# High-Pressure X‑ray Diffraction Investigation of Fe0.9Al0.1VO4

## TL;DR

This study uses high-pressure X-ray diffraction to explore structural changes in Fe0.9Al0.1VO4, revealing phase transitions and volume collapses that could impact its use in photocatalysis and batteries.

## Contribution

The study reveals novel phase transitions and structural behavior in Fe0.9Al0.1VO4 under high pressure, differing from pure FeVO4.

## Key findings

- Fe0.9Al0.1VO4 undergoes a first-order phase transition at 2.85 GPa with a 9% volume collapse.
- A second phase transition to monoclinic structure occurs at 6.1 GPa, completing at 9.15 GPa with a 13% volume collapse.
- Al incorporation alters structural sequence and compressibility, affecting potential applications.

## Abstract

This study demonstrates that the
influence of cationic composition
on the phase behavior of vanadates under high pressure must be meticulously
considered. In this investigation, we report an in situ high-pressure
powder X-ray diffraction investigation on triclinic Fe0.9Al0.1VO4 (space group P1̅)
up to 11 GPa. The structural sequence of Fe0.9Al0.1VO4 is different than that of FeVO4. Our analysis
shows that Fe0.9Al0.1VO4 undergoes
a first-order structural phase transition at 2.85 GPa to another triclinic
structure described by the same space group with a volume collapse
of ∼9%. At 6.1 GPa, we observed the onset of a second phase
transition to a monoclinic structure (space group P2/c), with coexistence of both phases until 8.55
GPa. The transformation to the second phase is completed at 9.15 GPa,
with a volume collapse of ∼13%. On release of pressure to ambient
conditions, we have observed the coexistence of the second and first
high-pressure phases. The compressibility of the three phases of the
compound has been studied too. We have observed variations in structural
sequence and compressibility behavior due to Al incorporation. Since
electronic properties could be modified by tuning the crystal structure,
the present results could have an impact on applications of the studied
compound such as photocatalysis and batteries.