Raman spectroscopic study of the lattice dynamics in the Rb2KMoO3F3 oxyfluoride

Крылов, А. С.; Merkushova, E. M.; Vtyurin, A. N.; Исаенко, Л. И.

doi:10.1134/s1063783412060170

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…Similarly, fac configurations are favored over mer for [MO 3 F 3 ] n − anionic groups. These observations have been independently confirmed by electron scattering, nuclear magnetic resonance, and vibrational spectroscopy experiments as well as computationally. ,− The preference for cis and fac configurations can be violated if non-d 0 transition metals cations are incorporated into the structure; for example, trans configurations have been reported in iodine oxyfluoride salts …”

Section: Introductionmentioning

confidence: 81%

Structural Diversity from Anion Order in Heteroanionic Materials

2018

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Heteroanionic materials leverage the advantages offered by two different anions coordinating the same or different cations to realize unanticipated or enhanced electronic, optical, and magnetic responses. Beyond chemical variations offered by the anions, the ability to control the anion order present within a single transition metal polyhedron via anion-sublattice engineering offers a potentially transformative strategy in tuning material properties. The set of design rules for realizing and controlling anion order, however, are incomplete, which is due in part to the limited anion-ordered diversity in known structures. This aspect makes formulating such principles from experiment alone challenging. Here, we demonstrate how computational methods at multiple levels of theory are effective at investigating the anion site order dependencies in heteroanionic materials, HAMs, and enable the construction of crystal-chemistry principles. Our approach relies on a database of anion ordered structure variants in which we manipulate the lattice degrees of freedom through the incorporation of structural distortions. Structure–property relationships and anion-order descriptors are data mined from group theoretical techniques and density functional theory calculations. Using our combined computational scheme, we uncover a hybrid improper mechanism to stabilize polar phases, propose the chemical link between local and long ranger anion order, and detail the sequence of order–disorder/displacive transitions observed experimentally in the oxyfluoride Na3MoO3F3. Our method is scalable and transferable to many heteroanionic chemistries and crystal families, facilitating the construction of heteroanionic materials design principles.

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Section: Introductionmentioning

confidence: 81%

Structural Diversity from Anion Order in Heteroanionic Materials

2018

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“…Thus, a set of phase transitions governed by the step-by-step anion ordering process is typically observed with the change of temperature, and highly ordered derivatives have been found in many oxyfluorides at low temperatures. ,,− On the other hand, oxyfluorides are commonly synthesized in powder forms only because of great technological difficulties. Up to now, the millimeter-sized single crystals have been grown for only very few oxyfluorides, by which the measurements on the optical and electronic properties in crystals can be fulfilled at high accuracy. − …”

Section: Introductionmentioning

confidence: 99%

Structural, Spectroscopic, and Electronic Properties of Cubic G0-Rb₂KTiOF₅ Oxyfluoride

Atuchin¹,

Исаенко²,

Kesler

et al. 2013

J. Phys. Chem. C

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The G0-Rb 2 KTiOF 5 single crystals with dimensions up to nearly a centimeter in size have been prepared by slow solidification method. The elpasolite-related crystal structure of G0-Rb 2 KTiOF 5 has been refined by Rietveld method at T = 298 K (space group Fm3̅ m, Z = 4, a = 8.880(1) Å, V = 700.16(2) Å 3 ; R B = 2.66%). The wide optical transparency range of 0.25−9 μm and forbidden band gap of E g = 3.87 eV have been obtained for the G0-Rb 2 KTiOF 5 crystal. Dominating photoluminescence bands at 3.36 and 2.33 eV are related to free and self-trapped excitons, respectively. The electronic structure of G0-Rb 2 KTiOF 5 has been evaluated by X-ray photoelectron spectroscopy and calculated with the first-principles methods. A good agreement between theoretical and experimental results has been achieved. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and a wide comparison with related oxides and fluorides. The competition between O 2− and F − ions for metal valence electrons has been found.

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“…The uncertainty of the measured temperature for a given rate can be estimated as a difference between adjacent measurements and it was ±0.12 K in one spectrum measurement. Overall time for a single spectrum accumulation was within 30 s. The spectra were acquired with a temperature step 0.25 K. This measurement protocol was the same as described in [13,14]. The temperature evolution of the Raman spectra in the temperature range of 8−296 K is presented in Fig.…”

Section: Methodsmentioning

confidence: 99%

Soft mode mechanism of the transition into the low-temperature ferroelastic phase in K-=SUB=-3-=/SUB=-Na(CrO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- crystals

Kitaev

Крылов

Maksimova

2016

Физика Твердого Тела

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The sequence of phase transitions P3m1 → C2/m → C2/c in K 3 Na(CrO 4) 2 crystals and existence of the intermediate phase have been studied both experimentally by the Raman scattering method and theoretically by programs and retrieval tools of the Bilbao Crystallographic Server. A zone-edge soft mode responsible for a transition from the intermediate C2/m to a low-symmetry C2/c phase at T = 210 K has been discovered experimentally for the first time. The symmetry of the soft mode has been established theoretically to be A + 2. The temperature interval of the intermediate monoclinic phase has been determined to be 239−210 K.

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Raman spectroscopic study of the lattice dynamics in the Rb2KMoO3F3 oxyfluoride

Cited by 11 publications

References 24 publications

Structural Diversity from Anion Order in Heteroanionic Materials

Structural Diversity from Anion Order in Heteroanionic Materials

Structural, Spectroscopic, and Electronic Properties of Cubic G0-Rb₂KTiOF₅ Oxyfluoride

Soft mode mechanism of the transition into the low-temperature ferroelastic phase in K-=SUB=-3-=/SUB=-Na(CrO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- crystals

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Raman spectroscopic study of the lattice dynamics in the Rb2KMoO3F3 oxyfluoride

Cited by 11 publications

References 24 publications

Structural Diversity from Anion Order in Heteroanionic Materials

Structural Diversity from Anion Order in Heteroanionic Materials

Structural, Spectroscopic, and Electronic Properties of Cubic G0-Rb2KTiOF5 Oxyfluoride

Soft mode mechanism of the transition into the low-temperature ferroelastic phase in K-=SUB=-3-=/SUB=-Na(CrO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- crystals

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Structural, Spectroscopic, and Electronic Properties of Cubic G0-Rb₂KTiOF₅ Oxyfluoride