Year: 2026
Type: preprint
Abstract: Multiphonon relaxation decides whether a lanthanide ion emits light or heats its host. Since 1968 it has been predicted from the host’s maximum phonon energy, although the excitation resides on a single ion. First-principles force constants and five decades of relaxation measurements show that the accepting vibration is the stretch of the dopant’s coordination cage, a site property set by local chemistry. Aliovalent substitution stiffens the cage by up to 27%, and across seven halide hosts the cage frequency departs from the host frequency by −21% to +19%. It predicts measured effective phonon frequencies three times more accurately than the host frequency, and in its quanta the seven energy-gap laws share one room-temperature slope. The site-resolved laws map the lattice limits of optical refrigeration from 2 to 6 µm. The phonon count of a lanthanide emitter becomes a site property that chemistry can tune and theory can compute before synthesis.
Source: ChemRxiv
Author: Daqian Bian
Institution: University of Chicago
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221541628