Sauerstoff-selbstdiffusion in Rutilkristallen

Haul, R.; Dümbgen, G.

doi:10.1016/0022-3697(65)90066-1

Cited by 120 publications

(55 citation statements)

References 15 publications

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“…Values for the number-averaged molecular weights Mn, weight-averaged molecular weights Mw, and weight distribution of molecular weights were obtained by computer analysis of the chromatographs using the procedure described by Pickett et at. (11).…”

Section: Polymethyl Methacrylate As An Electron Sensitive Resist R Amentioning

confidence: 99%

Charge Trapping in Polymers

Davies

Lock

1973

J. Electrochem. Soc.

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An investigation is described of the role of unsaturated groups in the molecular structure on charge trapping in synthetic polymers. An attempt has also been made to quantify the effect on carrier migration of doping these materials with halogens. Using a surface charge decay technique carrier mobility has been determined in vacuo for a number of synthetic polymers and also for both high-and low-density polyethylenes doped with halogens. These data are presented together with an account of concurrent measurements of optical absorption in the same materials. The data indicate a tendency for "pure polymers" with known higher unsaturation content to exhibit a lower carrier mobility. Increased mobility was observed with either bromine or iodine impregnation of polyethylene. The optical data show that the iodine enters the polymer as neutral molecules most of which emerge under atmospheric conditions. The remainder, however, form charge exchange complexes at unsaturation sites in the polymer. The role of complexes in carrier transport is discussed.The charge storage property of insulating materials--as exemplified in the electret--is becoming of widespread technological importance from microphones (6; and references therein) to prostheses (1). The elucidation of the underlying charge injection and carrier Key words: polymers, carrier mobility, conduction. migration processes in synthetic polymers is vital to the future utility of these materials in almost any capacity.Modern experimental techniques are yielding increasingly more definitive models of the basic mechanisms. It has been shown (3, 7) that carrier mobility in low conductivity polymers is extremely small, the carriers being predominantly located in traps. Carrier migration is described by a hopping process. Recently published data (2) indicate that both polymer crystallinity and molecular symmetry significantly affect the electret stability, that is, charge trapping, and further, that phenyl and unsaturated groups in the molecular structure can form traps. Previous work (4) has also shown that carrier mobility in these materials may be greatly increased by impregnating the polymer with iodine. This effect has been interpreted by postulating charge exchange complex formation in the polymer, the complexes effectively reducing trapping effects by "handing-on" the carriers. A charge exchange complex in the present context means an interaction between two species, the strength of which lies between a full chemical bond and a small orbital overlap.The present paper describes an investigation of the role of unsaturated groups in carrier trapping and an attempt to quantify the effects of doping on the transport mechanism. Using a surface-charge decay technique, carrier mobility has been determined in vacuo for a number of synthetic polymers and also for both high-density (HDPE) and low-density (LDPE) polyethylenes impregnated with halogens. An account of concurrent measurements of optical absorption in the same materials is also presented.The experimental r...

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Section: Polymethyl Methacrylate As An Electron Sensitive Resist R Amentioning

confidence: 99%

Charge Trapping in Polymers

Davies

Lock

1973

J. Electrochem. Soc.

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“…Haul and Dumbgen (1965) obtained the self-diffusion coefficients in Table 1. Using these values and the volume diffusion model as the dominant sintering mechanism, gives the sintering time as Figure 15 compares the calculated values based on the models for r given above to the measured results.…”

Section: Comparison Of Several Sintering Models and Physical Propertiesmentioning

confidence: 99%

Evaluation of Sintering of Nanometer-Sized Titania Using Aerosol Method

Seto

Shimada

Okuyama

1995

Aerosol Science and Technology

127

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“…The other type of restructing occurs due to sintering. Haul and Diimbgen (1965) used the tracer technique to obtain the self-diffusion coefficient for titania particles. Astier and Vergnon (1976) obtained the grain boundary diffusion coefficient and the volume diffusion coefficient based on the kinetics of neck growth using photographically measured shrinkage of titania particle pellets.…”

Section: Introductionmentioning

confidence: 99%

Study of the Sintering of Nanosized Titania Agglomerates in Flames UsingIn SituLight Scattering Measurements

Yang

Biswas

1997

Aerosol Science and Technology

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OH 4 5 2 2 2 1 -0 0 7 1 ABSTRACT. A premixed flame aerosol reactor was used to produce titania particles by oxidation of titanium isopropoxide vapor. The growth, aggregation of particles, and the agglomerate structure were determined as a function of height in the flame using in situ light scattering and transmission electron microscopy (TEM) measurements. A methodology to determine the sintering characteristic time using light scattering data was established. The light scattering data provided the evolution of the fractal dimension which was then related to the normalized surface area change using a computer simulation. The sintering equation was redeveloped in terms of the normalized surface area, thus not having to account for coagulation effects. Experimental results indicate that isolated titania particles were observed at the high temperatures due to fast sintering. An agglomerate was obtained at downstream locations with an associated change in fractal dimension due to sintering.

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Sauerstoff-selbstdiffusion in Rutilkristallen

Cited by 120 publications

References 15 publications

Charge Trapping in Polymers

Charge Trapping in Polymers

Evaluation of Sintering of Nanometer-Sized Titania Using Aerosol Method

Study of the Sintering of Nanosized Titania Agglomerates in Flames UsingIn SituLight Scattering Measurements

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