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1.
Photochromic ormosil coatings containing Ag(Cl 1–x
Br
x
) microcrystals were formed on a glass substrate via the sol-gel process. Methyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane were used as starting materials of the ormosil matrices. 3-chloropropyltrimethoxysilane and bromophenyltrimethoxysilane were added as halogen sources and silver colloidal dispersion was introduced into the precursor sol. The coated glass became transparent and photosensitive after Ag(Cl 1–x
Br
x
) microcrystals were precipitated in the coatings above 300°C. Insertion of a SiO 2 buffer layer between the substrate and photochromic layer was effective in preventing Ag + migration into the substrate. Photochromic performances were improved by the substitution of Cl with Br and the incorporation of a minute amount of Cu. 相似文献
2.
Sol-gel coatings in the xM (100- x) SiO 2 system, (M = Cu, Ag and Au) x =0.1–10 mol%), are deposited on soda lime glass slides by using silicon tetramethoxide Si(OCH 3) 4) and methyltriethoxysilane (SiCH 3[OCH 2CH 3] 3) as silica precursors. Anhydrous CuCl, CuCl 2 2H 2O, Cu(NO 3) 2 3H 2O, CuSO 4 5H 2O, AgNO 3 and HAuCl 4 3H 2O are used as copper, silver and gold sources. Coatings with thicknesses ranging from 100 to 900 nm are deposited on the subs trates by dip-coating and subsequently densified at 500°C for 1 h in air. Spectroscopic studies of the coatings as a function of the thicknesses and the metal concentration are carried out by photoluminescence (PL) and optical absorption (OA). In addition, direct observations of some gold coatings were performed by transmission electron microscopy (TEM). Results indicate that for silver and copper containing coatings the excitation and emission spectra arise from electronic transitions in Ag + and Cu + ions and no significant absorption bands due to colloidal precipitation are observed. Gold containing coatings show purple coloration due to an absorption peaking in the 520–560 nm range, which is characteristic of gold colloids. The presence of these colloids is confirmed by TEM observations. 相似文献
3.
Reaction of AgNO 3 and 2,2′‐bipyridine (bipy) under ultrasonic treatment gave the title compound, [Ag(C 10H 8N 2)(NH 3)]NO 3. The crystal structure consists of dimers formed by two symmetry‐related Ag I–bipy monomers connected through intra‐dimer π–π stacking and ligand‐unsupported Ag...Ag interactions. A crystallographic C2 axis passes through the mid‐point of and is perpendicular to the Ag...Ag i(− x + 1, y, − z + ) axis. In addition, each Ag I cation is coordinated by one chelating bipy ligand and one ammine ligand, giving a trigonal coordination environment capped by the symmetry‐equivalent Ag atom. Molecules are assembled by Ag...Ag, π–π, hydrogen‐bond (N—H...O and C—H...O) and weak Ag...π interactions into a three‐dimensional framework. Comparing the products synthesized under different mechanical treatments, we found that reaction conditions have a significant influence on the resulting structures. The luminescence properties of the title compound are also discussed. 相似文献
4.
The gas-phase chemistry of AgFe + was studied by using Fourier transform ion cyclotron resonance mass spectrometry. AgFe + is unreactive with alkanes but reacts with cyclic and linear (C4–C8) alkenes. The primary reactions are dominated by dehydrogenation and condensation. In addition, cluster splitting is observed in the reaction of AgFe + with benzene. Secondary reactions generally involve cluster splitting with the loss of Ag, although AgFeC 5H
6
+
is observed to dehydrogenate cyclopentene to yield AgFeC 10H
12
+
. Ion-molecule reactions, collision-induced dissociation, and photodissociation experiments were used to determine the bond energies D°(Fe +–Ag)=53±7 kcal/mol and D°(Ag +–Fe)=46±7 kcal/mol. These values in turn were used to calculate H
f
(AgFe +)=296±7 kcal/mol and IP(AgFe)=6.5±0.3 eV. Related chemical and physical properties of CuFe + are presented for comparison. 相似文献
5.
Ag-TiO 2 thin films were prepared with a sol-gel route, using titanium isopropoxide and silver nitrate as precursors, at 0.03 and 0.06 Ag/Ti nominal atomic ratios. After drying at 80°C, the films were fired at 300°C and 500°C for 30 min. The films were analysed by X-ray diffraction (XRD) with glancing angle, and X-ray photoelectron spectroscopy (XPS), with depth profiling of the concentration. XPS analysis showed the presence of C and N as impurities in the nanocomposite films. Their concentration decreased with increasing the firing temperature. Chemical state analysis showed that Ag was present in metallic state, except for the very outer layer where it was present as Ag +. For the films prepared with a Ag/Ti concentration of 0.06, depth profiling measurements of the film fired at 300°C showed a strong Ag enrichment at the outer surface, while composition remained almost constant within the rest of the film, at 0.019. For the films heated to 500°C, two layers were found, where the Ag/Ti ratios were 0.015 near the surface and 0.026 near the substrate. 相似文献
6.
Silver clusters on SiO 2 support have been synthesized using 60Co gamma radiation. The irradiation of Ag + in aqueous suspension of SiO 2 in the presence of 0.2 mol dm −3 isopropanol resulted in the formation of yellow suspension. The absorption spectrum showed a band at 408 nm corresponding to typical characteristic surface plasmon resonance of Ag nanoparticles. The effect of Ag + concentration on the formation of Ag cluster indicated that the size of Ag clusters vary with Ag + concentration, which was varied from 4×10 −4 to 5×10 −3 mol dm −3. The results showed that Ag clusters are stable in the pH range of 2–9 and start agglomerating in the alkaline region at pH above 9. The effect of radiation dose rate and ratio of Ag +/SiO 2 on the formation of Ag clusters have also been investigated. The prepared clusters have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which showed the particle size of Ag clusters to be in the range of 10–20 nm. 相似文献
7.
Ag-TiO 2 thin films were prepared with a sol-gel route, using titanium isopropoxide and silver nitrate as precursors, at 0, 0.03 and 0.06 Ag/Ti nominal atomic ratios. After drying at 80°C, the films were fired at 300°C, 500°C, and 600°C for 30 min and 5 h. Glancing angle X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS), with depth profiling of the concentration, were used to study the films. XPS analysis showed the presence of C and N as impurities in the nanocomposite films. Their concentration decreased with increasing the firing temperature. Chemical state analysis showed that Ag was present in metallic state, except for the outer layer where it was present as Ag +. For the films prepared with a Agt/Ti concentration of 0.06, depth profiling measurements of the film fired at 300°C showed a strong Ag enrichment at the outer surface, while composition remained almost constant within the rest of the film, at Ag/Ti atomic ratio of 0.02. Two layers were found for the films heated to 500°C, where the Ag/Ti ratios were 0.015 near the surface and 0.03 near the substrate. The photoelectrochemical properties of Ag-TiO 2 were studied for thin films deposited on ITO substrates. Photocurrents of Ag-TiO 2 nanocomposite electrodes fired at 300°C were observed even at visible light, for wavelengths longer than 400 nm. 相似文献
8.
Preparation and Structure of Ag 2C 4O 4 Ag 2C 4O 4 occurs in a yellow and a colourless modification. Both forms decompose to metallic silver upon heating. Ag + is coordinated in two different fashions in the yellow Ag 2C 4O 4. Ag(1) shows distorted tetrahedral coordination, Ag(2) is coordinated in an unusual distorted square planar manner. The connection of Ag + and C 4O 42? leads to a complicated three-dimensional framework. C 4O 42? is planar with C? O and C? C bonds lengths typical of complete delocalization of the π-electron system. 相似文献
9.
An X-ray crystal structure analysis of yellow Ag 3SO 3N · H 2O was carried out at room temperature: M=435.69, monoclinic, P2 1/n, a=11.628 (5) Å, b=8.058 (4) Å, c=12.034 (5) Å, =86.49 (3)°, V=1125.5 Å 3, Z=8, d
x
=5.142 Mgm –3, MoK , =0.71069 Å (graphite monochromator), =10.5 mm –1, R=5.44%, R
w
=5.85% (877 reflections, 118 parameters). The structure contains Ag planes with Ag-Ag distances shorter than in metallic silver. The nitrogen atoms of the SO 3N anion are covalently bonded to 4Ag atoms of these Ag planes, thus assuming the extraordinary coordination number of 5. The five crystallographically independent Ag atoms forming the Ag planes have approximate linear N-Ag-N coordination. In addition, the structure contains two Ag atoms which are ionically coordinated to 4 resp. 5O atoms of SO 3N and water. The colour-structure correlation of Ag(I) compounds with colourless anions is discussed. Herrn Prof. Dr. mult.V. Gutmann zum 65. Geburtstag gewidmet. 相似文献
10.
Nanostructured Ag films composed of nanoparticles and nanorods can be formed by the ultrasonication of ethanol solutions containing Ag 2O particles. The present work examined the formation process of these films from ethanol solutions by two different agitation methods, including ultrasonication and mechanical stirring. The mass-transfer process from Ag 2O particles to ethanol solvent is accelerated by the mechanical effects of ultrasound. Ag + ions and intermediately reduced Ag clusters were released into the ethanol. These Ag + ions and Ag clusters provide absorption bands at 210, 275 and 300 nm in UV-vis spectra. These bands were assigned to the absorption of Ag +, Ag 4 2+ and Ag n ( n?≈?3). The Ag n clusters that readily grow to become Ag nanoparticles were formed due to the surface reaction of Ag 2O particles with ethanol under ultrasonication. The reactions of Ag + ions in ethanol to form Ag nanomaterials (through the formation of Ag 4 2+ clusters) were also accelerated by ultrasonication. 相似文献
11.
The evolution of spectral and luminescent properties of Ag-containing composite coatings prepared by liquid technique has been studied. Double stabilization allows forming thin oxide films containing luminescent small Agn (n?<?5) molecular clusters using the liquid technique. These clusters are non-stable intermediate products during the formation of Ag nanoparticles from the ions and neutral atoms. It was found that small luminescent Agn molecular clusters (n?<?5) formed in the solutions at the presence of polyvinylpyrrolidone (PVP) remain in PVP/metal nitrates composite coatings and in the calcined metal oxide coatings. Spatial separation of small Ag molecular clusters in the coatings by the oxide nanoparticles of ZnO and MgO prohibits silver clusters growth and non-luminescent silver nanoparticles formation and allows saving coatings’ luminescence properties during thermal treatment. 相似文献
12.
Several powder samples of TiO 2 are pretreated thermally at 300, 480 and 540°C, subjected to -irradiation and after irradiation added in one of the compartment of the concentration cell made up of Ag/Ag +. The adsorbed oxygen species O
2ad
–
, HO
2ad
–
and O
ad
–
on TiO 2 provide negatively charged sites and develop EMF in the cell. The radiation damage, measured in terms of equilibrium EMF, received at lower doses is partially recovered at higher doses. It is proposed that in heating at 480°C, ad species react with Ti 3+ ions in the surface and produce –O–O– peroxy linkages and block the negatively charged sites while in heating at 540°C Ti 4O 7 phase is produced on the surface which adsorbs O 2 and provide large number of negatively charged sites. During -irradiation peroxy linkages are broken and the Ti 4O 7 phase is destroyed. Observed oscillatory variation in equilibrium EMF is explained on the basis of several reactions mentioned above proceeding at different rates during radiolysis. 相似文献
13.
[Ag 2(CH 3CH 2C(CH 3) 2COO) 2] ( 1), [Ag 2(CH 3CH 2C(CH 3) 2COO) 2(PMe 3) 2] ( 2) and [Ag 2(CH 3CH 2C(CH 3) 2COO) 2(PEt 3) 2] ( 3) were prepared and characterized by MS-EI; 1H, 13C, 31P NMR, variable temperature IR (VT-IR) spectroscopy and thermal analysis. MS and VT-IR data analysis suggests bidentate bridging carboxylates and monodentately bonded phosphines in the solid phase. The same methods used for gas phase analysis of 1–2 proved [(CH 3CH 2C(CH 3) 2COO)Ag 2] + as the main ion, which could be transported in the gas phase during the CVD process. In the case of 3, similar intensity to the latter ion revealed [Ag{P(C 2H 5)}] + and it is responsible for the CVD performance of 3. Thermal analysis results revealed that decomposition of 1–3 proceed in one endothermic process, with metallic silver formation between 197 and 220 °C. In the case of 1, VT-IR studies of the gaseous decomposition products demonstrate the presence of ester molecules and CO 2, whereas for 2 the main gaseous product appeared to be acid anhydride. Therefore, 2 was not used as a silver CVD precursor. Metallic layers were produced from 3 in hot-wall CVD experiments, (between 200 and 280 °C), under a total reactor pressure of 2.0 mbar, using argon as a carrier gas. Thin films deposited on Si(1 1 1) substrate were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Silver films obtained at moderate temperature (220–250 °C) revealed a thickness below 50 nm, and were whitish colored and slightly matt. 相似文献
14.
127-year 108Ag m is an (n,) activation product of 107Ag and is produced in nuclear power reactors. Due to the wide range of reported values for the o
0
cross section of the 107Ag(n,) 108Ag m reaction new measurements were made—resulting in a o
0
value of 0.477±0.033 barn, and an I value of 0.80±0.15 barn. The environmental importance of the 110Ag m and 108Ag m radionuclides is discussed. 相似文献
15.
The solvus lines of the PbTe and Ag 2Te phases in the pseudo-binary PbTe-Ag 2Te system have been determined using diffusion couples and unidirectional solidification by the Bridgman method. The solubilities of both Ag 2Te in PbTe and PbTe in Ag 2Te decrease with decrease in temperature. For the former, this change is from 14.9 at% Ag (694 °C) to 0.5 at% Ag (375 °C), while for the latter it is from 12.4 at% Pb (650 °C) to 3.1 at% Pb (375 °C). The decrease in solubilities leads to the formation of precipitates of Ag 2Te in PbTe and PbTe in Ag 2Te. In particular, fast atomic diffusion in Ag 2Te results in the precipitation of PbTe even in quenched samples. From the temperature dependence of these solubilities, heats of solution have been determined. In the diffusion couple, the phase boundary moves toward PbTe. In the region between the phase boundary and the initial interface, PbTe transforms to β-Ag 2Te (cubic) retaining the cube-on-cube orientation relationship. 相似文献
16.
Redox potentials: E(UO
2
2+
/UO
2
+
)=60±4 mV/NHE, E(U 4+/U 3+)=–630±4mV/NHE measured at 25°C in acidic medium (HClO 4 1M) using cyclic voltametry are in accordance with the published data. From 5°C to 55°C the variations of the potentials of these systems (measured against Ag/AgCl electrode) are linear. The entropies are then constant: [S(UO
2
2+
/UO
2
+
)–S(Ag/AgCl)]/F=0±0.3 mV/°C, [S(U 4+/U 3+)–S(Ag/AgCl)]/F=1.5±0.3 mV/°C. From 5°C to 55°C, in carbonate medium (Na 2CO 3=0.2M), the Specific Ionic Interaction Theory can model the experimental results up to I=2M (Na +, ClO
4
–
, CO
3
2–
): E(UO 2(CO 3)
3
4–
/UO 2(CO 3)
3
5–
)=–778±5 mv/NHE (I=0, T=25°C, (25°C)=(UO 2(CO 3)
3
4–
, Na +)–(UO 2(CO 3)
3
5–
, Na +)=0.92 kg/mole, S(UO 2(CO 3)
3
4–
/UO 2(CO 3)
3
5–
=–1.8±0.5 mV/°C (I=0), =(Cl –, Na +)=(1.14–0.007T) kg/mole. The U(VI/V) potential shift, between carbonate and acidic media, is used to calculate (at I=0,25°C):
相似文献
17.
Structural evolution of WO x species on the surface of titania nanotubes was followed by in situ thermo-Raman spectroscopy. A total of 15 wt% of W atoms were loaded on the surface of a hydroxylated titania nanotubes by impregnation with ammonium metatungstate solution and then, the sample was thermally treated in a Linkam cell at different temperatures in nitrogen flow. The band characteristic of the WO bond was observed at 962 cm −1 in the dried sample, which vanished between 300 and 700 °C, and reappear again after annealing at 800 °C, along with a broad band centered at 935 cm −1, attributed to the v1 vibration of WO in tetrahedral coordination. At 900 and 1000 °C, the broad band decomposed into four bands at 923, 934, 940 and 950 cm −1, corresponding to the symmetric and asymmetric vibration of WO bonds in Na 2WO 4 and Na 2W 2O 7 phases as determined by X-ray diffraction and High resolution transmission electron microscopy (HRTEM). The structure of the nanotubular support was kept at temperatures below 450 °C, thereafter, it transformed into anatase being stabilized at temperatures as high as 900 °C. At 1000 °C, anatase phase partially converted into rutile. After annealing at 1000 °C, a core-shell model material was obtained, with a shell of ca. 5 nm thickness, composed of sodium tungstate nanoclusters, and a core composed mainly of rutile TiO 2 phase. 相似文献
18.
The phase composition of electrochemically obtained Ag-In alloy coatings electrodeposited at different conditions was determined.
With the increase in the current density, both indium content and heterogeneity of the deposited layers increase. The amount
of the indium-richer phase increase as well. Before the thermal treatment, the phases Ag, Ag 3In, and In 4Ag 9 are observed in coatings with spatio-temporal structures. As a result of heating the new phase Ag 4In appears at temperatures above 500 °C and indium is oxidized up to In 2O 3 from the oxygen in the heating chamber. Up to 500 °C, the spatio-temporal structures are still visible. Probably they consist
of both Ag-rich α-phase and one of the phases of the alloy system with small indium content, such as Ag 4In or Ag 3In. 相似文献
19.
Silver(I) Orthoborate Solid state reaction of Ag 2O and B 2O 3 (molar ratio 3/1) applying elevated O 2 pressures yields Ag 3BO 3. In the temperature range of 180 to 210°C silver orthoborate changes its colour from yellow to red. DTA shows in this region a weak endothermic effect, but no structural changes are observable. At atmospheric pressure Ag 3BO 3 decomposes at 375°C to Ag and B 2O 3. The crystal structure (space group: R 32, a = b = 987.3, c = 338.1 pm) contains BO 3 groups and Ag/O chains as structure-building elements. 相似文献
20.
New Ternary Silver (II) Fluorides: Ag M F 14 (M IV = Zr, Hf) Single crystals of deeply blue violet coloured fluorides Ag 3IIM 2IVF 14 (M IV = Zr, Hf) have been obtained by heating powder samples under F 2/N 2 (1:2) at T ≈? 600°C. The isotypic compounds crystallizes monoclinic with a = 924.9, b = 668.6, c = 907.3 pm, β = 90.30° (Ag 3Hf 2F 14) and a = 922.5, b = 667.6, c = 906.3 pm, β = 91.30° (Ag 3Zr 2F 14) (Four circle diffractometer data, Philips PW 1100), spcgr. C2/m-C 2h3 (No. 12), Z = 2. There are two different sorts of Ag 2+:Ag(1) with coordination number C.N. [Ag(1)] = 4 + 2 and Ag(2) with C.N.[Ag(2)] = 4 + 4 against F ?. Ag(1) can be substituted by Cu 2+, Ni 2+, Zn 2+, Mg 2+ (all of blue/red violet colour), Ag(2) by Ca 2+, Cd 2+, Hg 2+ (bright green). From (preliminary) powder data CuAg 2Zr 2F 14 with a = 912.3(4), b = 661.2(2), c = 899.4(2) pm, β = 90.70° (3) is isotypic, the other compounds seems to be of closely related type of structure. 相似文献
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