Coupled Chemical and Mechanical Control of Phase Stability in Lanthanide-Substituted BiVO 4

Sypkes, Kathryn I. [University of Sydney, NSW (Australia)]; Maynard-Casely, Helen E. [Australian Centre for Neutron Scattering (ANSTO), Kirrawee, NSW (Australia)] (ORCID:0000000163649665); Ridley, Christopher J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000230609656); Kennedy, Brendan J. [University of Sydney, NSW (Australia)] (ORCID:0000000271874579)

doi:10.1021/acs.jpcc.6c01299

DOE OSTI · 3384947

Coupled Chemical and Mechanical Control of Phase Stability in Lanthanide-Substituted BiVO 4

Sypkes, Kathryn I. [University of Sydney, NSW (Australia)]·Maynard-Casely, Helen E. [Australian Centre for Neutron Scattering (ANSTO), Kirrawee, NSW (Australia)] (ORCID:0000000163649665)·Ridley, Christopher J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000230609656)·Kennedy, Brendan J. [University of Sydney, NSW (Australia)] (ORCID:0000000271874579)

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Abstract

Doping is widely used to enhance the photoelectrochemical performance of BiVO 4 , yet solubility limits and polymorphic stability constrain compositional tuning. Here, in this study, the role of trivalent cation substitution (Ln = La, Nd, Dy, Ho, Y) on pressure-induced phase transformations in Bi 1–x Ln x VO 4 (x ≤ 0.5) is described. Powder X-ray and neutron diffraction reveal that increasing Ln content stabilizes the tetragonal zircon-type polymorph under ambient conditions, while applied pressures of up to ∼5 GPa promote conversion to the monoclinic fergusonite-type polymorph. In-situ neutron diffraction on Bi 0.8 La 0.2 VO 4 shows a reversible monoclinic to tetragonal transition near 2–3 GPa with a bulk modulus of 147 GPa. The extent of conversion depends strongly on dopant identity, concentration, and synthetic route, with mixed-phase solid-state samples converting more efficiently than phase-pure coprecipitated materials. These results demonstrate pressure as a viable pathway to access metastable, doped BiVO 4 compositions beyond conventional solubility limits.

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Sypkes, Kathryn I. [University of Sydney, NSW (Australia)], Maynard-Casely, Helen E. [Australian Centre for Neutron Scattering (ANSTO), Kirrawee, NSW (Australia)] (ORCID:0000000163649665), Ridley, Christopher J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000230609656), Kennedy, Brendan J. [University of Sydney, NSW (Australia)] (ORCID:0000000271874579). 2026-06-08. Coupled Chemical and Mechanical Control of Phase Stability in Lanthanide-Substituted BiVO 4. https://doi.org/10.1021/acs.jpcc.6c01299

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