Structural, optical and magnetic properties of samarium doped zinc phosphate glasses embedded with nickel nanoparticles

Abstract

Two series of 40ZnO-(60-x)P2O5-xSm2O3 and 40ZnO-(59-y)P2O5-Sm2O3- yNiO glasses are prepared by melt-quenching technique with 1.0 = x = 4.0 mol% and 0.5 = y = 2.0 mol% respectively. The glass is characterized by X-Ray Diffractometer (XRD), Transmission Electron Microscope (TEM), High Resolution Transmission Electron Microscope (HRTEM), Fourier Transform Infrared (FTIR) spectrometer, Raman spectrometer, UV-Vis NIR spectrophotometer, Photoluminescence (PL) spectrometer, Vibrating Sample Magnetometer (VSM) and Electron Spin Resonance (ESR) spectrometer. The XRD pattern confirms the amorphous nature of the glass and the TEM image reveals the existence of nickel nanoparticles (Ni NPs) with average size ~8 nm. Meanwhile, HRTEM reveals the lattice spacing of face centered cubic (FCC) structure of nickel is 0.35 nm at (100) plane. Four major IR absorption peaks are found to be at 723 cm-1, 916 cm-1, 1081 cm-1 and 1280 cm-1 corresponding to stretching vibration of symmetric (P-O-P), asymmetric (P-O-P), asymmetric (P-O-) and asymmetric (P=O) respectively. Raman spectra display two significant peaks at 708 cm-1 and 1201 cm-1 attributed to the symmetric and asymmetric stretching vibrations of P-O-P, respectively. The Raman intensities for both peaks exhibit a rapid decrease with the increase of Ni NPs concentration. The absorption spectra of samarium ions consist of five bands attributed to absorption from the ground state 6H5/2 to the excited states 6F1/2, 6F3/2, 4F5/2, 4F7/2 and 6F9/2. The surface plasmon resonance (SPR) peaks of Ni NPs are detected at 433 nm and 475 nm. Photoluminescence emission exhibits four peaks corresponding to 4G5/2 - 6H5/2, 6H7/2, 6H9/2, and 6H11/2 transitions. It is observed that all peaks experience significant quenching effect with increasing concentration of Ni NPs, suggesting that there is a strong energy transfer from excited samarium ions to the nickel ions. The glass magnetization and susceptibility in magnetic field up to 12 kOe at room temperature is found to be in the range of (0.11-2.02) x10-2 emu/g and (0.09-1.68) x10-6 emu/Oeg respectively. The obtained hysteresis curve and g-factor value of 1.99 to 2.34 indicate that the glass samples are superparamagnetic. It is concluded that samarium doped zinc phosphate glass embedded with nickel nanoparticles could be useful for magneto-optical and solid state devices.