Figure 68.
Ellingham Richardson diagram showing the Gibbs free energy for several metal oxides together with Gibbs free energy lines for hydrogen and the H+ radical,143,145,254 present (among many other ionized species) in a hydrogen-containing plasma.255 Other versions of Ellingham diagrams with several types of higher-order plasma-related hydrogen radicals have been published in refs (145, 237, 253, and 256−258) (see also Figure 59). The figure is reproduced with permission from ref (259) under an open access Creative Common CC BY license. Copyright 2022, MDPI.