Ion recombination processes in rigid solutions

1977 ◽  
Vol 55 (11) ◽  
pp. 1867-1875 ◽  
Author(s):  
John R. Miller
Keyword(s):  
Aromatic Hydrocarbon ◽  
Charge Separation ◽  
Pulse Radiolysis ◽  
Room Temperature ◽  
Triplet States ◽  
Trapped Electrons ◽  
Recombination Processes ◽  
Free Ion ◽  
The Matrix ◽  
Ion Recombination

It is known that the free ion yield is small in irradiated aromatic hydrocarbon liquids. This study uses pulse radiolysis to observe anions of aromatic solutes in matrices at 77 K. In aliphatic matrices, trapped electrons tunnel to aromatic solutes and the anion yield is observed to grow with time. If the concentration of aromatic solute is large (0.1 M) or if the matrix is aromatic, ion recombination via tunneling dominates the anion kinetics, and long lived triplet states are observed to grow in. These results and the effects of other charge scavengers indicate that just a few percent of added aromatic material can dramatically increase the probability of charge recombination in aliphatic media, and that this effect involves decreased charge separation distances. The same effect apparently also occurs in alkane liquids at room temperature.

Geminate-ion kinetics with competing ion fragmentation in nonpolar liquids with halocarbons

1990 ◽  
Vol 68 (9) ◽  
pp. 918-924 ◽  
Author(s):  
Rolf E. Bühler
Keyword(s):  
Low Temperatures ◽  
Pulse Radiolysis ◽  
Room Temperature ◽  
Ion Concentration ◽  
Geminate Recombination ◽  
Rate Law ◽  
Ion Fragmentation ◽  
Nonpolar Liquids ◽  
Ion Recombination ◽  
Semi Empirical

The semi-empirical rate law for geminate-ion recombination by van den Ende, Warman, and Hummel, which predicts a linear dependence of the ion concentration with t−0.6, is modified to include simultaneous ion fragmentation. The theory is applied to the kinetics, as observed by pulse radiolysis of liquid methylcyclohexane (MCH) solutions of N2O, CHCl3, or tert-butylchloride (t-BuCl) at low temperatures. In MCH saturated with N2O (−130 °C), the solvent cation (MCH+, λmax = 550 nm) moves about 400 times faster than prediced by diffusion. With the known conductivity data at room temperature, an activation energy of about 2.7 kJ/mol can be derived. The solvent cation MCH+ does not appear to fragment. With t-BuCl added to MCH (−134 °C), MCH+ (λmax = 550 nm) and t-BuCl− (λmax = 450 nm) are observed simultaneously. The initial kinetics corresponds to the parent ion (MCH+) recombination with t-BuCl−. Then the MCH+ fragmentation with k1(−134 °C) = 3 × 105 s−1 is observed, followed by the geminate recombination of some fragment cation with t-BuCl−. The fragment cation recombines 300 times slower than the parent cation. With CHCl3 added to MCH (−130 °C), the MCH+ absorption is hidden within the [Formula: see text] band (λmax = 470 nm); however, the fragmentation is detected from kinetic analysis to occur in about 2 × 106 s−1. The modified t−0.6 rate law appears to be a very useful tool to study simultaneous ion recombination and ion fragmentation.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

The butterfly martensite nucleation in an iron and nickel alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 906-907
Author(s):  
Q.Z. Chen ◽  
X.F. Wu ◽  
T. Ko
Keyword(s):  
Nickel Alloy ◽  
Ethyl Alcohol ◽  
Dislocation Structure ◽  
Martensite Transformation ◽  
Room Temperature ◽  
The Matrix

Some butterfly martensite nuclei were observed in an Fe-27.6Ni-0.89V-0.05C alloy. The alloy was austenitized at 1200°C for 1 hour. Some samples were aged at 850° C for 40 minutes and quenched in 10% brine at room temperature. All the samples were cooled in ethyl alcohol for martensite transformation.A nucleus in an unaged specimen is shown in Fig.1. The nucleus has certain contrast different from the matrix and is shaped like one wing of a butter fly martensite. The SADP of the circled region is measured to be: da=dh, and approximate to dγ(111) and dm(110) with ∠AOB = 55° . It is similar to [011]f.c.c and b patterns in the anglez ∠AOB and the ratio ra/rb, respectively. The SADP shows that the structure of the nucleus is between f.c.c and b.c.c. The dislocation structure within the nucleus is shown in Fig.2. Their Burgers vectors and line directions are also given in it. There are many long dislocations near it without dislocations piled up as shown in Fig.3.Long dislocations are closed at one end as an envelope.

scholarly journals Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation

RSC Advances ◽  
2020 ◽  
Vol 10 (48) ◽  
pp. 28516-28522 ◽  
Author(s):  
Kazutaka Akiyoshi ◽  
Tatsuya Kameyama ◽  
Takahisa Yamamoto ◽  
Susumu Kuwabata ◽  
Tetsu Tatsuma ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Metal ◽  
Oxidation State ◽  
Molybdenum Oxide ◽  
Charge Separation ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Oxide Nanoparticles ◽  
Induced Charge ◽  
Molybdenum Oxide Nanoparticles

MoOx NPs, prepared by sputtering Mo metal on a room-temperature ionic liquid (RTIL) followed by heating in air, produced anodic photocurrents with the excitation of their LSPR peak.

CsOH and its Lighter Homologues – a Comparison

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1229-1236
Author(s):  
Matthias Wörsching ◽  
Constantin Hoch
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Structure Type ◽  
Alkali Metal Hydroxide ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Cesium Hydroxide ◽  
Free Ion ◽  
The One ◽  
First Time

Abstract Cesium hydroxide, CsOH, was for the first time characterised on the basis of single-crystal data. The structure is isotypic to the one of the room-temperature modification of NaOH and can be derived from the NaCl structure type thus allowing the comparison of all alkali metal hydroxide structures. Raman spectroscopic investigations show the hydroxide anion to behave almost as a free ion as in the gas phase. The X-ray investigations indicate possible H atom positions.

Lead inclusions in aluminium

1989 ◽  
Vol 157 ◽  
Author(s):  
E. Johnson ◽  
L. Gråbaek ◽  
J. Bohr ◽  
A. Johansen ◽  
L. Sarholt-Kristensen ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Room Temperature ◽  
Noble Gas ◽  
Melting Transition ◽  
X Ray Diffraction ◽  
Free Surfaces ◽  
The Matrix ◽  
Mean Size ◽  
The Mean ◽  
Spontaneous Phase

ABSTRACTIon implantation at room temperature of lead into aluminium leads to spontaneous phase separation and formation of lead precipitates growing topotactically with the matrix. Unlike the highly pressurised (∼ 1–5 GPa) solid inclusions formed after noble gas implantations, the pressure in the lead precipitates is found to be less than 0.12 GPa.Recently we have observed the intriguing result that the lead inclusions in aluminium exhibit both superheating and supercooling [1]. In this paper we review and elaborate on these results. Small implantation-induced lead precipitates embedded in an aluminium matrix were studied by X-ray diffraction. The (111) Bragg peak originating from the lead crystals was followed during several temperature cycles, from room temperature to 678 K. The melting temperature for bulk lead is 601 K. In the first heating cycle we found a superheating of the lead precipitates of 67 K before melting occurred. During subsequent cooling a supercooling of 21 K below the solidification point of bulk lead was observed. In the subsequent heating cycles this hysteresis at the melting transition was reproducible. The full width of the hysteresis loop slowly decreased to 62 K, while the mean size of the inclusions gradually increased from 14.5 nm to 27 nm. The phenomena of superheating and supercooling are thus most pronounced for the small crystallites. The persistence of the hysteresis loop over successive heating cycles demonstrate that its cause is intrinsic in nature, and it is believed that the superheating originates from the lack of free surfaces of the lead inclusions.

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