Raman and Density Functional Theory Studies of Li₂Mo₄O₁₃ Structures in Crystalline and Molten States

Abstract

The LiMoO melt structure and its Raman spectral characteristics are the key for establishing the composition-structure relationship of lithium molybdate melts. In this work, Raman spectroscopy, factor group analysis, and density functional theory (DFT) were applied to investigate the structural and spectral details of the H-LiMoO crystal and a LiMoO melt. Factor group analysis shows that the crystal has 171 vibrational modes (84A + 87A), including three acoustic modes (3A), six librational modes (2A + 4A), 21 translational modes (7A + 14A), and 141 internal modes (75A + 66A). All of the A modes are Raman-active and were assigned by the DFT method. The LiMoO melt structure was deduced from the H-LiMoO crystal structure and demonstrated by the DFT method. The results show that the LiMoO melt is made up of Li ions and MoO groups, each of which is formed by four corner-sharing MoOØ/MoOØ tetrahedra (Ø = bridging oxygen). The melt has three acoustic modes (3A) and 54 optical modes (54A). All of the optical modes are Raman-active and were accurately assigned by the DFT method.

Promoting Li/MgO Catalyst with Molybdenum Oxide for Oxidative Conversion of n-Hexane

“…We also observed the formation of such species by XRD ( Figure 6). We tentatively assign the Raman bands at 289 cm −1 and 891 cm −1 to the bending and symmetric stretching modes of the terminal Mo-Ot bond in a well-defined Li2Mo4O13 phase, while other Raman bands expected for Li2Mo4O13 (160-420 cm −1 , 420-746 cm −1 , and 845-991 cm −1 ) [54] were not clearly detected. We hence suggest in catalysts with 7.1 wt % MoO3 the possible presence of Li2Mo4O13 polymolybdate species.…”

Controlling Operating Voltages in Molybdenum Oxide Anodes through Inductive Effects

“…19 Therefore, in addition to XRD, Raman spectroscopy (Figure 2) was used to carefully assess the phase purity by investigating the vibrational modes of the lattice. The Raman spectrum of the molybdenum oxide can be divided into three regions: 22 Figure 2 presents the Raman spectra of Li 2 Mo 4 O 13 , which shows multiple strong peaks in the high-frequency region from 800 to 1000 cm −1 that corresponds to Mo�O stretching modes (1001, 990, 973, 947, 921, 913, 899, and 853 cm −1 ). A large number of peaks in this regime result from the combination of multiple octahedral coordination environments.…”

“…This ternary lithium molybdenum oxide has been reported previously, 18−20 but its electrochemistry has not yet been well characterized. 21,22 Here, we prepare and characterize this compound using electrochemistry, X-ray diffraction, and UPS. UPS measurements support the hypothesis that the addition of electropositive Li to the structure pushes the Mo d-electrons closer to the vacuum level.…”

Near‐ultraviolet light–induced dazzling red emission in CaGd2(MoO4)4:2xSm3+ compounds for phosphor‐converted WLEDs

“…In general, these inorganic materials that show low phonon energies are preferable for luminescent hosts since they can efficiently decrease the ratio of nonradiative transition and boost the luminescent efficiency . Compared with other developed inorganics, the molybdates with a representative structure of scheelite are considered as potential candidates for luminescent hosts owing to their immanent optical properties (i.e., strong absorption in the ultraviolet [300‐350 nm] region originating from the O 2‒ → Mo 6+ transition) and proper phonon energy . Cao et al revealed that the Sm 3+ ‐activated LiLaMo 2 O 8 phosphors can emit visible red emission under the excitation of NUV light .…”

“…12,13 Compared with other developed inorganics, the molybdates with a representative structure of scheelite are considered as potential candidates for luminescent hosts owing to their immanent optical properties (i.e., strong absorption in the ultraviolet [300-350 nm] region originating from the O 2-→ Mo 6+ transition) and proper phonon energy. 14,15 Cao et al revealed that the Sm 3+ -activated LiLaMo 2 O 8 phosphors can emit visible red emission under the excitation of NUV light. 16 Jeong et al reported that the Sr 2 CaMoO 6 :Sm 3+ phosphor which showed potential application in WLEDs can be simultaneously excited by the NUV and blue light.…”