«Ellestadite»-type anionic [PO4]3– → [SO4]2– substitutions in β-Ca3(PO4)2 type compounds: A new route to design the inorganic phosphors. Issue 16 (15th August 2022)

• Record Type: Journal Article
• Authors: Deyneko, Dina V.; Titkov, Vladimir V.; Fedyunin, Fedor D.; Spassky, Dmitry A.; Volkov, Sergey N.; Borovikova, Elena Yu.; Lazoryak, Bogdan I.; Aksenov, Sergey M.
• Is Part Of: Ceramics international. Volume 48:Issue 16(2022)
• Page Start: 24012
• Page End: 24020
• Publication Date: 2022-08-15
• Subjects: Crystal structure -- Phosphates -- Sulfates -- Mixed salts -- Anionic substitution -- Photoluminescence -- Tricalcium phosphate -- Inorganic phosphors -- Optical materials; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.05.077
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Sulfate anion plays an important role in the development of inorganic phosphors and is considered as the path for for the enhancement of the luminescent properties. The heterovalent [PO4 ] 3– → [SO4 ] 2– anion substitution in the β-Ca3 (PO4 )2 -type compounds was realized using the "ellestadite"-type strategy called by the analogy with the apatite-type structures. The novel compounds belonging to the Ca10.5–0.5 x – y M y (PO4 )7– x (SO4 ) x, M = Ca 2+, Mg 2+ and Zn 2+ series have been synthesized using high-temperature solid state reaction. The used isomorphous scheme was [PO4 ] 3– + ½ Ca 2+ = [SO4 ] 2– + ½ □ with the formation of the vacancy for the charge compensation. The successful incorporation of [SO4 ] 2– groups was approved by Fourier-transform infrared spectroscopy, EDX method, and powder X-ray diffraction analysis. It was found that the sulfur atoms predominantly occupied T2 sites in the anionic sublattice according to crystal structure refinement based on the analysis of interatomic distances. The photoluminescent properties were studied for the Eu 3+ -doped samples and it was shown that Zn 2+ -containing samples exhibit a 1.5 times higher intensity in comparison with Mg 2+ -containing substituted phosphates. Thus, a new "ellestadite"-type substitution in β-Ca3 (PO4 )2 -type structure significantly expands the crystal chemistry and give more insights into the deeper understanding of the dependence of luminescent properties on the cation distribution. The pathways of the [SO4 ] 2– incorporation into the crystal structures are discussed in details.