Temperature and Pressure Dependent Phase Transitions of β'-LiZr2(PO4)3 Studied by Raman Spectroscopy

Influence of rare earth elements (REEs) on the structure and optical properties of lithium zirconium phosphate (LZP)

The objective of presented study was to verify the concept of the formation of the REE–LZP solid solutions according to two different substitution models and to examine optical absorption properties of the samples for pigment application.

Formation of Amorphous H3Zr2Si2PO12 by Electrochemical Substitution of Sodium Ions in Na3Zr2Si2PO12 with Protons

The sodium ions in Na₃Zr₂Si₂PO₁₂ (NASICON) were substituted with protons using an electrochemical alkali-proton substitution (APS) technique at 400 °C under a 5% H₂/95% N₂ atmosphere. The sodium ions in NASICON were successfully substituted with protons to a depth of <400 μm from the anode. Completely protonated NASICON, i.e., H₃Zr₂Si₂PO₁₂, was obtained to a depth <40 μm from the anode, although complete protonation of NASICON cannot be achieved by ion exchange in aqueous acid. H₃Zr₂Si₂PO₁₂ was amorphous, whereas the partially protonated NASICON was crystalline, and its unit cell volume decreased with an increase in the extent of substitution. Amorphous H₃Zr₂Si₂PO₁₂ was prepared by pressure-induced amorphization of the NASICON framework, in which an internal pressure of ∼3.5 GPa was induced by the substitution of large sodium ions with small protons during APS at 400 °C.