Strontium Phosphate Composite Designed to Red-Emission at Different Temperatures

Abstract

Eu3+-doped Sr10(PO4)6(OH)2–Sr3(PO4)2 (SrHAp-TSP) composites were obtained via the microwave-stimulated hydrothermal method and post-heat-treated from 750 to 950 °C. Concentration of the Eu3+ ions was set to be 0.5, 1, 2, 3, 5 mol% in a ratio of the strontium ions molar content. The structural and morphological properties were investigated by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FT-IR) techniques. The average particle size of the studied materials annealed at 750, 850 and 950 °C were counted about 100, 131 and 173 nm, respectively. The luminescence properties depending on the dopant ion concentration, heat-treatment temperature, excitation wavelength and temperature were investigated. In the emission spectra, a broad peak corresponding to the 4f65d1 → 4f7 (8S7/2) emission of Eu2+ ions as well as narrow 4f-4f transitions typical for Eu3+ ions can be observed. The luminescence intensity of the 1 mol% Eu3+:Sr10(PO4)6(OH)2–Sr3(PO4)2 was measured depending on the ambient temperature in the range of 80–550 K. The CIE 1931 (International Commission on Illumination) chromaticity diagram was determined from emission spectra measured in 80, 300 and 550 K. The reduction mechanism of the Eu3+ to the Eu2+ was explained by the charge compensation mechanism based on the Kröger–Vink-notation. The decay times were measured and the Judd–Ofelt (J–O) theory was applied to analyze the observed structural and spectroscopic features.

Probing the influence of strontium doping and annealing temperature on the structure and biocompatibility of hydroxyapatite nanorods

“…This is due to the fact that the substitution of the larger Sr 2+ ions into smaller Ca 2+ ion sites of HAp causes a denser atomic packing of the system, causing retardation of crystal growth. 39 From the Rietveld refinement data, Sr7-UA has the smallest crystallite size (16.78 nm), which is also evident from its broader XRD peak. In addition, the crystallite size increased with increasing annealing temperature.…”

“…This is due to the fact that the substitution of the larger Sr 2+ ions into smaller Ca 2+ ion sites of HAp causes a denser atomic packing of the system, causing retardation of crystal growth. 39 From the Rietveld refinement data, Sr7-UA has the Fig. 4 FESEM micrographs and aspect ratios of Sr-HAp nanostructures (unannealed).…”

Europium doped Sr2YNbO6 double perovskite phosphor for photoluminescence and thermoluminescence properties

“…The average decay lifetime (τ) for the double exponential curve was calculated using the equation, . The decay curves for the 396 and 467 nm excitation wavelengths were fitted through the single exponential function given in Equation (5) [ 51 ] : The decay lifetime calculated for the 274 nm, 395 nm and 467 nm excitations were 1.298 μs, 1.957 μs, and 2.618 μs, respectively. The decay lifetimes of the PL emission decreased rapidly due to the reduction in Eu 3+ –Eu 3+ transitions, which could have occurred due to cross‐relaxation.…”

“…where τ 1 and τ 2 are the decay constants for the fast decay and slow decay exponential components of the PLE day curve, respectively, and A 1 and A 2 were the fitting constants. The average decay lifetime (τ) for the double exponential curve was calculated using the equation, 467 nm excitation wavelengths were fitted through the single exponential function given in Equation ( 5) [51] :…”

Anomalous luminescence properties and cytotoxicity assessment of Sr3(PO4)2 co-doped with Eu2+/3+ ions for luminescence temperature sensing

“…The mechanism of such behaviour is reported in the literature and described as abnormally intense Eu 2+ emission at high temperatures. 5,18–20 According to the charge compensation mechanism in this material, two possible defect traps and are present. The Eu 3+ ions could recombine with the electrons released from defects, which can be written as or .…”