Structural distortions in Sr3-xAxMO4F (A=Ca, Ba; M=Al, Ga, In) anti-Perovskites and corresponding changes in photoluminescence

Sullivan, Eirin; Avdeev, Maxim; Vogt, Thomas

doi:10.1016/j.jssc.2012.05.033

Cited by 20 publications

(19 citation statements)

References 24 publications

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“…Perovskites constitute a family of materials that exhibit many interesting properties and are widely used in modern chemical industry as catalysts, solid oxide fuel cell components, − solar cells and phosphors, among many other applications. Recently, there have been extensive studies on perovskites as solid electrolytes for Li-ion batteries due to their fast ionic conduction and as electrocatalysts for Li–O 2 batteries and regenerative fuel cells. − However, very limited studies on perovskites as battery electrode materials have been reported, despite the intrinsic high diffusion rate of ions in many perovskite phases.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

Chen

Cheng

et al. 2017

Chem. Mater.

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Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the nonoxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials A x K 1−x FeF 3 (A = Li, Na). By starting with KFeF 3 , approximately 75% of K + ions were subsequently replaced by Li + and Na + through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe 2+/3+ redox couple. A computational study by density functional theory showed agreement with the structural and electrochemical data obtained experimentally, which suggested the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.

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Section: Introductionmentioning

confidence: 99%

Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

Chen

Cheng

et al. 2017

Chem. Mater.

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“…). , The calculated G values for Ba 2 SrGaO 4 F (air) and Ba 2 SrGaO 4 F (r) are consistent with the increased substitution of Ba 2+ into the Sr 3– x A x AlO 4 F ( x ≤ 1) and Sr 3– x A x GaO 4 F ( x ≤ 1.2) host in our earlier work, whereby G decreases to a value lower than 0.2 v.u. While this structure is considered to be strained based on G , it still possesses the ability to accommodate isovalent and aliovalent substitutions of larger ions at the A(1), A(2), and M sites via tilting in alternating layers about the c -axis allowing for the overall stability to be maintained. , …”

Section: Resultsmentioning

confidence: 99%

Structural and Photoluminescence Characterization of Oxyfluorides for Phosphor Applications

Green

2023

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Rare-earth-containing phosphors were crucial to the advances made to compact fluorescent lamps (CFLs), which assisted in protecting a widely used halophosphate phosphor from degrading after exposure to a high ultraviolet flux. The CFL phosphors are often coated twice by depositing a light coat of rareearth-containing phosphors over the inexpensive halophosphate phosphor, which generates white light with high efficacy and a good color rendering index and possesses a balance between phosphor cost and performance. Costs of phosphors can be mitigated by requiring lower rare-earth ion concentrations or by completely eliminating rare-earth ions, which was one of the main goals of investigating the oxyfluorides Sr 3 AlO 4 F and Ba 2 SrGaO 4 F as potential phosphors. Changes in the Sr 3 AlO 4 F and Ba 2 SrGaO 4 F structures were studied using high-resolution neutron diffraction annealing these materials in 5%H 2 /95%Ar and 4%H 2 /96% Ar, respectively. Annealing in these atmospheres causes self-activated photoluminescence (PL) to occur under 254 nm light, which makes them ideal materials for rare-earth-free CFL phosphors. Additionally, these hosts possess two distinct sites for isovalent or aliovalent substitution of Sr denoted as the A(1) and A(2) sites. Ga 3+ can be substituted for Al 3+ at the M site, which is known to have an impact on the self-activated PL emission color. The structural distortions noted included closer packing in the FSr 6 octahedrons and AlO 4 tetrahedrons in the Sr 3 AlO 4 F structure as compared to in air-annealed samples, which show no PL emission. Temperature-dependent studies reveal that both the air-and reductively annealed samples have identical thermal expansion within this temperature range (3−350 K). High-resolution neutron diffraction at room temperature confirmed the tetragonal structure (I4/ mcm) for Ba 2 SrGaO 4 F, a novel material in the Sr 3 AlO 4 F family of materials, has been synthesized via a solid-state method. Analysis of the refined Ba 2 SrGaO 4 F structure at room temperature revealed expansion in the lattice parameters and its polyhedral subunits between the reductively annealed and air-annealed samples, which are correlated with the PL emission. Previous studies related to the application of these host structure types revealed that they have potential as commercial solid-state lighting phosphors due to their ability to resist thermal quenching as well as accommodate various levels of substitutions that will assist with color tunability.

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“…The global instability factor for both Na 3 Mo 0.5 W 0.5 O 4 F and Na 3 MoO 4 F was 0.15 vu which falls into the range categorized as indicative for the presence of strain (0.1-0.2 vu [32,33]). This is in line with the observation that polycrystalline samples of Na 3 W 1 À x Mo x O 4 F consistently decomposed to spinel Na 2 WO 4 /Na 2 MoO 4 and NaF during the course of this study.…”

Section: Neutron Powder Diffractionmentioning

confidence: 86%

“…These are summarized in Table 8. The global instability factor calculated from these data was 0.09 vu, which is at the borderline between a strained and unstrained structure (G o 0.1 vu) [32,33]. As the evidence for strain was less clear-cut from the single crystal data for Na 3 WO 4 F than the NPD data for Na 3 Mo 0.5 W 0.5 O 4 F and Na 3 MoO 4 F, this raised the question of whether strain only arose from the incorporation of Mo 6 þ on the W 6 þ or whether the strain was indeed present in all Na 3 W 1 À x Mo x O 4 F (x ¼0, 0.25, 0.5, 0.75, 1) materials and only elucidated by the superior unit cell parameters and atom positions obtained from powder diffraction studies.…”

Section: Single Crystal X-ray Diffractionmentioning

confidence: 97%

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Structure, stability, and photoluminescence in the anti-perovskites Na3W1−Mo O4F (0≤x≤1)

Sullivan

Avdeev

Blom

et al. 2015

Journal of Solid State Chemistry

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a b s t r a c tSingle-phase ordered oxyfluorides Na 3 WO 4 F, Na 3 MoO 4 F and their mixed members Na 3 W 1 À x Mo x O 4 F can be prepared via facile solid state reaction of Na 2 MO 4 Á 2H 2 O (M¼ W, Mo) and NaF. Phases produced from incongruent melts are metastable, but lower temperatures allow for a facile one-step synthesis. In polycrystalline samples of Na 3 W 1 À x Mo x O 4 F, the presence of Mo stabilizes the structure against decomposition to spinel phases. Photoluminescence studies show that upon excitation with λ¼254 nm and λ¼365 nm, Na 3 WO 4 F and Na 3 MoO 4 F exhibit broad emission maxima centered around 485 nm. These materials constitute new members of the family of self-activating ordered oxyfluoride phosphors with anti-perovskite structures which are amenable to doping with emitters such as Eu 3 þ .

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Structural distortions in Sr3-xAxMO4F (A=Ca, Ba; M=Al, Ga, In) anti-Perovskites and corresponding changes in photoluminescence

Cited by 20 publications

References 24 publications

Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

Structural and Photoluminescence Characterization of Oxyfluorides for Phosphor Applications

Structure, stability, and photoluminescence in the anti-perovskites Na3W1−Mo O4F (0≤x≤1)

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