Synthesis and Characterization of High-Efficiency Nanocrystal Up-Conversion Phosphors:  Ytterbium and Erbium Codoped Lanthanum Molybdate

Abstract

Nanocrystal up-conversion phosphors (UCP), ytterbium-and erbium-codoped lanthanum molybdate (La 2 (MoO 4 ) 3 :Yb,Er), were prepared for the first time for potential uses in bioassays especially in biochip-based analysis. The La 2 (MoO 4 ) 3 :Yb,Er nanocrystals, with an average diameter of 50 nm, were prepared via a hydrothermal method. After being annealed at 800°Cfor 5 h, strong emission of these nanocrystals was observed when excited with a 980 nm infrared (IR) laser. Fluorescent intensity of these nanocrystals is much stronger than that of bulk materials. Down-conversion spectrum of the nanocrystal phosphors was also examined. Two-photon excitation mechanism was proposed for the up-conversion process. Factors affecting the up-conversion fluorescent intensity were also studied. The particlesize-dependent phenomenon was first observed for nanocrystal UCP, and the mechanism was discussed.

Multicolor Core/Shell‐Structured Upconversion Fluorescent Nanoparticles

“…[11,12] These nanoparticles are usually synthesized in organic solvents or at high temperatures. [22][23][24] Ethylenediamine tetraacetic acid (EDTA) has been used as a chelating agent to control the growth of NaYF 4 nanocrystals, and thermal decomposition of mixed trifluoroacetates has been used to produce high-quality cubic-and hexagonal-phase NaYF 4 nanocrystals. [11,[24][25][26] However, these nanocrystals can be dispersed only in some organic solvents to form colloidal solutions after sonication, but not in water.…”

Morphology-controlled nonaqueous synthesis of anisotropic lanthanum hydroxide nanoparticles

“…They have been widely used in phosphors for fluorescent lighting [1] and [2], semiconductors [3] and [4], or time-resolved fluorescence labels for biological detection [5]. Lanthanum, the lightest element among the lanthanides, has been extensively examined as oxide, hydroxide, phosphate, or oxychloride for optical [6] and [7], solid electrolyte [8], catalytic [9], [10] and [11], and sorbent properties [12].…”

Upconversion nanoparticles conjugated with curcumin as a photosensitizer to inhibit methicillin-resistant Staphylococcus aureus in lung under near infrared light

“…[19][20][21] However, most of these nanoparticles are synthesized at high temperatures. 22,23 In recent years, a hydrothermal synthesis method at lower temperature has been found.…”