Structural, optical and magnetic properties of Y3-0.02-xEr0.02Yb x Al5O12 (0 < x < 0.20) nanocrystals: effect of Yb content

Fabrication and optical properties of garnet ceramics based on Y3-xScxAl5O12 doped with ytterbium and erbium

Optical ceramics YSAG:Yb,Er with an average grain size of 6 ± 1 microns were fabricated by vacuum sintering of nanocrystalline powders of the compositions Y2.34Yb0.45Er0.09Sc0.20Al4.92O12, Y1.66Yb0.45Er0.09Sc1.00Al4.80O12 and Y0.96Yb0.45Er0.09Sc1.70Al4.80O12. The linear transmittance coefficients of the YSAG:Yb,Er ceramic samples exceed 80% in the visible and infrared regions. The refractive index of ceramics increased from 1.827 to 1.859 with an increase in scandium content. The effect of scandium cations at the dodecahedral site of the YSAG crystal lattice on the optical and luminescence characteristics of Yb3+ (2F7/2 and 2F5/2) and Er3+ (4I15/2, 4I13/2, 4F9/2 and 4S13/2) in wavelength ranges of 530-690 nm, 890-1080 nm, and 1430-1680 nm was revealed.

Microwave-Assisted Preparation of Luminescent Inorganic Materials: A Fast Route to Light Conversion and Storage Phosphors

Luminescent inorganic materials are used in several technological applications such as light-emitting displays, white LEDs for illumination, bioimaging, and photodynamic therapy. Usually, inorganic phosphors (e.g., complex oxides, silicates) need high temperatures and, in some cases, specific atmospheres to be formed or to obtain a homogeneous composition. Low ionic diffusion and high melting points of the precursors lead to long processing times in these solid-state syntheses with a cost in energy consumption when conventional heating methods are applied. Microwave-assisted synthesis relies on selective, volumetric heating attributed to the electromagnetic radiation interaction with the matter. The microwave heating allows for rapid heating rates and small temperature gradients yielding homogeneous, well-formed materials swiftly. Luminescent inorganic materials can benefit significantly from the microwave-assisted synthesis for high homogeneity, diverse morphology, and rapid screening of different compositions. The rapid screening allows for fast material investigation, whereas the benefits of enhanced homogeneity include improvement in the optical properties such as quantum yields and storage capacity.