Materials Science and Engineering: An Introduction

Fick’s first law states steady that state diffusion is given by: $$J=-D\frac{dc}{dx}$$ where $\frac{dc}{dx}$ is the concentration gradient, D is the diffusion coefficient, and J is the diffusion flux. In Fick’s first law it is assumed that the concentration gradient is independent of time, so flux is also independent of time.
Fick’s first law states steady that state diffusion is given by: $$J=-D\frac{dc}{dx}$$ where $\frac{dc}{dx}$ is the concentration gradient, D is the diffusion coefficient, and J is the diffusion flux. In Fick’s first law it is assumed that the concentration gradient is independent of time, so flux is also independent of time.