Tracing Tb-SrAl2O4 hydration dynamics through Tb–NV- interactions using Direct Optically Detected Magnetic Resonance (dODMR)

Abstract: 
An advanced magnetometry technique was employed to gain deeper insight into the hydration processes
of Tb-doped SrAl2O4 and ordinary Portland cement (OPC) binders during the first few hours of
hydration. Strontium aluminate-based materials are of particular interest for space applications due to
their persistent luminescence, VIS–IR transparency, and potential for passive illumination and visual
marking in spacecraft and extraterrestrial environments. We introduce a new term direct optically
detected magnetic resonance (direct ODMR), based on coupling luminescence from Tb3+-doped SrAl2O4
to negative nitrogen-vacancy (NV-
 
) centers in nanodiamonds (NDs). Upon blue-light excitation, Tb3+
ions emit green luminescence that selectively optically pumps the NV− centers, thereby enabling
spatially localized ODMR measurements to probe hydration processes within individual cement
particles with high spatial resolution. Hydration kinetics were quantified by measuring the longitudinal
relaxation time (T1) of the NV centers and correlating these data with X-ray diffraction (XRD), micro
Raman microscopy, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR)
analyses. The obtained results shed light on the microstructural evolution that underpins cement
bonding. Changes in the T1 relaxation time were associated with exothermic reactions, including the
dissolution of the primary cement phases, the release of Sr2+, Al(OH)4−, and OH− ions, and the
subsequent formation of an amorphous SrO–Al2O3–H2O hydrated phase.
Autorzy / Authors: 
A. Kruk, M. Mrózek, S. Kreissl, D. Madej
Czasopismo: 
Arch. Civ. Mech. Eng.
Rok: 
2026
Tematyka badań: 
Inna tematyka