Photoluminescence of Perovskite Nanosheets Prepared by Exfoliation of Layered Oxides, K₂Ln₂Ti₃O₁₀, KLnNb₂O₇, and RbLnTa₂O₇ (Ln: Lanthanide Ion)

Abstract

Luminescent perovskite nanosheets were prepared by exfoliation of single- or double-layered perovskite oxides, K2Ln2Ti3O10, KLnNb2O7, and RbLnTa2O7 (Ln: lanthanide ion). The thickness of the individual nanosheets corresponded to those of the perovskite block in the parent layered compounds. Intense red and green emissions were observed in aqueous solutions with Gd1.4Eu0.6Ti3O10- and La0.7Tb0.3Ta2O7-nanosheets, respectively, under UV illumination with energies greater than the corresponding host oxide band gap. The coincidence of the excitation spectrum and the band gap absorbance indicates that the visible emission results from energy transfer within the nanosheet. The red emission intensity of the Gd1.4Eu0.6Ti3O10-nanosheets was much stronger than that of the La0.90Eu0.05Nb2O7-nanosheets reported previously. The strong emission intensity is a result of a two-step energy transfer cascade within the nanosheet from the Ti-O network to Gd(3+) and then to Eu(3+). The emission intensities of the Gd1.4Eu0.6Ti3O10- and La0.7Tb0.3Ta2O7-nanosheets can be modulated by applying a magnetic field (1.3-1.4 T), which brings about a change in orientation of the nanosheets in solution. The emission intensities increased when the excitation light and the magnetic field directions were perpendicular to each other, and they decreased when the excitation and magnetic field were collinear and mutually perpendicular to the direction of detection of the emitted light.

A bona fide two-dimensional percolation model: an insight into the optimum photoactivator concentration in La2/3-xEuxTa2O7nanosheets

“…Recently, a new kind of phosphor materials, which consist of rare-earth (Ln) photoactivators incorporated within the oxide nanosheet structures, have been reported and opened a new field in phosphor materials design [5][6][7][8][9]. The oxide nanosheets can be prepared by soft chemical exfoliation of layered compounds, and they have a unique sheet-like morphology with less than 3 nm thickness and micrometer-order lateral size [10][11][12][13].…”

Chemical Nanomanipulation of Two-Dimensional Nanosheets and Its Applications

“…In the case of metal oxides, protonation usually resulted in electrostatic repulsions that facilitated exfoliation. By this procedure, single layers of Ti oxides, [19][20][21][22] Mn oxides, 23 Nb/Ta oxides, [24][25][26] Mo oxides, 27 Ru oxides, 28 and W oxides, 29 as well as sheets of several perovskites 7,9,[30][31][32][33][34][35] have been separated from bulk samples (Fig. 2).…”

Time-resolved Fluorescent Detection for Glucose Using a Complex of Luminescent Layered Titanates and Enzymes

“…[15][16][17][18] By using lanthanides, luminescent properties can be added to thin layered materials. [19][20][21] Although inorganic nanosheets are unique and attractive materials in this way, applications of the materials in analytical chemistry are very few at this stage, compared with inorganic semiconductor nanoparticles (quantum dots). [22][23][24][25][26][27] In this study, fluorescent europium-doped titanate nanosheets (Eu-TiOx) were synthesized, and complexed with horseradish peroxidase (HRP) and glucose oxidase (GOx).…”