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Effects of Heat-Treatment on Photoluminescence Spectra and Photocatalytic Properties of Solution-Combusted ZnO Nanopowders
摘要： ZnO nanopowders were prepared by a solution combustion method (SCM). The SCM ZnO nanopowders were heat-treated at 200, 400, 500, or 700 °C for 30 min in air and the photoluminescence (PL) of the nanopowders was evaluated. Two strong PL emission peaks are generally recognized as the unique PL signature of ZnO, one is from the band-edge emission and the other corresponds to green emission. The green emission is derived from crystalline defects, and is a critical obstacle for the electrooptical applications of ZnO. Surprisingly, the PL spectra of the SCM ZnO powders showed a single sharp peak near 390 nm. Furthermore, the intensity of this blue emission doubled when the synthesized ZnO powder was heat-treated at 400 °C. The green emission appeared for the sample treated at 500 °C, and was the highest for that treated at 700 °C. To confirm the photocatalytic activity of the ZnO powder heat-treated at 400 °C, the removal of Ag ions from a used photofilm developer was evaluated, with complete removal within 10 min. The removal of the Ag ions by the ZnO powder heat-treated at 400 °C was more than two orders of magnitude faster than that achieved with the SCM ZnO powder. The relation between PL and photocatalytic activity was explained in terms of recombination of the photogenerated electrons. These results might be very useful for highly efficient photocatalyst applications.
关键词： Heat-Treatment,ZnO Nanopowder,PL Spectra,Solution Combustion Method
更新于2025-09-23 15:22:29
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Effect of Bi <sup>3+</sup> ion on upconversion-based induced optical heating and temperature sensing characteristics in the Er <sup>3+</sup> /Yb <sup>3+</sup> co-doped La <sub/>2</sub> O <sub/>3</sub> nano-phosphor
摘要： The upconversion-based optical heating and temperature sensing characteristics are investigated in the Er3+/Yb3+/Bi3+ tri-doped La2O3 nano-phosphor synthesized through a solution combustion method. The structural measurements reveal an increase in lattice parameters and particles size of the phosphor on increasing the concentrations of Bi3+ ions. The energy dispersive spectroscopic (EDS) measurements confirm the presence of La, Er, Yb, Bi and O elements in the tri-doped phosphor. The absorption spectra show the large number of bands due to Er3+, Yb3+ and Bi3+ ions. The Er3+/Yb3+ co-doped phosphor gives strong green emission bands at 523 and 548 nm upon 976 nm excitation due to 2H11/2 / 4I15/2 and 4S3/2 / 4I15/2 transitions of Er3+ ion, respectively. The emission intensity of these bands is enhanced upto 15 times in the presence of Bi3+ ions. The emission intensities of the 523 and 548 nm bands vary non-linearly with the pump power. The fluorescence intensity ratio (FIR) of the thermally coupled 523 and 548 nm emission bands shows efficient optical heating in the tri-doped phosphor. The FIR of the 523 and 548 nm emission bands further varies with the increase in temperature of the phosphor. The relative temperature sensing sensitivity has been calculated to be 71 × 10?4 K?1 at 450 K for the tri-doped phosphor. Thus, the Er3+/Yb3+/Bi3+ tri-doped La2O3 nano-phosphor may provide a platform to use it in the photonic devices, as an optical heater and temperature sensor.
关键词： La2O3 nano-phosphor,temperature sensing,optical heating,solution combustion method,Er3+/Yb3+/Bi3+ tri-doped,upconversion
更新于2025-09-19 17:15:36
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AIP Conference Proceedings [AIP Publishing DAE SOLID STATE PHYSICS SYMPOSIUM 2018 - Hisar, Haryana, India (18–22 December 2018)] DAE SOLID STATE PHYSICS SYMPOSIUM 2018 - Mixed fuel approach for the fabrication of TiO2:Dy3+(1-11?mol%) nanophosphors: Applications towards wLED and latent finger print detection
摘要： The pure and Dy3+(1-11 mol%) ions doped TiO2 nanophosphors (NPs) were prepared by solution combustion method using grouping of fuels; glycine and ammonium acetate. PXRD studies establishes that the pure and doped samples show rutile and anatase phases respectively. The Raman spectra illustrates that the absorption peaks noticed at ～ 142, 446 and 609 cm-1 were due to the active vibrational optical phonon modes pertaining to B1g, Eg and A1g respectively of the pure tetragonal rutile phase, whereas the peaks at ～ 395, 513 and 639 cm-1 were attributed due the active modes B1g, A1g and Eg respectively of anatase phase of TiO2. The active mode observed at ～ 142 cm-1 was a characteristic mode whereas the mode at ～ 229 cm-1 was attained due to second order effect [SOE] of pure rutile phase of TiO2. The Raman studies validate the PXRD studies. The CIE and CCT outcomes show that NPs can be used for wLED and household applications. The optimized product TiO2:Dy3+(9 mol% ) was utilized for the visualization of latent finger prints (LFPs). The results reveal that, all the levels (I to III) of ridge feature were clearly visualized under normal light indicating that the powder was a reliable and promising labeling agent for LFPs.
关键词： TiO2:Dy3+,latent finger print detection,wLED,solution combustion method,nanophosphors
更新于2025-09-19 17:13:59
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Comparative study of photoluminescence of single and mixed phase ZrTiO4 prepared by solution combustion and polymeric precursor method
摘要： This work aims to study synthesis methods and photoluminescence properties of ZrTiO4. Wet chemical routes used for synthesis are solution combustion method and polymeric precursor method. Urea and glycine are two different fuels used in solution combustion synthesis. Scanning Electron Microscope studies con?rms that morphology of the nanoparticles depends on synthesis method. Photoluminescent property depends on the phase of the material, rather than the method of synthesis. Characterization such as X-ray diffraction, SEM, Re?ectance and Photoluminescence studies prove the role of synthesis methods on the properties of the ZrTiO4. Both upconversion and down conversion luminescence have been achieved by synthesizing ZrTiO4 from solution combustion method using urea as fuel, where ZrTiO4 exists in mixed phase.
关键词： Polymeric precursor method, (PPM),Photoluminescence,Single phase,Mixed phase,ZrTiO4,Solution combustion method, (SCS)
更新于2025-09-09 09:28:46