Direct Single Crystal to Amorphous Transformation and Memory Effect in AlPO₄-17

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Amorphous materials are typically synthesized through methods like rapid quenching or sol-gel processes.
• Pressure-induced amorphization offers an alternative route to create amorphous solids.
• Aluminophosphate-17 (AlPO4-17) is a crystalline porous material.

Purpose of the Study:

• To investigate the direct transformation of single-crystal AlPO4-17 into an amorphous state under pressure.
• To characterize the structural evolution and properties of the pressure-induced amorphous material.
• To explore the potential for synthesizing novel amorphous materials with controlled structures.

Main Methods:

• Single crystals of AlPO4-17 were subjected to high-pressure treatment.
• X-ray diffraction was used to analyze structural changes during compression and decompression.
• Microscopic observations were employed to assess the morphology of the transformed material.

Main Results:

• Single crystals of AlPO4-17 directly transformed into an amorphous state starting at 0.6 GPa, without polycrystalline fragmentation.
• The amorphous material preserved the original single-crystal morphology and the orientation of remnant crystalline domains.
• Compression primarily occurred around the empty pores in the xy plane, leading to pore collapse by 2.5 GPa.
• A notable memory effect was observed, with the amorphous material expanding significantly upon decompression.

Conclusions:

• Pressure-induced amorphization is a viable method for creating amorphous materials from crystalline precursors while preserving structural form.
• The observed amorphization mechanism highlights a direct structural relationship between the crystalline and amorphous states.
• This process enables the synthesis of topologically ordered amorphous materials, potentially leading to "perfect glasses" with superior mechanical properties.