E. A. Sulyanova

Nanostructured crystals of fluorite phases Sr1 − xRxF2 + x (R are rare earth elements) and their ordering: 5. A study of the ionic conductivity of as-grown Sr1 − xRxF2 + x crystals

The ionic conductivity σ of Sr1 − xRxF2 + x crystals (R = Y, La-Lu) has been measured in the temperature range of 324–933 K. The isomorphic introduction of R3+ ions into SrF2 is accompanied by an increase in conductivity up to four orders of magnitude, which makes these crystals superionic conductors. It is shown that the conduction mechanism in Sr1 − xRxF2 + x crystals changes when passing from R = La-Nd to R = Sm-Lu. A change in the type of cluster of structural defects between Nd and Sm is suggested. The concentration dependences of σ and the activation energy of charge-carrier migration (Ea) for Sr1 − xRxF2 + x are nonlinear. For crystals with R = La or Nd, these dependences are interpreted within the percolation model of “defect regions,” the minimum size of which is estimated to be ∼700 Å3. It is shown that the electrical properties of the crystals can be controlled by varying the RF3 type and concentration. The Sr1 − xRxF2 + x crystals (R = La-Nd, 0.3 ≤ x ≤ 0.5), for which σ = (2−3) × 10−2 S/cm at 673 K and Ea = 0.6−0.7 eV, have the best electrolytic characteristics.

Nanostructured crystals of the fluorite phases Sr1 − xRxF2 + x(R—rare-earth elements) and their ordering: II. Crystal structure of the ordered Sr4Lu3F17 phase

AbstractThe crystal structure of the ordered phase Sr4Lu3F17 prepared by directed crystallization of the melt has been investigated. The crystals have a trigonally distorted fluorite lattice (space group R % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXgatC % vAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDharyavP1wz % ZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbb % L8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpe % pae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaam % aaeaqbaaGcbaGafG4mamJbaebaaaa!3BD7!

Single crystals of the fluorite nonstoichiometric phase Eu0.9162+Eu0.0843+F2.084 (conductivity, transmission, and hardness)

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Nanostructured crystals of fluorite phases Sr 1− x R x F 2+ x and their ordering: VIII. Imperfect crystal structure of Sr 0.71 Ce 0.29 F 2.29

, Z = 6, a = 10.615(2) Å, c = 19.547(6) Å). The Sr4Lu3F17 phase is isostructural to Ba4R3F17 (R = Y, Yb). The distortions of the fluorite cation sublattice manifest themselves in the splitting of the only mixed position (Sr, Lu) into three positions: Sr(1), Sr(2), and Lu. All Lu3+ atoms are displaced from the center of the [Sr8{Lu6F36 + 1}F32] octacubic cluster in the [001]cub direction, and the Sr(1) cations are displaced toward the center of the octacubic cluster in the [111]cub direction. The coordination numbers of the Lu, Sr(1), and Sr(2) cations are 8, 10, and 11, respectively. The distortions of the fluorite anion sublattice are caused by the incorporation of additional anions into both the center of the octacubic cluster and the {F8} cubic holes outside the cluster.

Defect structure and ionic conductivity of Ca1 − xScxF2 + x (0.02 ≤ x ≤ 0.15) single crystals

The thermal conductivity of crystals of a continuous series of isovalent Ca1 − xSrxF2 solid solutions has been experimentally investigated in the temperature ranges of 50–300 K (0 ≤ x ≤ 1) and 54–303 K (x = 0.743). The concentration dependence k(x) of the thermal conductivity has been revealed for Ca1−xSrxF2 crystals. It is shown that k > 3 W/(m K) at 300 K for any x. Being extrapolated to the melting temperature range, the phonon mean free path l(T) in Ca0.257Sr0.743F2 crystal approaches to the unit-cell parameter a.

Thermophysical characteristics of EuF2.136 crystal

AbstractThe nonstoichiometric phase EuF2+x has been obtained via the partial reduction of EuF3 by elementary Si at 900–1100°C. Eu0.9162+Eu0.0843+F2.084 (EuF2.084) single crystals have been grown from melt by the Bridgman method in a fluorinating atmosphere. These crystals belong to the CaF2 structure type (sp. gr. Fm

Growth and defect structure of CdF{sub 2} crystal and nonstoichiometric Cd{sub 1-x}R{sub x}F{sub 2+x} phases (R are rare earth elements and in): 6. Growth and ionic conductivity of Cd{sub 0.904}In{sub 0.096}F{sub 2.096} single crystal

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