Influence of annealing temperature on the spectroscopic properties of hydroxyapatite analogues doped with Eu³⁺

Abstract

Nanosized calcium and strontium hydroxyapatites doped with 2 mol% Eu3+ ions were obtained by using a microwave-assisted hydrothermal method.

Strontium Phosphate Composite Designed to Red-Emission at Different Temperatures

“…Two different types of crystallographic sites of Sr 2+ ions in hydroxyapatite lattice are current: four at the Sr(1) site with C 3 point symmetry situated on the ternary axes and six at the Sr(2) site with C S symmetry [ 30 , 31 ]. Moreover, in apatite structure, cis and trans symmetry of C S crystallographic site correlated with arrangements of Eu 3+ ions along the channel is well-known [ 8 ]. In the Sr 3 (PO 4 ) 2 matrix, there are two nonequivalent crystallographic sites of Sr 2+ ions: three at the Sr(1) site and six at the Sr(2) site.…”

“…The decay profiles and the lifetime values are alike to each other and only minor differences were observed. The decay times of Eu 3+ ions in Sr 10 (PO 4 ) 6 (OH) 2 –Sr 3 (PO 4 ) 2 are typical for this kind of ion and are longer than for strontium apatite [ 7 , 8 ], which is caused by the presence of Sr 3 (PO 4 ) 2 phase.…”

“…Strontium phosphate (Sr 10 (PO 4 ) 6 (OH) 2 –Sr 3 (PO 4 ) 2 ) composite doped with Eu 3+ ions was synthesised by microwave stimulated hydrothermal method and then post-treated at elevated temperature [ 7 , 8 ]. The Sr(NO 3 ) 2 (99.0% min Alfa Aesar, Karlsruhe, Germany), (NH 4 ) 2 HPO 4 (≥ 99.0% Fluka, Bucharest, Romania), Eu 2 O 3 (99.99% Alfa Aesar, Karlsruhe, Germany) and NH 3 ∙H 2 O (99% Avantor, Gliwice, Poland) for pH modification were used as substrates.…”

“…Apatite is applied in plenty industrial fields as catalysts, laser hosts, luminescent materials, gas sensors, ionic conductors and adsorbents [ 3 , 4 ]. Moreover, calcium phosphates are also used in implantology due to high similarity to the inorganic part of hard tissues in bones, high biocompatibility, osteoconductivity, nontoxicity, non-immunogenicity and bioactivity [ 5 , 6 , 7 ] Apatite doped with lanthanide ions are extensively investigated as bio-labels that can be used in in vitro and in vivo imaging [ 8 , 9 , 10 ].…”

“…In the present work, for the first time to the best of our knowledge [ 7 , 8 , 21 , 22 , 23 , 24 ], synthesis of strontium phosphate composite (Sr 10 (PO 4 ) 6 (OH) 2 –Sr 3 (PO 4 ) 2 ) co-doped with Eu 3+ and Eu 2+ ions prepared in the air at high temperature and the structural, morphological as well as spectroscopic properties have been studied.…”