Phase transition and optical properties of Ba1-xZnxAl2O4:0.1% Eu3+ prepared via citrate sol-gel method

Effects of Varying Alx Moles on the Structure and Luminescence Properties of ZnAlxO1.5x + 1:0.1% Tb3+ Nano Phosphor Prepared using Citrate sol-gel Method

“…When x ≥ 1.5, the (311) diffraction peak shifts towards higher diffraction angle signifying a decrease in lattice constant. Meaning that some of the Al 3+ (ionic radius = 0.53 Å [7,34]) are occupying the Zn 2+ (ionic radius = 0.74 Å [9,34]) site. This behaviour can be explained using the Vegard's law [35,36] which suggests that the substitution or replacement of a certain ion with the smaller or bigger ionic radius is expected to shrink or expand the lattice constant, respectively.…”

“…The ZnAl2O4 normally crystallizes in the cubic crystal structures of the 3 ̅ space group, where Zn and Al respectively occupies the tetrahedral (Td) and octahedral (Oh) sites in the crystal matrix while oxygen atoms occupies the Wyckoff 32e position located at (u, u, u), where u ≈ 0.25 [1,16,17]. The positioning of the atoms or the structural configuration of the ZnAl2O4 depends on synthesis parameter such as the temperature [18,19] or concentration of the constituent elements [9,15,20]. These can lead in the crystallisation of metal ion in the normal (ZnAl2O4) configuration as described above (where Zn occupies Td and Al occupies Oh sites) or in an inversion (Al[ZnAl]2O4) configuration where the Td is now fully occupied by Al ion and the Oh sites is half-sheared by Al and Zn ions.…”

“…Most researchers introduce foreign ions (i.e. dopants) mostly form the lanthanides or rare earths within the different host at various doping concentrations [7][8][9][22][23][24]. Trivalent terbium ion (Tb 3+ ) is one of the most explored dopant due to its emission broadband covering the entire visible wavelength with an intense green emission colour around 525-560 nm [19,[22][23][24][25].…”

“…In the past few decades, metal oxides (MO) have enticed many researches in different field due to their unique physical and chemical properties [1]. MO are on the cutting edge of technology in various field of science such as water splitting [2][3][4], energy storage and conversions [5,6], photoluminescence (PL) [7][8][9] and transparent conducting oxide [1,10,11]. This is because of their band gap located directly at the Г point which was determined theoretically and experimentally to be around few electron volts (eV) [12][13][14].…”

“…3 (b)), which subsequently affect the lattice constant.The stacked zoomed analysis of the ZnO (101) and ZnAl2O4 (311) displayed inFig. 3 (b)shows that both peaks are shifting towards a lower diffraction angle as x increases up to 1.5 resulting in the expansion of the lattice constant[9,15]. On the ZnAl2O4 phase, this can be caused by the excess Zn 2+…”