Dear Md. Sazzadur Rahman,

Vegards rule is applicated for a certain class of materials - solid solutions, alloys, mixing crystal systems. Normally, the A and B-materials must have the same crystal structure. This is necessary, that the mixing crystal exists within the whole concentration region x. Furthermore, the linear interpolation between the components A and B is valid only for the lattice constant. The Vegards rule can be applied for the gap energies too, but you have to consider additionally a bowing. This is an additive component b*x*(1-x) with b the bowing parameter. Therefore, it is useful to have a third value near x = 0,5.

With regards

R. Mitdank

Dear Rüdiger Mitdank ,

Thank you for your explanation. It really cleared some of my confusions.

Actually I am trying to obtain the 'absorption profile' of A(x)B(1-x) alloy (having same crystal structure) from the experimentally obtained absorption profile of A & B. Is it anyhow possible from Vegard's Rule?

I have another question:

Can b (bowing parameter) be negative? What should be the physical significance of b?

Best Regards.

I have performed an analysis on test basis for (Ag0.4Cu0.6)2ZnSnS4 material to see how much close result can be obtained, so that I can use it for my simulations. I got the following result (please check the attached file) after using a bowing parameters -0.3. Now I am kinda skeptic or wanna make sure if I can do use this for my simulation based research. I will highly appreciate any comment on this.