Concentration dependences of the unit-cell parameters of nonstoichiometric fluorite-type Na0.5 − x R 0.5 + x F2 + 2x phases (R = rare-earth elements)

Федоров, П. П.; Aleksandrov, V. B.; Бондарева, О. С.; Buchinskaya, I. I.; Val'kovskii, M. D.; Соболев, Б. П.

doi:10.1134/1.1358401

Cited by 36 publications

(20 citation statements)

References 11 publications

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“…225) is isomorphic with CaF 2 . In the NaF–MF 3 system the charge on the lanthanide ions is balanced by an appropriate number of sodium ions, and this is the case not only for the fluorite‐type structure but also for the nonstoichiometric phases with varying compositions given by Na 0.5− x M 0.5+ x F 2+2 x , where 0≤ x ≤1/7 409. Several groups investigated the doping of alkaline‐earth fluoride nanocrystals with lanthanide ions.…”

Section: Synthesis Growth and Properties Of Rare‐earth‐doped Nanmentioning

confidence: 99%

Upconverting Nanoparticles

2011

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Upconversion (UC) refers to nonlinear optical processes in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength (anti-Stokes type emission). In contrast to other emission processes based on multiphoton absorption, upconversion can be efficiently excited even at low excitation densities. The most efficient UC mechanisms are present in solid-state materials doped with rare-earth ions. The development of nanocrystal research has evoked increasing interest in the development of synthesis routes which allow the synthesis of highly efficient, small UC particles with narrow size distribution able to form transparent solutions in a wide range of solvents. Meanwhile, high-quality UC nanocrystals can be routinely synthesized and their solubility, particle size, crystallographic phase, optical properties and shape can be controlled. In recent years, these particles have been discussed as promising alternatives to organic fluorophosphors and quantum dots in the field of medical imaging.

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Section: Synthesis Growth and Properties Of Rare‐earth‐doped Nanmentioning

confidence: 99%

Upconverting Nanoparticles

2011

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“…From the bulk materials it is known that the composition of the cubic α-phase, better described by Na x REF 3+x , can be varied within 5/9 ≤ x ≤ 1 for all rare earth elements belonging to group II and group III. [48][49][50] For the case of NaGdF 4 particles we show that the sodium to gadolinium ratio of the α-phase particles determines the number of β-seeds emerging during the synthesis of the larger β-phase particles. Nearly monodisperse β-NaGdF 4 particles can therefore be prepared within a wide range of sizes when α-phase particles with controlled composition are used as precursors.…”

Section: Introductionmentioning

confidence: 98%

Size Control of Nearly Monodisperse β-NaGdF₄ Particles Prepared from Small α-NaGdF₄ Nanocrystals

2015

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NaGdF 4 nanocrystals of the hexagonal β-phase can be prepared with very narrow size distribution from small particles of the cubic α-phase of NaGdF 4 , but, until now, this method does not allow to control the final particle size. Here we show that the size of β-NaGdF 4 particles can be varied between 4 nm and more than 60 nm by using small α-phase particles with different sodium content as precursor. Heating of the 3-4 nm α-phase particles dispersed in oleic acid/octadecene solvent leads to Ostwald ripening and the formation of β-NaGdF 4 particles with narrow size distribution in all cases. The size of the β-NaGdF 4 particles increases with increasing sodium deficiency of the α-phase particles indicating that the number of β-phase seeds nucleating in the system depends on the ratio of sodium to gadolinium used in the synthesis of the α-phase material.

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“…4. According to the paper reported by Fedorov et al [16], within the homogeneity ranges of the Na 0.5 À x R 0.5 + x F 2 + 2x (R¼ Y, Pr-Lu) phases, the parameters of the cubic lattice vary linearly with change in composition (larger in high Lu/Na ratio). The data obtained in this work also indicate that lattice constants increase with the increment of Lu/Na ratio.…”

Section: Crystal Growth and X-ray Characterizationmentioning

confidence: 88%

Crystal growth and characterization of (Na Ca1−2Lu )F2 single crystals

Furuya

Tanaka

Fukuda

et al. 2011

Journal of Crystal Growth

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Concentration dependences of the unit-cell parameters of nonstoichiometric fluorite-type Na0.5 − x R 0.5 + x F2 + 2x phases (R = rare-earth elements)

Cited by 36 publications

References 11 publications

Upconverting Nanoparticles

Upconverting Nanoparticles

Size Control of Nearly Monodisperse β-NaGdF₄ Particles Prepared from Small α-NaGdF₄ Nanocrystals

Crystal growth and characterization of (Na Ca1−2Lu )F2 single crystals

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Concentration dependences of the unit-cell parameters of nonstoichiometric fluorite-type Na0.5 − x R 0.5 + x F2 + 2x phases (R = rare-earth elements)

Cited by 36 publications

References 11 publications

Upconverting Nanoparticles

Upconverting Nanoparticles

Size Control of Nearly Monodisperse β-NaGdF4 Particles Prepared from Small α-NaGdF4 Nanocrystals

Crystal growth and characterization of (Na Ca1−2Lu )F2 single crystals

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Size Control of Nearly Monodisperse β-NaGdF₄ Particles Prepared from Small α-NaGdF₄ Nanocrystals