scholarly journals Moisture Induced Degradation of Porous Low-k Materials

2006 ◽  
Vol 914 ◽  
Author(s):  
Mikhail Baklanov ◽  
David O'Dwyer ◽  
Adam M Urbanowicz ◽  
Quoc Toan Le ◽  
Steven Demuynck ◽  
...  
Keyword(s):  
Water Film ◽  
Internal Surface ◽  
Hydrophobic Surface ◽  
Adsorbed Water ◽  
Bulk Water ◽  
Oh Groups ◽  
Film Bulk ◽  
Low K

AbstractInteraction of moisture with porous low-k films is evaluated by using in situ ellipsometry setup. The adsorbed water amount is calculated from change of refractive index measured during the adsorption. Pristine low-k films reversibly adsorb 2 - 5% of water that reflects presence of constitutive hydrophilic centrums. Plasma and thermal treatments increase the number of hydrophilic centrums. Once the amount of these centrums has reached a certain critical value sufficient to form a continuous water film, bulk water condensation is observed. Change of properties during the water adsorption in the damaged films is not fully reversible. Each additional adsorption cycle increases the dielectric function of the film because of decreasing porosity, increasing skeleton density and shrinkage. The pressure corresponding to the bulk condensation allows us to calculate internal contact angle (internal surface energy) of low-k materials. The water molecules adsorbed on separate OH groups play the role of a catalyst that hydrolyses the siloxane bridges initially present on hydrophobic surface.

scholarly journals In situ formation of ZnOx species for efficient propane dehydrogenation

Nature ◽  
2021 ◽  
Vol 599 (7884) ◽  
pp. 234-238
Author(s):  
Dan Zhao ◽  
Xinxin Tian ◽  
Dmitry E. Doronkin ◽  
Shanlei Han ◽  
Vita A. Kondratenko ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Supported Catalysts ◽  
Decisive Role ◽  
Propane Dehydrogenation ◽  
Propane Conversion ◽  
Characterization Methods ◽  
Oh Groups ◽  
Reductive Treatment

AbstractPropane dehydrogenation (PDH) to propene is an important alternative to oil-based cracking processes, to produce this industrially important platform chemical1,2. The commercial PDH technologies utilizing Cr-containing (refs. 3,4) or Pt-containing (refs. 5–8) catalysts suffer from the toxicity of Cr(vi) compounds or the need to use ecologically harmful chlorine for catalyst regeneration9. Here, we introduce a method for preparation of environmentally compatible supported catalysts based on commercial ZnO. This metal oxide and a support (zeolite or common metal oxide) are used as a physical mixture or in the form of two layers with ZnO as the upstream layer. Supported ZnOx species are in situ formed through a reaction of support OH groups with Zn atoms generated from ZnO upon reductive treatment above 550 °C. Using different complementary characterization methods, we identify the decisive role of defective OH groups for the formation of active ZnOx species. For benchmarking purposes, the developed ZnO–silicalite-1 and an analogue of commercial K–CrOx/Al2O3 were tested in the same setup under industrially relevant conditions at close propane conversion over about 400 h on propane stream. The developed catalyst reveals about three times higher propene productivity at similar propene selectivity.

Control of capillary hydraulic conductivity via membrane potential-dependent changes in Ca2+ influx

1992 ◽  
Vol 262 (1) ◽  
pp. H144-H148 ◽  
Author(s):  
R. S. Zhang ◽  
V. H. Huxley
Keyword(s):  
Membrane Potential ◽  
Repeated Measures ◽  
Chloride Concentration ◽  
Barrier Properties ◽  
Extracellular Potassium ◽  
High K ◽  
Important Regulator ◽  
Low K

Capillary permeability has been shown to be sensitive to the levels of intracellular calcium. We examined the role of membrane potential in the regulation of capillary water permeability by a Ca2+ leak mechanism. Repeated measures of Lp were taken in situ on individually perfused mesenteric capillaries of cerebrally pithed frogs (Rana pipiens). A rise in extracellular potassium ([K+]o) to 24 mM induced a 45% decrease in Lp (n = 20), whereas lowering [K+]o to 0.24 mM elevated Lp by twofold (n = 9). To investigate whether these changes in Lp were due specifically to changes in membrane potential and consequent changes in the driving force for Ca2+ influx, we performed the following experiments: 1) [K+]o was elevated while the product of [K+]o and extracellular chloride concentration [Cl-]o was kept constant, 2) [K+]o was elevated under nominally Ca(2+)-free conditions, 3) K+ leak was induced by addition of 10 microM valinomycin, and 4) Na(+)-K+ pump was blocked by 10 microM ouabain. A constant [K+]o [Cl-]o product did not prevent high K+ from lowering Lp. Nominally Ca(2+)-free conditions abolished the effect of high K+. Valinomycin mimicked the response to low K+, and ouabain failed to change Lp. The data from this study conform to the hypothesis that membrane potential is an important regulator of capillary barrier properties via changes in Ca2+ influx through leak channels.

The influence of water in the synthesis of Zr-based metal-organic framework UiO-66: isolation and reactivity of the new species [ZrCl(OH)2(DMF)2]Cl

2020 ◽  
Author(s):  
Marco Taddei ◽  
Jeroen A. van Bokhoven ◽  
Marco Ranocchiari
Keyword(s):  
Crystallite Size ◽  
Aging Process ◽  
Metal Organic Framework ◽  
Aging Effect ◽  
Oh Groups ◽  
Influence Of Water ◽  
Metal Organic ◽  
Organic Framework

We recently discovered that aging a solution of zirconium(IV) tetrachloride (ZrCl<sub>4</sub>) in N,N-dimethylformamide (DMF) in the presence of water, followed by addition of terephthalic acid linker, reduces the crystallite size of the metal-organic framework UiO-66 [<i>Chem. Commun.</i> <b>2016</b>, <i>52</i>, 6411-6414]. In an effort to shed light into the nature of the aging effect and on its relationship with the crystallite size of UiO-66, we report here the isolation and structural characterization of a microcrystalline zirconium-based compound of formula [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl, which is formed during the aging process. The Zr(IV) ions are coordinated by hydroxide, DMF and chloride to produce a one-dimensional polymer. Thanks to the presence of two –OH groups per zirconium atom, [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl is a suitable precursor for the synthesis of UiO-66 in dry DMF, affording a product having smaller crystallite size than that obtained from a reaction mixture having the same chemical composition, but using ZrCl<sub>4</sub> as the Zr(IV) source. By starting from ZrCl<sub>4</sub> and generating [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in situ in solution through aging, we obtained smaller crystallites as the aging time increased, proving that [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl plays a role in the aging process. The possible role of [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in the crystallization mechanism of UiO-66 is also discussed, with emphasis on its relationship with the amount of water in the reaction mixture.<br>

Behaviour of CoNaA zeolites in interaction with water

1980 ◽  
Vol 45 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Blanka Wichterlová ◽  
Ludmila Kubelková ◽  
Pavel Jírů
Keyword(s):  
Catalytic Activity ◽  
Infrared Spectroscopy ◽  
Adsorbed Water ◽  
The State ◽  
Molecular Water ◽  
Oh Groups ◽  
Adsorption Of Water ◽  
Stretching Vibrations

The influence of dehydration and adsorption of water on the coordination of cations, the state of adsorbed water, and stretching vibrations of CoNaA and NaA zeolites was investigated by means of electronic and infrared spectroscopy. Complexes of Co2+ change their symmetry from octahedral through tetrahedral to planar trigonal. The role of ligands play both skeletal oxygens and molecular water. The formation of OH groups either on skeleton or on Co2+ ions was not found; the existence of these groups was assumed in the literature to explain the catalytic activity of CoNaA zeolites in the isomerization of butenes.

scholarly journals Intermediates in the Synthesis of Zr-Based Metal-Organic Framework UiO-66

2019 ◽  
Author(s):  
Marco Taddei ◽  
Jeroen A. van Bokhoven ◽  
Marco Ranocchiari
Keyword(s):  
Crystallite Size ◽  
Aging Process ◽  
Metal Organic Framework ◽  
Aging Effect ◽  
Oh Groups ◽  
Metal Organic ◽  
Organic Framework

We recently discovered that aging a solution of zirconium(IV) tetrachloride (ZrCl<sub>4</sub>) in N,N-dimethylformamide (DMF) in the presence of water, followed by addition of terephthalic acid linker, reduces the crystallite size of the metal-organic framework UiO-66 [<i>Chem. Commun.</i> <b>2016</b>, <i>52</i>, 6411-6414]. In an effort to shed light into the nature of the aging effect and on its relationship with the crystallite size of UiO-66, we report here the isolation and structural characterization of a microcrystalline zirconium-based compound of formula [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl, which is formed during the aging process. The Zr(IV) ions are coordinated by hydroxide, DMF and chloride to produce a one-dimensional polymer. Thanks to the presence of two –OH groups per zirconium atom, [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl is a suitable precursor for the synthesis of UiO-66 in dry DMF, affording a product having smaller crystallite size than that obtained from a reaction mixture having the same chemical composition, but using ZrCl<sub>4</sub> as the Zr(IV) source. By starting from ZrCl<sub>4</sub> and generating [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in situ in solution through aging, we obtained smaller crystallites as the aging time increased, proving that [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl plays a role in the aging process. The possible role of [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in the crystallization mechanism of UiO-66 is also discussed.<br>

ELECTRON SCATTERING IN BURIED InGaAs/HIGH-K MOS CHANNELS

2011 ◽  
Vol 20 (01) ◽  
pp. 95-103 ◽  
Author(s):  
S. OKTYABRSKY ◽  
P. NAGAIAH ◽  
V. TOKRANOV ◽  
M. YAKIMOV ◽  
R. KAMBHAMPATI ◽  
...  
Keyword(s):  
Dominant Role ◽  
Interface Layer ◽  
Barrier Thickness ◽  
Channel Mobility ◽  
High K ◽  
Amorphous Si ◽  
Inp Substrates ◽  
Low K

Hall electron mobility in buried QW InGaAs channels, grown on InP substrates with HfO 2 gate oxide, is analyzed experimentally and theoretically as a function of top barrier thickness and composition, carrier density, and temperature. Temperature slope α in μ ~Tα dependence is changing from α=-1.1 to +1 with the reduction of the top barrier thickness indicating the dominant role of remote Coulomb scattering (RCS) in interface-related contribution to mobility degradation. Insertion of low-k SiO x interface layer formed by oxidation of thin in-situ MBE grown amorphous Si passivation layer has been found to improve the channel mobility, but at the expense of increased EOT. This mobility improvement is also consistent with dominant role of RCS. We were able to a obtain a reasonable match between experiment and simple theory of the RCS assuming the density of charges at the high-k/barrier interface to be in the range of (2-4)×1013 cm-2.

The influence of water in the synthesis of Zr-based metal-organic framework UiO-66: isolation and reactivity of the new species [ZrCl(OH)2(DMF)2]Cl

2020 ◽  
Author(s):  
Marco Taddei ◽  
Jeroen A. van Bokhoven ◽  
Marco Ranocchiari
Keyword(s):  
Crystallite Size ◽  
Aging Process ◽  
Metal Organic Framework ◽  
Aging Effect ◽  
Oh Groups ◽  
Influence Of Water ◽  
Metal Organic ◽  
Organic Framework

We recently discovered that aging a solution of zirconium(IV) tetrachloride (ZrCl<sub>4</sub>) in N,N-dimethylformamide (DMF) in the presence of water, followed by addition of terephthalic acid linker, reduces the crystallite size of the metal-organic framework UiO-66 [<i>Chem. Commun.</i> <b>2016</b>, <i>52</i>, 6411-6414]. In an effort to shed light into the nature of the aging effect and on its relationship with the crystallite size of UiO-66, we report here the isolation and structural characterization of a microcrystalline zirconium-based compound of formula [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl, which is formed during the aging process. The Zr(IV) ions are coordinated by hydroxide, DMF and chloride to produce a one-dimensional polymer. Thanks to the presence of two –OH groups per zirconium atom, [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl is a suitable precursor for the synthesis of UiO-66 in dry DMF, affording a product having smaller crystallite size than that obtained from a reaction mixture having the same chemical composition, but using ZrCl<sub>4</sub> as the Zr(IV) source. By starting from ZrCl<sub>4</sub> and generating [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in situ in solution through aging, we obtained smaller crystallites as the aging time increased, proving that [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl plays a role in the aging process. The possible role of [ZrCl(OH)<sub>2</sub>(DMF)<sub>2</sub>]Cl in the crystallization mechanism of UiO-66 is also discussed, with emphasis on its relationship with the amount of water in the reaction mixture.<br>

scholarly journals Role of interfacial water in adhesion, friction, and wear—A critical review

Friction ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1-28
Author(s):  
Lei Chen ◽  
Linmao Qian
Keyword(s):  
Friction And Wear ◽  
Normal Load ◽  
Water Layer ◽  
Adsorbed Water ◽  
Bulk Water ◽  
Interfacial Water ◽  
Molecular Configuration ◽  
Water Condensation ◽  
Adhesion Friction

Abstract Surficial water adsorption and interfacial water condensation as natural phenomena that can alter the contact status of the solid interface and tribological performances are crucial in all length scales, i.e., from earthquakes to skating at the macroscale level and even to micro/nano-electromechanical systems (M/NEMS) at the microscale/nanoscale level. Interfacial water exhibits diverse structure and properties from bulk water because of its further interaction with solid surfaces. In this paper, the evolutions of the molecular configuration of the adsorbed water layer depending on solid surface chemistry (wettability) and structure, environmental conditions (i.e., relative humidity and temperature), and experimental parameters (i.e., sliding speed and normal load) and their impacts on tribological performances, such as adhesion, friction, and wear, are systematically reviewed. Based on these factors, interfacial water can increase or reduce adhesion and friction as well as facilitate or suppress the tribochemical wear depending on the water condensation kinetics at the interface as well as the thickness and structure of the involved interfacial water.

scholarly journals Genesis of trondhjemite by low-pressure low-melt fraction anatexis of hornblende-gabbro at Alvand Plutonic Complex (Hamedan, NW Iran): insights from geochemical modelling

2021 ◽  
Vol 14 (17) ◽  
Author(s):  
Federico Lucci ◽  
Adel Saki ◽  
Mirmohammad Miri ◽  
Ahmad Rabiee ◽  
John Charles White
Keyword(s):  
Mafic Rock ◽  
Nw Iran ◽  
Natural Case ◽  
Hornblende Gabbro ◽  
Plutonic Complex ◽  
Low K ◽  
Experimental Melting

AbstractAmphibole-dominated dehydration melting of gabbro is the primary process responsible for the genesis of adakites, low-K tonalites, modern trondhjemites, and plagiogranites as well as Archean tonalite-trondhjemite-granodiorite suites that represent the earliest examples of continental crust. Previous literature has mostly focused on the role of Al-rich amphibole during anatexis of a mafic source and many of these studies have investigated this process through experimental melting runs. However, due to experimental boundary conditions, little is known about partial melting of amphibole-bearing mafic rock at temperatures < 800°C for upper crustal conditions (pressure < 500 MPa). Classic and forward thermobarometric modelling suggests that in situ trondhjemite leucosomes, hosted by Cheshmeh-Ghasaban mafic metatexites (Alvand Plutonic Complex, Hamedan, NW Iran), represent a rare natural case study of a low-temperature incipient amphibole-dominated anatectic event of a mafic source with a primary assemblage (Pl+Hbl+Cpx+Bt+Opx) typical of a hornblende-bearing gabbroic rock.

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