Fluorite M1 − x R xF2 + x phases (M = Ca, Sr, Ba; R = rare earth elements) as nanostructured materials

Supercooling at Melt Growth of Single and Mixed Fluorite Compounds: Criteria of Interface Stability

“…This criterion, derived under suggestions of stationary crystallization caused by CMSc, small concentration for the second component and constant values for k o and m, has been proved being valid for concentrated melts as well (Kaminskii et al, 2008;Sobolev et al, 2003).…”

“…Importantly, in the low T-interval there occurs a transition from behavior typical of single crystals (with a maximum in T-dependence) to behavior characteristic for glasses, with a monotonic decrease in thermal conductivity with Tdecrease. As firmly considered such transition to glasslike structures is connected with formation, accumulation, and agglomeration of clusters of oppositely charged defects, which leads to disturbance of short-range order with retention of long-range order [Fedorov, 1991[Fedorov, , 2000Kazanskii et al, 2005;Sobolev et al, 2003). Within the next compositional interval, x = 0.09-0.25, the thermal conductivity, was found out to grow up monotonically with T, which is typical behavior for any disordered systems but is completely inadmissible for crystals of simple stoichiometric compounds.…”

Electron paramagnetic resonance of Gd3+ ions in Ca1 − x − y Y x Gd y F2 + x + y crystals

“…In the first one, the octahe dron composed of 6 R and M ions in cationic positions embraces a cuboctahedron of 12 anions situated at the edges of the initial fluorine cube [1][2][3][4][5][6][7][8], and therefore the nearest neighborhood of the R(M) ion is a square antiprism or a Thomson cube (Fig. 1).…”

“…Doping of alkaline earth fluorides MF 2 (M = Ca, Cd, Sr, Ba) with a fluorite structure by trivalent ions R (R are the rare earth, yttrium or scandium, ions) with a concentration of more than 0.1 mol % leads to the formation of detectable rare earth clusters in the crystal, which include the groups of interstitial fluorine ions and are coherently conjugate with the host lattice [1,2].…”

“…Doping of alkaline earth fluorides MF 2 (M = Ca, Cd, Sr, Ba) with a fluorite structure by trivalent ions R (R are the rare earth, yttrium or scandium, ions) with a concentration of more than 0.1 mol % leads to the formation of detectable rare earth clusters in the crystal, which include the groups of interstitial fluorine ions and are coherently conjugate with the host lattice [1,2].Two types of cluster structures are most known in MF 2 -RF 3 solid solutions. In the first one, the octahe dron composed of 6 R and M ions in cationic positions embraces a cuboctahedron of 12 anions situated at the edges of the initial fluorine cube [1][2][3][4][5][6][7][8], and therefore the nearest neighborhood of the R(M) ion is a square antiprism or a Thomson cube (Fig.…”