New phases with fluorite-derived structure in CaF2(Y, Ln)F3 systems

Федоров, П. П.; Izotova, O.E.; Alexandrov, V.B.; Соболев, Б. П.

doi:10.1016/0022-4596(74)90096-6

Cited by 50 publications

(9 citation statements)

References 5 publications

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“…Therefore, in the aforementioned Ca 1−x Sr x F 2 system, only the synthesis in the NaNO 3 melt produced equilibrium phases. This observation demonstrates quite unique perspectives for the preparation of the lower temperature equilibrium phases in the fluoride systems: making and studying such phases has been quite limited up to the present moment due to the above experimental obstacles [46,75,76]. Also, it is worth noting that the absence of NaLaF 4 in our synthesized specimens can be easily explained in view of the aforementioned observations, for NaLaF 4 , easily obtainable by sintering or melting, is not stable at lower temperatures, while being stable at the higher temperatures [32,60,61].…”

Section: Discussionmentioning

confidence: 99%

The Melt of Sodium Nitrate as a Medium for the Synthesis of Fluorides

et al. 2018

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The preparation of NaLnF 4 complexes, LnF 3 (Ln = La, Ce, Y) rare earth binary fluorides, CaF 2 and SrF 2 alkali earth fluorides, as well as mixtures of these compounds from their nitrates dissolved in molten NaNO 3 has been studied in order to select the ideal solvent for fluoride synthesis by spontaneous crystallization from flux. Sodium fluoride (NaF) was used as a fluorinating agent. The results of our experiments have confirmed that NaNO 3 melt is one of the most promising media for precipitating said inorganic fluoride materials within a broad temperature range (300-500 • C). Also, in contrast with precipitation/co-precipitation from aqueous solutions, our syntheses have resulted in obtaining equilibrium phases only.

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Section: Discussionmentioning

confidence: 99%

The Melt of Sodium Nitrate as a Medium for the Synthesis of Fluorides

et al. 2018

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“…The structural stability of some cluster models was confirmed by calculations of Catlow and co-workers. [7][8][9] The x-ray 14 and electron diffraction 15 studies revealed a superstructural lattice ordering of the nonstoichiometric fluorite-related solid solutions A 1−y Ln y F 2+y with compositions y =5/m, where m is an integer in the range of 13-19, prepared under some specific conditions. The superstructures were found in CaF 2 solid solutions with the trifluorides of Dy↔ Lu, Y ͑as well as in tveitite, a natural yttrofluorite min-eral͒, SrF 2 doped with the trifluorides of Eu↔ Lu, Y, and in BaF 2 doped with the trifluorides of the whole Ln series except La.…”

Section: Introductionmentioning

confidence: 99%

EPR spectra and crystal field of hexamer rare-earth clusters in fluorites

et al. 2005

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Disordered fluorite-related solid solutions ͑AF 2 ͒ 1−x−y ͑LnЈF 3 ͒ x ͑LnЉF 3 ͒ y , where A = Ca, Sr, Ba; LnЈ = Er, Tm, Yb; LnЉ = Lu, Y; and x Ӷ y = 0.001-0.4, were studied by both optical detection and conventional electron paramagnetic resonance ͑EPR͒ techniques. The EPR spectra of paramagnetic rare-earth ions Er 3+ , Tm 3+ , and Yb 3+ in clusters of diamagnetic Y 3+ and Lu 3+ ions were recorded. It appears that the crystalline electric field at the sites of Ln ions in the clusters is of "nearly" tetragonal symmetry and provides for high values of factors g ʈ , approaching the theoretical limits, and small values of factors g Ќ ϳ 0 in the ground states of the paramagnetic Ln ions. It was assumed that all the clusters of Ln ions in the solid solutions appear to be similar in structure to the hexameric clusters, which are the basic structural units of the homologous series of fluoriterelated superstructures ͑AF 2 ͒ 1−y ͑LnF 3 ͒ y with compositions y =5/m, where m is an integer in the range of 13-19. The structure of "symmetric" hexameric clusters in CaF 2 , SrF 2 , and BaF 2 hosts was established by computer simulation. The crystalline electric field and the spectroscopic ground-state parameters for Er 3+ , Tm 3+ , and Yb 3+ ions in the hexameric clusters were calculated and found to be in agreement with the experimental data, being totally different from those known for the "isolated" simple cubic and tetragonal centers in the fluorite crystals.

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“…Heating the specimen resulted in about 11.3 wt. % mass loss (Supplemental Information), which might [7] (1) and Gettmann and Greis [12] (2), (all specimens were synthesized by solid phase synthesis) along with the present work data for Ca 1−x Y x F 2+x nanopowders (3). Straight-line dependence according to Fedorov and Sobolev [55] have come from 8 wt.…”

Section: Resultsmentioning

confidence: 97%

“…Solid solution of yttrium fluoride in calcium fluoride is a classic example of heterovalent isomorphism [5]. Its study was initially discussed by Vogt in treatises on yttrofluorite [6], and has continued for more than a hundred years [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] (for a more detailed history of this study, please see [18]): the said CaF 2 -YF 3 system has become a model for describing the interaction of calcium fluoride with the rare earth fluorides from yttrium group of elements (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Also, introducing yttrium fluoride into the calcium fluoride crystal lattice causes dramatic changes in its physical properties, including fluoride-ion ionic conductivity, hardness, cleavage and heat conductivity (the latter two parameters decrease significantly) [23,30]. Relatively high yttrium concentrations complicate Ca 1−x Y x F 2+x single crystal growth from the melts due its incongruent melting, and the formation of a cellular substructure [31,32], and local ordering of the formed solid solution [7,12]. Additional increase in the YF 3 content in the CaF 2 -YF 3 system leads to the formation of another berthollide-type variable-composition solid solution at 65-75 mol.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of CaF2–YF3 nanopowders by coprecipitation from aqueos solutions

Федоров¹,

Mayakova²,

Kuznetsov³

et al. 2017

Nanosystems: Phys. Chem. Math.

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Study of the CaF 2 -YF 3 system by co-precipitation from aqueous nitrate solutions revealed the formation of Ca 1−x YxF 2+x solid solution precipitate containing up to 20 mol. % yttrium fluoride (x ≤ 0.2). A higher yttrium to calcium ratio in the starting solutions caused additional precipitation of orthorhombic β-YF 3 nanophase elongated along the b axis. Cubic (H 3 O)Y 3 F 10 phase was also formed (SSG Fm3m, a = 11.60Å, KY 3 F 10 structural type).

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New phases with fluorite-derived structure in CaF2(Y, Ln)F3 systems

Cited by 50 publications

References 5 publications

The Melt of Sodium Nitrate as a Medium for the Synthesis of Fluorides

The Melt of Sodium Nitrate as a Medium for the Synthesis of Fluorides

EPR spectra and crystal field of hexamer rare-earth clusters in fluorites

Synthesis of CaF2–YF3 nanopowders by coprecipitation from aqueos solutions

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