TY - JOUR A1 - Mishmastnehi, M. A1 - Van Driessche, A. A1 - Smales, Glen Jacob A1 - Moya, A. A1 - Stawski, Tomasz T1 - Advanced materials engineering in historical gypsum plaster formulations N2 - We show how historical gypsum plaster preparation methods affect the microstructure and the wettability properties of the final stucco materials. We reproduced a traditional Persian recipe (Gach-e Koshteh, ~14th century AD), which involves a continuous mechanical treatment during plaster hydration. These samples were compared with a laboratory-replicated historical recipe from Renaissance Italy (Gesso Sottile, ~15th century AD) and contemporary low-strength plaster. The Koshteh recipe induces the formation of gypsum platelets, which exhibit preferential orientation in the plaster bulk. In contrast, the Italian and low-strength plasters comprise a typical needle-like morphology of gypsum crystals. The platelets in Koshteh expose the more hydrophilic {010} face of gypsum in a much more pronounced manner than needles. Consequently, the Iranian plaster displays enhanced wettability, enabling its direct use for water-based decoration purposes, or as a fine finishing thin layer, without the need of mixing it with a binder material. Contrary, in Sottile, gypsum crystals are left to equilibrate in large excess of water, which promotes the growth of long needles at the expense of smaller crystals. Typically, such needles are several times longer than those found in a control regular plaster. For this crystal habit, the total surface of hydrophilic faces is minimized. Consequently, such plaster layers tend to repel water, which can then be used, e.g., as a substrate for oilbased panel paintings. These findings highlight the development of advanced functional materials, by tuning their microtexture, already during the premodern era. KW - Gypsum KW - Calcium sulfate KW - Diffraction KW - Force microscopy PY - 2023 DO - https://doi.org/10.1073/pnas.2208836120  VL - 120 IS - 7 SP - 1 EP - 9 PB - National Academy of Sciences of the USA AN - OPUS4-57219 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Towards sustainable solution-driven recycling of gypsum N2 - Calcium sulfate hemihydrate (CaSO4ᐧ0.5H2O), also known as bassanite, has been used as a precursor to produce gypsum (dihydrate, CaSO4ᐧ2H2O) for various construction and decorative purposes since prehistoric times. The main route to obtain hemihydrate is a thermal treatment of gypsum at temperatures typically between 150 °C and 200 °C to remove some of the structural water. In this contribution, we introduce (Fig. 1) a more efficient and sustainable method (T < 100 °C) that enables the direct, rapid, and reversibly conversion of gypsum to bassanite using reusable high salinity aqueous solutions (brineswith c[NaCl] > 4 M). The optimum conditions for the efficient production of bassanite in a short time (< 5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the typical behaviour of the bassanite phase in low salt environments. Traditionally, hemihydrate is obtained through a solid state thermal treatment because bassanite is considered to be metastable with respect to gypsum and anhydrite in aqueous solutions, and therefore gypsum-to-bassanite conversion should not occur in water. Its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures is inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline structure for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios. T2 - RAL-SAS - UK Small angle scattering meeting 2025 CY - Oxford, United Kongdom DA - 16.06.2025 KW - Scattering KW - SAXS KW - Calcium sulfate KW - Gypsum PY - 2025 AN - OPUS4-64682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Towards sustainable solution-driven recycling of gypsum N2 - Gypsum (CaSO₄·2H₂O) is a crucial mineral across sectors such as construction, agriculture, and biomedicine. Despite its potentially full recyclability, a shortage looms due to limited mining in Europe and decreasing production of flue gas desulfurization (FGD) gypsum, a byproduct of coal power plants. With current EU consumption at 24 MT/a (17 MT mined, 7 MT FGD), a deficit of 10-35 MT/a is projected by the 2030s as CaSO₄ becomes a critical raw material [1]. Meanwhile, substantial CaSO₄ waste is produced in various industries (e.g., phosphogypsum, red gypsum), but its recycling remains limited (10% in Germany, 5% in the EU) due to contamination and separation challenges. This contribution introduces a sustainable, efficient wet-chemical method for converting gypsum to bassanite (CaSO₄·0.5H₂O), and thus recycling gypsum, under mild conditions (T < 100 °C) using reusable high-salinity aqueous solutions (brines with c[NaCl] > 4 M) [2]. The optimal conversion conditions (T > 80°C, c[NaCl] > 4 M) enable rapid (<5 min) and reversible transformation (Fig. 1). Upon cooling, gypsum re-forms, offering a temperature-dependent control over phase transition. Unlike conventional thermal dehydration (150-200 °C), this approach promotes the dissolution of gypsum, allowing contaminants to be separated via selective precipitation or adsorption. Additionally, the wet-chemical process facilitates the physical removal of impurities from gypsum matrices, making it advantageous for recycling gypsum waste from sources such as demolition or urban mining, where it is often mixed with other materials. Our approach presents a sustainable pathway for recovering high-purity bassanite from contaminated gypsum waste, aligning with EU goals for resource conservation and waste reduction. T2 - MaterialsWeek 2025 CY - Frankfurt am Main, Germany DA - 02.04.2025 KW - Gypsum KW - Calcium sulfate KW - Recycling PY - 2025 AN - OPUS4-64677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Towards circular economy of gypsum N2 - Gypsum (CaSO₄·2H₂O) is a crucial mineral across sectors such as construction, agriculture, and biomedicine. Despite its potentially full recyclability, a shortage looms due to limited mining in Europe and decreasing production of flue gas desulfurization (FGD) gypsum, a byproduct of coal power plants. With current EU consumption at 24 MT/a (17 MT mined, 7 MT FGD), a deficit of 10-35 MT/a is projected by the 2030s as CaSO₄ becomes a critical raw material [1]. Meanwhile, substantial CaSO₄ waste is produced in various industries (e.g., phosphogypsum, red gypsum), but its recycling remains limited (10% in Germany, 5% in the EU) due to contamination and separation challenges. This talk introduces a sustainable, efficient wet-chemical method for converting gypsum to bassanite (CaSO₄·0.5H₂O), and thus recycling gypsum, under mild conditions (T < 100 °C) using reusable high-salinity aqueous solutions (brines with c[NaCl] > 4 M) [2]. The wet-chemical process facilitates the physical removal of impurities from gypsum matrices, making it advantageous for recycling gypsum waste from sources such as demolition or urban mining, where it is often mixed with other materials. The approach presents a sustainable pathway for recovering high-purity bassanite from contaminated gypsum waste, aligning with EU goals for resource conservation and waste reduction. T2 - GFZ Interface Geochemistry Seminars Spring 2025 CY - Potsdam, Germany DA - 06.05.2025 KW - Calcium sulfate KW - Circular economy KW - Gypsum PY - 2025 AN - OPUS4-64681 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Towards solution-driven recycling of gypsum N2 - Gypsum (CaSO₄·2H₂O) is a crucial mineral across sectors such as construction, agriculture, and biomedicine. Despite its potentially full recyclability, a shortage looms due to limited mining in Europe and decreasing production of flue gas desulfurization (FGD) gypsum, a byproduct of coal power plants. With current EU consumption at 24 MT/a (17 MT mined, 7 MT FGD), a deficit of 10-35 MT/a is projected by the 2030s as CaSO₄ becomes a critical raw material [1]. Meanwhile, substantial CaSO₄ waste is produced in various industries (e.g., phosphogypsum, red gypsum), but its recycling remains limited (10% in Germany, 5% in the EU) due to contamination and separation challenges. This contribution introduces a sustainable, efficient wet-chemical method for converting gypsum to bassanite (CaSO₄·0.5H₂O), and thus recycling gypsum, under mild conditions (T < 100 °C) using reusable high-salinity aqueous solutions (brines with c[NaCl] > 4 M) [2]. The optimal conversion conditions (T > 80°C, c[NaCl] > 4 M) enable rapid (<5 min) and reversible transformation. Upon cooling, gypsum re-forms, offering a temperature-dependent control over phase transition. Unlike conventional thermal dehydration (150-200 °C), this approach promotes the dissolution of gypsum, allowing contaminants to be separated via selective precipitation or adsorption. Additionally, the wet-chemical process facilitates the physical removal of impurities from gypsum matrices, making it advantageous for recycling gypsum waste from sources such as demolition or urban mining, where it is often mixed with other materials. T2 - Geo4Göttingen 2025 CY - Göttingen, Germany DA - 14.09.2025 KW - Calcium sulfate KW - Gypsum PY - 2025 DO - https://doi.org/10.48380/fhck-bv98 AN - OPUS4-64684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stawski, Tomasz A1 - Karafiludis, Stephanos A1 - Pimentel, Carlos A1 - Montes-Hernández, German A1 - Kochovski, Zdravko A1 - Bienert, Ralf A1 - Weimann, Karin A1 - Emmerling, Franziska A1 - Scoppola, Ernesto A1 - Van Driessche, Alexander E.S. T1 - Solution-driven processing of calcium sulfate: The mechanism of the reversible transformation of gypsum to bassanite in brines N2 - Here, we show that calcium sulfate dihydrate (gypsum) can be directly, rapidly and reversibly converted to calcium sulfate hemihydrate (bassanite) in high salinity solutions (brines). The optimum conditions for the efficient production of bassanite in a short time (<5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the better-known behaviour of the bassanite phase in low-salt environments. In low-salinity aqueous solutions, bassanite is considered to be metastable with respect to gypsum and anhydrite, and therefore gypsum-to-bassanite conversion does not occur in pure water. Interestingly, the high-salinity transformation of gypsum-to-bassanite has been reported by many authors and used in practice for several decades, although its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures was inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline phase for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios. KW - Industrial and Manufacturing Engineering KW - Strategy and Management KW - General Environmental Science KW - Renewable Energy, Sustainability and the Environment KW - Building and Construction KW - Calcium sulfate KW - Gypsum KW - Bassanite KW - Scattering KW - Raman KW - In situ KW - Synchrotron KW - BESSY KW - MySpot PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594698 UR - https://www.sciencedirect.com/science/article/pii/S0959652624004591#appsec1 DO - https://doi.org/10.1016/j.jclepro.2024.141012 SN - 0959-6526 VL - 440 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-59469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stawski, Tomasz A1 - Smales, Glen Jacob A1 - Scoppola, E. A1 - Jha, D. A1 - Morales, L. F. G. A1 - Moya, A. A1 - Wirth, R. A1 - Pauw, Brian Richard A1 - Emmerling, Franziska A1 - Van Driessche, A. E. S. T1 - Seeds of imperfection rule the mesocrystalline disorder in natural anhydrite single crystals N2 - In recent years, we have come to appreciate the astounding intricacies associated with the formation of minerals from ions in aqueous solutions. In this context, a number of studies have revealed that the nucleation of calcium sulfate systems occurs nonclassically, involving the aggregation and reorganization of nanosized prenucleation species. In recent work, we have shown that this particle-mediated nucleation pathway is actually imprinted in the resultant micrometer-sized CaSO4 crystals. This property of CaSO4 minerals provides us with the unique opportunity to search for evidence of nonclassical nucleation pathways in geological environments. In particular, we focused on large anhydrite Crystals extracted from the Naica Mine in Mexico. We were able to shed light on this mineral's growth history by mapping defects at different length scales. Based on this, we argue that the nanoscale misalignment of the structural subunits, observed in the initial calcium sulfate crystal seeds, propagates through different length scales both in morphological, as well as in strictly crystallographic aspects, eventually causing the formation of large mesostructured single crystals of anhydrite. Hence, the nonclassical nucleation mechanism introduces a “seed of imperfection,” which leads to a macroscopic “single” crystal whose fragments do not fit together at different length scales in a self-similar manner. Consequently, anisotropic voids of various sizes are formed with very welldefined walls/edges. However, at the same time, the material retains in part its single crystal nature. KW - Calcium sulfate KW - Anhydrite KW - Mesocrystal KW - Nucleation KW - Naica PY - 2021 DO - https://doi.org/10.1073/pnas.2111213118 SN - 0027-8424 VL - 118 IS - 48 SP - 1 EP - 11 PB - National Academy of Sciences (USA) CY - Washington AN - OPUS4-53820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Solution-driven processing of calcium sulfate: the mechanism of the reversible transformation of gypsum to bassanite in brines N2 - Calcium sulfate hemihydrate (CaSO4ᐧ0.5H2O), also known as bassanite, has been used as a precursor to produce gypsum (dihydrate, CaSO4ᐧ2H2O) for various construction and decorative purposes since prehistoric times. The main route to obtain hemihydrate is a thermal treatment of gypsum at temperatures typically between 150 °C and 200 °C to remove some of the structural water. In this contribution, we introduce (Fig. 1) a more efficient and sustainable method (T < 100 °C) that enables the direct, rapid, and reversibly conversion of gypsum to bassanite using reusable high salinity aqueous solutions (brines with c[NaCl] > 4 M). The optimum conditions for the efficientproduction of bassanite in a short time (< 5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the typical behaviour of the bassanite phase in low salt environments. Traditionally, hemihydrate is obtained through a solid state thermal treatment because bassanite is considered to be metastable with respect to gypsum and anhydrite in aqueous solutions, and therefore gypsum-to-bassanite conversion should not occur in water. Its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures is inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline structure for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios. T2 - Granada Münster Discussion Meeting GMDM 10 CY - Münster, Germany DA - 29.11.2023 KW - Gypsum KW - Bassanite KW - Calcium sulfate KW - Recycling KW - Scattering PY - 2024 AN - OPUS4-59162 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Seeds of imperfection rule the mesocrystalline disorder in natural anhydrite single crystals N2 - In recent years, we have come to appreciate the astounding intricacy of the formation process of minerals from ions in aqueous solutions. In this context, a number of studies have revealed that nucleation in the calcium sulfate system is non-classical, involving the aggregation and reorganization of nanosized prenucleation particles. In a recent work we have shown that this particle-mediated nucleation pathway is actually imprinted in the resultant single micron-sized CaSO4 crystals. This property of CaSO4 minerals provides us with an unique opportunity to search for evidence of non-classical nucleation pathways in geological environments. In particular, we focused on the quintessential single crystals of anhydrite extracted from the Naica mine in Mexico. We elucidated the growth history from this mineral sample by mapping growth defects at different length scales. Based on these data we argue that the nano-scale misalignment of the structural sub-units observed in the initial calcium sulfate crystal seed propagate through different length-scales both in morphological, as well as strictly crystallographic aspects, eventually causing the formation of large mesostructured single crystals of anhydrite. Hence, the nanoparticle mediated nucleation mechanism introduces a 'seed of imperfection', which leads to a macroscopic single crystal, in which its fragments do not fit together at different length-scales in a self-similar manner. Consequently, anisotropic voids of various sizes are formed with very well-defined walls/edges. But, at the same time the material retains its essential single crystal nature. These findings shed new light on the longstanding concept of crystal structure. T2 - S4SAS Conference 2021 CY - Online meeting DA - 01.09.2021 KW - SAXS KW - Calcium sulfate KW - Anhydrite KW - Mesocrystals PY - 2021 AN - OPUS4-53630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Stawski, Tomasz A1 - Smales, Glen Jacob A1 - Scoppola, E. A1 - Jha, D. A1 - Morales, L. F. G. A1 - Moya, A. A1 - Wirth, R. A1 - Pauw, Brian Richard A1 - Emmerling, Franziska A1 - Van Driessche, A. E. S. T1 - Supplementary data set for "Seeds of imperfection rule the mesocrystalline disorder in natural anhydrite single crystals" N2 - In recent years, we have come to appreciate the astounding intricacy of the formation process of minerals from ions in aqueous solutions. In this context, a number of studies have revealed that nucleation in the calcium sulfate system is non-classical, involving the aggregation and reorganization of nanosized prenucleation particles. In a recent work we have shown that this particle-mediated nucleation pathway is actually imprinted in the resultant single micron-sized CaSO4 crystals. This property of CaSO4 minerals provides us with an unique opportunity to search for evidence of non-classical nucleation pathways in geological environments. In particular, we focused on the quintessential single crystals of anhydrite extracted from the Naica mine in Mexico. We elucidated the growth history from this mineral sample by mapping growth defects at different length scales. Based on these data we argue that the nano-scale misalignment of the structural sub-units observed in the initial calcium sulfate crystal seed propagate through different length-scales both in morphological, as well as strictly crystallographic aspects, eventually causing the formation of large mesostructured single crystals of anhydrite. Hence, the nanoparticle mediated nucleation mechanism introduces a 'seed of imperfection', which leads to a macroscopic single crystal, in which its fragments do not fit together at different length-scales in a self-similar manner. Consequently, anisotropic voids of various sizes are formed with very well-defined walls/edges. But, at the same time the material retains its essential single crystal nature. These findings shed new light on the longstanding concept of crystal structure. KW - Calcium sulfate KW - Mesocrystal KW - Anhydrite PY - 2021 DO - https://doi.org/10.5281/zenodo.4943234 PB - Zenodo CY - Geneva AN - OPUS4-53765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -