Phase relationships in the system HxMoO3 (0&lt;x⩽2.0)

Birtill, J.J.; Dickens, Peter

doi:10.1016/0025-5408(78)90008-9

Cited by 146 publications

(72 citation statements)

References 7 publications

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“…Chains of MoO 6 octahedrons are fused together by edge sharing to form corrugated layers. The intercalation of hydrogen into MoO 3 does not markedly modify the structural motif apart from slight increase of the cell volume, lattice distortion and hydrogen ordering121314. As already suggested by the vicinity of hydrogens to oxygen, water is formed at higher concentrations.…”

Section: Figurementioning

confidence: 54%

“…The phase transformation causes only small crystallographic rearrangements (topotactic reduction): hydrogen atoms occupy sites in the van der Waals gaps between double layers of MoO 6 octahedra as well as intralayer sites on zigzag chains along the channels1213. This results in a relatively small increase of the cell volume and slight distortion of the lattice changing the overall crystal symmetry from orthorhombic orthorhombic (phase I) to monoclinic (phases II, IV)1214. Although lattice distortion and hydrogen ordering increase the complexity of the system12, the electronic structure may be described using the semiconductor model with hydrogen as dopant (Fig.…”

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confidence: 99%

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Hydrogen reduction of molybdenum oxide at room temperature

Borgschulte

Sambalova

Delmelle

et al. 2017

Sci Rep

160

156

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The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

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Section: Figurementioning

confidence: 54%

mentioning

confidence: 99%

Hydrogen reduction of molybdenum oxide at room temperature

Borgschulte

Sambalova

Delmelle

et al. 2017

Sci Rep

160

156

View full text Add to dashboard Cite

show abstract

“…Virgin and colored MoO 3 films have also been widely characterized by some physical techniques, such as AES [137], AFM [129,148], ESR [6,7,131,[149][150][151][152], FT-IR absorption spectra [132,142,148], SAXS [38], XPS [33,35,36,133,135,148,153], XRD [7,126,137,140,142,148,[154][155][156][157], electrical characterization [6,138,139,149,158], electron diffraction [6,7,137], energy dispersive spectrometer (EDS) [137], neutron diffraction and scattering [155], Raman spectroscopy [53,[159][160][161], scanning electron microscopy (SEM) [38,126,…”

Section: Photochromic Behavior and Mechanismmentioning

confidence: 99%

Photochromism in transition-metal oxides

He¹,

Yao²

2004

Res. Chem. Intermed.

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Transition-metal oxides -including tungsten oxide, molybdenum oxide, titanium dioxide, vanadium pentoxide, niobium pentoxide and zinc oxide -exhibit photochromism upon bandgap excitation. These oxides constitute an important group of inorganic chromogenic materials, which is of great significance in the perspective of science and technology. During the past several decades, great progresses have been made in the microstructure, photochromic behavior and mechanism of these oxides, specifically of tungsten oxide. These studies underscore the opportunity of using these materials in photonic applications. The details will be presented in this review.

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“…These phases are low-dimensional mixed conductors displaying a wide range of colors and properties [215][216][217]. Every one of the four stable phases-I (x%0.33), II (x%1), III (x%1.66), and IV (x%2)-exhibits a different type of superstructure.…”

Section: Molybdenum and Tungsten Oxides And Bronzesmentioning

confidence: 99%