Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se

article Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se published yes Yu Liu author 2A70014E-F248-11E8-B48F-1D18A9856A870000-0001-7313-6740 Tobias Kleinhanns author 8BD9DE16-AB3C-11E9-9C8C-2A03E66974250000-0003-1537-7436 Maria Chiara Spadaro author Aziz Genç author Sharona Horta author 03a7e858-01b1-11ec-8b71-99ae6c4a05bc Navita Navita author 6ebe278d-ba0b-11ee-8184-f34cdc671de40000-0001-7408-8197 Tommaso Costanzo author D93824F4-D9BA-11E9-BB12-F207E66974250000-0001-9732-3815 Ewelina Dutkiewicz author 0601cc46-c082-11ec-9b07-bb29641d1de9 Jordi Arbiol author Min Hong author Maria Ibáñez author 43C61214-F248-11E8-B48F-1D18A9856A870000-0001-5013-2843 MassSpec department MaIb department GradSch department EM-Fac department HighTE: The Werner Siemens Laboratory for the High Throughput Discovery of Semiconductors for Waste Heat Recovery project Silver selenide (Ag2Se) is a promising near-room-temperature thermoelectric material, but its narrow stoichiometric window and β–α phase transition complicate reproducible microstructure control. Here, we present a mismatch-assisted microstructure engineering strategy in which Ag2Se particles are treated with polyanionic ZnSe complexes and consolidated through the β–α transition to introduce ZnSe nanoprecipitates, Ag2Se/ZnSe interfaces, and local strain fields. The crystallographic mismatch between ZnSe and Ag2Se, together with the Zn2+/Ag+ size difference, amplifies phase-transition-induced deformation and promotes high-density dislocations with periodic strain modulations. This defect architecture suppresses grain coarsening, removes excess Ag, limits Ag-interstitial formation, and reduces lattice thermal conductivity through lattice softening and multiscale phonon scattering. Ag2Se–4%ZnSe nanocomposites achieve a peak zTmax of 1.13 at 369 K and a zTavg of 1.08 from 300 to 380 K, demonstrating mismatch-driven defect engineering through the β–α phase transition as a route for optimizing Ag2Se-based thermoelectrics. https://research-explorer.ista.ac.at/download/22734/22736/2026_ACSEnergyLetters_Liu.pdf application/pdfno American Chemical Society2026 eng ACS Energy Letters 2380-819510.1021/acsenergylett.6c01499 1185752-5762 Liu, Yu, Tobias Kleinhanns, Maria Chiara Spadaro, Aziz Genç, Sharona Horta, Navita Jakhar, Tommaso Costanzo, et al. “Exploiting Mismatch Strain and the β–α Phase Transition for Microstructural Engineering in Thermoelectric Ag2Se.” ACS Energy Letters. American Chemical Society, 2026. <a href="https://doi.org/10.1021/acsenergylett.6c01499">https://doi.org/10.1021/acsenergylett.6c01499</a>. Y. Liu, T. Kleinhanns, M.C. Spadaro, A. Genç, S. Horta, N. Jakhar, T. Costanzo, E. Dutkiewicz, J. Arbiol, M. Hong, M. Ibáñez, ACS Energy Letters 11 (2026) 5752–5762. Liu, Yu, et al. “Exploiting Mismatch Strain and the β–α Phase Transition for Microstructural Engineering in Thermoelectric Ag2Se.” ACS Energy Letters, vol. 11, no. 8, American Chemical Society, 2026, pp. 5752–62, doi:<a href="https://doi.org/10.1021/acsenergylett.6c01499">10.1021/acsenergylett.6c01499</a>. Liu Y, Kleinhanns T, Spadaro MC, et al. Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se. ACS Energy Letters. 2026;11(8):5752-5762. doi:<a href="https://doi.org/10.1021/acsenergylett.6c01499">10.1021/acsenergylett.6c01499</a> Y. Liu et al., “Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se,” ACS Energy Letters, vol. 11, no. 8. American Chemical Society, pp. 5752–5762, 2026. Liu Y, Kleinhanns T, Spadaro MC, Genç A, Horta S, Jakhar N, Costanzo T, Dutkiewicz E, Arbiol J, Hong M, Ibáñez M. 2026. Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se. ACS Energy Letters. 11(8), 5752–5762. Liu, Y., Kleinhanns, T., Spadaro, M. C., Genç, A., Horta, S., Jakhar, N., … Ibáñez, M. (2026). Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se. ACS Energy Letters. American Chemical Society. <a href="https://doi.org/10.1021/acsenergylett.6c01499">https://doi.org/10.1021/acsenergylett.6c01499</a> 227342026-08-18T11:34:03Z2026-08-19T05:53:33Z