Mg2 Si Research Articles

Surface Degradation of Mg2X-Based Composites at Room Temperature: Assessing Grain Boundary and Bulk Diffusion Using Atomic Force Microscopy and Scanning Electron Microscopy.

Practical application of thermoelectric generators necessitates materials that combine high heat-to-electricity conversion efficiency with long-term functional stability under operation conditions. While Mg2(Si,Sn)-based materials exhibit promising thermoelectric properties and module prototypes have been demonstrated, their stability remains a challenge, demanding thorough investigation. Utilizing atomic force microscopy (AFM) and scanning electron microscopy (SEM), we investigate the surface degradation of a composite material comprising Si-rich and Sn-rich Mg2(Si,Sn) solid solutions. The investigation reveals a pronounced dependence of stability on Sn content, with the Sn-rich phase Mg2Si0.13Sn0.87 displaying the formation of a nonprotective oxide layer. Subsequent AFM measurements provide evidence of dominating grain boundary diffusion of loosely bound Mg, compared to bulk diffusion, observed within a few days, ultimately resulting in a complete surface oxidation of the Sn-rich phase within several weeks. On the other hand, Mg2Si and Si-rich Mg2Si0.80±0.05Sn0.20±0.05 remain stable against Mg diffusion to the surface even after prolonged exposure. Comparison with previous investigations confirms that the degradation rate is found to be highly dependent on the Sn content, with markedly higher rates observed for x = 0.87 compared to x = 0.70 in Mg2Si1-xSnx. These findings contribute to a better understanding of the stability challenges associated with Mg2(Si,Sn)-based materials, essential for the development of robust thermoelectric materials for practical applications.

Enhanced thermoelectric properties of Mg2Si0.3Sn0.7 via Bi-doping under high pressure

A series of n-type Mg2(Si0.3Sn0.7)1-xBix compounds with 0≤x≤0.02 were successfully synthesized through a combined approach involving solid-state reaction, high-pressure synthesis, and spark plasma sintering techniques. The method yielded homogeneously distributed single-phase materials at the micron scale, although minor compositional variations were detected within nanoscale precipitates embedded in the grains. The sample with Bi content of 0.01 exhibited enhanced thermoelectric properties, reaching a peak thermoelectric figure of merit (ZT) of 1.45 at 700 K while maintaining an average ZT of about 1.1 over the temperature range of 300−773 K. The enhancement in thermoelectric performance is ascribed to the optimized carrier concentration, band convergence, and refined microstructure. The findings suggest a simplified approach to doping that could be beneficial in creating high-performance thermoelectric materials for energy conversion.

Device level assessment of Ni and Ni45Cu55 as electrodes in Mg2(Si,Sn)-based thermoelectric generators

Owing to efficient thermoelectric conversion, non-toxicity, low density and cost, Mg2(Si,Sn)-based solid solutions hold potential for mid-to-high temperature waste heat recovery. Yet, challenges arise from n-Mg2(Si,Sn) degradation at ≥400 °C caused by Mg loss and charge carrier reduction, particularly in Sn-rich compositions. To build a thermoelectric generator (TEG) stable up to 400 °C, we propose binary Mg2Si as the n-type leg. Using Ni45Cu55and Ni yields low electrical contact resistance (<5 µΩ.cm2) without altering the thermoelectric properties of n-Mg2Si. We fabricated two 2×2 leg TE modules with the same electrode/TE combination for the p-type legs and with Ni or Ni45Cu55 for their n-type legs and tested up to 400 °C, allowing for a direct comparison between these twoelectrodes for n-Mg2Si at the device level. Ni45Cu55 outperformed Ni, resulting in a peak power density of 0.79 W/cm2 at ΔT ∼375 K and an efficiency competitive to Mg2(Si,Sn)-only TEG.Comparative simulations using a constant property model revealed a strong reduction of internal losses when using Ni45Cu55as the electrode for n-Mg2Si as the main reason for the high performance. The presented design overcame challenges such as Mg sublimation at targeted application temperature or electrode induced defect formation, resulting in a stable TEG.

Instability Mechanism in Thermoelectric Mg2(Si,Sn) and the Role of Mg Diffusion at Room Temperature

Mg2(Si,Sn) shows great promise as thermoelectric material as it is made from non‐toxic, abundant, and cost‐effective elements offering high performance. This has been emphasized by several thermoelectric generator prototypes, demonstrating technological maturity. However, material stability is paramount for large‐scale applications whereas we reveal here that the thermal stability of n‐type Mg2(Si,Sn) may be limited even at room temperature (RT). Integral thermoelectric properties measurements, locally resolved Seebeck coefficient analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and atomic force microscopy are employed to assess changes of n‐type samples stored in ambient atmosphere for years, revealing the evolution of the carrier concentration and transport properties in the material as well as surface degradation. This is caused by the diffusion of loosely bound Mg from the bulk towards the surface and subsequent oxidation, leading to a change of Mg‐based intrinsic defect concentrations, thereby degrading the thermoelectric performance. This microscopic mechanism is backed up by first‐principles calculations, revealing that Mg diffusivity in Mg2(Si,Sn) is high at RT and that diffusion occurs mainly via Mg vacancies. The observed much faster degradation of Sn‐rich Mg2(Si,Sn) can be correlated with the higher density of Mg vacancies in Mg2Sn compared to Mg2Si, as predicted from defect formation energies.

Dipole Coupling Accelerated H2 O Dissociation by Magnesium-Based Intermetallic Catalysts.

The water (H2 O) dissociation is critical for various H2 O-associated reactions, including water gas shift, hydrogen evolution reaction and hydrolysis corrosion. While the d-band center concept offers a catalyst design guideline for H2 O activation, it cannot be applied to intermetallic or main group elements-based systems because Coulomb interaction was not considered. Herein, using hydrolysis corrosion of Mg as an example, we illustrate the critical role of the dipole of the intermetallic catalysts for H2 O dissociation. The H2 O dissociation kinetics can be enhanced using Mgx Mey (Me=Co, Ni, Cu, Si and Al) as catalysts, and the hydrogen generation rate of Mg2 Ni-loaded Mg reached 80 times as high as Ni-loaded Mg. The adsorbed H2 O molecules strongly couple with the Mg-Me dipole of Mgx Mey , lowering the H2 O dissociation barrier. The dipole-based H2 O dissociation mechanism is applicable to non-transition metal-based systems, such as Mg2 Si and Mg17 Al12 , offering a flexible catalyst design strategy for controllable H2 O dissociation.

Reliability Investigation of Silicide-Based Thermoelectric Modules.

The reliability and failure mechanisms of silicide-based thermoelectric modules (n-type Mg2(Si,Sn)/p-type HMS) were investigated thanks to two types of thermal tests with either a fixed or a cycling thermal gradient, under different atmospheres. The hot interfaces of the thermoelectric modules were analyzed by scanning electron microscopy and X-ray diffraction after the reliability tests. The current thermoelectric modules do not exhibit any failure mechanism under ambient air for a hot side temperature of 250 °C for tests conducted either during 500 h at a fixed temperature gradient or after 1000 thermal cycles. However, when the temperature was increased to 350 °C, pesting phenomena were detected at the hot side of the n-type Mg2(Si,Sn) legs caused by the decomposition/oxidation of the material. These phenomena are strongly slowed down for thermoelectric modules tested under a primary vacuum, highlighting the predominant role of oxygen in the degradation mechanism. Interdiffusion phenomena are the most pronounced at the interface of the hot side of the n-type thermoelectric materials. The formation of a MgO layer, which is an electrical and thermal insulator, has decreased the thermoelectric modules' performances. For thermal cycling tests, cracks are observed on the hot side of the n-type legs. The presence of these cracks drastically increases the thermal and electrical resistances, leading to an overheating of the system and limiting its efficiency and failure by breaking electrical continuity. The interfaces at the hot side temperature of the p-type HMS legs remained intact whatever the test conditions were, indicating a high chemical stability and a good mechanical strength.

Metallurgical characteristics of AA6061 aluminium and AZ31B magnesium dissimilar joints by fusion welding technique.

Aluminium (Al) and magnesium (Mg) alloys are extensively used in the automobile sector because of their high strength-to-weight ratio, excellent castability low density and simplicity of recycling. Al-Mg structures used in the automotive sector can potentially reduce their weight. Although there is a significant opportunity for substantial cost reduction, the use of magnesium in aluminium structures remains restricted. This study aims to weld 3 mm-thick rolled sheets of AA6061 Al and AZ31B Mg alloy using the cold metal transfer (CMT) arc welding process. Three different filler wires (ER1100, ER4043, and ER5356) were used in the experiment. In this article, the mechanical and microstructure characteristics of Al/Mg dissimilar joints manufactured by CMT are evaluated and discussed in detail. Optical microscope (OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to analyze the CMT-welded Al/Mg dissimilar joints. Of the three filler wires used, ER4043 (Al-5%Si) filler wire yielded defect-free sound joints due to the presence of Si, which improves the flow ability of molten filler during welding. The presence of Mg-rich intermetallics-Al12Mg17)and Al-rich intermetallics-Al3Mg2 were observed. The fractured area of the CMT-welded Al/Mg dissimilar joints revealed the presence of the Mg-rich intermetallics (Al12Mg17), which is responsible for the decrease in tensile strength. The reduction of intermetallics, particularly of Mg-rich intermetallics (Al12Mg17) is important for improving joint strength. RESEARCH HIGHLIGHTS: Cold metal transfer (CMT) arc welding was used to control the Al-Mg-rich intermetallics in the Al/Mg dissimilar joints. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, TEM, EDS and XRD. The weld metal and AL substrate bonded with a strong interface, while weld metal and Mg substrate were joined at the epitaxial solidification area where the intermetallic compounds of Mg2Al3, Mg17Al12 and Mg2Si are generated. The weld metal on the Mg side experienced brittle fracture, with a continuous distribution of Mg2Al3, Mg17Al12 and Mg2Si.

Effect of load and sliding velocity on wear behaviour of magnesium AZ91D composites reinforced with Ca2SiO4 at ambient temperature

This article reports the dry sliding wear behaviour of AZ91D-Mg and AZ91D-Ca2SiO4 composites at different sliding velocities (1–3 m/s) and different normal loads (10 N, 30 N, and 50 N). The post-wear characterizations were carried out to determine the wear mechanisms under each tested condition. XRD analysis confirms the presence of CaO, SiO, MgO, Mg2 Si, and MgAl2O phases which play a vital role in improving the wear resistance of AZ91D-Ca2SiO4 composites. The oxidation mechanism was predominant at low sliding velocity and loading conditions. Further, plastic deformation, delamination and abrasive wear were dominant at high loading conditions. Furthermore, detailed study on the influence of Ca2SiO4 and wear parameters on the dry sliding wear behaviour of AZ91D-Mg and AZ91D-Ca2SiO4 composites are reported.

Sn–Sc microalloying-induced property improvement and micromechanisms of an Al–Mg–Si alloy

Microalloying is of great importance for the property modulation of lightweight high-strength aluminum alloys. Little is known, however, about the properties and micromechanisms of Al–Mg–Si alloys microalloyed with Sn and Sc. In this work, the property changes of Al–0.5Mg–0.4Si (wt%) alloys induced by 0.1Sn and 0.1Sn–0.1Sc (wt%) additions and underlying alloying mechanisms are revealed by atomic-scale transmission electron microscopy and first-principles calculations. The results show that the Sn–Sc coaddition results in a decreased diameter and an increased number density of the Sc-containing constituent particles of Mg2Si and Mg2(Si,Sn), as compared to the sole Sn addition. The featured Si-site columns in β'', B′ and β′ structures can be occupied by Sn and Sc. Substantial peak-aging β'' needles with confined cross-sectional coarsening are observed for the Sn–Sc containing alloy compared to the Sn containing alloy. The modified constituent particles and precipitates improve the plasticity and strength of peak-aging Al–Mg–Si–Sn–Sc alloy. The elevated peak-aging corrosion resistance and over-aging thermal stability of Al–Mg–Si–Sn–Sc alloy are associated with the sparse Sc-containing Mg2(Si,Sn) grain boundary precipitates and low strain filed of Al matrix around the β′ containing Sn/Sc, respectively. The obtained results are hoped to guide the design of high-performance Al alloys.

High-performance tellurium-free thermoelectric module for moderate temperatures using α-MgAgSb/Mg2(Si,Sn)

α-MgAgSb is a promising thermoelectric material with an average figure of merit above unity between room temperature and 573 K, making it attractive for low temperature waste heat recovery or temperature regulation applications. We demonstrate here the first α-MgAgSb/Mg2(Si,Sn)-based thermoelectric module, where Mg2(Si,Sn) was chosen as n-type counterpart due to its excellent thermoelectric properties, low weight, abundant, and eco-friendly constituents. By using this new material combination, a maximum conversion efficiency of 6.4% and maximum power of 0.68 W were achieved for a temperature difference of 275 K, superior to commercially available (Bi,Te,Sb)-based thermoelectric modules. The Constant Property Model was used to check the validity of the measurement results and to identify room for further improvement. The characterization of the prototype shows a relatively good match between measurement and calculation for most of the thermoelectric module performance parameters; however, the measured internal electrical resistance is around 10% higher than the predicted values, indicating opportunities for further enhancement.

Interface Engineering Boosting High Power Density and Conversion Efficiency in Mg2Sn0.75Ge0.25‐Based Thermoelectric Devices

AbstractElectrode contact interfaces for practical thermoelectric (TE) devices require high bonding strength, low specific contact resistivity, and superb stability. Herein, the state‐of‐the‐art Cu2MgFe/Mg2Sn0.75Ge0.25 interface is designed for Mg2Sn0.75Ge0.25‐based TE devices, adhering to the general strategy of high bonding propensity, thermal expansion matching, diffusion passivation, and dopant inactivation. The interfacial stability is verified by the in situ transmission electron microscopy analysis, thereby confirming the contributions from decreasing the chemical potential gradient and increasing the diffusion activation energy barrier. The single‐leg device exhibits a high power density (ωmax) of 2.6 W cm−2 and conversion efficiency (ηmax) of 8% under a temperature difference (ΔT) of 370 °C, which is the record‐breaking value in comparison to other Mg2(Si, Ge, Sn)‐based TE devices. Additionally, a two‐couple device with p‐type Bi2Te3 shows an excellent ωmax of 1.3 W cm−2 and ηmax of 5.4% under a ΔT of 270 °C, comparable to commercial Bi2Te3 devices. The proposed interface design strategy provides a general technique for constructing high‐performance devices using cutting‐edge TE materials.

Enhanced thermoelectric performance of Sb-doped Mg2Si0.4Sn0.6via doping, alloying and nanoprecipitation

With the advantages of eco-friendliness, low cost, and low density, Mg2(Si,Sn) solid solutions are promising candidates for thermoelectric applications. In this work, Sb-doped Mg2Si0.4Sn0.6 bulks were prepared with a combined method of solid-state reaction and high pressure synthesis, followed by spark plasma sintering. Our investigations show that Sb doping optimizes the carrier concentration, while Si/Sn alloying effectively suppresses the lattice thermal conductivity and induces a convergence of the two lowest-lying conduction bands. Additionally, numerous coherent Sn-rich nanoprecipitates are formed within micron-sized grains. All these factors contribute synergistically to improving the thermoelectric properties of Mg2Si0.4Sn0.6. The optimal Mg2(Si0.4Sn0.6)0.985Sb0.015 exhibits a power factor higher than 4 000 μW·m−1·K−2 and a lattice thermal conductivity less than 0.8 W·m−1·K−1 at temperatures higher than 600 K, leading to the highest ZT of 1.61 at 823 K. Current work demonstrates an effective approach to enhancing the thermoelectric performance of n-type Mg2X solid solutions through doping, alloying, and microstructure modification.

Thermoelectric properties of SiC nanocomposite Mg2Si0.4Sn0.6 with Sb doping prepared by vacuum induction levitation melting and spark plasma sintering

The SiC nanocomposite Mg2(Si0·4Sn0.6)Sb0.015/(y)SiC (0 ≤ y ≤ 0.01) with Sb doping were prepared using the vacuum induction levitation melting technique in conjunction with mechanical alloying and spark plasma sintering process. The microstructure and thermoelectric properties were systematically investigated. The hierarchical nanostructures for the samples are composed of point defects, SiC nanocomposite particles, coherent in-situ nanophases, and grains. The SiC nanocomposite cause a minor reduction in electrical performance, and the constructed hierarchical nanostructures significantly decreased the lattice thermal conductivities. The highest figure of merit value of 1.55 is obtained at 643 K for the y = 0.0075 SiC nanocomposite sample.

Analyzing the Performance of Thermoelectric Generators with Inhomogeneous Legs: Coupled Material–Device Modelling for Mg2X-Based TEG Prototypes

Thermoelectric generators (TEGs) possess the ability to generate electrical power from heat. As TEGs are operated under a thermal gradient, inhomogeneous material properties—either by design or due to inhomogeneous material degradation under thermal load—are commonly found. However, this cannot be addressed using standard approaches for performance analysis of TEGs in which spatially homogeneous materials are assumed. Therefore, an innovative method of analysis, which can incorporate inhomogeneous material properties, is presented in this study. This is crucial to understand the measured performance parameters of TEGs and, from this, develop means to improve their longevity. The analysis combines experimental profiling of inhomogeneous material properties, modelling of the material properties using a single parabolic band model, and calculation of device properties using the established Constant Property Model. We compare modeling results assuming homogeneous and inhomogeneous properties to the measurement results of an Mg2(Si,Sn)-based TEG prototype. We find that relevant discrepancies lie in the effective temperature difference across the TE leg, which decreases by ~10%, and in the difference between measured and calculated heat flow, which increases from 2–15% to 9–16% when considering the inhomogeneous material. The approach confirms additional resistances in the TEG as the main performance loss mechanism and allows the accurate calculation of the impact of different improvements on the TEG’s performance.

Effect of Mg deficiency on the thermoelectric properties of Mg2(Si, Sn) solid solutions

In this study, we analyze the change in the thermoelectric properties of a Mgx(Si, Sn) system upon varying nominal Mg content x (x = 1.8, 1.9, 2.1, 2.2, 2.3). We find that Mg deficiency induces multiple point defects, such as Mg vacancies and anion anti-site defects, as well as phase separation of crystal structure, both of which alter the band structure. Systematic investigations are followed to elucidate how thermoelectric properties of a Mgx(Si, Sn) system are influeced by the degree of Mg deficiency. Temperature-dependent measurements of the Seebeck coefficient and the Hall coefficient indicate that Mg deficiency induces p-type behavior; this is confirmed by an analysis of the thermoelectric transport properties by using a single parabolic band model at low temperature. The p-type conduction in the Mg-deficient system suggests that Mg vacancies are the predominant defects. However, the efficiency of p-type doping is two to three orders of magnitude lower (∼1018 cm−3) than expected when considering only Mg vacancies as the origin of charge carriers. Density functional theory calculations suggest that the anion anti-site defect on the Mg site is attributable for the low measured carrier concentration and low doping efficiency. Moreover, the energy band structure of the Mg-deficient Mgx(Si, Sn) system is shown to undergo significant deformation and allow the formation of an impurity band at the X point due to the Mg-deficient conditions, enabling the system to have a relatively anion-rich condition. Furthermore, Mg deficiency minimizes the thermal conductivity to 1–1.5 W/m∙K at room temperature owing to an early bipolar contribution and separated structural phases. This study provides the Mg deficiency as a new control parameter that can be utilized to enhance the p-type thermoelectric performance of Mg silicides.

Two-Dimensional Mg2 Si Nanosheet-Enabled Sustained Hydrogen Generation for Improved Repair and Regeneration of Deeply Burned Skin.

Molecular hydrogen holds a high potential for wound healing owing to its anti-inflammatory effect and high biosafety, but commonly used hydrogen administration routes hardly achieve the sustained supply of high-dosage hydrogen, limiting hydrogen therapy efficacy. Here, two-dimensional Mg2 Si nanosheet (MSN) is exploited as a super-persistent hydrogen-releasing nanomaterial with high biocompatibility, and the incorporation of MSN into the chitosan/hyaluronic acid hydrogel (MSN@CS/HA) is developed as a dressing to repair deeply burned skin. The MSN@CS/HA hydrogel dressing can continuously generate hydrogen molecules for about 1 week in the physiological conditions in support of local, long-term, and plentiful hydrogen supply and remarkably promotes the healing and regeneration of deep second-degree and third-degree burn wounds without visible scar and toxic side effect. Mechanistically, a sustained supply of hydrogen molecules induces anti-inflammatory M2 macrophage polarization in time by enhancing CCL2 (chemokine C-C motif ligand 2) expression to promote angiogenesis and reduce fibrosis and also enhances the proliferation and migration capability of skin cells directly and indirectly by locally scavenging overexpressed reactive oxygen species, synergistically favoring wound repair. The proposed synthesis method, therapeutic strategy, and mechanisms will open a window for synthesizing a variety of MSene nanomaterials and developing their various proangiogenesis applications besides wound healing.

High-Performance Functionalized Mg2Si0.9Sn0.1 Thermoelectric Leg Synthesis by a Single-Step Reactive SPS Process

Contact electrodes and their adequate joining are the main bottlenecks in realizing low-cost Mg2(Si,Sn) thermoelectric materials for thermoelectric generator applications. The resistance and diffusion chemistry between the thermoelectric elements and contact electrodes play an essential role in achieving high-performance thermoelectric generators for intermediate-temperature applications. A facile single-step spark plasma sintering process was employed to fabricate Sb-doped Mg2Si0.9Sn0.1 and contact joining simultaneously. The single-step-processed thermoelectric element’s power output characteristics with three different contacts (Ni, MnSi, and FeSi2) were investigated by employing a thermoelectric conversion efficiency evaluation system. Our experimental strategy demonstrated that the single-step processing of Mg2(Si0.9Sn0.1)0.95Sb0.05/Ni joining imparts the lowest internal resistance and high-power output characteristics and eliminates the main obstacle of Mg2(Si,Sn) material integration in thermoelectric power generators.

Efficient Mg2Si0.3Sn0.7 thermoelectrics demonstrated for recovering heat of about 600 K

Mg2(Si,Sn) alloys with all abundant and non-toxic constituents have been proven as a promising n-type thermoelectric material due to the large band degeneracy and strong phonon scattering by point defects. The current work focuses on a demonstration, at a device level, of thermoelectric efficiency for Mg2Si0.3Sn0.7-based alloys. A peak thermoelectric figure of merit, zT of ∼1.3 at 600 K and an average zTave of >1.0 within 300–675 K are realized, stemming from a precise optimization of carrier concentration by Bi-doping and a minimization of Mg oxidation by tantalum-sealing technique. Utilization of Mg2Cu as an interlayer between the thermoelectric material and Ag electrode enables a strong interfacial bondage, minimal chemical diffusions and a low contact resistance. A single-leg power generation efficiency of ∼7.5% is realized in the important temperature of <617 K for low-grade heat recovering, illustrating the extraordinariness of these alloys as eco-friendly applications.

Effect of Sb/Bi doping sites on electronic structure and transport properties of Mg2Si0.375Sn0.625 alloy from first-principles calculations

Defect formation energy, electronic structures, and transport properties of Sb/Bi-doped Mg2Si0.375Sn0.625 alloys were successfully determined by first-principles calculations. Si sites in these alloys were preferentially substituted by Sb and Bi atoms. At the same doping content, Sb atoms provided larger carrier effective mass and lower electron concentration compared with Bi atoms. Correspondingly, the maximum Seebeck coefficient and power factor value of Mg2Si0.365Sn0.625Sb0.01 alloy were −260 μVK−1 and 5.53 mWm−1 K−1, respectively. The highest electrical conductivity value of 1620 Scm−1 was achieved with Mg2Si0.375Sn0.615Bi0.01 alloy, due to higher electron concentration supplied by its Bi atoms. Experimental results were also obtained, verifying the reliability of calculations. These results provide theoretical reference for optimizing the performance of Sb/Bi-doped Mg2(Si, Sn)-based alloys.

Developing a two-parabolic band model for thermoelectric transport modelling using Mg2Sn as an example

Thermoelectrics is a field driven by material research aimed at increasing the thermal to electrical conversion efficiency of thermoelectric (TE) materials. Material optimisation is necessary to achieve a high figure of merit (zT) and in turn a high conversion efficiency. Experimental efforts are guided by the theoretical predictions of the optimum carrier concentration for which generally the single parabolic band (SPB) model is used which considers the contribution to electronic transport only from the majority carriers’ band. However, most TE materials reach peak performance (maximum zT) close to their maximum application temperature and when minority carrier effects become relevant. Therefore, single band modelling is insufficient to model the behaviour of TE materials in their most practically relevant temperature range. Inclusion of minority effects requires addition of the minority carrier band and necessitates the use of a two-band model—the simplest and, for most cases, sufficient improvement. In this study, we present a systematic methodology for developing a two-band model using one valence and one conduction band for any given TE material. The method utilises in part the SPB model and in part a simple cost function based analysis to extract material parameters like density of states masses, band gap, deformation potential constant etc., based on easily available experimental data. This simple and powerful method is exemplified using Mg2Sn, chosen due to its low band gap, the availability of experimental data in a wide range of dopant concentrations and its practical importance, being an end member of the highly popular Mg2(Si,Sn) solid solutions. Using the experimental data for p- and n-type Mg2Sn from literature, a two-band model was obtained. Optimum carrier concentration and maximum zT were predicted from both SPB and two-band models and at 650 K pronounced differences between the two models, which could prevent realisation of maximum zT, were observed, demonstrating the practical necessity to model the effect of minority carriers.