Fluorite oxides, such as ${\mathrm{HfO}}_2$, exhibit rich and tunable phase behaviors, making them promising candidates for next-generation electronic devices. In this field, a key challenge consists in the design of amorphous ${\mathrm{HfO}}_2$-based high-$k$ materials with both structural and performance stability. Here, using molecular dynamics simulations supported by experimental measurements, we reveal that Ba doping stimulates a polyamorphic transition in ${\mathrm{HfO}}_2$, yielding a semiordered amorphous phase characterized by amorphized oxygens embedded within an ordered metal sublattice. We find that this phase arises from degenerate short-range symmetry breaking modes, consistent with Pauling’s parsimony rule. Notably, the semiordered amorphous structure is thermodynamically stable and displays a wider bandgap and higher dielectric constant than the conventional continuous-random-network amorphous structure, owing to suppressed subgap states and increased Born effective charges. We further demonstrate that this structural motif generalizes to Ba-, Sr-, and Ca-doped ${\mathrm{HfO}}_2$ and ${\mathrm{ZrO}}_2$, establishing a broadly applicable strategy for designing high-performance amorphous dielectrics.

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• Band gap
• Dielectric properties
• Structural properties
• Amorphous materials
• Amorphous semiconductors
• Dielectrics