2 research outputs found
Thermodynamics and Kinetics Accounting for Antithermal Quenching of Luminescence in Sc<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub>: Yb/Er: Perspective beyond Negative Thermal Expansion
Defects are common in inorganic materials and not static
upon annealing
of the heat effect. Antithermal quenching of luminescence in phosphors
may be ascribed to the migration of defects and/or ions, which has
not been well-studied. Herein, we investigate the antithermal quenching
mechanism of upconversion luminescence in Sc2(MoO4)3: 9%Yb1%Er with negative thermal expansion via a fresh
perspective on thermodynamics and kinetics, concerning the thermally
activated movement of defects and/or ions. Our results reveal a second-order
phase transition taking place at ∼573 K induced by oxide-ion
migration. The resulting variation of the thermodynamics and kinetics
of the host lattice owing to the thermally induced oxide-ion movement
contributes to a more suppressed nonradiative decay rate. The dynamic
defects no longer act as quenching centers with regard to the time
scale during which they stay nearby the Yb3+/Er3+ site in our proposed model. This research opens an avenue for understanding
the antithermal quenching mechanism of luminescence via thermodynamics
and kinetics
Tunable Mesogens Based on Shape-Persistent Aromatic Oligoamides: From Lamellar, Columnar, to Nematic Liquid Crystalline Phase
Crescent aromatic oligoamides are shown to form thermotropic lamellar columnar, rectangular columnar, and discotic nematic mesophases according to structural variation, demonstrating their capability to serve as a new class of diverse mesogens of liquid crystals