Controllable Crystalline Phases of Multi-Cation Oxides.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Multi-cation oxides are crucial for solid-state applications due to their diverse functionalities.
• Vast compositional and structural complexity limits systematic exploration and rational design of these materials.
• Current material discovery relies on dispersed compositions under varied synthesis conditions.

Purpose of the Study:

• To construct a comprehensive crystalline-phase map for multi-cation rare-earth titanates.
• To understand the emergence and characteristics of different crystal phases (cubic, hexagonal, orthorhombic).
• To develop a machine learning approach for predictive exploration of stable oxide phases.

Main Methods:

• Experimental synthesis and characterization of multi-cation rare-earth titanates.
• X-ray diffraction, electron microscopy, and first-principles calculations for crystal structure analysis.
• Development and application of a machine learning procedure for phase map construction.

Main Results:

• A crystalline-phase map revealing cubic, hexagonal, and orthorhombic phases dependent on composition and temperature.
• Systematic changes in crystal structures across different phases were observed and characterized.
• Configurational entropies correlate with phase boundaries, supporting experimental observations.

Conclusions:

• The study establishes a systematic understanding of phase formation in multi-cation rare-earth titanates.
• Machine learning enables efficient prediction of stable crystalline phases within a large compositional space.
• Findings facilitate the rational design of multi-cation oxides with desired structures for advanced applications.