Synthesis, Structural, and Optical Properties in Monoclinic Er:KYb(WO₄)₂ Nanocrystals

Abstract

Monoclinic-nondoped and erbium-doped KYb(WO4)2 nanocrystals around 50 nm were synthesized using the modified Pechini sol−gel method. Differential thermal and thermogravimetric analysis (DTA-TG) was used to study the thermal evolution of the precursor powder. X-ray powder diffraction (XRD) was used to confirm the presence of the monoclinic phase. We used electron microscopy techniques (SEM and TEM) to observe the morphology and particle size, and we estimated the particle size using Scherrer’s equation. The optical spectroscopy of the trivalent ytterbium and erbium ions in monoclinic KYbW nanocrystals was studied by absorption and emission measurements at low and room temperature. The energy of the Stark sublevel of ytterbium and erbium in the ground- and excited-state KYbW nanocrystals has been determined. After exciting at 940 nm, the green photoluminescence (4S3/2 → 4I15/2) and the 1.5 μm infrared (4I13/2 → 4I15/2) emissions were observed because of the energy transfer from the ytterbium 2F5/2 level to the 4I11/2 erbium level. The decay times of Yb3+ (2F5/2) and Er3+ (4I13/2) excited levels were also studied at room temperature.

In situ preparation of novel p–n junction photocatalyst BiOI/(BiO)2CO3 with enhanced visible light photocatalytic activity

“…The average crystallite sizes of the (BiO) 2 CO 3 and BiOI in BiOI/(BiO) 2 CO 3 composites were calculated according to the Scherrer formula [46].…”

Bismuth oxybromide promoted detoxification of cylindrospermopsin under UV and visible light illumination

“…The intense and narrow diffraction peaks imply the good crystallinity of the BiOBr samples. The average crystalline size of BiOBr was calculated to be 28.3 nm according to the Scherrer formula (1) [37]:…”

Photocatalytic activity of novel AgBr/WO3 composite photocatalyst under visible light irradiation for methyl orange degradation

“…With increasing AgBr content, the intensities of diffraction peaks of AgBr increased whereas those of WO 3 decreased simultaneously. The average crystalline sizes of AgBr on the surface of WO 3 were calculated to be 37.2 nm (catalyst TB-0.10), 47.7 nm (catalyst TD-0.20), 50.6 nm (catalyst TF-0.30), 56.8 nm (catalyst TG-0.40) and 58.4 nm (pure AgBr), respectively, by using Scherrer equation [54].…”