Respected members, I am doing a study on Co, Cr, V and Ni based medium entropy alloys (i.e. NiCoCr, NiCoV and NiCoVCr) which are single phase FCC (confirmed through XRD). While doing the XPS analysis of these alloys, I noticed different charge states of elements along with metallic states. Interestingly the Charge states of Co goes from Co(0) to a mix of Co(2+) and Co(3+) when I substitute Cr with V in Ni-Co. And same goes from NiCoCrV sample. Theoretical results shows that inclusion of Vanadium creates very large lattice distortion compared to Cr which increases oxygen diffusivity through dislocation pipes during homogenization/solutionization followed by quenching to maintain single phase fcc structure.
So the reason I am having these multiple oxidation state can be attribute to fast oxygen diffusion due to large lattice distortion in NiCoV and NiCoVCr ?
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