How high is the entropy in high entropy ceramics?

Abstract

In this Perspective, I raise the question whether the terms high entropy ceramics, high entropy nitrides, high entropy oxides, high entropy borides, etc., are meaningful considering the magnitude of the calculated configurational entropy. Here, the origin of Boltzmann's equation is reviewed and the implications for application are discussed. This back to the roots’ excursion may be helpful for approaching an answer to the question raised in the title and for re-evaluating literature reports connecting superior performance with configurational entropy of so-called high entropy ceramics.