Abstract
Mixtures of lanthanum oxide, europium oxide, calcium carbonate, and phosphoric acid were heated with various ratios of P/(Eu + La + Ca) and La/Ca. Europium ratio was settled at Eu/(Eu + La + Ca) = 0.03. The obtained phosphates were estimated using X-ray diffraction (XRD) patterns, Fourier transform infrared spectroscopy (FT-IR) spectra, and scanning electron micrograph (SEM) images. The fluorescence spectra and resistance against hydrofluoric acid were estimated as functional properties of these phosphate materials. The mixture of lanthanum and calcium phosphates were formed from XRD patterns and IR spectra. Samples prepared in P/(Eu + La + Ca) = 2 and 3 had large particles in SEM images. The condensed phosphates showed a strong peak at 615 nm and high resistance against hydrofluoric acid.
Highlights
Phosphates are transformed to other forms of phosphates by hydrolysis and dehydration reactions at elevated temperatures [1,2]
Europium oxide, calcium carbonate, and phosphoric acid were heated with various ratios of P/(Eu + La + Ca) and La/Ca
In P/(La + Ca + Eu) = 2, X-ray diffraction (XRD) patterns were changed from lanthanum orthophosphate, LaPO4, and polyphosphate, La(PO3)3 to calcium polyphosphate, Ca(PO3)2
Summary
Phosphates are transformed to other forms of phosphates by hydrolysis and dehydration reactions at elevated temperatures [1,2]. Polyphosphate has a chain structure in which the PO4 unit shares two oxygen atoms and ultraphosphate has a network structure Formation of these condensed phosphates was affected by the ratio of phosphorus/cation, heating temperature, time, atmosphere, and so on [3,4,5]. Rare-earth orthophosphates, which are the main component of rare-earth ores, are stable phosphate groups in acidic and basic solutions Their resistance in acidic and basic solutions was developed into other phosphate materials [12]. In previous work [9], europium-substituted lanthanum phosphates were synthesized and estimated from the optical properties and the resistance against hydrofluoric acid. FUNAMOTO thermore, these phosphate materials were studied for their fluorescence properties and resistance in hydrofluoric acid
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