Crystallochemical Studies in the Family of Crystals Ba7−xNayF12Cl2−zBrz (x &lt; 0.1, y &lt; 0.2, z &lt; 1.5)

Hagemann, Hans‐Rudolf; Penhouet, Tiphaine; Rief, Andreas; Kübel, Frank

doi:10.1002/zaac.200700594

Cited by 4 publications

(11 citation statements)

References 12 publications

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“…18,19 Note however that in the presence of additional metal impurities (Ca, Na) there is a disordered modification of Ba 6.33 Ca 0.67 F 12 Cl 2(1−x) Br 2x with the value of x ranging from 0 to 1. 20 The compound BaFCl forms further solid solutions with SrFCl and SrFBr (refs 17 and 21 and references therein).…”

Section: ■ Crystallographic Datamentioning

confidence: 99%

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Crystal Chemistry in the Barium Fluoride Chloride System

Hagemann

D’Anna

Daku

et al. 2012

Crystal Growth & Design

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The crystal chemistry of the barium fluoride chloride system is studied both experimentally and theoretically. Different synthetic approaches yield nanocrystalline materials as well as large single crystals. The crystalline phases identified so far are BaFCl, Ba12F19Cl5 and Ba7F12Cl2 (in two modifications) and compared with analogous compounds. It is demonstrated that the compound Ba2F3Cl reported by Fessenden and Lewin 50 years ago corresponds to Ba7F12Cl2. The phase diagram of the BaCl2 – BaF2 system is reinvestigated for fluoride mole fractions between 0.5 and 1. The peritectic formation of Ba12F19Cl5 is observed. Periodic DFT calculations are performed for all structures in this system, including a hypothetical structure for Ba2F3Cl, based on the experimental structure of Ba2H3Cl. The energy of formation of the different barium fluoride chloride compounds from BaCl2 and BaF2 (normalized for one barium atom per formula unit), as calculated by DFT at 0K, is within only about ± 15 kJ/mol. Comparison with recent experimental results on calcium and strontium hydride chloride (bromide) compounds, suggest the possibility of a mutual exclusion between the M2X3Y and M7X12Y2 (M = Ca, Sr, Ba, Pb, X = H, F, Y = Cl,Br) structures. The single crystal structure of PbFBr is also reported

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Section: ■ Crystallographic Datamentioning

confidence: 99%

“…However, using alkali chloride-bromide as flux, partially mixed Ba 7 F 12 Cl 2−x Br x has been obtained. 19 Thermal Analysis and X-ray Study. Figure 4 shows the first derivative of the DTA cooling traces.…”

Section: Crystal Growth and Designmentioning

confidence: 99%

Crystal Chemistry in the Barium Fluoride Chloride System

Hagemann

D’Anna

Daku

et al. 2012

Crystal Growth & Design

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“…[14] The channel-type structure allows the replacement of Ba 2 + and Cl À with other ions and interstitial sites can be occupied. [15] Detailed order/ disorder studies on single crystals of substituted Ba 7 F 12 Cl 2 are still in progress. Nanocrystalline barium fluoride chloride samples might reveal further interesting optical properties.…”

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“…Ba 7 F 12 Cl 2 is a host for the rare‐earth element Eu II [13] and acts as an intense white phosphor 14. The channel‐type structure allows the replacement of Ba 2+ and Cl − with other ions and interstitial sites can be occupied 15. Detailed order/disorder studies on single crystals of substituted Ba 7 F 12 Cl 2 are still in progress.…”

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Comment on: “Nucleation and Growth of BaF_xCl_2−x Nanorods”

Kübel

Hagemann

2010

Chemistry A European J

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“…The disordered modification is stabilized by the presence of small amounts of Na . The crystal structure can further be modulated (Figure S3) by chemical substitutions for instance when partially replacing Ba by Ca and Cl by Br. − Several methods are available to obtain these Ba 7– x M y F 12 Cl 2– z Br z compounds (M = Na, Ca, Eu) with x , y ≤ 1, 0 ≤ z ≤ 2, − such as direct solid state reaction of the two binaries BaF 2 , BaCl 2 , or flux dissolution of BaF 2 in alkali fluorides/chlorides. This latter method allows to obtain needle-shaped single crystals.…”

Section: Introductionmentioning

confidence: 99%

Europium-Doped Ba₇F₁₂Cl₂, a Single Component Near-UV Excited Tunable White Phosphor

et al. 2014

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Europium-doped crystalline Ba7F12Cl2 phosphors have been prepared at temperatures between 650 and 900 °C using alkali chloride fluxes, yielding both disordered (with the incorporation of small amounts of Na) and ordered crystal modifications. The white emission spectrum excited in the near UV consists roughly of two broad emission bands at about 450 and 590 nm, as well as weak sharp Eu2+ 4f–4f emission bands around 360 nm. The incorporation of Eu2+ is further studied using EPR spectroscopy on single crystals and reveals a significant zero field splitting. The emission spectrum can be significantly tuned by varying the excitation wavelength between 300 and 390 nm. Fine tuning may also be achieved by chemical substitutions to form Ba7–x M y F12Cl2–z Br z (M = Na, Ca, Eu). Quantitative measurements of the light produced using commercial near UV LEDs show that the color temperature ranges between 4000 and 9700 K with CIE chromaticity coordinates close to the ideal values of x = y = 0.333. The best color rendering index (CRI) found was 0.83 and the highest light to light conversion yield was 171 lm/W. These results show that the title compound is a very promising candidate for white light generation using near UV LED excitation.

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Crystallochemical Studies in the Family of Crystals Ba_7−xNa_yF₁₂Cl_2−zBr_z (x < 0.1, y < 0.2, z < 1.5)

Cited by 4 publications

References 12 publications

Crystal Chemistry in the Barium Fluoride Chloride System

Crystal Chemistry in the Barium Fluoride Chloride System

Comment on: “Nucleation and Growth of BaF_xCl_2−x Nanorods”

Europium-Doped Ba₇F₁₂Cl₂, a Single Component Near-UV Excited Tunable White Phosphor

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Crystallochemical Studies in the Family of Crystals Ba7−xNayF12Cl2−zBrz (x < 0.1, y < 0.2, z < 1.5)

Cited by 4 publications

References 12 publications

Crystal Chemistry in the Barium Fluoride Chloride System

Crystal Chemistry in the Barium Fluoride Chloride System

Comment on: “Nucleation and Growth of BaFxCl2−x Nanorods”

Europium-Doped Ba7F12Cl2, a Single Component Near-UV Excited Tunable White Phosphor

Contact Info

Product

Resources

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Crystallochemical Studies in the Family of Crystals Ba_7−xNa_yF₁₂Cl_2−zBr_z (x < 0.1, y < 0.2, z < 1.5)

Comment on: “Nucleation and Growth of BaF_xCl_2−x Nanorods”

Europium-Doped Ba₇F₁₂Cl₂, a Single Component Near-UV Excited Tunable White Phosphor