Predicting the stable phase in a nanoscaled oxides is not an easy task since the surface energies can influence the stability trend observed in bulk-phase diagrams. Prof. Ricardo Castro and his team have created a new concept of phase diagram by using calorimetric data to directly measure surface energies of yttria-zirconia nanoparticles (one of the most technologically relevant ceramic compositions to date). This result was highlighted as cover of the April issue of the Journal of the American Ceramic Society, where it was published [J. Am. Ceram. Soc. 98, 1377 (2015)]. Read the article at http://onlinelibrary.wiley.com/doi/10.1111/jace.13504/full.