Year: 2024
Type: article
Abstract: During the synthetic exploration targeting the polycrystalline compound LK-99, an unexpected phase, Pb5(PO4)3OHδ, was identified as a byproduct. We elucidated the composition of this compound through single-crystal X-ray diffraction analysis. Subsequent synthesis of the target compounds was achieved via high-temperature solid-state pellet reactions. The newly identified Pb5(PO4)3OHδ was found to adopt an orthorhombic crystal structure with the space group Pnma, representing a unique structure differing from the hexagonal apatite phases of Pb10(PO4)6O and Pb5(PO4)3OH. Comprehensive temperature- and magnetic field-dependent magnetization studies unveiled a temperature-independent magnetic characteristic of Pb5(PO4)3OHδ. Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy was employed to decipher the origins of the phase stability and confirm the presence of hydrogens in Pb5(PO4)3OHδ. These investigations revealed the presence of protonated oxygen sites, in addition to the presence of interstitial water molecules within the structure, which may play critical roles in stabilizing the orthorhombic phase.
Institution: Michigan State University
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,220
Funder: U.S. Department of Energy
Award: G3691352189
OpenAlex ID: W4404906356