Preparation of undoped and Tb3+-doped fluorescent HfO2 spherical particles

Abstract

Undoped and Tb3+ -doped HfO2 spherical particles were prepared by a sol-gel method, by using hafnium tetra-t-butoxide (Hf(O-t-C4H9)4) as a precursor of hafnium dioxide, SPAN85 ® as a surfactant, mixed solvent of C2H5OH and n-C4H9OH, and H2O, followed by investigation of their structural and optical properties. Spherical particles with good morphology and comparatively high dispersibility were obtained from solutions with the molar ratio SPAN85 ® :H2O = 1:8-17.5, their sizes being 0.2-5 μm in diameter. Particles became small and aggregated when the molar ratio of H2O was more than 17.5, but became large when it was less than 8. Spherical particles heat treated at 400°C or below were amorphous, and those heat treated at 600°C or above were crystallized. Tb 3+ -doped HfO2 spherical particles showed green luminescence due to the 5 D4→ 7 FJ (J = 6, 5, 4, 3) transitions of the Tb 3+ ion, and relatively strong luminescence was observed both in dried gel particles and particles heat treated at 1000°C. These Tb 3+ -doped HfO2 spherical particles can be expected for new optical materials.

Blue-yellow photoluminescence from Ce3+→Dy3+ energy transfer in HfO2:Ce3+:Dy3+ films deposited by ultrasonic spray pyrolysis

“…HfO 2 can also be used for protective coatings due its thermal stability and hardness near to diamond in its tetragonal phase [20]. The large energy gap and low phonon frequencies of the HfO 2 [21] makes it appropriate as host material to incorporate rare earth ions, such as Ce 3+ [22], Er 3+ [23], Tb 3+ [24] and Eu 3+ [25], as well as Mn 2+ [26] and Sm 3+ [27] ions, which emit within their own energy levels.…”

Fabrication and Refractive Index Control of Transparent and Luminescent HfO2:Ln3+ (Ln3+ = Eu3+, Tb3+) Thin Films for Enhanced Surface Emissions

“…[19][20][21] Even for the HfO 2 host crystal, the 4f 8 → 4f 7 5d 1 excitation bands of Tb 3+ show a wavelength shift with the doping concentration due to the phase transformation. 11,13 Line emissions of the Tb 3+ ion are assigned to the intraconfigurational 5 D 4 → 7 F J transitions at 489 (J = 6), 543 (J = 5), 584 (J = 4), and 622 nm (J = 3). The PL intensity increases with the doping concentration increasing for the HfO 2 :Tb 3+ thin films.…”

“…10 Recent studies on HfO 2 :Ln 3+ nanoparticles and thin films have revealed that HfO 2 :Ln 3+ is an attractive phosphor material coming from the characteristics of HfO 2 : a high density, a large band-gap, the existence of polymorphs, a bioinert property, and so on. [11][12][13][14] We report herein the fabrication and characterization of HfO 2 :Ln 3+ thin films by the sol-gel method, focusing on their refractive index control and surface emission property.…”

Tantalatos de ítrio dopados com íons terras raras: avaliação das propriedades estruturais, fotoluminescentes e de cintilação para aplicações em fotônica e nanomedicina

“…Por esse motivo, a excitação em outros comprimentos de onda, em especial na região de 600 a 800 nm, têm sido utilizados recentemente para contornar o problema da absorção da água em 980 nm e do espalhamento da luz. No entanto, a excitação em 980 nm pode ainda ser utilizada em sistemas que apresentam um elevado rendimento quântico de emissão em baixas densidades de potência de excitação, como os sistemas em estudo neste projeto (BORGES et al, 2021;LI et al, 2021;SANADA et al, 2008).…”