Structural and optical properties of green emitting Y2SiO5∶Tb3+and Gd2SiO5∶Tb3+nanoparticles for mod

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The optical and structural properties of Tb3+-doped yttrium and gadolinium oxyorthosilicate(Y2SiO5 and Gd2SiO5)phosphors were analyzed.The samples were synthesized via sol-gel combustion method using organic fuel.The phase purity and structural properties of the samples were determined via combined approach of pow-der X-ray diffraction,Fourier transformation infrared(FTIR)and transmission electron microscopy(TEM).X-ray measurements revel monoclinic crystal lattice with P21/c symmetry for both M2SiO5(pure host)and M2SiO5∶Tb3+(doped)silicates,irrespective of the nature of metal(Y or Gd),presence or absence of Tb3+in lattice and change in calcination temperature up to 1050℃.FTIR analysis was applied to confirm the bonding of prepared materials.The appearance of bands corresponding to SiO4 tetrahedra(880-1020 cm-1)suggest the layered structure and support the diffraction measurements.TEM micro-graphs confirm the synthesis of spherical nanoparticles with filled morphology,narrow size distribution and slightly agglomerated crystallites of the samples.The ele-mental composition of prepared materials was determined using energy dispersive X-ray spectroscopy.The spectra show peaks only for elements assimilated within the host framework.The photoluminescence(PL)emission spectra of Tb3+-doped samples show 5D4 → 7FJ(J=3-6)transi-tions under 254 nm-excitation.The dominant peak at 544 nm for 5D4 → 7F5 transition is responsible for the emission of green light on ultraviolet-visible excitation in both the Tb3+-doped host matrixes.Owing to advantageous properties like intense PL and high crystallinity,these nanophosphors could possess potential applications in the mercury free lighting sources and optoelectronic devices.
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