Characterization and Optical Properties of Cobalt-Doped β-Tricalcium Phosphate Nanoparticles: Microwave Refluxing and High-Temperature Sintering
Science of Sintering, vol.58, no.1, pp.99-109, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 58 Issue: 1
- Publication Date: 2026
- Doi Number: 10.2298/sos250120007a
- Journal Name: Science of Sintering
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Central & Eastern European Academic Source (CEEAS), Compendex, Directory of Open Access Journals, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Page Numbers: pp.99-109
- Keywords: Characterizations, Cobalt, Microwave Refluxing, Optical Properties, β-tricalcium phosphate
- Middle East Technical University Affiliated: Yes
Abstract
This study investigates the synthesis, characterization, and optical properties of cobalt-doped β-tricalcium phosphate (Co-βTCP) nanoparticles prepared via microwave refluxing and sintered at 1000°C for 2 hours. Incorporating Co2+ ions into the βTCP structure significantly influences its microstructural and optical properties. X-ray diffraction analysis (XRD) reveals a contraction of the crystal lattice upon Co2+ doping, attributed to the substitution of larger Ca2+ ions (ionic radius 0.099 nm) with smaller Co2+ ions (ionic radius 0.074 nm). This reduces lattice parameters, cell volume, crystallinity, and smaller crystallite sizes. The degree of crystallinity decreases from 89.56% for pure β-TCP to 57.81% for 3Co-β-TCP. Scanning electron microscopy (SEM) shows that Co2+ doping produces more homogeneous powder with enhanced interconnectivity while maintaining a spheroidal agglomerated structure. The average particle size decreases from approximately 300 nm for pure βTCP to 246 nm for 3Co-βTCP. Fourier transform infrared spectroscopy confirms the successful integration of Co2+ ions into the βTCP lattice, evidenced by peak broadening and intensity reduction. Notably, incorporating Co2+ ions induces a striking colour change from white to pink, with intensity proportional to cobalt concentration. UV-Vis spectroscopy reveals characteristic absorption peaks at 530 and 678 nm, associated with Co2+ electronic transitions. The unique optical properties of Co2+ ions doped in βTCP open up new possibilities for its use in bioimaging and drug delivery systems.