Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, a simple thermodynamic model, and a five-component oxide formulation, we demonstrate beyond reasonable doubt that entropy predominates the thermodynamic landscape, and drives a reversible solid-state transformation between a multiphase and single-phase state. In the latter, cation distributions are proven to be random and homogeneous. The findings validate the hypothesis that deliberate configurational disorder provides an orthogonal strategy to imagine and discover new phases of crystalline matter and untapped opportunities for property engineering.

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The entropy landscape of high‐entropy carbides can be used to understand and predict their structure, properties, and stability. Using first principles calculations, the individual and temperature‐dependent contributions of vibrational, electronic, and configurational entropies are analyzed, and compare them qualitatively to the enthalpies of mixing. As an experimental complement, high‐entropy carbide thin films are synthesized with high power impulse magnetron sputtering to assess structure and properties. All compositions can be stabilized in the single‐phase state despite finite positive, and in some cases substantial, enthalpies of mixing. Density functional theory calculations reveal that configurational entropy dominates the free energy landscape and compensates for the enthalpic penalty, whereas the vibrational and electronic entropies offer negligible contributions. The calculations predict that in many compositions, the single‐phase state becomes stable at extremely high temperatures (>3000 K). Consequently, rapid quenching rates are needed to preserve solubility at room temperature and facilitate physical characterization. Physical vapor deposition provides this experimental validation opportunity. The computation/experimental data set generated in this work identifies “valence electron concentration” as an effective descriptor to predict structural and thermodynamic properties of multicomponent carbides and educate new formulation selections.

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Niobium-doped, {100} textured, gradient-free, lead zirconate titanate (PZT) films were fabricated from solutions with different lead contents. Film lead content was controlled through changes in the average solution lead excess from 14.7% to 17 at.%. The low field dielectric response as well as the polarization-electric field hysteresis loops were not a strong function of lead content. However, films with lower lead contents in the precursor tended to withstand higher poling fields than films prepared from more lead-rich precursors. Although no residual PbO was observed at the grain boundaries, films prepared from more lead-rich solutions had higher levels of grain-boundary porosity, lower breakdown strengths, and lower threshold electric fields at which cracking was observed.