Thermoelectric properties enhanced by band engineering and acoustic-optical branch crossover avoidanceZhang, Aojie; Wu, Chao; Guo, Mingxing; Zhang, Qiang; Fan, Wenhao; Chen, Shaoping
doi: 10.1007/s10853-025-10926-2pmid: N/A
Mg3Sb2-based thermoelectric materials have attracted considerable attention due to their non- toxicity, ease of fabrication, and outstanding performance in medium-to-low temperature ranges, yet a critical challenge remains in further enhancing electrical properties while effectively suppressing thermal conductivity. This study employs a Y-doping strategy combined with first-principles calculations to reveal the optimization mechanisms: Y incorporation shifts the Fermi level toward the conduction band, enabling n-type conductivity with a maximum carrier concentration of 1.26 × 1020 cm−3 and concurrently reducing the band gap to achieve a power factor of 14.82 μW cm−1 K−2; the substantial mass disparity between Y and Mg induces mass-field fluctuations, triggering an avoided crossing phenomenon in the phonon spectrum that weakens acoustic-optical phonon branch interactions and significantly reduces phonon group velocity, thereby suppressing lattice thermal conductivity. Ultimately, the thermoelectric figure of merit reaches 1.056 at 725 K. Crystal orbital Hamilton population (COHP) analysis further demonstrates strengthened Y–Mg bonding, which enhances structural stability. This work provides insights into dopant-mediated thermoelectric performance optimization through the coupling of electronic transport enhancement and phonon engineering.Graphical abstractBy doping foreign elements, the Fermi level shifts from the valence band to the conduction band, thereby optimizing carrier concentration, as shown in Figs. (a) and (b). In addition, introducing mass differences between dopant atoms and matrix atoms drives the avoidance of crossover behavior between the acoustic and optical branches, as shown in Figs. (c) and (d). This phenomenon reduces phonon group velocity, as shown in Figs. (d) and (e), thereby suppressing lattice thermal conductivity and enhancing thermoelectric performance.[graphic not available: see fulltext]
Road-compatible triboelectric nanogenerator applied to intelligent transportation systemsFu, Chongyang; Li, Yuankun; Zhai, Weihao; Zhang, Qikang; Li, QiZheng; Zhuang, Yating; Wang, Xiaoxiong
doi: 10.1007/s10853-025-10928-0pmid: N/A
With the development of intelligent transportation systems, the requirements for monitoring and sensing systems have become increasingly stringent. This study proposes a novel self-powered sensing system based on triboelectric nanogenerators (TENGs) for vehicle monitoring and energy harvesting in intelligent transportation systems. The system utilizes the friction between vehicle tires and road materials to generate electricity, enabling real-time monitoring and analysis of driving behavior through collected signals. The research designed a road-compatible triboelectric nanogenerator (r-TENG) using common materials such as natural rubber and asphalt as friction layers, successfully achieving identification and differentiation of various vehicle types. Machine learning algorithms were employed to further enhance recognition accuracy, reaching an identification rate of over 80%. Furthermore, this study demonstrates the potential of r-TENG in practical applications, such as vehicle identification, road traffic monitoring, and driver training, providing a sustainable and cost-effective technical solution for intelligent transportation systems. Experimental results show that r-TENG exhibits good electrical performance, durability, and environmental adaptability, capable of stable operation in complex traffic environments, offering an innovative perspective and theoretical basis for the future development of intelligent traffic management systems.
An advanced PVA-based hydrogel flexible electrolyte material with high anti-dehydration and electrochemistry performanceLiu, Qingye; Wang, Chenghua; Zou, Chang; Li, Jiangtao; Liu, Jun; Liu, Yilun; Sun, Xueyan; Zhao, Wei
doi: 10.1007/s10853-025-10933-3pmid: N/A
Polyvinyl alcohol (PVA) hydrogel as a hydrogel electrolyte faces issues such as fracture, dehydration, and poor conductivity, limiting its application in flexible zinc-air batteries. To address these, we propose a triethanolamine (TEA)-modified PVA-based hydrogel material (TPVA). TEA promoted formation of a uniform mesoporous structure and enables TPVA hydrogel to exhibit excellent mechanical properties, with an elongation at break (425%) approximately twice that of PVA (230%). Additionally, TPVA material retains excellent hydration after 120 h, demonstrating a significant enhancement in water retention. TPVA-based ZABs achieved a power density of 46.1 mW cm−3, which is 3.1 times enhancement than that of PVA-based (14.9 mW cm−3), and demonstrated significantly extended cycling stability, maintaining stable charge–discharge operation for 35.7 h, outperforming PVA system (11.5 h). Dynamic simulation revealed TEA-PVA interactions, with TPVA showing denser hydrogen bond networks and lower potential energy. This work proposes a promising approach to enhance PVA hydrogel electrolytes for flexible ZABs.
P2-type Na0.67Mn0.6Ni0.3Ti0.1O2 as cathode material for sodium-ion batteries: solid electrolyte versus liquid electrolyteBai, Shiyin; Ni, Qing; Yang, Shuaishuai; Fang, Debao; He, Jingxin; Chen, Lai; Su, Yuefeng; Jin, Haibo; Wang, Chengzhi
doi: 10.1007/s10853-025-10977-5pmid: N/A
P2-type Na0.67Mn0.6Ni0.3Ti0.1O2 is synthesized via a sol–gel method and its electrochemical performance is investigated as a cathode material for sodium-ion batteries (SIBs) employing both a Na3Zr2Si2PO12 solid electrolyte and an organic liquid electrolyte. In the liquid electrolyte cells, the Na0.67Mn0.6Ni0.3Ti0.1O2 cathode exhibits a high discharge capacity of 87.5 mAh g−1, with a capacity retention of 73.2% after 500 cycles at 0.1 C (10 mA g−1), while in the solid electrolyte cells, a higher discharge capacity of 94.5 mAh g−1 at 0.1 C and an improved high-rate capacity of 70.8 mAh g−1 at 2 C are demonstrated. Moreover, stable charge/discharge cycles are observed in the solid electrolyte cells, with a discharge capacity of 75.3 mAh g−1 and a retention of 60.7% over 100 cycles at 1 C. This work highlights the substantial effect of the electrolyte conditions on the performance of layered oxide cathode materials, providing potential strategies to overcome current challenges for high-performance SIBs.Graphical abstract[graphic not available: see fulltext]
Processing—microstructure—functional properties correlation for NiTi-based pseudoelastic shape memory alloyArohi, Adya Charan; Nayak, Priyadarshini; Punyamanthula, Kranti Kumar; Ramesh, Surla; Tarafder, Soumitra; Frenzel, Jan; Sen, Indrani
doi: 10.1007/s10853-025-10894-7pmid: N/A
Ni-rich NiTi-based shape memory alloys in the pseudoelastic state are promising candidates for various applications such as in cardiovascular stents, sensors, actuators, etc. However, achieving the desired pseudoelasticity for such applications mandates the alloy to be subjected to a critically optimized thermomechanical processing schedule. In this study, cold-rolled Ni-rich NiTi specimens are subjected to aging treatment at three different temperatures that are of industrial concern for shape setting. Systematic microstructural investigation reveals the presence of equiaxed grains with martensite structure in the processed alloys. Distinctly different phase transformation characteristics are noted for the cold-rolled and aged NiTi alloys as well. This is reflected in attaining no pseudoelasticity at all for the cold-rolled alloy, while strain recovery is regained for the aged alloys. Interestingly, subtle variation in aging temperature is noted to significantly affect the mechanical performance of NiTi alloy. Nanoindentation-based investigation reveals that highest aging temperature is beneficial in achieving maximum localized hardness for the NiTi alloy that is particularly related to the occurrence of precipitates. In contrary, best indentation depth recovery is noted for the NiTi alloy aged at an intermediate temperature. This particular aging condition also revealed highest pseudoelastic strain recovery for the studied NiTi alloy, at the global scale under monotonic or cyclic incremental tensile loading. Overall, this systematic investigation plays a pivotal role in identifying the optimized thermomechanical treatment consisting of cold rolling and aging at 525 °C to achieve the best combination of mechanical properties including pseudoelasticity for NiTi alloy that is of industrial significance.
Mössbauer characterisation of bearing steels and dark etching regionsEcheverri Restrepo, Sebastián; Huang, Hanzheng; Sherif, Mohamed Y.; Dugulan, A. Iulian
doi: 10.1007/s10853-025-10930-6pmid: N/A
Dark etching regions (DERs) are a widely studied phenomenon in the context of sub-surface microstructure decay in rolling bearings. These regions result from dislocation motion (plasticity) and carbon migration due to rolling contact fatigue (RCF). We conducted a systematic study using Mössbauer spectroscopy to identify phase evolution during tempering and DER formation. Our findings resolve a long-standing debate in the literature by demonstrating that fine temper carbides dissolve during DER formation. A slight decrease in non-stoichiometric carbides was observed in the DERs, indicating the dissolution of fine carbides. The released carbon is believed to back-diffuse into ferrite and/or martensite.
Effect of structure characteristics on age hardening response, strength, ductility and corrosion resistance of Al–Mg–Si–Cu–Zn–Fe–Mn alloyChen, Xiangyang; Guo, Mingxing; Peng, Ziteng; Du, Jinqing; Zhi, Jinming; Wang, Tongbo; Zhou, Wei; Lou, Huafen
doi: 10.1007/s10853-025-10961-zpmid: N/A
Developing high-performance aluminum (Al) alloy sheets has become an urgent issue for their extensive application in the field of transportation. In this study, a new Al–Mg–Si–Cu–Zn–Fe–Mn alloy with excellent mechanical properties was prepared by a novel short-flow thermomechanical route. Heterogeneous structure, including a microstructure with soft microdomain surrounding hard microdomain (specimen HS-0) and another microstructure with hard microdomain surrounding soft microdomain (specimen HS-10) were constructed by the short-flow thermomechanical processing routes. More importantly, both the high strength and ductility of hetero-structured specimens are attributed primarily to heterogeneous deformation induce (HDI) stress hardening. Moreover, the corrosion results indicated that the heterogeneous structures exhibit superior corrosion resistance compared to the uniform structure, and the specimen HS-0 exhibits the best corrosion resistance in this work. This current study provides a new short-flow thermomechanical process for the construction of soft/hard microdomain heterostructure, offering valuable insights into the promotion of Al alloys with enhanced strengths, ductility and corrosion resistance.