Spectres Raman de Basses Frequences de Cristaux de Derives Benzeniques Paradisubstitues: p‐Br2C6H4, p‐Br2C6D4, p‐BrClC6H4 et p‐ClC6H4. Étude du désordre dans le dérive p‐BrClC6H4

Calvé, N. Le; Parent, S.; Pasquier, B.

doi:10.1002/jrs.1250020414

Cited by 13 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2). The sixth phonon has been observed [7] before in DBB and bromochlorobenzene, but it is not resolved in our mixed crystal studies. The mixed crystal spectra show that ail phonons are amalgamated.…”

Section: Resultscontrasting

confidence: 58%

Phonon and exciton amalgamation - A criterion for true solid solutions: Vibrations of chemically and isotopically mixed para-dihalobenzene crystals

Bellows

Prasad

Monberg

et al. 1978

Chemical Physics Letters

View full text Add to dashboard Cite

The phonon and vtbratlonal exciton spectra are suggested as criteria for true solid solutions of molecular crystals. The short range character of the interactions that determine both the phonon and exclton properties makes these bands ideal for distinguishing between truly random mLxed lattices and segremated microscopic domains. Raman studies of the chemical-13, mixed p-dichlorobenzene-p-d~bromobenzene crystal and the isotopically mixed p-dtchlorobertzened2a-p-d~chlorobenzene-d 4 crystals dlustrate the principles involved. All phonon bands (external molecular vibrations) of both the chemically and the isotopicaUy mixed crystals are in the amalgamation limit. VChde mass defects appear to determine the phonon frequency shifts in these mixed crystals, deviations from a virtual crystal model axe observed and discussed. The 1o~ energy internal modes (vibrational excitons) are examined and found to be in the separated hand limit. Treating the pure p-dichlorobenzene crystal as an isotopically mixed crystal due to the natural abundance of the chlorine isotopes reveals that the chlorine stretch at 310 cm-r ts atso in the separated band limit. All these mixed crystal systems are concluded to be substitutionally random on the molecular scale.

show abstract

Section: Resultscontrasting

confidence: 58%

Phonon and exciton amalgamation - A criterion for true solid solutions: Vibrations of chemically and isotopically mixed para-dihalobenzene crystals

Bellows

Prasad

Monberg

et al. 1978

Chemical Physics Letters

View full text Add to dashboard Cite

show abstract

“…It should be mentioned that the selection of the paint systems was made in order to cover a large range of expected performance in field from poor to excellent systems, based on previous field studies such as in Ref. [7]. Prior to exposure, a vertical scribe parallel to the longest side of 100 Â 0.5 mm 2 was applied using an Elcometer 1538 scribing tool equipped with a rectangular blade of 0.5 mm in width.…”

Section: Test Panels and Evaluationmentioning

confidence: 99%

“…Finally, a cyclic corrosion test ISO 16701 recommended to simulate marine atmospheric conditions was also performed in a dedicated chamber for a total duration of 6 months [7]. The test cycle is presented in Fig.…”

Section: Standardised Testsmentioning

confidence: 99%

Performance of marine and offshore paint systems: Correlation of accelerated corrosion tests and field exposure on operating ships

LeBozec

Thierry

Calve³

et al. 2013

Materials & Corrosion

View full text Add to dashboard Cite

Corrosion resistance is an important property requirement for marine paint systems used in naval industry such as for ship's topsides and superstructures, which obliges testing the coating performance in order to make a durable selection of the paint systems. This can be achieved by performing laboratory accelerated corrosion tests recommended for C5M corrosivity class (in particular the standard neutral salt spray test ISO 9227 or the cyclic corrosion test ISO 20340‐Annex A) which give results in a rather short delay (up to 6 months) compared to field exposures in marine atmospheres (several years). It is however well known that these tests may not be fully representative of real ship environmental conditions. The aims of the present study were thus to compare and estimate the correlation of various accelerated corrosion tests including standardized tests (ISO 9227, ISO 20340, ISO 16701) and newly developed test conditions to field exposures on worldwide operating ships (container carrier vessel and oceanographic ship) and on conventional static marine atmospheric sites (C5M). Fifteen different marine paint systems commonly used for offshore and naval application were selected for the study. From the results, the exposure conditions on the container vessel were the most aggressive ones compared to static exposures after 2 years. The best correlation to such field exposure was observed using the cyclic test ISO 16701 with a deviation inferior to 25%, an acceleration factor of 4 and comparable corrosion aspect. If all testing conditions involving NaCl 5 wt% (including ISO 20340) showed a superior acceleration factor (e.g., about 12), a larger deviation (50%) was however found indicating that these tests did not accelerate the corrosion degradation of the paint systems similarly to field exposures. In addition, conditions for an optimization of ISO 20340 annex A test were found.

show abstract

Etude par Spectrométrie Raman de la Transition de Phase Structurale des Tétrachloro et Tétrabromo‐1,2,4,5 Benzenes

Pasquier

Calvé

1977

J Raman Spectroscopy

Self Cite

View full text Add to dashboard Cite

Raman and infrared spectra of crystalline 1,2,4,5-tetrachloro-and tetrabromobenzenes have been analysed between 10 and 100 cm-' over a range of temperature from 10 K to 400 K. An assignment of lattice modes is given. The first-order phase transition is of a displacive type as shown by the behaviour of librational modes. The small value of the estimated p critical exponent in the uJu0 = (T. -T/T&3 expression is interpreted in terms of predominant short-range interactions in these molecular crystals.

show abstract

Spectres Raman de Basses Frequences de Cristaux de Derives Benzeniques Paradisubstitues: p‐Br₂C₆H₄, p‐Br₂C₆D₄, p‐BrClC₆H₄ et p‐ClC₆H₄. Étude du désordre dans le dérive p‐BrClC₆H₄

Cited by 13 publications

References 12 publications

Phonon and exciton amalgamation - A criterion for true solid solutions: Vibrations of chemically and isotopically mixed para-dihalobenzene crystals

Phonon and exciton amalgamation - A criterion for true solid solutions: Vibrations of chemically and isotopically mixed para-dihalobenzene crystals

Performance of marine and offshore paint systems: Correlation of accelerated corrosion tests and field exposure on operating ships

Etude par Spectrométrie Raman de la Transition de Phase Structurale des Tétrachloro et Tétrabromo‐1,2,4,5 Benzenes

Contact Info

Product

Resources

About