Silicon-germanium (SiGe) alloy, as a representative medium and high temperature thermoelectric material, has been widely applied in auxiliary power supply of space exploration spacecraft. SiGe alloy has significant advantages such as stable structure, rich elements, non-toxic, high-temperature resistance, and easy industrial integration. However, the lower thermoelectric performance limits the practical application and promotion of SiGe alloys. Based on above, this article comprehensively describes the collaborative optimization strategies of SiGe alloys in both electrical and thermal properties, as well as relevant latest research progress. In terms of electrical properties, the importance of modulation doping and energy filtering mechanism to improve the power factor of SiGe alloys was revealed; In terms of thermal properties, a detailed review was conducted on the strategies for reducing lattice thermal conductivity of SiGe alloys, including nanostructure, SiGe-metal silicide/silicide composite, and SiGe-oxide composite strategies. And the effects of different optimization strategies on reducing lattice thermal conductivity were compared. Through collaborative optimization of electrical and thermal transport parameters, the zT values of p-type and n-type SiGe-based thermoelectric materials reached 1.81 (1100 K) and 1.7 (1173 K), respectively, which are the highest values reported in current research. This article provides a certain reference for further optimization of the thermoelectric properties of SiGe bulk materials.

The highly efficient degradation and purification of organic pollutants in wastewater by photocatalysis is still challenging. In this study, a piezoelectric potential-activated interfacial electric field (IEF) was constructed to endow BiFeO₃@BaTiO₃ (BFO@BTO) heterojunction with the ability to serve as a round-the-clock photocatalyst for polluted water remediation. BFO@BTO heterojunction is composed of BiFeO₃ nanoparticles decorated on the surface of BaTiO₃ nanorods, which shortens the carrier migration path. More importantly, the IEF can be activated and reconstructed under ultrasonic wave irradiation, leading to a lower potential barrier and enhanced separation efficiency for photogenerated carriers. The degradation rate constant k value of BFO@BTO heterojunction reached 0.038 min⁻¹, which was 1.9 and 7.0 times greater than that of piezocatalysis and photocatalysis alone, respectively. It also exhibited excellent stability in three light‒dark cycles for high concentrations (25 mg·L⁻¹) of rhodamine B (RhB) and tetracycline hydrochloride (TC). This study provides a promising strategy for designing highly active photoassisted piezocatalysts for environmental energy utilization and round-the-clock catalysis.

SiGe based alloy is a promising medium-high temperature thermoelectric material that has been applied in the field of aerospace exploration. So far, utilizing the second phase to promote the scattering of phonons is a common way to improve the thermoelectric performance of SiGe based alloy, but this often deteriorates the electrical properties. In this study, the Si₈₀Ge₂₀P₁/CoSi₂ composites have been prepared by mechanical alloying and spark plasma sintering, and the content of cobalt silicide (CoSi₂) nanoparticles have been manipulated. Since the CoSi₂ nanoparticles possess higher carrier concentration and smaller work function than the Si₈₀Ge₂₀P₁ matrix, the carrier concentrations of composites have been pushed up due the charge transfer effect. Meanwhile, the formation of nano-sized phase interfaces and stacking faults in the composites has enhanced the scattering of low-frequency phonons. As a result, the optimal power factor of 3.41 mW·m⁻¹·K⁻² and thermal conductivity of 2.29 W·m⁻¹·K⁻¹ have been achieved, and the corresponding zT reaches up to 1.3 in the Si₈₀Ge₂₀P₁+0.5% CoSi₂ (in mole) composite at 873 K. This work provides a new idea for developing the performance of SiGe based alloy.

SiGe is recognised as an excellent thermoelectric material with superior mechanical properties and thermal stability in regions with high temperatures. This study explores a novel strategy for co-regulating thermoelectric transport parameters to achieve high thermoelectric properties of p-type SiGe in the mid-temperature region by incorporating nano-TaC into SiGe combined ball milling with spark plasma sintering. By optimizing the amount of TaC in the SiGe matrix, the power factors were significantly increased due to the modulation doping effect based on the work function matching of SiGe with TaC. Simultaneously, the ensemble effect of the nanostructure leads to a significant decrease in thermal conductivity. Thus, a high ZT of 1.06 was accomplished at 873 K, which is 64 % higher than that of typical radioisotope thermoelectric generator. Our research offers a novel strategy for expanding and enhancing the thermoelectric properties of SiGe materials in the medium temperature range.