IR radiated Upconversion in Ho & Yb doped MgO-Y for security ink application: Temperature sensing and laser-induced thermal effects
No Thumbnail Available
Date
2026
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This study presents a comprehensive analysis of the novel composition of Ho (0.1–1 mol%) and Yb (0.5–20 mol
%) co-doped MgO-Y₂O₃ nanocomposites for upconversion (UC) and downconversion (DC) luminescence appli
cations. The nanocomposites were synthesized using a cost-efficient combustion method. X-ray diffraction (XRD)
confirmed stable MgO and Y₂O₃ phases, with peak shifts and unit cell parameter variations correlating with
increased dopant (Ho, Yb) concentrations. Transmission electron microscopy (TEM) revealed particle agglom
eration along with clear lattice fringes, while selected area electron diffraction (SAED) confirmed well-defined
ring patterns characteristic of MgO and Y₂O₃ crystals. Photoluminescence (PL) spectroscopy revealed strong
green, red, and near-infrared (NIR) emissions under both 448 nm (downconversion; DC) and 980 nm (upcon
version; DC) excitations. Power-dependent PL studies indicated three-photon absorption for green and two-
photon absorption for red/NIR emissions. Notably, the intensity of the green emission saturates rapidly at 5
mol% Yb
3+
and Yb
3+
, while red emission saturation occurs at 15 mol%, indicating efficient energy transfer between Ho
3+
ions. Power-dependent PL studies unveiled a three-photon absorption mechanism for green emissions
and two-photon absorption for red and NIR emissions. Temperature-dependent UC was examined over a range of
298 K to 683 K, demonstrating promising optical temperature sensing capabilities, with maximum sensitivity
recorded at 51.3 × 10
4
K
1
at 298 K. Moreover, the nanocomposites exhibited excellent stability under pro
longed laser exposure, underscoring their potential for practical applications. Power-dependent tunable colori
metric parameters further highlighted their suitability for warm and cool LED technologies. Finally, the
successful demonstration of these nanophosphors as security inks for anticounterfeiting applications opens new
possibilities for advanced security solutions.