Journal articles: 'Infrared nanocrystals'

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Della Gaspera, Enrico, Noel W. Duffy, Joel van Embden, et al. "Plasmonic Ge-doped ZnO nanocrystals." Chemical Communications 51, no. 62 (2015): 12369–72. http://dx.doi.org/10.1039/c5cc02429c.

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SHUBERT, V. ALVIN, and STEVEN P. LEWIS. "SIZE-DEPENDENCE OF INFRARED SPECTRA IN NIOBIUM CARBIDE NANOCRYSTALS." International Journal of Modern Physics C 23, no. 08 (2012): 1240001. http://dx.doi.org/10.1142/s0129183112400013.

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Niobium carbide nanocrystals of ~1:1 stoichiometry have recently been observed for particle sizes ranging from Nb4C4 to Nb50C50 . Infrared (IR) spectroscopic measurements show that a new band of IR vibrational modes appears with increasing particle size at Nb9C9 . Using density-functional theory, we show that the vibrational modes in the new band involve structural features present only in nanocrystals with three or more atomic layers in every direction. The Nb9C9 nanocrystal is right at this structural threshold.

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Lhuillier, Emmanuel. "Narrow band gap nanocrystals for infrared cost-effective optoelectronics." Photoniques, no. 116 (2022): 54–57. http://dx.doi.org/10.1051/photon/202211654.

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Infrared optoelectronics is driven by epitaxially grown semiconductors and the introduction of alternative materials is often viewed with some suspicion until the newcomer has demonstrated a high degree of viability. Infrared nanocrystals have certainly reached this degree of maturity switching from the demonstration of absorption by chemists to their integration into increasingly complex systems. Here, we review some of the recent developments relative to the integration of nanocrystal devices in the 1-5 µm range.

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Saez Cabezas, Camila A., Gary K. Ong, Ryan B. Jadrich, et al. "Gelation of plasmonic metal oxide nanocrystals by polymer-induced depletion attractions." Proceedings of the National Academy of Sciences 115, no. 36 (2018): 8925–30. http://dx.doi.org/10.1073/pnas.1806927115.

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Gelation of colloidal nanocrystals emerged as a strategy to preserve inherent nanoscale properties in multiscale architectures. However, available gelation methods to directly form self-supported nanocrystal networks struggle to reliably control nanoscale optical phenomena such as photoluminescence and localized surface plasmon resonance (LSPR) across nanocrystal systems due to processing variabilities. Here, we report on an alternative gelation method based on physical internanocrystal interactions: short-range depletion attractions balanced by long-range electrostatic repulsions. The latter are established by removing the native organic ligands that passivate tin-doped indium oxide (ITO) nanocrystals while the former are introduced by mixing with small PEG chains. As we incorporate increasing concentrations of PEG, we observe a reentrant phase behavior featuring two favorable gelation windows; the first arises from bridging effects while the second is attributed to depletion attractions according to phase behavior predicted by our unified theoretical model. Our assembled nanocrystals remain discrete within the gel network, based on X-ray scattering and high-resolution transmission electron microscopy. The infrared optical response of the gels is reflective of both the nanocrystal building blocks and the network architecture, being characteristic of ITO nanocrystals’ LSPR with coupling interactions between neighboring nanocrystals.

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Li, Xinke, Fangtian You, Hongshang Peng, and Shihua Huang. "Synthesis and Near-Infrared Luminescent Properties of NaGdF4:Nd3+@NaGdF4 Core/Shell Nanocrystals with Different Shell Thickness." Journal of Nanoscience and Nanotechnology 16, no. 4 (2016): 3940–44. http://dx.doi.org/10.1166/jnn.2016.11818.

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The near-infrared to near-infrared (NIR-to-NIR) photoluminescence of nanocrystals has outstanding advantages in biological imaging. NaGdF4:Nd3+ core nanocrystals and NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals with different shell thicknesses were synthesized by a simple solvothermal method. The obtained nanocrystals were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The phase of all nanocrystals is hexagonal. NaGdF4:Nd3+ core nanocrystals have an average size of 6 nm. By controlling core–shell ratio for 1:2 and 1:3, we obtained NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals with average sizes of 10 nm and 11 nm, respectively. When excited at 808 nm, strong NIR emission was observed. The emission peaks at ∼860 nm, ∼1060 nm and ∼1330 nm correspond to the transitions from the 4F3/2 statetothe 4I9/2, 4I11/2 and 4I13/2 state of Nd3+ ions, respectively. The emission intensity of NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals is stronger than that of the core. The intensity increases with the increase of shell thickness. The shell improves the luminous efficiency by reducing surface defects. The decay time of Nd3+ emission in NaGdF4:Nd3+@NaGdF4 core/shell nanocrystal is longer than that in NaGdF4:Nd3+ core, indicating that the shell isolates effectively the emitting ions (Nd3+)from the quenching defects. With the increase of shell thickness, the decay time becomes longer. Within a certain range of shell thickness, thicker shell can protect the emitting Nd3+ ions on the surface of core nanocrystals more effectively.

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Ницук, Ю. А., М. И. Киосе, Ю. Ф. Ваксман, В. А. Смынтына та И. Р. Яцунский. "Оптические свойства нанокристаллов CdS, легированных цинком и медью". Физика и техника полупроводников 53, № 3 (2019): 381. http://dx.doi.org/10.21883/ftp.2019.03.47291.8982.

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AbstractCadmium-sulfide nanocrystals are produced by the colloidal method. Doping with zinc and copper is conducted during nanocrystal growth. The optical absorption and photoluminescence spectra are studied. The maximum concentration of the optically active copper impurity is determined from a shift of the fundamental absorption edge to lower energies. It is shown that the long-wavelength luminescence of CdS and CdS:Zn nanocrystals is defined by optical transitions at donor–acceptor pairs. In CdS:Cu nanocrystals, optical absorption and photoluminescence in the visible spectral region are defined by recombination transitions involving the ground state of $${\text{Cu}}_{{{\text{Zn}}}}^{{2 + }}$$ ions. The infrared absorption and photoluminescence of CdS:Cu quantum dots are defined by intracenter transitions within $${\text{Cu}}_{{{\text{Zn}}}}^{{2 + }}$$ ions.

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Zhang, Xinhai, Qiuling Chen, and Shouhua Zhang. "Ta2O5 Nanocrystals Strengthened Mechanical, Magnetic, and Radiation Shielding Properties of Heavy Metal Oxide Glass." Molecules 26, no. 15 (2021): 4494. http://dx.doi.org/10.3390/molecules26154494.

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In this study, for the first time, diamagnetic 5d0 Ta5+ ions and Ta2O5 nanocrystals were utilized to enhance the structural, mechanical, magnetic, and radiation shielding of heavy metal oxide glasses. Transparent Ta2O5 nanocrystal-doped heavy metal oxide glasses were obtained, and the embedded Ta2O5 nanocrystals had sizes ranging from 20 to 30 nm. The structural analysis of the Ta2O5 nanocrystal displays the transformation from hexagonal to orthorhombic Ta2O5. Structures of doped glasses were studied through X-ray diffraction and infrared and Raman spectra, which reveal that Ta2O5 exists in highly doped glass as TaO6 octahedral units, acting as a network modifier. Ta5+ ions strengthened the network connectivity of 1–5% Ta2O5-doped glasses, but Ta5+ acted as a network modifier in a 10% doped sample and changed the frame coordination units of the glass. All Ta2O5-doped glasses exhibited improved Vicker’s hardness, magnetization (9.53 × 10−6 emu/mol), and radiation shielding behaviors (RPE% = 96–98.8%, MAC = 32.012 cm2/g, MFP = 5.02 cm, HVL = 0.0035–3.322 cm, and Zeff = 30.5) due to the increase in density and polarizability of the Ta2O5 nanocrystals.

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Chen, Yi Chuan, Yue Hui Hu, Xiao Hua Zhang, et al. "Structure and Properties of Doped ZnO Nanopowders Synthesized by Methanol Alcoholysis Method." Advanced Materials Research 287-290 (July 2011): 1406–11. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1406.

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Pured ZnO, Al doped ZnO and Al-In co-doped ZnO nanopowders were synthesized by the methanol alcoholysis method at 130 °C. Structure, morphology and optical properties of ZnO nanopowders were characterized using X-ray diffraction, Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Photoluminescence (PL) spectra. The results show that ZnO nanopowders can be obtained in methanol solution at low temperature (130 °C). TEM images show that Al doped ZnO nanocrystals grow along the [002] axis quicker than other axes. FTIR spectra show that ZnO nanocrystals synthesized by the methanol alcoholysis include a little organic impurity. PL spectrums reveal that pure ZnO and doped ZnO nanocrystals have a blue band emission at 440 nm and a green band emission at 520 nm and 530 nm, respectively. Compared with the pure ZnO nanocrystal, the Al doping improves the luminescent properties.

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Feng, Bin, Feng Teng, Ai-Wei Tang, Yan Wang, Yan-Bing Hou, and Yong-Sheng Wang. "Synthesis and Optical Properties of L-Cysteine Hydrochloride-Stabilized CdSe Nanocrystals in a New Alkali System." Journal of Nanoscience and Nanotechnology 8, no. 3 (2008): 1178–82. http://dx.doi.org/10.1166/jnn.2008.18168.

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Water-soluble CdSe nanocrystals were synthesized in a new alkali system at lower temperatures by using L-cysteine hydrochloride as a stabilizer and Na2SeSO3 as a selenium source to enable the synthesis of CdSe nanocrystals in a wider range of pHvalues. The CdSe nanocrystal powder was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. We systematically investigated the effect of synthesis conditions on the optical properties of the L-cysteine hydrochloride-stabilized CdSe nanocrystals, and found that different sizes of CdSe nanocrystals can be obtained by changing the pHvalue, the molar ratio of L-cysteine hydrochloride to Cd2+, or the refluxing time. The emission maxima of the obtained CdSe nanocrystals can be tuned in a wider range from 477 to 575 nm by changing the pHvalue from 7 to 13. We observed an obvious blue-shift of the absorption and photoluminescence peak position by varying the molar ratio of L-Cys to Cd2+ from 3.5:1 to 2:1 at the same pHvalue. The size of the obtained nanocrystals increased and the full width at half maximum became narrower as reflux time increased. Transmission electron microscopy images indicate that the as-prepared CdSe nanocrystals have a good dispersion, which means that L-cysteine hydrochloride can control the grouping of CdSe nanocrystals excellently as a stabilizer in the new alkali system.

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Fermi, Andrea, Mirko Locritani, Gabriele Di Carlo, et al. "Light-harvesting antennae based on photoactive silicon nanocrystals functionalized with porphyrin chromophores." Faraday Discussions 185 (2015): 481–95. http://dx.doi.org/10.1039/c5fd00098j.

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Silicon nanocrystals functionalized with tetraphenylporphyrin Zn(ii) chromophores at the periphery perform as light harvesting antennae: excitation of the porphyrin units in the visible spectral region yields sensitized emission of the silicon nanocrystal core in the near infrared with a long lifetime (λ<sub>max</sub>= 905 nm,τ= 130 μs). This result demonstrates that this hybrid material has a potential application as a luminescent probe for bioimaging.

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Sun, Dong-Mei, Da-Zhang Zhu, and Qing-Sheng Wu. "Bi-template effect of a vegetal system on the synthesis of alkaline-earth tungstate nanocrystals." Journal of Materials Research 24, no. 2 (2009): 347–51. http://dx.doi.org/10.1557/jmr.2009.0072.

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The MBS (mung bean sprouts) vegetal system, with its high penetrability, high selectivity, and space restriction, was explored to control nanocrystal synthesis. We found that the inside and outside of MBS have different structures and ion transformation properties. Two nanocrystals with distinct morphology, the nanorod and the nanosphere, were grown on the outer surface and the inner stem wall of MBS, respectively. The two XWO4 (X = Ca,Sr,Ba) nanocrystals were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR). The FTIR spectra of nanoproducts were different from bulk products due to the nano-size effect. A presumable mechanism was also determined. This work benefits the application of nanotungstates.

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Zhang, Yuqin, Shi He, Honghong Yao, et al. "Size Effect of Electrical and Optical Properties in Cr2+:ZnSe Nanowires." Nanomaterials 13, no. 2 (2023): 369. http://dx.doi.org/10.3390/nano13020369.

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Previous studies have shown that the nano-crystallization process has an appreciable impact on the luminescence properties of nanocrystals, which determines their defect state composition, size and morphology. This project aims to explore the influence of nanocrystal size on the electrical and optical properties of Cr2+:ZnSe nanowires. A first-principles study of Cr2+:ZnSe nanowires with different sizes was carried out at 0 K in the density functional framework. The Cr2+ ion was found to prefer to reside at the surface of ZnSe nanowires. As the size of the nanocrystals decreased, a considerable short-wave-length shift in the absorption of the vis-near infrared wavelength was observed. A quantum mechanism for the wavelength tunability was discussed.

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Kang, Jiho, Zachary M. Sherman, Hannah S. N. Crory, et al. "Modular mixing in plasmonic metal oxide nanocrystal gels with thermoreversible links." Journal of Chemical Physics 158, no. 2 (2023): 024903. http://dx.doi.org/10.1063/5.0130817.

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Gelation offers a powerful strategy to assemble plasmonic nanocrystal networks incorporating both the distinctive optical properties of constituent building blocks and customizable collective properties. Beyond what a single-component assembly can offer, the characteristics of nanocrystal networks can be tuned in a broader range when two or more components are intimately combined. Here, we demonstrate mixed nanocrystal gel networks using thermoresponsive metal–terpyridine links that enable rapid gel assembly and disassembly with thermal cycling. Plasmonic indium oxide nanocrystals with different sizes, doping concentrations, and shapes are reliably intermixed in linked gel assemblies, exhibiting collective infrared absorption that reflects the contributions of each component while also deviating systematically from a linear combination of the spectra for single-component gels. We extend a many-bodied, mutual polarization method to simulate the optical response of mixed nanocrystal gels, reproducing the experimental trends with no free parameters and revealing that spectral deviations originate from cross-coupling between nanocrystals with distinct plasmonic properties. Our thermoreversible linking strategy directs the assembly of mixed nanocrystal gels with continuously tunable far- and near-field optical properties that are distinct from those of the building blocks or mixed close-packed structures.

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Craievich, A. F., O. L. Alves, and L. C. Barbosa. "Formation and Growth of Semiconductor PbTe Nanocrystals in a Borosilicate Glass Matrix." Journal of Applied Crystallography 30, no. 5 (1997): 623–27. http://dx.doi.org/10.1107/s0021889897001799.

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Pb- and Te-doped borosilicate glasses are transformed by appropriate heat treatment into a composite material consisting of a vitreous matrix in which semiconductor PbTe nanocrystals are embedded. This composite exhibits interesting non-linear optical properties in the infrared region, in the range 10–20 000 Å. The shape and size distribution of the nanocrystals and the kinetics of their growth were studied by small-angle X-ray scattering (SAXS) during in situ isothermal treatment at 923 K. The experimental results indicate that nanocrystals are nearly spherical and have an average radius increasing from 16 to 33 Å after 2 h at 923 K, the relative size dispersion being time-invariant and approximately equal to 8%. This investigation demonstrates that the kinetics of nanocrystal growth are governed by the classic mechanism of atomic diffusion. The radius of nanocrystals, deduced by applying the simple Efros & Efros [Sov. Phys. Semicond. (1982), 16, 772–775] model using the energy values corresponding to the exciton peaks of optical absorption spectra, does not agree with the average radius determined by SAXS.

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Marpongahtun, Darwin Yunus Nasution, Nami Panindia, and Vivi Purwandari. "Influence of Acetylated Cellulose Nanocrystal Incorporated into Poly(e-Caprolactone) Nanocomposites on Its Thermal, Mechanical, and Physicochemical Properties." Journal of Southwest Jiaotong University 56, no. 3 (2021): 274–83. http://dx.doi.org/10.35741/issn.0258-2724.56.3.23.

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Poly(e-caprolactone) are synthetic biodegradable polymers that can potentially be used as biocompatible materials for biological applications. The purpose of this work was to investigate the effect of acetylated cellulose nanocrystals isolated from corncob waste loaded into poly(e-caprolactone) matrix blend on its thermal, mechanical, morphology, and crystallinity. The acetylated cellulose nanocrystal filler with various concentrations (namely 5, 10, 15, and 20%) was mixed with poly(e-caprolactone) matrix prepared using reflux method under N2 gas flow at 120oC for 10 min. Subsequently, the samples was characterized by thermal gravimetric analysis, DSC, tensile, Fourier transform infrared spectroscopy, tunneling electron microscope, SEM, and XRD to determine the thermal, mechanical, functional group, particle size, morphology, and crystallinity, respectively. Thermal gravimetric analysis and DSC analysis revealed that the thermal stability of poly(e-caprolactone) improved and the degree of crystallinity gradually increased with the addition of 10% acetylated cellulose nanocrystals, hence resulting in a higher Young's modulus. Fourier transform infrared spectroscopy results demonstrate that acetylated cellulose nanocrystal was successfully incorporated into poly(e-caprolactone) with an additional OH group. In addition, the particle size of 32 nm for acetylated cellulose nanocrystal and the formation of agglomeration was present based on TEM analysis, thus suggesting that acetylated cellulose nanocrystal was compatible as a reinforcing filler in the poly(e-caprolactone) matrix. SEM and XRD analysis suggests that the morphology was relatively smooth and higher crystallinity was achieved. The results of this research demonstrated the good feasibility of poly(e-caprolactone)/acetylated cellulose nanocrystal nanocomposites with improved thermal, mechanical, and physicochemical properties that were successfully prepared using simple and low-cost acetylated cellulose nanocrystal as a filler material.

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Pardhi, Vishwas P., Tejesh Verma, S. J. S. Flora, Hardik Chandasana, and Rahul Shukla. "Nanocrystals: An Overview of Fabrication, Characterization and Therapeutic Applications in Drug Delivery." Current Pharmaceutical Design 24, no. 43 (2019): 5129–46. http://dx.doi.org/10.2174/1381612825666190215121148.

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Approximately 40 % drugs in the market are having poor aqueous solubility related problems and 70 % molecules in discovery pipeline are being practically insoluble in water. Nanocrystals is a prominent tool to solve the issue related to poor aqueous solubility and helps in improving the bioavailability of many drugs as reported in the literature. Nanocrystals can be prepared by top down methods, bottom up methods and combination methods. Many patented products such as Nanocrystals®, DissoCubes®, NANOEDGE® and SmartCrystals ®, etc., are available, which are based on these three preparation methodologies. The particle size reduction resulted into unstable nanocrystalline system and the phenomenon of Ostawald ripening occurs. This instability issue could be resolved by using an appropriate stabilizers or combination of stabilizers. The nanosuspensions could be transformed to the solid state to prevent particle aggregation in liquid state by employing various unit operations such as lyophilisation, spray drying, granulation and pelletisation. These techniques are well known for their scalability and continuous nanocrystal formation advantages. Nanocrystals can be characterized by using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy, powdered x- ray diffraction and photon correlation spectroscopy. The downscaling of nanocrystals will enable rapid optimization of nanosuspension formulation in parallel screening design of preclinical developmental stage drug moieties. One of the most acceptable advantages of nanocrystals is their wide range of applicability such as oral delivery, ophthalmic delivery, pulmonary delivery, transdermal delivery, intravenous delivery and targeting (brain and tumor targeting). The enhancement in market value of nanocrystals as well as the amount of nanocrystal products in the market is gaining attention to be used as an approach in order to get commercial benefits.

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Liang, Kai, Yajing Zhou, and Yali Ji. "Full biodegradable elastomeric nanocomposites fabricated by chitin nanocrystal and poly(caprolactone-diol citrate) elastomer." Journal of Bioactive and Compatible Polymers 34, no. 6 (2019): 453–63. http://dx.doi.org/10.1177/0883911519881728.

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Chitin nanocrystal is a biocompatible and biodegradable nanofiller, with great potential in enhancing the mechanical and biological properties of polymers. Poly(caprolactone-diol citrate) is a kind of citrate-based biodegradable elastomer prepared by an additive-free melt polycondensation of polycaprolactone-diol and citric acid coupled with subsequent thermocuring. Here, a facile casting/evaporation method was utilized to prepare full biodegradable poly(caprolactone-diol citrate)/chitin nanocrystal nanocomposites, and their structure and properties were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, uniaxial tensile test, dynamic mechanical analysis, surface wettability and swelling analysis, thermogravimetric analysis, in vitro degradation, and cytocompatibility test. The results showed the chitin nanocrystals were uniformly distributed in the poly(caprolactone-diol citrate) matrix; with increasing chitin nanocrystal loading, the tensile modulus and strength significantly increased; furthermore, the incorporation of chitin nanocrystals endowed the poly(caprolactone-diol citrate) with more hydrophilicity, lower swelling in phosphate buffered saline solution, slow degradation rate, and greatly improved cytocompatibility. Thus, the chitin nanocrystal was a good bio-based nanofiller that could be used to tune the properties of poly(caprolactone-diol citrate) degradable bioelastomer.

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ZHANG, WEI-FENG, QIAN XING, and YA-BIN HUANG. "MICROSTRUCTURES AND OPTICAL PROPERTIES OF STRONTIUM TITANATE NANOCRYSTALS PREPARED BY A STEARIC-ACID GEL PROCESS." Modern Physics Letters B 14, no. 19 (2000): 709–16. http://dx.doi.org/10.1142/s0217984900000896.

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SrTiO3 nanocrystals with grain sizes from 26 to 86 nm were prepared by stearic-acid gel method. The microstructures, lattice vibration and luminescence spectra were examined by X-ray diffraction, infrared, Raman and photoluminescence (PL) spectroscopies. Hydroxyl defects were clearly found by infrared spectroscopy in the SrTiO3 nanocrystals. Raman measurement results showed that internal stress exists in the SrTiO3 nanocrystals, which induces first-order Raman scattering processes. Strong visible PL near 2.62 eV was observed under 3.54 eV light excitation in small SrTiO3 nanocrystals. Grain-size dependence of the PL spectrum is investigated and the origin for the PL is attributed to a charge transfer via intrinsic defects inside an oxygen octahedron.

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Rodina, Anna V. "Mid-infrared irradiation keeps nanocrystals bright." Nature Nanotechnology 16, no. 12 (2021): 1304–5. http://dx.doi.org/10.1038/s41565-021-01029-5.

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Nusir, Ahamd, Juan Aguilar, Justin Hill, Haley Morris, and M. Omar Manasreh. "Uncooled Infrared Photodetector Utilizing PbSe Nanocrystals." IEEE Transactions on Nanotechnology 15, no. 1 (2016): 109–12. http://dx.doi.org/10.1109/tnano.2015.2507058.

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Langevin, Marc-Antoine, Anna M. Ritcey, and Claudine Nì Allen. "Air-Stable Near-Infrared AgInSe2 Nanocrystals." ACS Nano 8, no. 4 (2014): 3476–82. http://dx.doi.org/10.1021/nn406439w.

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Mao, Baodong, Chi-Hung Chuang, Christopher McCleese, Junjie Zhu, and Clemens Burda. "Near-Infrared Emitting AgInS2/ZnS Nanocrystals." Journal of Physical Chemistry C 118, no. 25 (2014): 13883–89. http://dx.doi.org/10.1021/jp500872w.

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Koktysh, Dmitry S., Nikolai Gaponik, Martin Reufer, et al. "Near-Infrared Electroluminescence from HgTe Nanocrystals." ChemPhysChem 5, no. 9 (2004): 1435–38. http://dx.doi.org/10.1002/cphc.200400178.

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Dong, Hehe, Yinggang Chen, Yan Jiao, et al. "Nanocrystalline Yb:YAG-Doped Silica Glass with Good Transmittance and Significant Spectral Performance Enhancements." Nanomaterials 12, no. 8 (2022): 1263. http://dx.doi.org/10.3390/nano12081263.

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In this study, Yb:YAG-nanocrystal-doped silica glass with high transmission and excellent spectral properties was successfully prepared using a modified sol–gel method. The X-ray diffraction (XRD), micro-Raman spectroscopy, electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), and high-resolution TEM (HR-TEM) analyses confirmed that the Yb:YAG nanocrystals, with their low content, homogeneous distribution, and small crystal size, directly crystallized into the silica glass network without annealing treatment. In contrast with conventional microcrystalline glass having large particles (>0.1 μm) and a large particle content, nanocrystalline glass with a homogeneous distribution and sizes of ~22 nm had higher optical transmittance and better spectral properties. Compared with Yb3+ doped silica glass without nanocrystals, the Yb:YAG-nanocrystal-doped silica glass had a 28% increase in absorption cross-section at 975 nm and a 172% enhanced emission cross-section at 1030 nm without any changes in the spectral pattern of the Yb3+ ions in the silica glass. Meanwhile, the Yb:YAG-doped silica glass with large size and high optical quality was easily prepared. Therefore, the Yb:YAG-nanocrystal-doped silica glass is expected to be a promising near-infrared laser material.

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Fronya, Anastasiya A., Sergey V. Antonenko, Alexander Yu Kharin, et al. "Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures." Molecules 25, no. 3 (2020): 440. http://dx.doi.org/10.3390/molecules25030440.

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Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

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Tatarinov D. A., Sokolova A. V., Danilov D. V., and Litvin A. P. "Change of optical properties of inorganic perovskite nanocrystals of CsPbCl-=SUB=-x-=/SUB=-Br-=SUB=-3-x-=/SUB=-, alloyed with Yb-=SUP=-3+-=/SUP=- ions, when carrying out an anion exchange reaction." Optics and Spectroscopy 130, no. 8 (2022): 1034. http://dx.doi.org/10.21883/eos.2022.08.54778.2772-22.

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Alloying of perovskites nanocrystals by lanthanoids makes it possible to produce materials that luminesce effectively in both visible and near infrared spectra. In the present work, the influence of the width of the forbidden zone on the optical properties of the inorganic perovskites nanocrystals CsPbClxBr3-x alloyed by ions Yb3+ is investigated. For changing the chemical composition of nanocrystals, an anionic exchange method is used by adding bromide dodecyltrimethylammonium. As a result of the gradual substitution of chlorine ions with bromine ions, the forbidden area of nanocrystals is narrowed, resulting in a change in the spectral position of the optical transitions, the quantum output of photoluminescence in the near and infrared spectral ranges and the attenuation of photoluminescence. When the width of the forbidden area reaches 2.54 eV, the total quantum output of photoluminescence reaches 72%. Keywords: pervoskite nanocrystals, alloying, ytterbium, photoluminescence, anionic exchange.

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Ting Fan, Ting Fan, Qinyuan Zhang Qinyuan Zhang, and Zhonghong Jiang Zhonghong Jiang. "Enhanced near infrared emission in water-soluble NdF3 nanocrystals by Ba2+ doping." Chinese Optics Letters 10, no. 2 (2012): 021602–21605. http://dx.doi.org/10.3788/col201210.021602.

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Kim, Young Mi, Seok Ju Lee, and Ik Jin Kim. "Synthesis and Characterization of TMA-A Zeolite Nanocrystals." Solid State Phenomena 124-126 (June 2007): 563–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.563.

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Well-controlled cubic nanocrystal of TMA-A zeolite with a size of 60~100 nm were synthesized by a hydrothermal method in a solution having a Al(i-pro)3 : 2.2 TEOS : 2.4 TMAOH: 0.3 NaOH : 200H2O composition. The single TMA-A nanocrystals has an average lattice constant of 24.61 Å having a surface area of 742.36 m2/g. Thermal treatment of TMA zeolite crystals results in the formation of an amorphous above 900oC. Environmental scanning electron microscopy (ESEM). high resolution transmission electron microscopy(HRTEM), X-ray powder diffraction(XRD), fourier transform infrared(FT-IR) spectroscopy, DTA/TGA and BET analysis were used to characterize the initial materials and the obtained products after various heat treatments.

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Ortac, Inanc, and Feride Severcan. "Spectroscopy of biological nanocrystals." Spectroscopy 21, no. 1 (2007): 31–41. http://dx.doi.org/10.1155/2007/129283.

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Nanocrystals have gained much interest in recent years, due to their unusual properties allowing interesting applications in physical and biological science. In this literature review, biological nanocrystals are discussed from the spectroscopic point of view. Firstly, the theory behind the outstanding abilities of the nanocrystals is described. Secondly, the spectroscopic properties of biological nanocrystals are mentioned. Lastly, the use of nanocrystals with various spectroscopic applications is reviewed such as biosensor applications with UV–visible and surface plasmon resonance and Raman spectroscopy of biological materials. Finally, a short discussion of infrared nanocrystals and their abilities are included in the review.

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Wang, Baoyu, Rong Li, Jinhao Zeng, Min He, and Junrong Li. "Preparation of cellulose nanocrystals via successive periodate and bisulfite oxidation and mechanical and hydrophilic properties of the films." BioResources 16, no. 1 (2021): 1713–25. http://dx.doi.org/10.15376/biores.16.1.1713-1725.

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Microcrystalline cellulose was oxidized via periodate followed by sulfonation. The sulfonated cellulose nanocrystals were obtained through centrifugation, dialysis, and sonication. The sulfonated cellulose nanocrystals were rod-like and had an average length of 140 nm to 153 nm and an average width of 8 to 10 nm. The Fourier transform infrared profiles and polyelectrate titration demonstrated successful introduction of the sulfonated groups into the cellulose nanocrystals. The sulfonated cellulose nanocrystals had a higher crystallinity index than dialdehyde cellulose. The thin films fabricated via the casting of the sulfonated cellulose nanocrystals suspensions were highly hydrophilic.

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Lesyuk, Rostyslav, Eugen Klein, Iryna Yaremchuk, and Christian Klinke. "Copper sulfide nanosheets with shape-tunable plasmonic properties in the NIR region." Nanoscale 10, no. 44 (2018): 20640–51. http://dx.doi.org/10.1039/c8nr06738d.

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2D copper sulfide nanocrystals are promising building blocks of plasmonic materials in the near-infrared (NIR) spectral region. The shape of synthesized 2D CuS nanocrystals can effectively tune the NIR absorption and field distribution within the particle.

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MAGALHÃES, WASHINGTON LUIZ ESTEVES, XIAODONG CAO, MAGALY ALEXANDRA RAMIRES, and LUCIAN A. LUCIA. "Novel all-cellulose composite displaying aligned cellulose nanofibers reinforced with cellulose nanocrystals." April 2011 10, no. 4 (2011): 19–25. http://dx.doi.org/10.32964/tj10.4.19.

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Aligned cellulose nanocrystals/cellulose coelectrospun nanofibers were successfully prepared by using a home-built coelectrospinning and collection system. Cellulose I was dissolved in N-methyl morpholine oxide at 120°C and diluted with dimethyl sulfoxide, which was used in the external concentric capillary needle as the sheath (shell) solution. A cellulose nanocrystal suspension obtained by sulfuric acid hydrolysis of cotton fibers was used as the core liquid in the internal concentric capillary needle after transferring from water to dimethyl sulfoxide. The resultant coelectrospun nanocomposite films were collected onto a rotating wire drum and were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy, thermogravimetric analysis, and tensile measurements. The FE-SEM image showed that the cellulose nanocrystals did not appear to cluster in the film formed. Although the crystallinity index of nanocomposite fibers was lower than the unreinforced cellulose electrospun fibers, the cellulose type II reinforced with cellulose nanocrystals had a much higher tensile stress (about 140 MPa), almost twofold that of pure cellulose. This latter result indicated that the alignment and adhesion of amorphous cellulose nanofibers played a crucial role on the mechanical properties of electrospun cellulosic fiber mats.

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RUPASOV, VALERY I., and SERGEI G. KRIVOSHLYKOV. "LONG-WAVE INFRARED AND TERAHERTZ-FREQUENCY LASING BASED ON SEMICONDUCTOR NANOCRYSTALS." International Journal of High Speed Electronics and Systems 17, no. 02 (2007): 395–401. http://dx.doi.org/10.1142/s0129156407004588.

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ALTAIR Center develops long-wave infrared (LWIR) and terahertz-frequency (THz) lasers operating at room temperature employing intraband luminescence in colloidal semiconductor nanocrystals, in which the optical transition frequencies can be easily tuned to the desired values by an appropriate choice of the semiconductor material and radius of the nanocrystals.

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RUPASOV, VALERY I., and SERGEI G. KRIVOSHLYKOV. "LONG-WAVE INFRARED AND TERAHERTZ-FREQUENCY LASING BASED ON SEMICONDUCTOR NANOCRYSTALS." International Journal of High Speed Electronics and Systems 18, no. 01 (2008): 79–85. http://dx.doi.org/10.1142/s0129156408005151.

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ALTAIR Center develops long-wave infrared (LWIR) and terahertz-frequency (THz) lasers operating at room temperature employing intraband luminescence in colloidal semiconductor nanocrystals, in which the optical transition frequencies can be easily tuned to the desired values by an appropriate choice of the semiconductor material and radius of the nanocrystals.

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Sarwar, Abdur Rehman, Furqan Muhammad Iqbal, Muhammad Anjum Jamil, and Khizar Abbas. "Nanocrystals of Mangiferin Using Design Expert: Preparation, Characterization, and Pharmacokinetic Evaluation." Molecules 28, no. 15 (2023): 5918. http://dx.doi.org/10.3390/molecules28155918.

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Making nanoscale drug carriers could boost the bioavailability of medications that are slightly water soluble. One of the most promising approaches for enhancing the chemical stability and bioavailability of a variety of therapeutic medicines is liquid nanocrystal technology. This study aimed to prepare nanocrystals of mangiferin for sustained drug delivery and enhance the pharmacokinetic profile of the drug. The fractional factorial design (FFD) was used via a selection of independent and dependent variables. The selected factors were the concentration of mangiferin (A), hydroxypropyl methyl cellulose (HPMC) (B), pluronic acid (C), tween 80 (D), and the ratio of antisolvent to solvent (E). The selected responses were the particle size, polydispersity index (PDI), zeta potential, and entrapment efficiency. The nanocrystals were further evaluated for mangiferin release, release kinetics, Fourier transforms infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), particle size, zeta potential, and scanning electron microscopy (SEM). The stability studies of developed nanocrystals were performed for 6 months and pharmacokinetics on albino rabbits. The value of entrapment efficiencies ranged from 23.98% to 86.23%. The percentage release of mangiferin varied from 62.45 to 99.02%. FTIR and DSC studies showed the stability of mangiferin in the nanocrystals. The particle size of the optimized formulation was almost 100 nm and −12 mV the value of the zeta potential. The results of stability studies showed that the nanocrystals of mangiferin were stable for a period of six months. The peak plasma concentration of mangiferin from nanocrystals and suspension of mangiferin were 412 and 367 ng/mL, respectively. The value of AUC0−t of nanocrystals and suspension of mangiferin was 23,567.45 ± 10.876 and 18,976.12 ± 9.765 µg×h/mL, respectively, indicating that the nanocrystals of mangiferin showed greater availability of mangiferin compared to the suspension of the formulation. The developed nanocrystals showed a good release pattern of mangiferin, better stability studies, and enhanced the pharmacokinetics of the drug.

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B R, Venugopal. "Immobilization of Metal Sulfide Nanocrystals on Multiwalled Carbon Nanotubes Facilitated by Infrared Irradiation." Mapana - Journal of Sciences 13, no. 2 (2017): 17–32. http://dx.doi.org/10.12723/mjs.29.2.

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Uniformly distributed metal sulfide nanocrystals are immobilized on the surface of oxygenated multiwalled carbon nanotubes (MWCNTs) by reacting metal ions (Cu 2+ / Zn 2+ /Cd 2+ ) anchored to MWCNTs with hydrogen sulfide while irradiating with infrared (IR) radiation. The IR irradiation is the key step in the effective immobilization of metal sulfide nanocrystals on MWCNTs. The photoabsorption and photothermal properties of MWCNTs in the presence of IR irradiation raises the temperature of the CNTs in solution, facilitating the interaction between the acidic groups on CNTs and the metal ions, which results in effective immobilization of the nanocrystals. The metal sulfide-MWCNT hybrids are characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy.

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Onishchuk, D. A., A. S. Pavlyuk, P. S. Parfenov, A. P. Litvin, and I. R. Nabiev. "Near Infrared LED Based on PbS Nanocrystals." Optics and Spectroscopy 125, no. 5 (2018): 751–55. http://dx.doi.org/10.1134/s0030400x1811022x.

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Bigioni, T. P., R. L. Whetten, and Ö. Dag. "Near-Infrared Luminescence from Small Gold Nanocrystals." Journal of Physical Chemistry B 104, no. 30 (2000): 6983–86. http://dx.doi.org/10.1021/jp993867w.

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Lee, Doh C., Jeffrey M. Pietryga, Istvan Robel, Donald J. Werder, Richard D. Schaller, and Victor I. Klimov. "Colloidal Synthesis of Infrared-Emitting Germanium Nanocrystals." Journal of the American Chemical Society 131, no. 10 (2009): 3436–37. http://dx.doi.org/10.1021/ja809218s.

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Baride, Aravind, Ganesh Sigdel, William M. Cross, Jon J. Kellar, and P. Stanley May. "Near Infrared-to-Near Infrared Upconversion Nanocrystals for Latent Fingerprint Development." ACS Applied Nano Materials 2, no. 7 (2019): 4518–27. http://dx.doi.org/10.1021/acsanm.9b00890.

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Markovic, Zoran, Jovana Prekodravac, Dragana Tosic, et al. "Facile synthesis of water-soluble curcumin nanocrystals." Journal of the Serbian Chemical Society 80, no. 1 (2015): 63–72. http://dx.doi.org/10.2298/jsc140819117m.

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In this paper, facile synthesis of water soluble curcumin nanocrystals is reported. Solvent exchange method was applied to synthesize curcumin nanocrystals. Different techniques were used to characterize the structural and photophysical properties of curcumin nanocrystals. We found that nanocurcumin prepared by this method had good chemical and physical stability, could be stored in the powder form at room temperature, and was freely dispersible in water. It was established that the size of curcumin nanocrystals was varied in the range of 20-500 nm. Fourier transform infrared spectroscopy and UV-Vis analyses showed the presence of tetrahydrofuran inside the curcumin nanocrystals. Also, it was found that nanocurcumin emitted photoluminescencewith yellow-green colour.

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Mak, Chun Hin, Jiasheng Qian, Lukas Rogée, Wai Kin Lai, and Shu Ping Lau. "Facile synthesis of AgBiS2 nanocrystals for high responsivity infrared detectors." RSC Advances 8, no. 68 (2018): 39203–7. http://dx.doi.org/10.1039/c8ra08509a.

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Cai, Jing, Vijay Raghavan, Yu Jie Bai, et al. "Controllable synthesis of tetrapod gold nanocrystals with precisely tunable near-infrared plasmon resonance towards highly efficient surface enhanced Raman spectroscopy bioimaging." Journal of Materials Chemistry B 3, no. 37 (2015): 7377–85. http://dx.doi.org/10.1039/c5tb00785b.

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Yang, J., D. H. Li, and L. L. Ji. "A Low-Temperature Hydrothermal Synthesis of Prussian Blue Nanocrystal and Its Application in H2O2 Detection." Journal of Chemistry 2022 (July 21, 2022): 1–7. http://dx.doi.org/10.1155/2022/7593873.

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Uniform Prussian blue Fe3[Fe(CN)6]2 nanocrystals were synthesized by a direct dissociation and reduction of the single-Fe(III)-source precursor K3Fe(CN)6 under low-temperature hydrothermal conditions. UV-visible absorption spectrum, Fourier transform infrared spectrum, X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectra, high-resolution transmission electron microscopy, and electrochemical testing were used to characterize and verify the synthesized Prussian blue nanocrystal product. The size of the synthesized product had a strong dependence on the acidity condition and the concentration of K3Fe(CN)6 solution. This result may facilitate not only the exploration of preparing Fe3[Fe(CN)6]2 nanocrystals for particular applications but also an in-depth explanation of the nature of the hydrothermal reaction. The Prussian blue nanocrystals were deposited onto an electrode support through lyotropic liquid crystalline templates to detect hydrogen peroxide (H2O2) by reduction reaction. Cyclic voltammograms showed that the Prussian blue modified electrode was of excellent electrocatalytic activity for H2O2. This electrode demonstrated a detection limit (1 × 10−7 M) and a linear range starting from the detection limit and extending over 6 orders of magnitude of H2O2 concentrations (1 × 10−7 to 1 × 10−1 M), which was of excellent performance in detecting H2O2.

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Mazzanti, Andrea, Zhijie Yang, Mychel G. Silva, et al. "Light–heat conversion dynamics in highly diversified water-dispersed hydrophobic nanocrystal assemblies." Proceedings of the National Academy of Sciences 116, no. 17 (2019): 8161–66. http://dx.doi.org/10.1073/pnas.1817850116.

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We investigate, with a combination of ultrafast optical spectroscopy and semiclassical modeling, the photothermal properties of various water-soluble nanocrystal assemblies. Broadband pump–probe experiments with ∼100-fs time resolution in the visible and near infrared reveal a complex scenario for their transient optical response that is dictated by their hybrid composition at the nanoscale, comprising metallic (Au) or semiconducting (Fe3O4) nanostructures and a matrix of organic ligands. We track the whole chain of energy flow that starts from light absorption by the individual nanocrystals and subsequent excitation of out-of-equilibrium carriers followed by the electron–phonon equilibration, occurring in a few picoseconds, and then by the heat release to the matrix on the 100-ps timescale. Two-dimensional finite-element method electromagnetic simulations of the composite nanostructure and multitemperature modeling of the energy flow dynamics enable us to identify the key mechanism presiding over the light–heat conversion in these kinds of nanomaterials. We demonstrate that hybrid (organic–inorganic) nanocrystal assemblies can operate as efficient nanoheaters by exploiting the high absorption from the individual nanocrystals, enabled by the dilution of the inorganic phase that is followed by a relatively fast heating of the embedding organic matrix, occurring on the 100-ps timescale.

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Zang, Huidong, Prahlad K. Routh, Qingping Meng, and Mircea Cotlet. "Electron transfer dynamics from single near infrared emitting lead sulfide–cadmium sulfide nanocrystals to titanium dioxide." Nanoscale 9, no. 38 (2017): 14664–71. http://dx.doi.org/10.1039/c7nr03500d.

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Balci, Fadime Mert, Sema Sarisozen, Nahit Polat, et al. "Laser assisted synthesis of anisotropic metal nanocrystals and strong light-matter coupling in decahedral bimetallic nanocrystals." Nanoscale Advances 3, no. 6 (2021): 1674–81. http://dx.doi.org/10.1039/d0na00829j.

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The advances in colloid chemistry and nanofabrication allowed us to synthesize noble monometallic and bimetallic nanocrystals with tunable optical properties in the visible and near infrared region of the electromagnetic spectrum.

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Moharram, A. H. "Preparation and characterization of cobalt and copper oxide nanocrystals." Materials Science-Poland 37, no. 3 (2019): 347–52. http://dx.doi.org/10.2478/msp-2019-0048.

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AbstractCopper oxide and cobalt oxide (Co3O4, CuO) nanocrystals (NCs) have been successfully prepared using microwave irradiation. The obtained powders of the nanocrystals (NCs) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric (TGA) analysis and Fourier-transform infrared spectroscopy. The obtained results confirm the presence of both nanooxides which have been produced during chemical precipitation using microwave irradiation. TEM micrographs have shown that the obtained nanocrystals are characterized by high dispersion and narrow size distribution. The results of X-ray diffraction confirmed those obtained from the transmission electron microscope. Optical absorption analysis indicated the direct band gap for both kinds of the nanocrystals.

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Wang, J. B., X. L. Zhong, C. Y. Zhang, B. Q. Huang, and G. W. Yang. "Explosion Phase Formation of Nanocrystalline Boron Nitrides Upon Pulsed-Laser-Induced Liquid/Solid Interfacial Reaction." Journal of Materials Research 18, no. 12 (2003): 2774–78. http://dx.doi.org/10.1557/jmr.2003.0387.

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Boron nitride (BN) nanocrystals with explosion (E) phase were prepared by a novel laser-assisted materials fabrication, i.e., pulsed-laser-induced liquid (acetone)/solid (hexagonal boron nitride bulk) interfacial reaction at normal temperature and pressure. Typical diameters of these synthesized quasi-spherical BN nanocrystals were in the range of 30 to 80 nm. Transmission electron microscopy, x-ray diffraction, and Fourier transformed infrared spectroscopy were used to identify the morphologies and structures of the synthesized nanocrystals. Additionally, we proposed the formation mechanism of cubic-BN and E-BN nanocrystals upon pulsed-laser-induced liquid/solid interfacial reaction, in which both liquid and solid were simultaneously involved.

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Hao, Ji Yan, та Hai Tao Liu. "Fabrication and Microstructure of Ge-Sb-S-CsCl Chalcogenide Glass Containing β-GeS₂ Nanocrystals". Applied Mechanics and Materials 665 (жовтень 2014): 119–23. http://dx.doi.org/10.4028/www.scientific.net/amm.665.119.

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we report the fabrication and microstructure of Ge-Sb-S-CsCl chalcogenide glass containing β-GeS2 nanocrystals. A Ge-Sb-S-CsCl chalcogenide base glass with the better crystalline ability is first fabricated by melt-quenching method, and a further careful thermal process has led to the formation of β-GeS2 nanocrystals in the glass. Transmission electron microscopy showed that the size of β-GeS2 nanocrystals with nearly monodisperse spherical shape ranges from 30 to 45 nm in the glass. Powder X-ray diffraction results confirm that the β-GeS2 nanocrystals are of high crystallization with orthorhombic phase. Energy dispersive spectroscopy is employed for the information of nanocrystals glass composition. It is worthwhile to note that the obtained Ge-Sb-S-CsCl chalcogenide glass containing β-GeS2 nanocrystals still keeps higher transmittance in mid- and far- infrared spectral region.

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Journal articles on the topic 'Infrared nanocrystals'

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