Crystal transition control of NaYF4 upconversion microcrystals through addition of Na2HPO4. (25th December 2015)

• Record Type: Journal Article
• Authors: Lv, Meng; Li, Xia
• Is Part Of: Materials & design. Volume 88(2015:Dec.)
• Page Start: 514
• Page End: 519
• Publication Date: 2015-12-25
• Subjects: Upconversion -- Crystal transition control -- Solvothermal synthesis method; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2015.09.032
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Hexagonal upconversion microcrystals of β-NaYF4 were prepared through a simple, one-step, rapid, template-free and mild solvothermal synthesis method. Addition of Na2 HPO4 influenced crystal transition from the cubic phase to the hexagonal phase. Results showed that the phase (cubic or hexagonal) and upconversion emission intensity of NaYF4 can be rationally tuned by introducing inorganic dopant ions to achieve a precisely defined molar ratio of Na2 HPO4 to Ln 3 + . SEM observations and XRD analyses helped identify fundamental considerations for crystal transition control during upconversion of NaYF4 particles. Results also showed that Na2 HPO4 shortened the reaction time (3 h) of cubic-to-hexagonal crystal transition and significantly reduced the reaction temperature (200 °C) during the preparation of hexagonal phase upconversion microcrystals. Graphical abstract: Na2 HPO4 can be absorbed onto the crystal plane via physical or chemical bonding, resulting in rapid crystal transition of NaYF4 . Highlights: β-NaYF4 was prepared by solvothermal method without using template and catalyst carrier. Addition of inorganic ions influenced crystal transition. Inorganic ion addition shortened the reaction time (down to 3 h). Inorganic ion addition reduced the reaction temperature (down to 200 °C). Upconversion is dependent on their phase, shape and particle size.