F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

Abstract

Ion dynamics in nanocrystalline materials can be quite different compared to that in materials with lm-sized crystallites. In particular, the substitution of isoor aliovalent ions opens pathways to systematically control ion transport properties. Here we studied the incorporation of SrF 2 into the tysonite structure of LaF 3 and its effect on F À transport. High-energy ball milling directly transforms the binary fluorides in a structurally disordered, phase pure nanocrystalline ceramic. Compared to Sr-free LaF 3 , ionic conductivity could be increased by several orders of magnitude. We attribute this enhancement to the generation of lattice strain and the formation of F defect sites. In agreement with this increase, the activation energy E a of long-range ionic transport in the solid solution La 1Àx Sr x F 3Àx significantly decreases from 0.75 eV (x ¼ 0) to 0.49 eV (x ¼ 0:1).

Ionic Transportation and Dielectric Properties of YF3:Eu3+ Nanocrystals

“…It can be seen that the ion diffusion coefficient and conductivity increase with the doping concentration until they reach 4% and then decrease. The changing mechanism of the two parameters can be interpreted as the following: the Eu 3+ ionic radius is larger than that of Y 3+ ; while the size mismatch will lead to the structural disorder and lattice strain [1], which finally deduces the increase of the ion diffusion coefficient and conductivity. When the doping concentration is larger than 4%, the interaction of the neighboring doping ions emerges due to the decrease of distance between them [32], which results in the difficulty of ion migration and finally causes the decreases of the ion diffusion coefficient and conductivity.…”

“…Rare-earth fluoride nanomaterials have attracted a great deal of interest due to their unique physical and chemical properties and potential applications in luminescence, optoelectronic, down/up conversion devices, etc. [1,2,3,4,5,6]. Among the rare earth fluorides, YF 3 is an important material and has widespread potential applications in optical telecommunication, phosphors, down/up conversion luminescent devices, solid-state batteries, sensors [6,7,8,9,10,11,12,13,14], etc.…”

Spatial confinement – rapid 2D F−diffusion in micro- and nanocrystalline RbSn2F5

“…[5][6][7][8][9][10][11][12] In particular, highly conducting Li-bearing and Na-containing materials were developed to serve as non-flammable electrolytes in ion batteries. [12][13][14][15] Also cation-mixed fluorides, 16,17 such as La 1Àx Ba x F 3Àx , see ref. [18][19][20][21], and Ba 1Àx Ca x F 2 (0 o x o 1), see ref.…”

A study of matrix and admixture elements in fluorine‐rich ionic conductors by pulsed glow discharge mass spectrometry

“…The optimal concentration of doping component (SrF 2 ) for the LaF 3 :SrF 2 ceramics providing the highest ionic conductivity was reported to be 0.05 at% 11,12 . Breuer et al studied LaF 3 nanocrystals with SrF 2 doping of 0.01–0.10 at% Sr and observed an order‐of‐magnitude increase in conductivity, when changing from pure LaF 3 to 0.1 at% Sr‐doped material 13 . The presence of Sr considerably affects the properties of LaF 3 crystals and LaF 3 ‐based ceramics, thus requiring accurate control of Sr concentration at levels of about 0.01 at%.…”