Are There Ordering Effects in Ba(Pb,Bi)O3 and (Ba,K)BiO3?
A simple model is presented for the origin of the wide nonmetallic ranges in the (Ba, K)(Bi, Pb)O 3 alloy phase diagram, proposing that the semiconducting behaviour is caused by the presence of incommensurate oxygen breathing-type charge density waves as well as Bi/Pb ordering waves. The model is studied for large variety of supercell configurations using a simple, yet realistic tight-binding Hamiltonian. Good agreement with experiment is found. Crucial predictions of the model can be tested by diffuse elastic scattering experiments.
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