Hydrogen in amorphous and crystalline ytterbium films

Kuz'menko, V.M.; Vladychkin, A. N.

doi:10.1134/1.1130747

Cited by 9 publications

(3 citation statements)

References 9 publications

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“…These values are similar across the entire temperature range covered. A wide range of electron mean free paths in amorphous metallic films were reported in the literature, ranging from 3 nm in Co 94 Zr 6 films (at 300 K, with p = 0) to 18–30 nm in Y films (at 4.2 K, determined using another model) through 10–13 nm in Pt films (at 300 K, with p varying from 0.13 to 0.15). Based on these reported values, the large mean free paths obtained herein for higher p values, up to λ e = 240 nm for p = 0.9, are unrealistic.…”

Section: Resultsmentioning

confidence: 99%

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films

et al. 2020

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We report a detailed experimental investigation of the influence of the formation of nanocrystallites on the vibrational, electronic and optical properties of CrSi 2 thin films. Both amorphous and nanostructured thin films were investigated by means of electrical resistivity, Hall effect measurements as well as Raman and infrared spectroscopies. We show that both types of films exhibit a semiconducting-like behavior, with the notable difference that the high defect concentrations in amorphous films act as hole donors, modifying the electronic band structure and optical constants. The effect of the film thickness on electrical properties is well captured by the Fuchs-Sondheimer model indicating a decrease in the charge carrier mean free path, likely due to the formation of amorphous/nano-crystallite interfaces that contribute to strongly scatter the charge carriers. Raman spectroscopy performed on nano-crystallized thin films evidences the presence of a Raman-active mode at 229 cm -1 and confirms DFT calculations predicting a mode at 248 cm -1 , the observation of which had remained elusive so far in polycrystalline CrSi 2 . Measurements of the refractive index and dielectric constants of amorphous thin films show a very high refractive index in the mid-IR range. Our results illustrate how the controlled growth of nano-crystallites can be used to tailor the electronic, vibrational and optical properties of amorphous thin films.

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Section: Resultsmentioning

confidence: 99%

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films

et al. 2020

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“…38 Indeed, orthorhombic YbH 2 has been detected as a thin film at room temperature, 39 which is the form that may well prevail on the activated Yb-Pd/SiO 2 catalyst. It has been shown 40 that the hydrogen associated with Yb-H films is highly mobile, with hydrogen release at elevated temperatures. The presence of this additional source of reactive hydrogen in Yb-Pd/SiO 2 may be the predominant source of the observed superior dechlorination activity.…”

Section: Resultsmentioning

confidence: 99%

Gas‐phase hydrodechlorination of chlorobenzenes over silica‐supported palladium and palladium–ytterbium

Jujjuri

Ding

Shore

et al. 2003

Applied Organom Chemis

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A 5% w/w palladium loading on silica has been achieved via impregnation of the support with Pd(C 2 H 3 O 2 ) 2 and {(DMF) 10 Yb 2 [Pd(CN) 4 ] 3 } ∞ precursors to deliver monometallic (Pd/SiO 2 ) and bimetallic (Yb-Pd/SiO 2 ) catalyst systems respectively. The catalytic action of each has been assessed in the continuous gas-phase hydrodechlorination (HDC) of chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB) (T = 423 K, inlet chlorine/palladium mol ratio of 5 × 10 3 h −1 ) and the hydrogenation of benzene (T = 423 K, inlet C 6 H 6 /palladium mol ratio of 35 h −1 ). Activation of both catalysts delivered similar palladium crystallite size distributions with an average palladium diameter of 5-6 nm where the ytterbium component (in Yb-Pd/SiO 2 ) was present as a thin surface coating. The Pd-Yb bimetallic exhibited significantly higher HDC and hydrogenation activities, the former manifested by significantly greater fractional dechlorinations and benzene selectivities/yields. Yb/SiO 2 proved inactive in terms of promoting hydrogen scission or addition and the promotional effect of ytterbium in Yb-Pd/SiO 2 is discussed in terms of electron donation and hydrogen transfer via surface YbH 2 . Under identical reaction conditions, a lower HDC activity was recorded for 1,2-DCB compared with CB, a response that is attributed to steric constraints allied to the deactivating effect of the second chlorine substituent. Both Pd/SiO 2 and Yb-Pd/SiO 2 exhibited a decline in HDC activity with timeon-stream, but the bimetallic was significantly more resistant to deactivation.

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“…The promotion of catalysis may also be due to the formation of YbH 2 which is generated at room temperature and atmospheric pressure [16,17]. It has been shown that the hydrogen associated with lanthanide hydrides is highly mobile, with a ready hydrogen release at elevated temperatures [18][19][20]. The presence of this additional Table 1 Benzene yield (Y benzene ) at selected times-on-stream resulting from the hydrodechlorination of chlorobenzene and 1,2-dichlorobenzene over Pd/SiO 2 (prepared from Pd(C 2 H 3 O 2 ) 2 ) and Yb-Pd/SiO 2 : inlet Cl/Pd mol ratio = 5 × 10 3 source of reactive hydrogen in Yb-Pd/SiO 2 may be the predominant source of the observed superior hydrogen mediated catalyst performance.…”

Section: Hydrodechlorination Of Chlorobenzenesmentioning

confidence: 99%

Extended lanthanide–transition metal arrays with cyanide bridges: syntheses, structures, and catalytic applications

Liu

Poplaukhin

Ding

et al. 2006

Journal of Alloys and Compounds

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Hydrogen in amorphous and crystalline ytterbium films

Cited by 9 publications

References 9 publications

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films

Gas‐phase hydrodechlorination of chlorobenzenes over silica‐supported palladium and palladium–ytterbium

Extended lanthanide–transition metal arrays with cyanide bridges: syntheses, structures, and catalytic applications

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Hydrogen in amorphous and crystalline ytterbium films

Cited by 9 publications

References 9 publications

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi2 Thin Films

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi2 Thin Films

Gas‐phase hydrodechlorination of chlorobenzenes over silica‐supported palladium and palladium–ytterbium

Extended lanthanide–transition metal arrays with cyanide bridges: syntheses, structures, and catalytic applications

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Product

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Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films

Influence of Nanostructuration on the Vibrational, Electronic, and Optical Properties of CrSi₂ Thin Films