Electron paramagnetic resonance of Gd$^{3+}$ ions in powders of LaF$_{3}$:Gd$^{3+}$ nanocrystals

The observation of electron paramagnetic resonance of Gd$^{3+}$ ions in nanosized powders of rare-earth fluorides LaF$_{3}$:Gd$^{3+}$ has been reported. The measurements have been performed on a single crystal and micro- and nanosized powders at room temperature. Electron paramagnetic resonance spectra and spin-Hamiltonian parameters of Gd$^{3+}$ ions have been obtained. A qualitative difference of spectra in nano- and micropowders due to the increase in the spread of the crystal field parameters with the decrease in the particle size has been found. The relationship between the single-crystal domain size and the hydrothermal treatment time has been established.