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White light emission has been achieved by near full band excitation from 10.7 nm sized pure Gd6O5F8 nanoparticles. The position of the photoluminescence (PL) spectrum and the peak of the excitation spectrum show an obvious shift toward the red region, which increases with the excitation wavelength and the monitoring wavelength, respectively. Four kinds of emission state could exist on the surface of the Gd6O5F8 nanoparticles in cyclohexane. Multiple emission states with excitation-dependent PL are generated in Gd6O5F8 nanoparticles in cyclohexane, which are attributed to the inhomogeneous properties. Besides, Gd6O5F8 nanoparticles in cyclohexane exhibit high thermal stability and good paramagnetic properties. When the heating temperature reached 85 °C, the relative intensity was decreased to 69%. This work provides a new understanding of complex luminescence and a novel reference for a biological, white light-emitting diode (WLED) and other multi-functional applications. [ABSTRACT FROM AUTHOR]

Co-doped SrF2:Yb3+, Ho3+ nanoparticles (NPs) have been successfully synthesized and upconversion luminescence (UCL) was demonstrated under excitation at 980 nm. The integrated intensity of UC emissions was found to be markedly influenced by the concentration of Yb3+ and Ho3+ in the NPs. The optimized doping concentrations of Yb3+ and Ho3+ were determined to be 20% and 2%, respectively, to obtain maximum UCL intensities in the range of 500 nm to 800 nm. The phonon energy dependent behavior should essentially reflect the energy transfer excitation mechanism. Furthermore, the abnormal thermal quenching behavior is primarily considered to be induced by defects caused by non-equivalent lanthanide (Ln3+) ions replacing Sr2+ ions, in that upon an increase in the temperature, the emission intensity peak at 656 nm is relatively thermally stable at first and then decreases, and the emission intensities at 543 and 752 nm decrease gradually at first, and then increase and reach a maximum at 450 K, at which point the emission intensity starts to decrease. The ratio of the UC green (543 nm) to red emission (656 nm) can be fitted to a cubic equation in terms of the temperature from 306 to 523 K, meaning that this phosphor could be used to sense temperature. In addition, the SrF2:Yb3+, Ho3+ NPs were found to be paramagnetic with magnetization values of 1.32 emu g−1 (at 50 K and H = 15 kOe) and 0.299 emu g−1 (at 300 K and H = 15 kOe), respectively. The magnetization exhibits a good reciprocal response to the temperature from 50 to 300 K, which could open up a new pathway to sense temperature in a low-temperature environment. Due to the good UCL and excellent temperature stability of the SrF2: 20% Yb3+, 2% Ho3+ NPs, the current work shows that this material could be used for temperature sensing from 50 to 523 K, bioimaging and magnetic resonance imaging using a single system. [ABSTRACT FROM AUTHOR]

Co-doped SrF2:Yb3+, Ho3+ nanoparticles (NPs) have been successfully synthesized and upconversion luminescence (UCL) was demonstrated under excitation at 980 nm. The integrated intensity of UC emissions was found to be markedly influenced by the concentration of Yb3+ and Ho3+ in the NPs. The optimized doping concentrations of Yb3+ and Ho3+ were determined to be 20% and 2%, respectively, to obtain maximum UCL intensities in the range of 500 nm to 800 nm. The phonon energy dependent behavior should essentially reflect the energy transfer excitation mechanism. Furthermore, the abnormal thermal quenching behavior is primarily considered to be induced by defects caused by non-equivalent lanthanide (Ln3+) ions replacing Sr2+ ions, in that upon an increase in the temperature, the emission intensity peak at 656 nm is relatively thermally stable at first and then decreases, and the emission intensities at 543 and 752 nm decrease gradually at first, and then increase and reach a maximum at 450 K, at which point the emission intensity starts to decrease. The ratio of the UC green (543 nm) to red emission (656 nm) can be fitted to a cubic equation in terms of the temperature from 306 to 523 K, meaning that this phosphor could be used to sense temperature. In addition, the SrF2:Yb3+, Ho3+ NPs were found to be paramagnetic with magnetization values of 1.32 emu g−1 (at 50 K and H = 15 kOe) and 0.299 emu g−1 (at 300 K and H = 15 kOe), respectively. The magnetization exhibits a good reciprocal response to the temperature from 50 to 300 K, which could open up a new pathway to sense temperature in a low-temperature environment. Due to the good UCL and excellent temperature stability of the SrF2: 20% Yb3+, 2% Ho3+ NPs, the current work shows that this material could be used for temperature sensing from 50 to 523 K, bioimaging and magnetic resonance imaging using a single system. [ABSTRACT FROM AUTHOR]

This paper reports on a facile hydrothermal route that has been developed to synthesize a precursor Gd(OH)2.14F0.86 and a novel phosphor host Gd6O5F8. The morphology of the micro-sized Gd(OH)2.14F0.86/Gd6O5F8 can be easily tuned in a controlled manner by altering the fluorine sources, alkali solutions, reaction time and the pH values of the initial solution. Under ultraviolet (UV) light, vacuum ultraviolet (VUV) light and low-voltage electron beam excitation, the Gd(OH)2.14F0.86/Gd6O5F8:Ln3+ (Eu, Tb and Tm) samples show the characteristic f–f transitions of the Ln3+ ions and give bright red, green and blue emissions, respectively. The results prove that the as-synthesized Gd6O5F8 are excellent host lattices for rare earth luminescence, which may find potential applications in solid-state light, field emission displays (FEDs). [ABSTRACT FROM AUTHOR]

This paper reports on a facile hydrothermal route that has been developed to synthesize a precursor Gd(OH)2.14F0.86 and a novel phosphor host Gd6O5F8. The morphology of the micro-sized Gd(OH)2.14F0.86/Gd6O5F8 can be easily tuned in a controlled manner by altering the fluorine sources, alkali solutions, reaction time and the pH values of the initial solution. Under ultraviolet (UV) light, vacuum ultraviolet (VUV) light and low-voltage electron beam excitation, the Gd(OH)2.14F0.86/Gd6O5F8:Ln3+ (Eu, Tb and Tm) samples show the characteristic f–f transitions of the Ln3+ ions and give bright red, green and blue emissions, respectively. The results prove that the as-synthesized Gd6O5F8 are excellent host lattices for rare earth luminescence, which may find potential applications in solid-state light, field emission displays (FEDs). [ABSTRACT FROM AUTHOR]

This paper reports on a facile hydrothermal route that has been developed to synthesize a precursor Gd(OH)2.14F0.86 and a novel phosphor host Gd6O5F8. The morphology of the micro-sized Gd(OH)2.14F0.86/Gd6O5F8 can be easily tuned in a controlled manner by altering the fluorine sources, alkali solutions, reaction time and the pH values of the initial solution. Under ultraviolet (UV) light, vacuum ultraviolet (VUV) light and low-voltage electron beam excitation, the Gd(OH)2.14F0.86/Gd6O5F8:Ln3+ (Eu, Tb and Tm) samples show the characteristic f–f transitions of the Ln3+ ions and give bright red, green and blue emissions, respectively. The results prove that the as-synthesized Gd6O5F8 are excellent host lattices for rare earth luminescence, which may find potential applications in solid-state light, field emission displays (FEDs). [ABSTRACT FROM AUTHOR]

This paper reports on a facile hydrothermal route that has been developed to synthesize a precursor Gd(OH)2.14F0.86 and a novel phosphor host Gd6O5F8. The morphology of the micro-sized Gd(OH)2.14F0.86/Gd6O5F8 can be easily tuned in a controlled manner by altering the fluorine sources, alkali solutions, reaction time and the pH values of the initial solution. Under ultraviolet (UV) light, vacuum ultraviolet (VUV) light and low-voltage electron beam excitation, the Gd(OH)2.14F0.86/Gd6O5F8:Ln3+ (Eu, Tb and Tm) samples show the characteristic f–f transitions of the Ln3+ ions and give bright red, green and blue emissions, respectively. The results prove that the as-synthesized Gd6O5F8 are excellent host lattices for rare earth luminescence, which may find potential applications in solid-state light, field emission displays (FEDs). [ABSTRACT FROM AUTHOR]