Luminescence In Red Region Research Articles

Controlled fabrication of the strong emission YVO4:Eu3+ nanoparticles and nanowires by microwave assisted chemical synthesis

In this report, we are presenting the controlled fabrication results of the strong emission YVO4: Eu3+ nanoparticles and nanowires by microwave which is assisted chemical synthesis. The effects of incorporated synthesis conditions such as microwave irradiated powers, pH values and concentration of chemical composition on properties of nanomaterials are also investigated to obtain the controllable size and homogenous morphology. Morphological and optical properties of YVO4: Eu3+ prepared products which have been characterized by X-ray diffraction (XRD), field emission micrcroscopy (FESEM) and photoluminescence spectroscopy. As based from result of synthesized samples, we found that the changing of pH values, microwave irradiated powers and chemical composition rise to change reform the size and shape of materials from nanoparticles (diameter about 20nm) to wires shape (with about 500÷800nm length and 10÷20nm width). The photoluminescence (PL) spectroscopy measurements of YVO4: Eu3+ nanostructure materials under UV excitation showed that: the strong luminescence in red region with narrow lines corresponding to the intra-4f transitions of 5D0–7Fj (j=1, 2, 3, and 4) of Eu3+ ions with the highest luminescence intensity of 5D0→7F2 transition.

Upconversion luminescence properties of Er3+/Yb3+ in transparent α-Sialon ceramics

Er3+ stabilized transparent α-Sialon ceramics with upconversion (UC) luminescence properties were fabricated for the first time by hot press sintering method. The fabricated samples show better transparency as well as UC luminescence properties. Moreover, the effect of Yb2O3 as a sensitizer on UC properties was analyzed in Er-α-Sialon system. The change in Sialon phases and crystal structure were analyzed by X-ray diffraction. The chemical compositions and morphology of grains and intergranular phase were analyzed by EDS and Transmission Electron Microscopy, respectively. The UC emissions were observed around 527, 547 and 670nm corresponding to the 2H11/2, 4S3/2 and 4F9/2 transitions, respectively when excited by 980nm continuous wave (CW) laser diode. UC process in Er3+ is found to be two photon processes. Intense green UC luminescence was observed with Er3+ and low amount of Yb3+ addition but higher amount of Yb3+ addition shows higher UC luminescence in red region. The transparency was higher in higher Er2O3 and low Yb2O3 content Sialon that was around 60% in visible light region. The chromaticity was also calculated for different samples and high color purity above 90% was obtained for green and yellow emissions. The mechanical properties were also investigated in this study.