TY - JOUR
T1 - Fluorine translational anion dynamics in nanocrystalline ceramics
T2 - SrF2-YF3 solid solutions
AU - Breuer, Stefan
AU - Stanje, Bernhard
AU - Pregartner, Veronika
AU - Lunghammer, Sarah
AU - Hanzu, Ilie
AU - Wilkening, Martin
PY - 2018/3/5
Y1 - 2018/3/5
N2 - Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics, aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y3+ ions into the cubic structure of SrF2. As compared to pure nanocrystalline SrF2 the ionic conductivity of Sr1−x Yx F2+x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10−5 S cm−1 at 450 K. We discuss the effect of YF3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5.
AB - Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics, aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y3+ ions into the cubic structure of SrF2. As compared to pure nanocrystalline SrF2 the ionic conductivity of Sr1−x Yx F2+x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10−5 S cm−1 at 450 K. We discuss the effect of YF3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5.
KW - Aliovalent substitution
KW - Ball milling
KW - Binary fluorides
KW - Cation mixing
KW - Ionic conductivity
KW - Nanocrystalline ceramics
UR - http://www.scopus.com/inward/record.url?scp=85045652191&partnerID=8YFLogxK
U2 - 10.3390/cryst8030122
DO - 10.3390/cryst8030122
M3 - Article
AN - SCOPUS:85045652191
SN - 2073-4352
VL - 8
JO - Crystals
JF - Crystals
IS - 3
M1 - 122
ER -