Ferroelectric topological textures have attracted growing interest as nanoscale polarization states with rich structural and functional behavior. Here, using phase-field simulations, we study the controlled formation and stability of polar bubbles in square lead zirconate titanate nanodots. We show that zero-field-stable polar bubbles can be generated through an electric-field poling–depoling process: an out-of-plane electric field first drives the nanodot into a nearly single-domain state, and subsequent field removal allows spontaneous relaxation into a toroidal bubble configuration. We further examine how geometry, epitaxial misfit strain, temperature, and electrostatic screening regulate bubble morphology and stability. The results show that intermediate geometries favor single-ring polar bubbles, very small lateral sizes stabilize stripelike domains, and larger, thinner nanodots promote multiring target-skyrmion states. Moderate screening and weak compressive strain further stabilize fully enclosed polar bubbles over a broad temperature range. Electric-field cycling reveals reversible switching through contraction, collapse, and reformation of the ringlike domain wall. These results provide a unified physical picture of polar-bubble formation and tunability in confined ferroelectric nanostructures, offering insight into the mechanisms governing nanoscale ferroelectric textures.

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• Ferroelectric domains
• Ferroelectric phase transition
• Ferroelectrics
• Nanoparticles
• Phase-field modeling