Abstract

The defect structure of as grown Sr_0.72Pr_0.28F_2.28, Sr_0.87Tb_0.13F_2.13, Sr_0.88Dy_0.12F_2.12, Sr_0.89Ho_0.11F_2.11, and Sr_0.9R_0.1F_2.1 single crystals (R = Y, Er, Tm, Yb) prepared under identical conditions has been studied by X-ray diffraction analysis. All crystals belong to the CaF₂ structure type (sp. gr. \(Fm\bar {3}m\)) and have vacancies in the main anion motif and interstitial fluorine anions at site 32f in the crystal with R = Pr and site 48i for the other R. Interstitial fluorine anions are found near site 4b in the crystals with R = Tb and Dy (sites 32f and 24e, respectively) and at site 4b in the crystal with R = Er. Relaxation (static displacement of some main anions to site 32f) is observed in all crystals (except for R = Tb). Displacements of some Sr²⁺ cations to sites 32f and 24e is simultaneously observed in crystals with R = Tb, Dy, Tm, and Yb. In crystals with R = Ho, Y, and Er, some Sr²⁺ cations are displaced only to site 32f; no cation displacement is observed for R = Pr. A model of the defect structure of the phases is proposed based on the structure of crystals studied, according to which interstitial fluorine anions and R³⁺ cations are aggregated into [Sr_4–nR_nF₂₆] clusters of tetrahedral configuration for the phase with R = Pr or [Sr_14–nR_nF_64+n] clusters of octacubic configuration for other R.

中文翻译：

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萤石相Sr 1–x R x F 2 + x（R是稀土元素）的纳米结构晶体及其有序化。16：生长的非化学计量相Sr 1–x R x F 2 + x（R = Pr，Tb–Yb）的缺陷结构

摘要

生长的Sr _0.72 Pr _0.28 F _2.28，Sr _0.87 Tb _0.13 F _2.13，Sr _0.88 Dy _0.12 F _2.12，Sr _0.89 Ho _0.11 F _2.11和Sr _0.9 R _0.1 F _2.1单晶的缺陷结构（R = Y，Er，通过X射线衍射分析研究了在相同条件下制备的Tm，Yb）。所有晶体均属于CaF ₂结构类型（sp。gr。\（Fm \ bar {3} m \）），并有在现场32中的主要阴离子基序空位及间隙氟阴离子˚F与晶体在ř = Pr和站点48我为其他ř。间质性氟阴离子附近发现部位4 b与晶体- [R = Tb和Dy（上站点32 ˚F和24 ë分别），并在部位4 b与晶体在ř =尔。松弛（一些主要阴离子的静态位移到站点32 ˚F）在所有晶体中观察到（除- [R = Tb）的。一些Sr ²⁺阳离子向位点32f和24的位移在具有R = Tb，Dy，Tm和Yb的晶体中同时观察到e。在R = Ho，Y和Er的晶体中，一些Sr ²⁺阳离子仅位移到位点32 f；对于R = Pr，没有观察到阳离子位移。根据所研究的晶体结构，提出了相缺陷结构的模型，据此，间隙氟阴离子和R ³⁺阳离子聚集到该相的四面体构型的[Sr _{4– n} R _n F ₂₆ ]簇中与[R = PR或[锶_{14- ñ} ř _ñ ˚F其他R的八角配置的_{64+ n} ]个群集。