Soft chemical synthesis of a high-pressure phase of molybdenum trioxide: MoO3-II

Baker, Bonnie E.; Feist, Thomas; McCarron, E.M.

doi:10.1016/0022-4596(95)80030-s

Cited by 28 publications

(29 citation statements)

References 9 publications

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“…The Raman spectrum observed in this work at 16.9 GPa is similar to the spectrum of the MoO 3 -II phase provided by previous workers. 22 They also reported that the phase conversion of the a-MoO 3 phase to the MoO 3 -II phase involved changes in the stacking sequence of MoO 11 O 22 O 33 layers, from aba ͑ortho͒ to aaa ͑mono͒. Our high-pressure x-ray experiments confirm such phase transition from the a-MoO 3 phase to the MoO 3 -II phase.…”

Section: A Pressure Dependence Of the Vibrational Modessupporting

confidence: 79%

“…However, the stacking sequence of the layers of MoO 3 -II ͑aaa͒ differs from that of ␣-MoO 3 ͑aba͒. 22 It is important to understand the phase transition mechanism of MoO 3 in order to promote the formation of specific metastable polymorphic forms. In a previous work on single crystal ␣-MoO 3 , Åsbrink et al 23 reported the lattice parameters of ␣-MoO 3 as a function of pressure up to 7.4 GPa at ambient temperature, but did not find any highpressure phase transition.…”

Section: Introductionmentioning

confidence: 99%

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High-pressure Raman scattering and x-ray diffraction of phase transitions in MoO3

Liu

Lei

Hao

et al. 2009

Journal of Applied Physics

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The high-pressure behavior of molybdenum trioxides ͑MoO 3 ͒ has been investigated by angle-dispersive synchrotron x-ray powder diffraction and Raman spectroscopy techniques in a diamond anvil cell up to 43 and 30 GPa, respectively. In the pressure range of up to 43 GPa, structural phase transitions from the orthorhombic ␣-MoO 3 phase ͑Pbnm͒ to the monoclinic MoO 3-II phase ͑P2 1 / m͒, and then to the monoclinic MoO 3-III phase ͑P2 1 / c͒, occurred at pressures of about 12 and 25 GPa at room temperature, respectively. Our observation of the transition from the orthorhombic ␣-MoO 3 to the monoclinic MoO 3-II phase is in disagreement with earlier studies in which the phase transition could not be obtained when only pressure is applied. The changes in the MoO distances and O-MoO and MoO -Mo angles may explain the changes in Raman spectrum. The pressure dependence of the volume of two monoclinic high-pressure phases is described by a third-order Birch-Murnaghan equation of state, which yields a bulk modulus value of B 0 = 143.41͑3͒ GPa with B 0 Ј= 12, and B 0 = 261.9͑3͒ GPa with B 0 Ј= 3.5.

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Section: A Pressure Dependence Of the Vibrational Modessupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

High-pressure Raman scattering and x-ray diffraction of phase transitions in MoO3

Liu

Lei

Hao

et al. 2009

Journal of Applied Physics

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show abstract

“…These observations suggest that a kinetically hindered transformation to the denser monoclinic polymorph might be responsible for PIA at !4 GPa. Quenching from temperatures in the range 740-825 8C and pressures above 4 GPa led to a mixture of products, including the high-temperature high-pressure form of MoO 3 [52,53]. This suggests that a kinetically hindered decomposition may be important in PIA at higher pressures.…”

Section: Introductionmentioning

confidence: 89%

Pressure-induced amorphization of cubic ZrMo2O8 studied in situ by X-ray absorption spectroscopy and diffraction

Varga

Wilkinson

Lind

et al. 2005

Solid State Communications

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“…The differences between the diffraction patterns of these phases are not very obvi ous and manifest themselves only upon the detailed analysis of the diffraction spectra. The structures of the orthorhombic and monoclinic phases of МоО 3 according to the data of [20][21][22] are compared in Fig. 10.…”

Section: Discussionmentioning

confidence: 99%

“…It appeared that these transformations might be [20][21][22]. The diffraction patterns of these two phases are rather similar; their dashed schemes are presented in the lower part of Fig.…”

Section: Ray Diffraction Analysismentioning

confidence: 90%

Defect structure of nanosized mechanically activated MoO3

et al. 2015

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Defect structure of mechanically activated MoO 3 has been studied with the use of X ray diffrac tion, Raman spectroscopy, electron paramagnetic resonance, laser granulometry, and adsorption methods. Two stages of mechanical activation have been distinguished. At mechanical activation doses below 1 kJ/g, the fracture of oxide particles is the main process. At this stage, MoO 3 particle sizes decrease from 30 μm to 60 nm and specific surface area linearly increases to 30 m 2 /g, the sizes of coherent scattering regions decrease to 18 nm, paramagnetic centers are accumulated, and the Raman spectral bands corresponding to three dif ferent types of Mo-O bonds widen and shift. At doses above 1 kJ/g, the main process consists in the friction and aggregation of particles, which is accompanied by some reduction in the specific surface area and an increase in the particle sizes. At the stage of friction, the phase transition from an orthorhombic modification to a monoclinic modification of MoO 3 occurs seemingly due to a shift of one layer of the material in plane (100). The shift is accompanied by the accumulation of lattice microstrains in the same plane, formation of "stressed" Mo-O-Mo bridge bonds, and a substantial rise in the concentration of Mo 5+ radicals. The max imum total concentration of paramagnetic centers is 1 × 10 18 g -1 . It may be assumed that the radicals are formed due to the rupture of the most stressed molybdenum-oxygen bridge bonds.

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Soft chemical synthesis of a high-pressure phase of molybdenum trioxide: MoO3-II

Cited by 28 publications

References 9 publications

High-pressure Raman scattering and x-ray diffraction of phase transitions in MoO3

High-pressure Raman scattering and x-ray diffraction of phase transitions in MoO3

Pressure-induced amorphization of cubic ZrMo2O8 studied in situ by X-ray absorption spectroscopy and diffraction

Defect structure of nanosized mechanically activated MoO3

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