The significance of phosphate source in the preparation of functional luminescent phosphate materials

Abstract

The stability and reactivity of phosphate raw materials, including two water-soluble phosphates, ethylene glycol-conjugated phosphate (EG-P), and polyethylene glycol-conjugated phosphate (PEG-P) developed by our group, were examined with the aim of synthesizing phosphates with high functionalities. EG-P was found to gradually hydrolyze in an aqueous solution, resulting in the formation of H 3 PO 4 , while PEG-P was stable for more than two months. EG-P and PEG-P did not form insoluble materials in aqueous solution in the presence of many other cations, while precipitates were often observed using conventional phosphate raw materials. In particular, there were no precipitates in an aqueous solution of PEG-P in the presence of Ca 2+ and Li + ions, which easily formed insoluble phosphates in a given aqueous condition. Consequently, single-phase LiCaPO 4 with high luminescence properties could be obtained by a polymerizable complex method employing PEG-P, while impurity phases were formed using other P sources, and KSrPO 4 was formed as a single phase using EG-P and PEG-P.

Crystal structures and luminescence properties of Eu2+-activated new NaBa0.5Ca0.5PO4 and Na3Ba2Ca(PO4)3

“…In this study, we have attempted the solution-based synthesis of NaBaPO 4 -NaCaPO 4 solid solutions via a polymerizable complex (PC) method using a water-soluble and stable P source developed by our group, 7 aiming at the application for phosphor. Two novel compounds, Na 3 Ba 2 Ca(PO 4 ) 3 and NaBa 0.5 Ca 0.5 PO 4 , were developed and their crystal structures were determined by single crystal X-ray analysis.…”

“…In addition, the photoluminescence properties of Eu 2+ -doped samples were investigated. ester (PEG-P) 7 as a P source. PEG-P was synthesized from reactions among polyethylene glycol 300, phosphorus pentoxide, and polyphosphoric acid under a N 2 atmosphere at 353 K. Details of the PEG-P preparation procedure are described elsewhere.…”

“…PEG-P was synthesized from reactions among polyethylene glycol 300, phosphorus pentoxide, and polyphosphoric acid under a N 2 atmosphere at 353 K. Details of the PEG-P preparation procedure are described elsewhere. 7 Na 2 CO 3 (99.5%, Kanto Chemical), BaCO 3 (99.9%, Kanto Chemical), CaCO 3 (99.99%, Kanto Chemical), and Eu(NO 3 ) 3 ( prepared by the dissolution of Eu 2 O 3 (99.9%, Furuuchi Chemical) in HNO 3 ) were dissolved in an aqueous solution of citric acid (CA) at a molar ratio of Na : Ba : Ca : Eu : P : CA = 1 : (1 − x − y) : x : y : 1 : 12. In the present research, y was fixed at 0.01, that is, the 1 mol% Eu-doped samples were synthesized.…”