1. A sheet (with a thickness of 0.05 cm) of MgO lies in between layers of Ni and Ta to avoid reaction between these two metals . At 1400 ºC, ions of Ni are created and diffuse through the ceramic MgO to the Ta. Find the number of ions that go through the MgO per second, knowing that the diffusion coefficient of the nickel ions in the MgO is 9*10^(-12) (cm^2)/s, and the lattice constant of Ni at 1400 ºC is 3.6*10^(-8) cm. 2. Relevant equations Fick's First Law: J=-D*gradient(n) , n being the concentration of the species in cause 3. The attempt at a solution The exercise is pretty straight forward. The real issue is to calculate the gradient. With the lattice constant and Ni's type of structure (FCC) it's easy to find Ni's concentration, but I am lacking another concentration to make the gradient. Is the 'ceramic' suppose to imply some lattice constant and/or type of structure? (All the information given is highlighted) Thanks in advance, Gonçalo X. R. N.