Insights into the Local Structure of Tb-Doped KY3F10 Nanoparticles from Synchrotron X-ray Diffraction

Pure and Tb-doped nanocrystalline KY3F10 specimens were synthesized by coprecipitation, and portions of the samples underwent further heat treatment at 600 °C in a fluorinated atmosphere. Synchrotron X-ray diffraction patterns acquired at 30 keV allowed to determine both long- and short-range ordered structures by Rietveld and pair distribution function (PDF) analyses, respectively. PDF examination of the as-synthesized sample allowed to discern a slight deviation from the basic cubic building unit because the Y–F bond lengths could be explained in S.G. I4/mmm with cell parameters a = 8.1520(9) A and c = 11.5876(29) A, whereas Rietveld analysis could equally well fit both the cubic and tetragonal descriptions for the heat-treated specimens. Also, PDF revealed that the as-synthesized sample exhibited less structural coherence than the heat-treated one.