Self‐Assembled 3D Architectures of LuBO₃:Eu³⁺: Phase‐Selective Synthesis, Growth Mechanism, and Tunable Luminescent Properties

Abstract

Rhombohedral-calcite and hexagonal-vaterite types of LuBO(3):Eu(3+) microparticles with various complex self-assembled 3D architectures have been prepared selectively by an efficient surfactant- and template-free hydrothermal process for the first time. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, photoluminescence, and cathodoluminescence spectra as well as kinetic decays were used to characterize the samples. The pH, temperature, concentration, solvent, and reaction time have a crucial influence on the phase formation, shape evolution, and microstructure. The reaction mechanism is considered as a dissolution/precipitation process; it is proposed that the self-assembly evolution occurs by homocentric layer-by-layer growth. Under UV excitation and low-voltage electron beam excitation, calcite-type LuBO(3):Eu(3+) particles show a strong orange emission corresponding to the (5)D(0)-->(7)F(1) transition of Eu(3+) whereas vaterite-type LuBO(3):Eu(3+) particles exhibit a strong red emission with much higher R/O values (that is, chromatically redder fluorescence than that of crystals grown from a direct solid-state reaction). The tunable luminescent properties have potential applications in fluorescent lamps and field emission displays.

Controlled synthesis of different multilayer architectures of GdBO3:Eu3+ phosphors and shape-dependent luminescence properties

“…Among a variety of borate phosphors, GdBO 3 :Eu 3+ is one of the excellent and efficient phosphors available for the red primary of the color picture in plasma display panels and possibly be used in Hg-free lamp [16]. However, most of the previous works about the synthesis of lanthanide orthoborates are mainly concentrated on using H 3 BO 3 as boron source to obtain different structures via hydrothermal process [17][18][19][20], and only limited information is available on using borate (such as Na 2 B 4 O 7 ·10H 2 O or NaBO 2 ·4H 2 O) as boron source [21][22][23][24]. To the best of our knowledge, up till now, there are no systematic studies on using different boron sources to control different morphologies of GdBO 3 via a facile and general hydrothermal conversion method without using any surfactant or catalyst.…”

Highly Uniform YBO3 Hierarchical Architectures: Facile Synthesis and Tunable Luminescence Properties

“…During the hydrothermal process, complexing agents or surfactants always play an important role in controlling the dynamics of crystal growth and determining the final morphology of the hierarchical nano-/microstructures. [22][23][24] However, the addition of complexing agents or surfactants usually involves a complicated process and incurs a high cost, and may result in impurities in the products. Therefore, it is desirable to develop environmentally friendly, facile, and low-cost methods for the fabrication of uniform inorganic hierarchical architectures without any organic solvent, catalyst, or surfactant.…”

“…The multilayered hierarchical architectures possess especially large surface areas and high surface energies, which not only provide a driving force for the self-assembly, but also result in a high degree of disorder near the surface and corresponding lower symmetry of the crystal field around the Eu 3 + ions than in the bulk materials. [22,38] According to the Judd-Ofelt theory, [48] a lower symmetry of the crystal field around the Eu 3 + ions would result in a higher R/O value The excitation spectrum of a YBO 3 /5 % Tb 3 + sample is composed of two intense bands and some weak lines (Figure 5c). The intense bands centered at 241 and 285 nm can be attributed to the spin-allowed transition (DS = 0) with higher energy and the spin-forbidden transition (DS = 1) with lower energy from the 4f to the 5d level of the Tb 3 + ions.…”

Спектральные и структурные характеристики ортоборатов Lu-=SUB=-1-x-y-=/SUB=-Ce-=SUB=-x-=/SUB=-Tb-=SUB=-y-=/SUB=-BO-=SUB=-3-=/SUB=-, полученных методом гидротермального синтеза

“…• C в автоклаве [5][6][7][8][9][10]. Продуктом такого синтеза являются частицы шарообразной формы размером 5−10 µm, состоящие из наноразмерных эле-ментов, имеющих форму пластин.…”

“…Продуктом такого синтеза являются частицы шарообразной формы размером 5−10 µm, состоящие из наноразмерных эле-ментов, имеющих форму пластин. При этом определен-ная структурная модификация (кальцит или ватерит) мо-жет быть получена при разных величинах кислотности водной реакционной среды [7]. В работах [5][6][7][8][9][10] …”