Eu3+-doped SiO2–Gd2O3 prepared by the sol–gel process: structural and optical properties

Abstract

Eu 3? -doped SiO 2 -Gd 2 O 3 materials were prepared by the sol-gel process changing the Si 4? :Gd 3? molar ratio of 100:0, 70:30, 50:50, 30:70 and 0:100 mol%. The amount of Eu 3? was fixed at 0.2 mol% in relation to the total number of moles of [Si 4? ? Gd 3? ] in the systems. The xerogels obtained from sols were heat-treated at 900, 1000 and 1100°C for 8 h. By TGA/DTA, XRD and Raman spectroscopy analysis, the formation of Gd 2 O 3 crystalline was detected. The microstrains and crystallite size were calculated by the Williamson-Hall and Scherrer's equation, respectively. The results showed the direct dependence of microstrain and crystallite size as a function of the heat-treatment temperature. By the FTIR analysis was observed the elimination of species like H 2 O, O-H and C-H groups, which can act as photoluminescence quenchers. All materials obtained in this work showed intense photoluminescence emission in the red region due to the 5 D 0 ? 7 F 2 transition of Eu 3? . The emission can be observed through the naked eye. The excited state lifetime shows to be dependent on values of refractive index and heat-treatment temperatures. The microstrain values affected the lifetime values and consequently the photoluminescence properties. In summary, the materials obtained in this work showed great absorption in the ultraviolet region promoting intense emission in the visible region, making them potential candidates for future applications in devices such as solar cells, image generator, biomarkers, among others.

White‐Light and Yellow/Blue Photoluminescence Emission Based on Dy3+‐Doped SiO2–Gd2O3 Composites

“…The results obtained in the calculations are shown in Table . The cubic materials present crystallite sizes around 41 and 62 nm, similar to materials obtained via this methodology . The lattice parameters calculated shows proximity with standard values of JCPDS card 00‐012‐0797, showing the effective incorporation of Dy 3+ in the host matrix and absence of major changes in the Gd 2 O 3 lattice parameters.…”

“…Dy 3+ ‐doped Gd 2 O 3 –SiO 2 composites were obtained by sol–gel process, and the molar ratio between Si 4+ and Gd 3+ ions was 70 and 30, respectively, according previous results . Tetraethyl orthosilicate – TEOS (Sigma Aldrich, Steinheim, Germany – 98%), Dy 2 O 3 and Gd 2 O 3 (Sigma Aldrich – 99.99%) powders were used as precursors.…”

“…Its low‐energy phonon lattice (600 cm −1 ), high thermal stability, compatibility with dopant due to the similar chemical and physical properties of RE 3+ , and its crystalline phase influences directly on RE 3+ photoluminescent properties. Gd 2 O 3 , when embedded in SiO 2 , have shown interesting results . In these glass‐ceramic systems, SiO 2 can act on the Gd 2 O 3 surface, reducing the Gd 2 O 3 surface defects, contributing to the photoluminescence properties like, for instance, lifetime values.…”

“…These works related that RE 3+ tend to occupy Gd 3+ sites in the Gd 2 O 3 . Gd 2 O 3 in the Gd 2 O 3 –SiO 2 system, obtained by sol–gel process, presented excellent optical properties as host matrix, favoring the photoluminescent RE 3+ such as Eu 3+ , Er 3+ , and Yb 3+ . Due to its similar ionic radii and valence, Dy 3+ can be introduced easily as a dopant in this host matrix.…”

SiO2-TiO2 doped with Er3+/Yb3+/Eu3+ photoluminescent material: A spectroscopy and structural study about potential application for improvement of the efficiency on solar cells

“…Binary oxide systems are excellent matrices for RE 3+ incorporation [23][24][25]. The variation of their composition significantly alters several properties of the materials, for example: refractive index, the solubility of the RE 3+ , the crystallite sizes, the resistivity, the surface roughness, the thickness, and others [26,27].…”