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A task-specific ionic liquid (IL) is employed as a structure directing agent for the synthesis of quantum cutting BaGdF5:Eu3+ nanophosphors. Herein, IL and temperature dependent quantum cutting is observed. Maximum (160%) and minimum (123%) quantum cutting efficiencies (QCEs) are obtained in the presence and absence of IL, respectively, at room temperature (295 K). However, at low temperature (10 K), the emission spectrum is dominated by Eu2+ 5d–4f emission which is further confirmed by X-ray excited luminescence study. It is also observed that decay kinetics recorded for Eu2+ 5d–4f emission demonstrate longer (with lifetime from 580 ns to 1.5 μs) and faster (with lifetime from 35 to 50 ns) decay components related to normal and surface quenched emission, respectively. In addition, maximum quantum yield (η = 73.5%) is obtained for the sample prepared in the presence of IL compared to that for the sample prepared without IL (η = 65%). The easy yet highly phase selective green synthesis of the materials is promising for large scale industrial application in nanothermometry as well as in environmentally benign energy efficient lighting. [ABSTRACT FROM AUTHOR]

An ionic liquid (IL)‐based solvothermal method is employed to prepare single‐phase, luminescent, cubic rare‐earth doped and silica‐coated BaF2 nanomaterials. High energy transfer efficiency (∼60%) from Ce3+ to Tb3+ for BaF2:Ce3+/Tb3+ nanoparticles dispersed in DMSO solution is observed. Furthermore, for the first time to the best of our knowledge, as‐prepared RE ion/s doped and silica‐coated BaF2 nanoparticles are used for the toxicological assessment on live zebrafish larvae. Interestingly, static exposure of these nanoparticles from 6 hpf till 96 hpf period at high concentration (70 mg/L) do not show any developmental anomalies as judged by bright‐field and birefringence optical imaging method which promises its large‐scale applications in imaging and other biological purposes.However, as a positive control, cypermethrin‐based pesticide could induce developmental defects at 0.1 mg/L concentration. It is worth mentioning that the concentration of BaF2 nanoparticles chosen in present study is much higher than the other nanoparticles reported so far. [ABSTRACT FROM AUTHOR]

Phase pure BaF2 doped with Ce3+ (0.1%) nanocrystals are synthesized using an ionic liquid (IL) ([C4mim][BF4]) assisted solvothermal method where the IL is not only used as a reaction medium and a capping agent, but also as a reaction partner. Subsequently, upon calcining the as-prepared nanocrystals at various temperatures (200, 400, 600 and 800 °C), athough the crystal phase remains the same, however, a significant change in the lattice strain and morphology is observed. Tensile strain appears in the nanocrystals calcined at temperatures up to 400 °C, but a reversal of the strain, i.e. compressive strain, takes place when calcination is performed at 600 °C and onwards. Nanoflakes are obtained until calcination at 400 °C. However on calcination at 600 °C and beyond, a drastic modification in the morphology is observed. Layer or step-like structures appear due to secondary nucleation of nanoparticles. Meanwhile, the photoluminescence (PL) intensity of Ce3+ ions gradually decreases with the calcination temperature and finally vanishes at 600 °C/800 °C. To investigate the reasons for the quenching of the PL intensity, thermally stimulated luminescence (TSL) and thermally stimulated exoelectron emission (TSEE) measurements are performed. The TSL and TSEE results indicate that in addition to the domination of deeper electron traps that appear as a high-temperature shift of TSEE glow peaks for both 600 °C and 800 °C, some new types of defects like F vacancies (F-centers) can be present, especially in the 800 °C calcined sample. The conditions leading to the quenching of Ce3+ luminescence in the nanoparticles are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Phase pure BaF2 doped with Ce3+ (0.1%) nanocrystals are synthesized using an ionic liquid (IL) ([C4mim][BF4]) assisted solvothermal method where the IL is not only used as a reaction medium and a capping agent, but also as a reaction partner. Subsequently, upon calcining the as-prepared nanocrystals at various temperatures (200, 400, 600 and 800 °C), athough the crystal phase remains the same, however, a significant change in the lattice strain and morphology is observed. Tensile strain appears in the nanocrystals calcined at temperatures up to 400 °C, but a reversal of the strain, i.e. compressive strain, takes place when calcination is performed at 600 °C and onwards. Nanoflakes are obtained until calcination at 400 °C. However on calcination at 600 °C and beyond, a drastic modification in the morphology is observed. Layer or step-like structures appear due to secondary nucleation of nanoparticles. Meanwhile, the photoluminescence (PL) intensity of Ce3+ ions gradually decreases with the calcination temperature and finally vanishes at 600 °C/800 °C. To investigate the reasons for the quenching of the PL intensity, thermally stimulated luminescence (TSL) and thermally stimulated exoelectron emission (TSEE) measurements are performed. The TSL and TSEE results indicate that in addition to the domination of deeper electron traps that appear as a high-temperature shift of TSEE glow peaks for both 600 °C and 800 °C, some new types of defects like F vacancies (F-centers) can be present, especially in the 800 °C calcined sample. The conditions leading to the quenching of Ce3+ luminescence in the nanoparticles are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Abstract: Phase pure quantum confined In2S3 nanocrystals with high catalytic/photocatalytic efficiency are accessible solvothermally using task specific ionic liquid (IL) as structure directing agent and thiourea as sulphur source. Selective tuning of the shape, morphology and most importantly purity of the nanomaterials are controlled by changing the reaction time, IL and specially sulphur concentration. For instances, at 150oC, when IL is used cubic phase is obtained; however in absence of IL, tetragonal phase with bigger crystallite size appears. In most of the cases In(OH)3 is coming as an impurity; however pure In2S3 with highest catalytic efficiency and band gap of 2.23 eV is achieved when 18 times sulphur concentration is used keeping other reaction parameters same. Photoluminescence emission spectra show that quantum confined pure In2S3 nanoparticles are blue emitting material. Furthermore, pure In2S3 nanoparticles are used for degradation of both cationic [crystal violet, methylene blue, rhodamine B] and anionic organic dyes [methyl orange]. Rate and overall catalytic efficiency are found highest for crystal violet (91%) followed by methylene blue (77%), rhodamine B (44.7%) and least for methyl orange (15.29%). Analysis reveals that along with electrostatic interaction, molecular structures of dye molecules have also significant impact on adsorption capacity which finally governs the catalytic (even in the dark) and photocatalytic efficiency of nanocrystals. [ABSTRACT FROM AUTHOR]

Highly crystalline, phase pure Cu3P nanocrystals (NCs) have been successfully synthesized using ionic liquid-assisted solvothermal method at relatively low temperature (200 °C). Herein, ionic liquids (ILs) are used as a structure directing/templating agent. Effect of ILs and precursor concentration on crystal phase, crystallite size, lattice strain, morphology and grain size of Cu3P NCs is studied. In the presence of IL, crystallite size and lattice strain significantly change with changing the concentration of red phosphorus. For example, smaller crystallite size (38.5 nm) and compressive lattice strain are obtained when 10 times of red phosphorous is used. However, bigger size (41.9 nm) and tensile lattice strains are obtained for the lower concentration of phosphorous (5 times). At higher phosphorus concentration, hexagonal shaped micro-crystals with prominent grain are observed. HRTEM images reveal that spherical-shaped particles on further agglomeration through Ostwald ripening process form hexagonal-shaped bigger microstructures. However, on doping the rare-earth ions (RE3+ = Ce3+/Tb3+) in the Cu3P NCs show the green luminescence (at 542 nm) which is attributed to the emission of Tb3+ ions. To the best of our knowledge, this is the first report on rare-earth doped Cu3P nanoparticles and shows promise on the luminescence aspect of Cu3P nanomaterials along with its already existing plasmonic and semiconducting properties. [ABSTRACT FROM AUTHOR]