“…Nanoparticles of ZnAl 2 O 4 doped with Tb (1.0 mol %) and pure ZnAl 2 O 4 were synthesized by a citrate sol gel method at 1170 K [23]. Stoichiometric quantities of nitrates of Zn and Al materials were dissolved in distilled water and 0.1-1.0 mole percent of Terbium nitrate was added to it at the initial stage for better homogeneity.…”
“…Nanoparticles of ZnAl 2 O 4 doped with Tb (1.0 mol %) and pure ZnAl 2 O 4 were synthesized by a citrate sol gel method at 1170 K [23]. Stoichiometric quantities of nitrates of Zn and Al materials were dissolved in distilled water and 0.1-1.0 mole percent of Terbium nitrate was added to it at the initial stage for better homogeneity.…”
“…In the hydrated materials, the broad excitation band in the higher energy region (235-315 nm) was composed by two bands owing to the energy transference from the BTC to Eu 3+ . One band was centered around 265 nm and was attributed to (BTC)O 2-→Eu 3+ LMCT [29,[38][39][40]. The other band, centered at 290 nm, corresponded to the BTC singlet transition S 0 →S n [41][42][43] with subsequent energy transfer to Eu 3+ .…”
Layered double hydroxides (LDHs) containing Eu 3+ activators were synthesized by coprecipitation of Zn 2+ , Al 3+ , and Eu 3+ in alkaline NO 3 − -rich aqueous solution. Upon calcination, these materials transform into a crystalline ZnO solid solution containing Al and Eu. For suitably low calcination temperatures, this phase can be restored to LDH by rehydration in water, a feature known as the memory effect. During rehydration of an LDH, new anionic species can be intercalated and functionalized, obtaining desired physicochemical properties. This work explores the memory effect as a route to produce luminescent LDHs intercalated with 1,3,5-benzenetricarboxylic acid (BTC), a known anionic photosensitizer for Eu 3+ . Time-dependent hydration of calcined LDHs in a BTC-rich aqueous solution resulted in the recovery of the lamellar phase and in the intercalation with BTC. The interaction of this photosensitizer with Eu 3+ in the recovered hydroxide layers gave rise to efficient energy transfer from the BTC antennae to the Eu 3+ ions, providing a useful tool to monitor the rehydration process of the calcined LDHs.
“…The energy levels approach the more distinct atomic levels as particle size decreases. The reduction of absorbance might have taken place due to agglomeration of nanoparticles [ 25 , 26 , 27 ]. Figure 5 Diffused reflectance UV–Vis spectra of a) undoped CuCr 2 O 4 b) 0.01, c) 0.02, and d) 0.03 La doped CuCr 2 O 4 .…”
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