Since the first report of ferroelectricity in a Si-doped HfO₂ film in 2011, HfO₂-based materials have attracted much interest from the ferroelectric materials and devices community. However, in HfO₂-based bulk materials, the ferroelectric phase is not the one with the lowest free energy. It is, therefore, crucial to identify the possible thermodynamic and kinetic drivers for such an unexpected phase formation. The main difference between this type of material and conventional perovskite-based ferroelectrics is the movement of oxygen ions upon polarization switching, which complicates the structural examination of samples. Nonetheless, concerted efforts in academia and industry have substantially improved our understanding of the material properties and root causes of the unexpected formation of the ferroelectric phase. These insights help us understand how to induce the polar phase even in bulk materials. In this Review, we discuss in depth the properties and origin of ferroelectricity in HfO₂-based materials, carefully evaluating numerous reports in the field, which are sometimes contradictory, and showing how thermodynamic and kinetic factors influence phase formation almost equally. We also survey possible applications and prospects for further development.

自2011 年首次报道 Si 掺杂 HfO _{2薄膜中的铁电性以来，HfO 2}基材料引起了铁电材料和器件界的极大兴趣。然而，在 HfO ₂基块体材料，铁电相不是自由能最低的相。因此，确定这种意外相形成的可能的热力学和动力学驱动因素至关重要。这种类型的材料与传统的基于钙钛矿的铁电体之间的主要区别在于氧离子在极化切换时的移动，这使样品的结构检查变得复杂。尽管如此，学术界和工业界的共同努力大大提高了我们对铁电相意外形成的材料特性和根本原因的理解。这些见解有助于我们了解如何在散装材料中诱导极性相。在这篇综述中，我们深入讨论了 HfO _{2中铁电的性质和起源}基材料，仔细评估了该领域的许多报告，这些报告有时是相互矛盾的，并展示了热力学和动力学因素如何几乎同等地影响相的形成。我们还调查了可能的应用和进一步发展的前景。