Up- and Downconversion Luminescence Properties of Nd3+ Ions Doped in Bi2O3–BaO–B2O3 Glass System

Physical, optical, and luminescence properties of Nd3+ ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd2O3 concentrations in compositions (40-x)B2O3 : 40Bi2O3 : 20BaO : xNd2O3 (where x = 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between 4F3/2 → 4I9/2 (900 nm), 4F3/2 → 4I11/2 (1,060 nm), and 4F3/2 → 4I13/2 (1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm (λex=591 nm). The processes are associated with excited state absorption (ESA) from 4F3/2 level to 4D3/2 level and it is the radiative decay from the 4D3/2 to ground levels (4D3/2 → 4I13/2) which are responsible for the emission at 394 nm

Up-and Downconversion Luminescence Properties of Nd 3+ Ions Doped in Bi 2 O 3 -BaO-B 2 O 3 Glass System

Physical, optical, and luminescence properties of Nd 3+ ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd 2 O 3 concentrations in compositions (40-x)B 2 O 3 : 40Bi 2 O 3 : 20BaO : xNd 2 O 3 (where x = 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between 4 F 3/2 → 4 I 9/2 (900 nm), 4 F 3/2 → 4 I 11/2 (1,060 nm), and 4 F 3/2 → 4 I 13/2 (1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm ( ex = 591 nm). The processes are associated with excited state absorption (ESA) from 4 F 3/2 level to 4 D 3/2 level and it is the radiative decay from the 4 D 3/2 to ground levels ( 4 D 3/2 → 4 I 13/2 ) which are responsible for the emission at 394 nm

Structural and optical properties of multilayered un-doped and cobalt doped TiO2 thin films

The present investigation reports the effect of multilayers (1, 3 and 7 layers) and cobalt (Co) doping on structural and optical properties like transmittance, refractive index, extinction coefficient, etc. of TiO2 thin films prepared by a sol-gel spin coating technique. X-ray diffraction (XRD) and Raman spectroscopy were used to investigate the phase and structure of the prepared films which confirm the formation of single phase anatase TiO2 structure of the films. Morphology study by SEM indicate development of cracks with increase in number of layers at large scale but in the small (nano) scale the films are compact and smooth. Thickness study by cross sectional SEM shows increase in thickness with increase in number of layers. Energy Dispersive X-ray spectra were used to study the presence of cobalt in doped films. UV-Visible spectroscopy was used to study the transmittance of the films and spectroscopic ellipsometry was used to study the optical constants like refractive index and extinction coefficient which indicate the highest refractive index and the lowest extinction coefficient for single layered cobalt doped TiO2 thin films while 7 layered films show the lowest refractive index and the highest transmittance. Spectroscopic ellipsometry studies indicate increase in packing density of coated layers in Co-doped TiO2 films due to which refractive index as well as transmittance of these films are significantly more in comparison to undoped films. Photoluminescence spectra show increase in oxygen vacancies in Co-doped multilayered TiO2 films indicating increase in blue emission. Thus, the enhanced values of refractive index as well as transmittance and blue emission in Co-doped TiO2 multilayers films are promising for optical device applications