Pressure-induced charge amorphisation in BiNiO₃.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Electron order/disorder dictates material properties, mirroring states of matter.
• Charge ordered (CO) insulating states in mixed valence materials transition to metallic phases upon heating.
• Examples include Verwey transition in Fe3O4, colossal magnetoresistance in manganites, and superconductivity in BaBiO3.

Purpose of the Study:

• To report the observation of pressure-induced charge amorphization in a crystalline material.
• To investigate the behavior of BiNiO3 under varying pressure and temperature conditions.
• To provide fundamental insights into amorphization processes using charge states.

Main Methods:

• High-pressure experiments on BiNiO3.
• Structural and charge state analysis under pressure.
• Temperature-dependent measurements to observe phase transitions.

Main Results:

• BiNiO3 exhibits a charge distribution of Bi3+0.5Bi5+0.5Ni2+O3 with ordered Bi states at ambient pressure.
• At 4-5 GPa and below 200 K, BiNiO3 enters a charge glassy, insulating phase, despite maintaining a crystalline structure.
• Metallization occurs above 6 GPa, indicating a transition from the charge glassy state.

Conclusions:

• BiNiO3 demonstrates pressure-induced charge amorphization, analogous to atomic amorphization.
• The study highlights accessible melting of the charge glassy state under specific pressure/temperature conditions.
• This provides a novel system for studying amorphization phenomena through charge states.