2026-08-28T05:06:11Zhttps://riubu.ubu.es/oai/request
oai:riubu.ubu.es:10259/119782026-08-28T00:05:21Zcom_10259_4313com_10259_5086com_10259_2604col_10259_4314
Urbaneja Miguel, Álvaro 42da027b-cecb-4930-bda8-f27d571c1e9d 600 Torija López, Alba 570ebd0f-1b98-4dc0-89e2-cf6b6950fd2e 600 Carrancho Alonso, Ángel 104 600 0000-0001-7119-6424 Iriarte Avilés, Eneko 297 600 0000-0001-8365-5616 González Moreno, Sara 642 600 0000-0002-7600-0045 González Martín, José Manuel 254 600 0000-0003-2593-3192 Trigo López, Miriam 556 600 0000-0001-5948-1230 Vallejos Calzada, Saúl 567 600 0000-0001-5522-6574 2026-08-27T11:52:34Z 2026-08-27T11:52:34Z 2026-05-29 2238-7854 https://hdl.handle.net/10259/11978 10.1016/j.jmrt.2026.05.175 Controlled-atmosphere thermal processing was investigated as a method to engineer iron-oxide phase assemblages in iron-bearing silicate materials. Natural sandstone was heated between 200 and 1000 °C under air, N2 and CO2 atmospheres to evaluate how oxygen partial pressure governs redox transformations and the resulting macroscopic optical behaviour. The treatments produced a wide and reproducible range of optical responses from a single starting material. Colour evolution, quantified in the CIELAB space, correlates with bulk mineral transformations. Oxidizing conditions stabilize hematite-dominated assemblages and generate red hues, whereas reduced-oxygen atmospheres promote magnetite formation and progressive darkening. Rock-magnetic measurements identify atmosphere-dependent phase assemblages, including a high-coercivity iron oxide under strongly oxidizing conditions. The magnetic response mirrors the optical evolution, indicating that colour development originates from internal phase transformations. Compressive strength remained within the same order of magnitude as the untreated material across the studied conditions, indicating no catastrophic mechanical degradation. These results show that oxygen availability acts as a key processing variable controlling iron-oxide stability and optical response. The study establishes a process-based approach for tuning optical properties in mineral materials through atmosphere-controlled thermal processing without chemical additives. Unlike previous studies focused on temperature-driven effects or isolated observations, this work demonstrates a reproducible process-based approach to tune optical properties in natural silicate materials through controlled atmosphere engineering. We gratefully acknowledge the financial support provided by all funders. Authors S. Vallejos and Á. Carrancho received Grant PID2023-147301OB-I00 and Grant PID2024-159094NB-I00, respectively, funded by MICIU/AEI/10.13039/501100011033 and FEDER. The financial support provided by Fondo Europeo de Desarrollo Regional-European Regional Development Fund (FEDER, ERDF) and Regional Government of Castilla y León -Consejería de Educación, Junta de Castilla y León- (BU025P23 and BU037P23) is gratefully acknowledged. This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGenerationEU PRTR. Author Saul Vallejos received grant BG22/00086 funded by Spanish Ministerio de Universidades. application/pdf eng Elsevier Journal of Materials Research and Technology. 2026, V. 42, p. 10750-10759 https://doi.org/10.1016/j.jmrt.2026.05.175 Atribución 4.0 Internacional http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Iron-oxide phase equilibria Redox-controlled thermal processing Process–structure–property relationship Magnetite–hematite transformation Atmosphere-controlled heat treatment Functional optical materials Ciencia de materiales Mineralogía Materials science Mineralogy Atmosphere-controlled thermal processing enables tunable optical properties via iron-oxide phase engineering in natural silicate materials info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Journal of Materials Research and Technology 42 10750 10759 THUMBNAIL Urbaneja-jmrt_2026.pdf.jpg Urbaneja-jmrt_2026.pdf.jpg IM Thumbnail image/jpeg 4899 https://riubu.ubu.es/bitstream/10259/11978/4/Urbaneja-jmrt_2026.pdf.jpg 62b6ab8611389de0d80d8ff8908452bd MD5 4 LICENSE license.txt license.txt text/plain; charset=utf-8 998 https://riubu.ubu.es/bitstream/10259/11978/3/license.txt aa90105e1c90a1b4fe810649aa967b7d MD5 3 CC-LICENSE license_rdf license_rdf application/rdf+xml; charset=utf-8 908 https://riubu.ubu.es/bitstream/10259/11978/2/license_rdf 0175ea4a2d4caec4bbcc37e300941108 MD5 2 ORIGINAL Urbaneja-jmrt_2026.pdf Urbaneja-jmrt_2026.pdf application/pdf 7892326 https://riubu.ubu.es/bitstream/10259/11978/1/Urbaneja-jmrt_2026.pdf c0d5677aae30ce381c587b44591aa088 MD5 1 10259/11978 oai:riubu.ubu.es:10259/11978 2026-08-28 02:05:21.398 Repositorio Institucional de la Universidad de Burgos bubrep@ubu.es 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