Synchrotron X-ray diffraction computed tomography to non-destructively study inorganic treatments for stone conservation

Elena Possenti; Claudia Conti; G Diego Gatta; Nicoletta Marinoni; Marco Merlini; Marco Realini; Gavin B M Vaughan; Chiara Colombo

doi:10.1016/j.isci.2022.105112

Synchrotron X-ray diffraction computed tomography to non-destructively study inorganic treatments for stone conservation

iScience. 2022 Sep 12;25(10):105112. doi: 10.1016/j.isci.2022.105112. eCollection 2022 Oct 21.

Authors

Elena Possenti¹, Claudia Conti¹, G Diego Gatta², Nicoletta Marinoni², Marco Merlini², Marco Realini¹, Gavin B M Vaughan³, Chiara Colombo¹

Affiliations

¹ Istituto di Scienze del Patrimonio Culturale (ISPC), Consiglio Nazionale delle Ricerche (CNR), Via R. Cozzi 53, 20125 Milano, Italy.
² Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via S. Botticelli 23, 20133 Milano, Italy.
³ European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France.

Abstract

The characterization of consolidating products formed by conservation treatments within Cultural Heritage (CH) materials is a burning issue and an analytical challenge, as non-destructive approaches, phase analysis, and volume distribution analysis are simultaneously required. This paper proposes the use of synchrotron X-ray diffraction computed tomography (XRDCT) to non-destructively study diammonium hydrogen phosphate (DAP) consolidating treatments for stone conservation. The mineralogical composition and localization of crystalline phases formed in a complex mixture have been explored and spatially resolved. The coexistence of hydroxyapatite and octacalcium phosphate has been finally demonstrated. The image analysis highlights the 3D distribution of calcium phosphates, their arrangement in a binding network down to the voxel scale, and their consolidating action. Above all, this study demonstrates the feasibility and high potential of XRDCT to investigate the interactions of conservation treatments with CH stone materials, and opens new analytical perspectives for XRDCT in conservation science and materials science.

Keywords: Environmental science; Inorganic chemistry.