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oai:gredos.usal.es:10366/1668472026-01-12T15:14:08Zcom_10366_138651com_10366_4512com_10366_3823col_10366_138661

Epitactic growth of celestite on anhydrite: substrate induced twinning and morphological evolution of aggregates Forjanes, Pablo Gómez Barreiro, Juan Morales, Juan Astilleros, José Manuel Fernández Díaz, Lourdes Epitactic growth Synchrotron X-ray diffraction analysis Celestite Texture analysis SEM [EN] Epitactic crystal growth plays a main role in the development of mineral processes and in the synthesis of advanced materials. Celestite (SrSO4) forms epitactic overgrowths on anhydrite (CaSO4) (100), (010) and (001) surfaces upon interacting with Sr-bearing aqueous solutions. Two populations of differently oriented celestite crystals related by symmetry operators of substrate are identified on (001)Anh and (100)Anh anhydrite substrates by SEM observations and synchrotron X-ray diffraction analysis. Substrate-induced twins arise after the coalescence of individuals belonging to these populations. Progressing growth results in a marked morphological evolution of epitactic celestite, whose crystals undergo sustained branching and loss of co-orientation that result in the formation of sheaf-like aggregates, on (100)Anh, and swan-like aggregates, on (001)Anh. We relate this evolution to celestite growth in a Ca-rich environment due to continued anhydrite dissolution and incorporation of small amounts of Ca into celestite structure. This incorporation would induce lattice strain which would be released through the formation of dislocations. The regular arrangement of these dislocations in small-angle boundaries would result in progressive splitting, driving the evolution from celestite single crystals to aggregates. Sharp compositional gradients in the boundary layer could explain the anisotropic development that leads to the formation of the swan-like celestites. 2025-08-29T09:06:37Z 2025-08-29T09:06:37Z 2025-08-29T09:06:37Z 2020 info:eu-repo/semantics/article "Forjanes, Pablo; Gómez-Barreiro, Juan; Morales, Juan; Astilleros, José Manuel; Fernández-Díaz, Lurdes", "Epitactic growth of celestite on anhydrite: substrate induced twinning and morphological evolution of aggregates", "CrystEngComm", "2020", volumen 22, issue 35, pages 5743-5759, publisher "The Royal Society of Chemistry", doi 10.1039/D0CE00755B, url http://dx.doi.org/10.1039/D0CE00755B, http://hdl.handle.net/10366/166847 10.1039/D0CE00755B 1466-8033 eng http://dx.doi.org/10.1039/D0CE00755B CGL2016-77138-C2-1-P FPU17/01689 IEDI-2016-00691 CGL2016-78560-P info:eu-repo/semantics/openAccess The Royal Society of Chemistry