Abstract
AbstractNine silicates with the apatite structure type (space group P63/m) containing both rare‐earth elements (REEs: Pr, Nd, Sm, Tb, Ho and Er) and various metals (K, Sr, Ba and Cd) were synthesised by high‐temperature flux‐growth techniques and characterised by single‐crystal X‐ray diffraction, scanning electron microscopy, Raman spectroscopy and laser‐induced photoluminescence spectroscopy. In all of the compounds, the 6h Wyckoff position is predominantly or solely occupied by REE3+ cations, whereas the cations shows a mixed occupancy at the larger, nine‐coordinate 4f site with 55–75 % of REE3+ cations and 45–25 % of other metal cations. The O4 (“free” oxygen) site is fully occupied by O2– anions, except for a Ba–Pr member with full occupancy by F– anions. The refined formulas are Cd2Er8(SiO4)6O2, Cd2Tb8(SiO4)6O2, KHo9(SiO4)6O2, KTb9(SiO4)6O2, KSm9(SiO4)6O2, Sr2Nd8(SiO4)6O2, Ba2Nd8(SiO4)6O2, Ba2Sm8(SiO4)6O2 and Ba4Pr6(SiO4)6F2. Changes in the metaprism twist angle (φ) and correlations between the unit‐cell parameters, average cationic radii (of M+/M2+–REE3+ pairs) and the chemistry of both the synthesised M+/M2+–REE3+ silicate apatites and those reported previously are evaluated. Photoluminescence measurements of undoped samples yielded emission bands in the visible region from green to red; therefore, these compounds are potential candidates for luminescent materials.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
