Trivalent gadolinium doped SrZrO3 perovskite ceramic: Sol-gel synthesis, paramagnetic centres, and luminescence studies

Abstract

Trivalent gadolinium (Gd3+) doped SrZrO3 perovskite ceramic has been prepared and their X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), and photoluminescence (PL) spectra are recorded. The existence of divalent and tetravalent cations in SrZrO3 along with a trivalent dopant ion provides an opportunity to study the effect of charge compensators on the system properties. The cubic phase is evident from XRD diffraction patterns of the product. The SEM analysis suggests the formation of voids and pores in the ceramics caused by gases those liberated during the process of sintering. The EPR technique has been used to investigate the un-doped and Gd3+-doped SrZrO3 ceramics. The un-doped SrZrO3 shows an axially symmetric EPR line with g∥ = 1.94 and g⊥ = 1.99, which is attributed to the Zr3+ ion. The Gd3+-doped SrZrO3 shows dominant EPR lines with effective g-values at 1.93, 2.04, and 2.35. Weak lines are observed at 2.72, 3.64, 6.08, and 15.5. At higher dopant concentrations, a broad line with geff ~2.1 is seen, together with low field lines. In the low field region of the EPR spectrum, lines appear because of immediate environment distortions. Under the excitation of 273 nm, the emission spectrum shows band 6P7/2 → 8S7/2 (313 nm). The emission at 313 nm suggests that the prepared sample can be used as a narrow band UV radiation source. Emission and EPR analysis of the sample confirm that Gd3+ is distributed in both Sr2+ and Zr4+ sites in the SrZrO3 matrix.