Translation-rotation paradox for diffusion in fragile glass-forming liquids

by: Frank H Stillinger, Jennifer A Hodgdon

Physical Review E, Vol. 50, No. 3. (1994), pp. 2064-2068.

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Abstract

Translational and rotational diffusion rates in low-molecular-weight liquids tend to conform well to the predictions of the classic Stokes-Einstein-Debye model if temperature T is not too low. Specifically; the diffusion constants D trans and D rot are proportional to T /η( T ); where η is the shear viscosity. However; fragile glass formers seem to present a paradox: near the glass transition temperature T g this proportionality continues for D rot ; but D trans can be enhanced by 10 2 . A ‘‘fluidized domain’’ model is proposed to explain these observations. Owing to a suitable combination of domain parameters (mean size; lifetime; concentration; internal viscosity); the observed diffusion rate discrepancy can indeed be rationalized. Rough estimates for these domain parameters are provided for two fragile glass formers (orthoterphenyl and 1;3;5-tri-α-naphthyl benzene) at their respective T g ’s.

@article{stillinger94, abstract = {Translational and rotational diffusion rates in low-molecular-weight liquids tend to conform well to the predictions of the classic Stokes-Einstein-Debye model if temperature T is not too low. Specifically; the diffusion constants D trans and D rot are proportional to T /η( T ); where η is the shear viscosity. However; fragile glass formers seem to present a paradox: near the glass transition temperature T g this proportionality continues for D rot ; but D trans can be enhanced by 10 2 . A ‘‘fluidized domain’’ model is proposed to explain these observations. Owing to a suitable combination of domain parameters (mean size; lifetime; concentration; internal viscosity); the observed diffusion rate discrepancy can indeed be rationalized. Rough estimates for these domain parameters are provided for two fragile glass formers (orthoterphenyl and 1;3;5-tri-α-naphthyl benzene) at their respective T g ’s.}, author = {Stillinger, Frank H. and Hodgdon, Jennifer A. }, citeulike-article-id = {1201313}, doi = {10.1103/PhysRevE.50.2064}, journal = {Physical Review E}, keywords = {diffusion, rotation}, number = {3}, pages = {2064--2068}, posted-at = {2007-11-17 21:56:55}, priority = {5}, publisher = {American Physical Society}, title = {Translation-rotation paradox for diffusion in fragile glass-forming liquids}, url = {http://dx.doi.org/10.1103/PhysRevE.50.2064}, volume = {50}, year = {1994} }

RIS record

TY - JOUR ID - stillinger94 L3 - citeulike-article-id:1201313 TI - Translation-rotation paradox for diffusion in fragile glass-forming liquids JF - Physical Review E VL - 50 IS - 3 SP - 2064 EP - 2068 PB - American Physical Society N2 - Translational and rotational diffusion rates in low-molecular-weight liquids tend to conform well to the predictions of the classic Stokes-Einstein-Debye model if temperature T is not too low. Specifically; the diffusion constants D trans and D rot are proportional to T /η( T ); where η is the shear viscosity. However; fragile glass formers seem to present a paradox: near the glass transition temperature T g this proportionality continues for D rot ; but D trans can be enhanced by 10 2 . A ‘‘fluidized domain’’ model is proposed to explain these observations. Owing to a suitable combination of domain parameters (mean size; lifetime; concentration; internal viscosity); the observed diffusion rate discrepancy can indeed be rationalized. Rough estimates for these domain parameters are provided for two fragile glass formers (orthoterphenyl and 1;3;5-tri-α-naphthyl benzene) at their respective T g ’s. KW - diffusion KW - rotation AU - Stillinger, Frank AU - Hodgdon, Jennifer PY - 1994/// UR - http://dx.doi.org/10.1103/PhysRevE.50.2064 ER -

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