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Updated: Nov 20, 2025
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Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides
Published on: May 29, 2018
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Kinetically stabilized ferroelectricity in bulk single-crystalline HfO2:Y
Xianghan Xu1,2, Fei-Ting Huang1,2, Yubo Qi2
1Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ, USA.
Nature Materials
|January 26, 2021
Summary
Researchers achieved bulk ferroelectricity in Hafnium Oxide (HfO2) using Yttrium doping. This breakthrough enables ferroelectric properties in larger crystals, paving the way for advanced electronic devices.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Hafnium oxide (HfO2) is a key material for semiconductor technology.
- Ferroelectricity in HfO2 is typically observed in ultrathin films, attributed to the polar orthorhombic phase.
- This ferroelectric phase was previously thought unattainable in bulk HfO2 crystals.
Purpose of the Study:
- To investigate the possibility of achieving ferroelectricity in bulk single-crystalline HfO2.
- To explore the role of Yttrium (Y) doping in stabilizing ferroelectric phases in HfO2.
- To understand the polymorphic nature and phase control of HfO2 for device applications.
Main Methods:
- Utilized a laser-diode-heated floating zone technique for crystal growth.
- Employed neutron diffraction and atomic imaging for crystallographic analysis.
- Performed density-functional-theory (DFT) calculations to model phase stabilization.
Main Results:
- Successfully synthesized bulk single-crystalline HfO2:Y exhibiting the polar orthorhombic (Pbc21) ferroelectric phase.
- Observed the antipolar Pbca phase in HfO2:Y at varying Y concentrations.
- Demonstrated switchable polarization with minimal wake-up effects and abundant ferroelectric domains.
- Identified Yttrium doping and rapid cooling as critical for stabilizing the ferroelectric phase in bulk.
Conclusions:
- Ferroelectricity is achievable in bulk single-crystalline HfO2:Y, overcoming previous size limitations.
- Phase control in HfO2 is influenced by doping and processing conditions.
- This work opens avenues for next-generation ferroelectric devices based on bulk HfO2.
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