Tens of micron-sized unilamellar nanosheets of Y/Eu layered rare-earth hydroxide: efficient exfoliation via fast anion exchange and their self-assembly into oriented oxide film with enhanced photoluminescence
نویسندگان
چکیده
Layered rare-earth hydroxide (LRH) crystals of (Y0.95Eu0.05)2(OH)5NO3·nH2O with a lateral size of ∼ 300 μm and a thickness of ∼ 9 μm have been synthesized via a hydrothermal reaction of mixed nitrate solutions in the presence of mineralizer NH4NO3 at 200 °C for 24 h. LRH exhibits the ability to undergo intercalation and anion exchange with DS- (C12H25OSO3-) via hydrothermal treatment. Compared with traditional anion exchange at room temperature, hydrothermal processing not only shortens the anion exchange time from 720 to 24 h but also increases the basal spacing. The arrangements of DS- in the interlayer of LRH are significantly affected by the DS- concentration and reaction temperature, and the basal spacing of the LRH-DS sample in the crystal edge is assumed to be larger than that in the crystal center. A higher DS- concentration and reaction temperature both induce more intercalation of DS- anions into the interlayer gallery, thus yielding a larger basal spacing. Unilamellar nanosheets with a lateral size of ≽60 μm and a thickness of ∼ 1.6 nm can be obtained by delaminating LRH-DS in formamide. The resultant unilamellar nanosheets are single crystalline. Transparent (Y0.95Eu0.05)2O3 phosphor films with a uniform [111] orientation and a layer thickness of ∼ 90 nm were constructed with the nanosheets as building blocks via spin-coating, followed by proper annealing. The oriented oxide film exhibits a strong red emission at 614 nm (the 5D0-7F2 transition of Eu3+), whose intensity is ∼ 2 times that of the powder form owing to the significant exposure of the (222) facets.
منابع مشابه
Hydrothermal-assisted exfoliation of Y/Tb/Eu ternary layered rare-earth hydroxides into tens of micron-sized unilamellar nanosheets for highly oriented and color-tunable nano-phosphor films
Efficient exfoliation of well-crystallized (Y0.96Tb x Eu0.04-x )2(OH)5NO3 · nH2O (0 ≤ x ≤ 0.04) layered rare-earth hydroxide (LRH) crystals into tens of micron-sized unilamellar nanosheets has been successfully achieved by inserting water insoluble oleate anions (C17H33COO(-)) into the interlayer of the LRH via hydrothermal anion exchange at 120°C, followed by delaminating in toluene. The inter...
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