the spin-up channel. The magnetic attributes indicate a ferromagnetic nature, thus categorizing some double perovskite compounds as materials displaying half-metallic ferromagnetism (HM-FM) in addition to some other properties such as metallic and semiconductor in paramagnetic or antiferromagnetic states. The outcomes derived from the analysis of elastic constants confirm the mechanical robustness of the studied double perovskite compounds. Notably, the computed data for bulk modulus (B), shear modulus (G), and Young’s modulus (E) for Ba2MgReO6 surpass those of Ba2YMoO6. The calculated ratio of Bulk to shear modulus (B/G) indicates that both compounds possess ductile characteristics, rendering them suitable for device fabrication. Furthermore, both compounds display outstanding electronic and elastic properties, positioning them as promising contenders for integration within mechanical and spintronic devices. Finally, we investigate into the thermoelectric potential by evaluating parameters such as the Seebeck coefficient, electrical conductivity, thermal conductivity, figure of merit, and power factor. This assessment is conducted using the semiclassical Boltzmann theory and the constant relaxation time approximation, implemented through the BoltzTraP code. The results indicate that the investigated double perovskite oxides hold promise for utilization in thermoelectric applications.

Thermoelectric properties of M[formula omitted]AgAlBr[formula omitted] (M = K, Rb, Cs) double perovskites: A first principles study

Structural, electronic, and transport properties of aluminum-based double halide perovskite M2AgAlBr6 (M = K, Rb, Cs) are here subject of investigation, using first-principles approaches based on density functional theory, as implemented in the plane-wave pseudopotential method. Thermoelectric performance was evaluated by analyzing the results of first-principles band structure calculations and semiclassical Boltzmann theory within the constant relaxation time approximation. The theoretically predicted values for the electronic contribution for the figure of merit are close to 1.0 at room temperature, suggesting that all compounds studied are promising candidates for applications in thermoelectric devices.

Insight into the improvement of service performance of Sn/Cu solder joint by Pt doping in Cu6Sn5 interfacial intermetallic compound

The effects of Pt doping on the mechanical properties of (Cu,Pt)6Sn5 interfacial intermetallic compound (IMC), bonding properties of the (Cu,Pt)6Sn5/Cu interface, and growth behavior of (Cu,Pt)6Sn5 IMC during the aging stage were investigated using first-principles calculations. The results indicate that Pt doping improves both the deformation resistance and ductility of the (Cu,Pt)6Sn5 phase, and that Cu2Pt4Sn5 demonstrates the highest ductility, as indicated by the maximum B/G value (3.14) and Poisson’s ratio (0.356). This phenomenon can be attributed to the smallest standard deviation of the charge density of 0.097 e/Å3. Comparisons of the interfacial work of adhesion and tensile strength of the Cu2Pt4Sn5/Cu and Cu6Sn5/Cu interfaces show that Pt doping enhances interfacial atomic interaction. Based on semi-classical Boltzmann theory, the electrical conductivity of the Cu2Pt4Sn5/Cu interface is smaller than that of the Cu6Sn5/Cu interface, with an amplitude of 9.26%, owing to the enhanced electron localization after Pt doping and resulting in a slight increase in the service temperature. Nevertheless, Pt doping still significantly suppresses the diffusion of Cu atoms, as evidenced by the millions of times reduction in the diffusion coefficient of Cu atoms across the Cu2Pt4Sn5/Cu interface compared to that across the Cu6Sn5/Cu interface because of the latter interface’s larger diffusion activation energy (3.52 eV > 2.08 eV), which was investigated by climbing image nudged elastic band methods. Therefore, Pt doping not only strengthens the mechanical properties of the (Cu,Pt)6Sn5 phase and improves the bonding strength of the (Cu,Pt)6Sn5/Cu interface, but also suppresses the growth of IMC during the aging stage, playing a positive role in obtaining a highly reliable Sn/Cu solder joint.

Thermoelectric properties of Fe2VAl in the temperature range 300–800 K: A combined experimental and theoretical study

Here, the experimentally observed thermoelectric (TE) properties of Fe2VAl are understood through electronic structure calculations in the temperature range of 300–800 K. The Seebeck coefficient (S) is observed as ∼−138μV/K at 300 K. Then, the |S| decreases with increase in temperature, with a value of ∼−18μV/K at 800 K. The temperature dependence of electrical conductivity, σ (thermal conductivity, κ) exhibits the increasing (decreasing) trend with values of ∼1.2× 105Ω−1 m−1 (∼23.7 W/m K) and ∼2.2× 105Ω−1 m−1 (∼15.3 W/m K) at 300 K and 800 K, respectively. In order to understand these transport properties, the DFT based semi-classical Boltzmann theory is used. The contributions of multi-band electron and hole pockets are found to be mainly responsible for the temperature dependent trend of these properties. The present study suggests that DFT based calculations provide reasonably good explanations of experimental TE properties of Fe2VAl in the high-temperature range of 300–800 K.

Comprehensive study of Cesium-Tantalum Oxide for electronic, optical and thermoelectric properties under the effect of pressure for energy applications

The perovskites are important class of materials which are utilized for memory as well as spintronic devices. The thermoelectric response calculations for some perovskite oxides are also reported but their attributes under pressure had not really been touched. This study covers the repercussions of pressure on structure, electronic dispersions, optical constants and transport parameters of CsTaO3 perovskite oxides in cubic phase by employing semi-classical Boltzmann theory. The CsTaO3 was previously reported dynamically stable through optimization of energy against volume and phonon properties at ambient pressure conditions, having wide (direct) energy gap of 2.90 eV. This gap is decreasing with increasing pressure and behaves like the interesting diluted magnetic semiconductors. The comprehensive insights of the imaginary part of dielectric constant is predicting it’s utility in optoelectronic devices and sensors. The different transport parameters are computed in the temperature range 50 K to 1200 K with 50 K step size and pressure 0–100 GPa with 10 GPa step. The calculated power factor value and optical parameter proving CsTaO3 as a latent material for energy application.

DFT modeling techniques to understand the potential applicability of novel double perovskite semiconductor Ba2LuNbO6 for sustainable thermoelectrics and optoelectronic perspectives

Searching for novel functional materials represents an important direction in the research and development of renewable energy. Herein, experimentally synthesised Ba2LuNbO6 (BLNO) host double perovskite has been theoretically computed by first principles techniques to understand its several physical properties like electronic-structure, mechanical behaviour, transport along with optical and thermal properties upon the basis of full potential linearized augmented plane wave (FP-LAPW) followed by density functional theory (DFT). First and foremost, the attempt was significant made to relax the molecular crystal structure of BLNO at an experimental lattice constant to evaluate its total ground state and cohesive energy (Ecoh) for descripting its required structural stability. After that, we have overseen its mechanical stability from the computation of second order elastic constants (SOEC's). Later on, the electronic properties of this alloy have been executed within the two potential schemes like Perdew-Burke Generalized gradient approximation (PBE-GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ) which alternatively certifies the retention of the semiconducting nature respectively. Besides this, the essential use of semi-classical Boltzmann theory within the sophisticated scheme of BoltzTraP has been inducted to explore its transport coefficients. And finally, the optical has been summarised to see the applicability of this particular alloy towards optoelectronic application purposes. Therefore, the overall tendency of this particular alloy can favor their potential multiple applications in sustainable thermoelectrics, optoelectronic features etc.

Electronic, electrical and thermoelectric properties of Ba0.95Ca0.05Ti0.95Y0.05O2.975 compound: Experimental study and DFT-mBJ calculation

This article explores the impact of co-doping BaTiO3 ceramics with Ca2+ and Y3+ using solid-state reactions to improve its dielectric constant and decrease losses. The oxide BCTYO (Ba0.95Ca0.05Ti0.95Y0.05O2.975) exhibits a tetragonal crystal structure, characterized by a space group of P4mm. By examining the behavior of the doped BaTiO3 sample and performing simulations, researchers can better understand the underlying mechanisms and optimize material properties for specific applications. DFT study shows a semiconductor behavior with an indirect gap (Eg = 2.5 eV). The partial DOS proves that the hybridization between the orbitals Ti 3d, Y 3d, and O 2p is responsible for the band gap and the hopping processes. The analysis of conductivity curves provides evidence for the semiconductor characteristics of the material under investigation. By determining the activation energy (Ea) through analyzing Ln(fmax) and conductivity as a function of 1000/T, the interconnection between conduction and relaxation phenomena is demonstrated. The study of the real part of the dielectric permittivity (ε′) shows a transition at Tc = 380 K. The obtained results are promising and indicate that the studied material has the potential for various electronic applications (energy storage and diode fabrication …). Moreover, the thermal, electrical, and thermoelectric characteristics were examined utilizing the semi-classical Boltzmann theory. The findings revealed an intriguing result, suggesting that Ba0.95Ca0.05Ti0.95Y0.05O2.975 holds promise as a potential candidate for application in thermoelectric devices.

Tuning the electronic and thermoelectric properties of selenium monolayers through atomic impurities: A DFT study

The structural, electronic, and thermoelectric properties of selenium monolayer with impurity adsorption and substitutional atoms have been studied using density functional theory (DFT) combined with semiclassical Boltzmann theory. The adsorption energy of the impurity adatoms in their stable position ranged from −1.46 eV for Te to −4 .44 eV for Pt. Regarding the atomic substitution, Pt impurities exhibited the highest stability in the intermediate position, with a formation energy of −150.5 meV, followed by Sn with a formation energy of −90.40 meV. We further investigated the impact of atomic impurities on the electronic properties of the material and found that the bandgap energy was significantly reduced, resulting in a semiconductor-to-metal transition. These results highlight the effectiveness of defect engineering for electronic band tuning. Furthermore, we discovered that a selenium monolayer with substitution of an Sn or Te atom in the intermediate layer exhibits a maximum value of the dimensionless figure of merit (including electronic and phononic contributions) of 0.51 and 0.52, respectively, while the clean selenium monolayer has a maximum value of ZT=0.43. These finding suggest that selenium monolayer with Sn defects could be a promising thermoelectric materials that offer an alternative for recovering waste heat and transforming it into electricity.

DFT study of structural optoelectronic and thermoelectric properties of CuNiO ferromagnetic alloys

In this study, the structural, electronic, and thermoelectric properties of pure NiO and Cu-doped NiO were investigated. The structural and optoelectronic properties of nickel oxide and in the supercell containing atoms CuNi15O16 were obtained by density functional theory (DFT) using the generalized gradient approximation (GGA) with the Hubbard correction potential U. The theoretical results obtained using the quantum espresso code show that the ferromagnetic character of the supercell structure is more stable than the antiferromagnetic configuration, and incorporating copper in the NiO matrix reduces the spin-up band structure. The value of the band gap channel is approximately 1.7 eV. The spin-down states cross the Fermi level and indicate the half-metal character of the CuNiO alloys. These results suggest that Cu-doped NiO is a potential candidate for infrared light and spintronic applications. The transport coefficients of the nickel oxide and copper doped NiO were calculated using the semi-classical Boltzmann theory implemented in BoltzTraP code. The thermoelectric properties, such as the Seebeck coefficient, power factor, and figure of merit, are calculated with respect to the chemical potential and carrier concentration in the temperature range of 300 K–800 K. We found an increase in the factor of merit and switching of NiO oxide from n-type to p-type after copper incorporation.

Insights into structural, elastic, mechanical, opto-electronic, and thermoelectric properties of rubidium-based fluoroperovskites RbXF3 (X = Zn, Cd, Hg)

In this study, we investigate the structural, electronic, optical, thermoelectric, elastic, and mechanical characteristics of Rb-based perovskites RbXF3 (X = Zn, Cd, Hg) by using ab-initio calculations based on density functional theory and semi-classical Boltzmann theory through the FP-LAPW method in WIEN2k. The ground-state computations were performed by using three approximations of the GGA, i.e., PBE-GGA, WC-GGA, PBE-sol GGA, and LSDA, as exchange correlation potentials. The optimized structural data obtained were consistent with the results for similar compounds. All samples were found to be indirect band gap semiconductors along the direction of high Γ-M symmetry, and the conclusions were consistent with those obtained for similar compounds in past studies. Furthermore, we explored the elastic constants of the fluoroperovskites to inspect their mechanical behavior by using the IRelast approach. The dependencies of ε(ω), optical conductivity σ(ω), loss function L(ω), and refractive index n(ω) of the materials on the spectral frequency provide a fundamental basis for attaining optical characteristics that are suitable for use in applications of optoelectronics. The Seebeck coefficient, electrical and thermal conductivities, power factor, and figure of merit of the samples were also calculated by using semi-classical Boltzmann theory in BoltzTraP code. The results of thermoelectric computations showed that the Rb-based fluoroperovskite compounds investigated here have promising thermoelectric properties.