• Treffer 1 von 2
Zurück zur Trefferliste

Raman band widths of anhydrite II reveal the burning history of high‐fired medieval gypsum mortars

  • When used as a mineral binder, gypsum is thermally dehydrated and mixed with water, resulting in a paste hardening in the backreaction to calcium sulphate dihydrate (CaSO4 · 2 H2O). Although nowadays mainly hemihydratebased (CaSO4 · ½ H2O) binders are employed, higher firing temperatures in medieval kilns yielded anhydrite II (CaSO4). Except for the discrimination of the metastable phases anhydrite III and I due to different crystal structures, variations within the production temperature range of anhydrite II (approximately 300 to 1180°C) were not analytically accessible until recently. This study describes the development of an analytical technique, which is based on steady changes of band widths in room‐temperature Raman spectra of anhydrite II as a function of burning temperature. Raman microspectroscopic mapping experiments enable to pinpoint individual unreacted grains of thermal anhydrite in mortars and to discriminate them from natural anhydrites originating from the rawWhen used as a mineral binder, gypsum is thermally dehydrated and mixed with water, resulting in a paste hardening in the backreaction to calcium sulphate dihydrate (CaSO4 · 2 H2O). Although nowadays mainly hemihydratebased (CaSO4 · ½ H2O) binders are employed, higher firing temperatures in medieval kilns yielded anhydrite II (CaSO4). Except for the discrimination of the metastable phases anhydrite III and I due to different crystal structures, variations within the production temperature range of anhydrite II (approximately 300 to 1180°C) were not analytically accessible until recently. This study describes the development of an analytical technique, which is based on steady changes of band widths in room‐temperature Raman spectra of anhydrite II as a function of burning temperature. Raman microspectroscopic mapping experiments enable to pinpoint individual unreacted grains of thermal anhydrite in mortars and to discriminate them from natural anhydrites originating from the raw gypsum. The determination of band full widths at half maximum of down to 3 cm−1 and differences between them of a few tenths of wavenumbers is not a trivial task. Thus, a focus of this work is on peak fitting and strategies for correction of instrument‐dependent band broadening, which is often neglected also beyond the field of mortar analysis. Including other potential influences on band widths, burning temperatures of 400 to 900°C can be retraced in high‐fired medieval gypsum mortars with an uncertainty of approximately ± 50 K, as demonstrated with sample material of a stucco sculpture dated around 1400.zeige mehrzeige weniger

Volltext Dateien herunterladen

  • 82_JRamanSpectrosc_2019.pdf
    eng
  • 82_JRamanSpectrosc_2019SupportingInformation.pdf
    eng

    Supporting Information

  • 82_JRamanSpectrosc_2019Cover.pdf
    eng

    Passend zum Artikel veröffentlichtes Cover (veröffentlicht unter dem eigenen DOI 10.1002/jrs.5724)

Metadaten exportieren

Weitere Dienste

Teilen auf Twitter Suche bei Google Scholar Anzahl der Zugriffe auf dieses Dokument
Metadaten
Autor*innen:Thomas SchmidORCiD, R. Jungnickel, P. Dariz
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Journal of Raman Spectroscopy
Jahr der Erstveröffentlichung:2019
Organisationseinheit der BAM:1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.4 Prozessanalytik
Verlag:Wiley
Jahrgang/Band:50
Ausgabe/Heft:8
Erste Seite:1154
Letzte Seite:1168
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Analytical methods; Gypsum dehydration; High-fired gypsum mortar; Raman band width determination; Thermal anhydrite
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
DOI:10.1002/jrs.5632
ISSN:1097-4555
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:26.08.2019
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:26.08.2019
Einverstanden
Diese Webseite verwendet technisch erforderliche Session-Cookies. Durch die weitere Nutzung der Webseite stimmen Sie diesem zu. Unsere Datenschutzerklärung finden Sie hier.