Academic literature on the topic 'Diffusion, Adolf Fick'

The science of diffusion had its beginnings in the 19th century, although the blacksmiths and metal artisans of antiquity already used diffusion phenomena to make such objects as iron swords and gilded bronze wares. Diffusion as a scientific discipline is based on several corner stones. The most important ones are: (i) The continuum theory of diffusion originated from the work of the German physiologist Adolf Fick, who was inspired by elegant experiments on diffusion in gases and of salt in water performed by the Scotsman Thomas Graham. (ii) The Brownian motion, observed for the first time by the British botanist Robert Brown, was interpreted decades later by Albert Einstein and almost at the same time by the Polish physicist Marian Smoluchowski. Their theory related the mean square displacement of atoms to the diffusion coefficient. This provided the statistical cornerstone of diffusion and bridged the gap between mechanics and thermodynamics. The Einstein-Smoluchowski relation was verified in tedious experiments by the French Nobel laureate Jean Baptiste Perrin and his coworkers. (iii) The atomistics of solid-state diffusion had to wait for the birthday of solid-state physics heralded by the experiments of the German Nobel laureate Max von Laue. Equally important was the perception of the Russian and German scientists Jakov Frenkel and Walter Schottky, reinforced by the experiments of the American metallurgist Ernest Kirkendall, that point defects play an important role for properties of crystalline substances, most notably for those controlling diffusion and the many properties that stem from it. This paper is not meant as systematic history of diffusion. It is devoted to some major landmarks and eminent pioneers of diffusion including also people from recent decades until today.

Adolf Fick’s work represents in many ways an important starting point for modern scientific research on diffusion. Diffusion itself is a slow process taking long time to progress. In this talk, we aim to discuss the progress of diffusion science. For this purpose, we present a highly subjective review of the study of diffusion since the times of Adolf Fick. Our focus is on mutual diffusion in liquids which is at the heart of many processes in (bio)chemical systems. Here, diffusion is often the rate-limiting step and thus decisive for overall process performance.

Atoms and molecules are not completely immobile within a solid material. They move by jumping into vacancies or interstitial sites in the crystal lattice. The laws describing their motion were discovered by Adolf Fick in the mid-19th century, modelled on analogous laws for the flow of heat (Fourier’s law) and electricity (Ohm’s law). According to Fick’s first law, the rate at which atoms move is proportional to the concentration gradient, with the diffusion coefficient defined as the constant of proportionality. Fick’s second law generalises the first law to a wide range of situations and is called the diffusion equation. This chapter examines a number of characteristic diffusion profiles; the difference between self, intrinsic, inter- and tracer diffusion coefficients; the Kirkendall effect and porosity formation when different components move at different speeds; and the Arrhenius temperature dependence of diffusion. Fick was a physiologist and derived his laws initially to describe the flow of blood through the heart. He made advances in anatomy, physiology and medicine, developing methods of monitoring blood pressure, muscular power, corneal pressure and glaucoma. He lived at the time of Bismarck’s post-Napoléonic unification of Germany and the associated flowering of German science, engineering, medicine and culture.