Semi-classical Boltzmann Theory Research Articles

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.

Exploring Rb2YCuCl6 and Cs2YCuCl6 double perovskites: Structural, electronic, optical, elastic, and thermoelectric properties via density functional theory

Double perovskites have gathered momentous attention due to their structural, optoelectronics, and thermal properties. FP-LAPW + lo technique was employed along with the PBEsol-GGA and TB-mBJ potential. The optimized parameters and E-V parabolic curve were computed employing Birch Murnaghan's equation of state (BM-EOS). The negative formation energy Ef for Rb2YCuCl6 and Cs2YCuCl6 confirms the thermodynamic stability of these double perovskites. The mechanical stability of both compounds was confirmed by their elastic constants Cij, Pugh's ratio, and anisotropy. The indirect band plots of Rb2YCuCl6 (2.57eV) and Cs2YCuCl6 (2.39eV) double perovskites confirm the semiconductor nature. The optical properties like dielectric function, reflectivity, optical conductivity, absorption coefficient, and energy loss function were determined within an energy range of up to 18 eV. The high absorption spectra for the under-study compounds 147.21 × 104 cm−1 at 14.60 eV for Rb2YCuCl6 and 261.30 × 104 cm−1 at 15.57 eV for Cs2YCuCl6 lies in the far UV region determines its potential use in the high-frequency devices. The thermoelectric properties such as the Seebeck coefficient, ZT, and power factor, are investigated using the semi-classical Boltzmann theory implemented in the BoltzTrap code. The peak value of ZT for Rb2YCuCl6 is 0.38 and for Cs2YCuCl6 is 0.33. The suggested findings indicate that Rb2YCuCl6 and Cs2YCuCl6 are potential candidates for thermoelectric and photovoltaic applications.

Insight on thermodynamic and thermoelectric properties of Ge based perovskites AGeO3 (A = Mg, Cd) for energy harvesting applications: A DFT approach

In this manuscript, transport properties like thermoelectric and thermodynamic properties of AGeO3 (A = Mg, Cd) perovskites have been performed in detail along with effect of chemical potential on various thermoelectric parameters. Furthermore, we present the electronic effects and thermodynamic stability of these materials. The MgGeO3 and CdGeO3 alloys have a gap of 3.368 and 2.555 eV, respectively, making them indirect band gap semiconductors. Furthermore, using a constant relaxation time approximation and semiclassical Boltzmann theory, the thermoelectric (TE) properties of both materials have been studied. The lattice thermal conductivity magnitudes for MGeO3 and CdGeO3 are 7.47 W/mK and 21.55 W/mK, respectively, at 300 K. Power Factor (PF) has been measured at approximately 0 chemical potential, or approximately 14 (1011 W/K2 ms) at 1200 K, 7.5 (1011 W/K2 ms) at 700 K, and 3.5 (1011 W/K2 ms) at 300 K for both MgGeO3 and CdGeO3. At room temperature, the electrical conductivities of MgGeO3 and CdGeO3 were measured to be 1.43 × 1015W/mK and 1.08 × 1015W/mK, respectively. Over a broad temperature range (0–1200 K), the thermodynamic parameters, such as heat capacity, entropy, thermal expansion, and Debye temperature, were also computed and discussed.

Structural stability, optoelectronic, thermoelectric, and elastic characteristics of X2ScBiO6 (X= Mg, Ca, and Ba) double perovskites for energy harvesting: First-principles analysis

Double perovskites have emerged as a potential new material for optoelectronic and thermoelectric applications. We explored structural, electronic, optical, thermoelectric, and elastic properties of double oxides perovskite, X2ScBiO6 (X = Mg, Ca, and Ba) through density functional theory (DFT). The most stable structure, according to the optimized structural parameters, is a cubic Fm3m (225) symmetry with a nonmagnetic (NM) state. We have utilized TB-mBJ to estimate the band structure and density of states. The semiconductor nature is predicted with indirect bandgap values of 1.90 eV, 1.39 eV, and 1.11 eV for Mg2ScBiO6, Ca2ScBiO6, and Ba2ScBiO6, respectively. Notable optical responses such as higher absorption (>105 cm−1) and low reflectivity for X2ScBiO6 suggest appropriate candidates for optoelectronic device applications. The efficient thermoelectric order has been investigated under semiclassical Boltzmann theory and constant relaxation time approximation as implemented in the BoltzTraP (BT) code. Several parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit, have been calculated. The ductile character of the X2ScBiO6 (X = Mg, Ca, and Ba) compounds is further supported by the elastic properties. Consequently, the results show that the compounds investigated could be good alternatives for thermoelectric and photovoltaic applications.

Exploring the physical properties of novel double perovskites A2InAsO6 (A=Sr, Ba) for renewable energy applications: Ab-initio calculations

Nowadays, double perovskites for renewable energy are emerging materials because of their interesting properties such as simple and stable crystal structure. In our study, we theoretically explored the optoelectronic along with mechanical and thermoelectric characteristics of A2InAsO6 (A = Sr, Ba) using density functional theory and semi-classical Boltzmann theory followed by WIEN2k code. The thermodynamic and structural stabilities are determined based on the cohesive energy, enthalpy of formation and tolerance factor. The ductile and brittle behaviour has been checked by Pugh's ratios. The measured values of narrow direct energy band gaps are 0.70 eV for Sr2InAsO6, and 0.18 eV for Ba2InAsO6 with TB-mBJ approximation. These compositions are potentially used in optoelectronic applications because their electronic characteristics are tuneable. In the energy range 0–12 eV, the compositions under consideration exhibit a single-peaked response while the replacement of cation Sr with Ba caused a shift in optical structures towards lower energies. These compositions are also suitable for thermoelectric systems as they possess high values of the figure of merits at room temperature and the measured values 0.049 eV for Sr2InAsO6, and 0.10 eV for Ba2InSbO6 are recorded.

Enhanced thermoelectric performance of Hf-doped ZrNiSn: a first principle study.

In this work, we perform a systematic study on the thermoelectric properties of Zr1-xNiSnHfx using first-principles calculations combined with Boltzmann transport equations. The power factor of Zr1-xNiSnHfx increases as the temperature increases from 300 to 1200K, because the increase in electrical conductivity is greater than the decrease in the Seebeck coefficient. The power factor of Zr7/8NiSnHf1/8 is larger than that of other Zr1-xNiSnHfx thermoelectric materials, but the thermoelectric figure of merit (ZT) is similar to that of others materials. This is due to the higher electronic thermal conductivity of Zr7/8NiSnHf1/8 compared to other materials. The maximum ZT of p-type (n-type) Zr1-xNiSnHfx is 0.98 (0.97), 0.9 (0.89), 0.83 (0.80), and 0.72 (0.73) at 300K, 600K, 900K, and 1200K, respectively, which are greater than those of the pure ZrNiSn. In conclusion, Hf-doped ZrNiSn can enhance the thermoelectric performance and are promising candidates for thermoelectric materials. This paper uses FP-LAPW implemented in the WIEN2K code. The thermoelectric performance is calculated based on the semi-classical Boltzmann theory implanted using the BoltzTraP code. The electronic thermal conductivity (κe) and the carrier concentration (n) have been calculated using the density functional theory.

Exploring novel filled skutterudites: A comprehensive DFT Modeling study on electronic, magnetic, curie temperature, elastic, thermal, and thermoelectric properties

Embarking on a captivating journey through the intricacies of two groundbreaking Skutterudite compounds, BaMn4X12 (X = As, Sb), employing first-principles calculations based on the Generalized Gradient Approximation (GGA) and modified Beck-Johnson approximation (mBJ) of density functional theory (DFT), has unveiled intriguing revelations. These compounds showcase exceptional stability within the ferromagnetic phase of the BaMn4As12 and BaMn4Sb12 cubic-type structure, boasting equilibrium lattice parameters of 0.933 nm for BaMn4As12 and 0.92 nm for BaMn4Sb12. The electronic properties point to their half-metallic nature, and a thorough analysis of elastic properties confirms their remarkable stability, high rigidity, anisotropy, and minimal deformation, exhibiting a ductile behavior. The magnetic properties analysis underscores the ferromagnetic state of both compounds, revealing a computed total magnetic moment of 4.76 μB for BaMn4As12 and 4.60 μB for BaMn4Sb12. Finally, our examination of the thermodynamic parameters of these compounds, conducted across temperatures ranging from 0 to 800 K and pressures from 0 to 40 GPa using the quasi-harmonic Debye model, underscores their immense potential for diverse applications. These findings inspire excitement, showcasing the promising avenues for the utilization of BaMn4X12 (X = As, Sb) compounds in various fields, including materials science, engineering, and technology. Additionally, the fundamental application of semi-classical Boltzmann theory has been incorporated into the advanced framework of BoltzTraP to investigate its transport coefficients. Hence, the general inclination of these specific compounds may support their potential for various applications in sustainable thermoelectrics, spintronics features, and more.

Tuning band gaps in lead chalcogenides under pressure: implications for infrared detection applications

This study employs first-principle calculations within density functional theory (DFT) to explore the structural, electronic, optical, and thermoelectric properties of lead chalcogenides (PbS, PbSe, and PbTe). The investigation focuses on their potential application as infrared photodetectors, leveraging their narrow-band gap semiconductor characteristics. The influence of pressure on the band gap and various electronic, optical, and thermoelectric properties is thoroughly analyzed. The calculated band gap values for PbS, PbSe, and PbTe are determined to be 0.29 eV, 0.18 eV, and 0.18 eV, respectively, aligning well with experimental data. Notably, the study reveals non-linear changes in band gap values under pressure, with phase transitions observed at specific pressure thresholds in PbS and PbSe, but not in PbTe. Under varying pressure conditions, the optical peaks shift towards lower energy levels with increased intensity. The static dielectric constant of PbS, PbSe, and PbTe exhibits distinct variations within pressure ranges of 0–8 GPa. Transport coefficients (S, σ, ke) are calculated using semi-classical Boltzmann theory across different temperatures and pressures, indicating that heavier compounds exhibit higher electrical and thermal conductivity values. At 300 K, the maximum ZT values are determined to be 0.85, 0.8, and 0.52 for PbS, PbSe, and PbTe, respectively. The study suggests enhanced thermoelectric properties of these structures at lower temperatures, particularly highlighting PbS and PbSe as promising candidates for thermoelectric applications below 500 K. Exploring the impact of pressure on the thermoelectric parameters of lead chalcogenides reveals interesting trends, with PbTe demonstrating higher thermoelectric efficiency under increased pressure compared to PbS and PbSe. These findings provide valuable insights into the potential applications and performance of lead chalcogenides in IR detection and thermoelectric systems.

Mechanical and thermoelectric properties of ZrX2 and HfX2 (X = S and Se) from Van der Waals density-functional theory

The structural, mechanical, and thermoelectric characteristics of layered transition metal dichalcogenides MX2 (M = Zr, Hf; X = S, Se) have been studied using density functional theory along with van der Waals correction. The exchange-correlation functional, enhanced with corrections for van der Waals interactions, has been evaluated for the hexagonal bulk structures of these materials. The analysis of elastic properties reveals that these compounds exhibit brittleness at zero pressure and conform to Born's criteria for mechanical stability. Examination of elastic constants and moduli suggests that the compounds possess reasonable machinability, moderate hardness, and anisotropy in terms of sound velocity. Transport properties, including the Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor, have been computed using the semi-classical Boltzmann theory implemented in the BoltzTraP code. All investigated compounds exhibit excellent thermoelectric performance at high temperatures. This result suggests that our compounds are highly promising candidate for practical utilization in the thermoelectric scope.

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.