Alkali Metal Substitution for Modulating Three-Dimensional Halide Double Perovskite Ferroelectric

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Organic-inorganic hybrid halide double perovskites are crucial for applications like data storage and signal processing.
• Developing ferroelectric halide double perovskites with alkali metal components remains a significant challenge.
• Alkali metal incorporation is key to achieving novel functionalities in these materials.

Purpose of the Study:

• To synthesize a novel homochiral K/Bi-based halide double perovskite ferroelectric.
• To investigate the structural, phase transition, and ferroelectric properties of the new material.
• To explore the impact of alkali metal substitution on ferroelectric characteristics.

Main Methods:

• Fabrication of a K/Bi-based halide double perovskite using an alkali metal substitution strategy.
• Structural analysis to determine the crystal framework and topology (Schläfli symbol 6^6).
• Phase transition analysis at 357 K and 420 K, identifying symmetry-breaking for ferroelectricity.

Main Results:

• Successful synthesis of (S-3-hydroxypyrrolidinium)2KBiBr6, a homochiral K/Bi-based halide double perovskite ferroelectric.
• The material exhibits ferroelasticity and ferroelectricity with a remnant polarization (Pr) of 1.86 μC cm⁻² and a coercive field (Ec) of 1.4 kV cm⁻¹.
• Alkali metal substitution maintained Pr while reducing Ec by 17.6%, indicating enhanced stability and performance.

Conclusions:

• The study introduces a new class of alkali metal-containing hybrid bimetal halides.
• The synthesized material demonstrates promising ferroelectric and ferroelastic properties.
• This work provides valuable insights for designing stable, multifunctional ferroelectric materials.