Microstructural Control and Heat Transport Enhancement in Lanthanum Sulfate for Thermochemical Heat Storage
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arXiv
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| Natura: | Preprint |
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2025
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| author | Shizume, Kunihiko Hatada, Naoyuki |
| author_facet | Shizume, Kunihiko Hatada, Naoyuki |
| contents | Enhancing heat transport within thermochemical heat storage (TCHS) materials is essential for improving the heat output. A common strategy is combining salts with highly conductive additives such as carbon or metals. However, such composites often suffer from drawbacks including interfacial instability and a reduction of gas permeability. In this work, we propose an alternative approach based on microstructural orientation control, aiming to create efficient heat transport pathways without relying on conductive additives. As a model material, La$_2$(SO$_4$)$_3$ was selected, which undergoes reversible hydration and dehydration below 250 °C. Centimeter-scale hexagonal prismatic La$_2$(SO$_4$)$_3\cdot$9H$_2$O grains were grown from solution and then formed into plate-shaped specimens either parallel to the longitudinal direction or transverse to it, and then dehydrated to $β$-La$_2$(SO$_4$)$_3$. Laser flash analysis revealed clear orientation-dependent thermal diffusivity of pre-dehydrated $β$-La$_2$(SO$_4$)$_3$, with values of about 0.24 mm$^2$/s for the longitudinal plate and about 0.15 mm$^2$/s for the transverse plate at room temperature. Microstructural observations indicated the formation of aligned rod-like domains, suggesting that orientation provides an efficient heat transport pathway. These findings demonstrate that controlling orientation provides a viable route to enhance heat transport in TCHS materials, offering a new design approach. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_08585 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Microstructural Control and Heat Transport Enhancement in Lanthanum Sulfate for Thermochemical Heat Storage Shizume, Kunihiko Hatada, Naoyuki Materials Science Enhancing heat transport within thermochemical heat storage (TCHS) materials is essential for improving the heat output. A common strategy is combining salts with highly conductive additives such as carbon or metals. However, such composites often suffer from drawbacks including interfacial instability and a reduction of gas permeability. In this work, we propose an alternative approach based on microstructural orientation control, aiming to create efficient heat transport pathways without relying on conductive additives. As a model material, La$_2$(SO$_4$)$_3$ was selected, which undergoes reversible hydration and dehydration below 250 °C. Centimeter-scale hexagonal prismatic La$_2$(SO$_4$)$_3\cdot$9H$_2$O grains were grown from solution and then formed into plate-shaped specimens either parallel to the longitudinal direction or transverse to it, and then dehydrated to $β$-La$_2$(SO$_4$)$_3$. Laser flash analysis revealed clear orientation-dependent thermal diffusivity of pre-dehydrated $β$-La$_2$(SO$_4$)$_3$, with values of about 0.24 mm$^2$/s for the longitudinal plate and about 0.15 mm$^2$/s for the transverse plate at room temperature. Microstructural observations indicated the formation of aligned rod-like domains, suggesting that orientation provides an efficient heat transport pathway. These findings demonstrate that controlling orientation provides a viable route to enhance heat transport in TCHS materials, offering a new design approach. |
| title | Microstructural Control and Heat Transport Enhancement in Lanthanum Sulfate for Thermochemical Heat Storage |
| topic | Materials Science |
| url | https://arxiv.org/abs/2509.08585 |