Synthesis and studies room temperature conductivity, dielectric analysis of LaF$_{3}$ nanocrystals

Lanthanum fluoride (LaF$_{3}$) was synthesized using LaCl$_{3}$ and NH$_{4}$F as starting materials in deionized water as solvent via a microwavea-ssisted technique. The structure of LaF$_{3}$ nanocrystals, analyzed by XRD and TEM, was found to be hexagonal with an average crystalline particle size of 20 nm (JCPDS standard card (32-0483) of pure hexagonal LaF$_{3}$ crystals). The resistivity and conductivity at room temperature for LaF$_{3}$ was verified and found to depend on the applied DC field. At an applied voltage of 20 V/cm – 30 V/cm, the resistivity and conductivity changes rapidly due to the liberation of extra fluoride (F$^-$) ions, whereas the conductivity of LaF$_3$ nanocrystals depends upon temperature. The variation of dielectric constant ($\varepsilon$') and dielectric loss ($\varepsilon$") with applied frequency shows normal dielectric behavior, attributable to the space charge formation. The observed peak in the plot of tangent loss (tan $\delta$) vs. $\log F$ around 2.6 KHz can be attributed to interface charge relaxation at the grain boundaries.