Green-Emitting Gd(3)Ga(5)O(12): Tb(3+) Nanoparticles Phosphor: Synthesis, Structure, and Luminescence

Nano- and microceramics of Gd(3)Ga(5)O(12) garnet doped with 1 mol % Tb(3+) ions were synthesized via co-precipitation and high-temperature solid-state reaction methods. X-ray diffraction measurements confirmed the formation of the garnet structure with Ia3d space group in all investigated samples. Atomic force microscopy surface images and grain-size distribution diagrams of Gd(3)Ga(5)O(12): 1 mol % Tb(3+) nanoceramics with 300 and 400 g/mol of polyethylene glycol (PEG) were obtained. The relationship between the content of polyethylene glycol and the particle size of Gd(3)Ga(5)O(12): Tb(3+) phosphors was revealed. An intense broad band (λ (m) = 266 nm) related to spin-allowed 4f (8)-4f (7)5d (1) transitions of Tb(3+) ions was found in photoluminescence excitation spectra of Gd(3)Ga(5)O(12): Tb(3+) nanocrystalline ceramics with PEG-300 and PEG-400 at 300 K. The broad excitation band caused by spin-forbidden (λ (m) = 295 nm) 4f-5d transitions in Tb(3+) ions was additionally observed in the photoluminescence excitation spectra of Gd(3)Ga(5)O(12): Tb(3+) microceramics. Emission of Tb(3+) ions under X-ray and UV excitations is presented by two groups of sharp lines which correspond to (5)D(3) and (5)D(4) → (7)F(j) transitions of Tb(3+) ions with the most intense line at 546 nm ((5)D(4) → (7)F(5)). It was established that the increasing of PEG content leads to the decreasing of the X-ray and photoluminescence emission intensities.