High dielectric constant and capacitance in ultrasmall (2.5 nm) SrHfO<sub>3</sub> perovskite nanoparticles produced in a low temperature non-aqueous sol–gel route

Karmaoui, Mohamed; Ramana, E. Venkata; Tobaldi, David Maria; Lajaunie, Luc; Graça, M.P.F.; Arenal, Raúl; Seabra, M.P.; Labrincha, J.A.; Pullar, Robert C.

doi:10.1039/c6ra06990h

Cited by 22 publications

(22 citation statements)

References 59 publications

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“…35 This method is useful to investigate the crystalline nature of ultrasmall NPs. 36,37 Successful indexation of the FFT pattern was obtained, with the CoPt 3 Pm-3m structural data in good agreement with XRD analysis. The elemental quantification of the NPs was obtained from EDS analysis (Figure 2b).…”

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confidence: 68%

“…The analysis of the fast Fourier transform (FFT) pattern (Figure c), obtained from one single NP (top inset of Figure b), and the comparison with the simulation, obtained using JEMS software, gives the structure of these NPs . This method is useful to investigate the crystalline nature of ultrasmall NPs. , Successful indexation of the FFT pattern was obtained, with the CoPt 3 Pm -3 m structural data in good agreement with XRD analysis. The elemental quantification of the NPs was obtained from EDS analysis (Figure b). − …”

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confidence: 52%

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Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

Karmaoui

Amaral

Lajaunie

et al. 2016

J. Phys. Chem. Lett.

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We present for the first time a nonaqueous sol-gel route to produce ultrasmall (<2 nm) magnetic bimetallic CoPt nanoparticles (NPs). The one-pot procedure is carried out at low temperature (180 °C) using benzyl alcohol, acting as both reducing agent and solvent. The highly monodisperse CoPt NPs were investigated with innovative advanced X-ray methods (whole powder pattern modeling), HR-STEM, XPS, and SQUID magnetometry. XPS showed Co was mostly in metallic form, but with a very small amount of CoO on the NP surface. The spherical NPs had an ultrasmall diameter of 1.6 nm and could self-assemble in aligned linear chains, or nanobelts, of single NPs. They are superparamagnetic, with blocking temperature of ∼20 K and coercivity at 10 K of 27.9 kA m (∼350 Oe). However, there is evidence of a second magnetic phase (probably CoO) in the ZFC magnetization curve, which enhances their magnetization values, without significantly affecting their superparamagnetism.

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confidence: 68%

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confidence: 52%

Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

Karmaoui

Amaral

Lajaunie

et al. 2016

J. Phys. Chem. Lett.

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“…Nonaqueous sol–gel processing is a flexible and powerful approach to obtain functionally active NPs. 14−18 Here, we present a facile, one-pot, nonhydrolytic synthesis of SnO 2 NPs with controllable average size and with a narrow size distribution at low temperature.…”

Section: Introductionmentioning

confidence: 99%

One-Step Synthesis, Structure, and Band Gap Properties of SnO₂ Nanoparticles Made by a Low Temperature Nonaqueous Sol–Gel Technique

et al. 2018

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Because of its electrically conducting properties combined with excellent thermal stability and transparency throughout the visible spectrum, tin oxide (SnO 2 ) is extremely attractive as a transparent conducting material for applications in low-emission window coatings and solar cells, as well as in lithium-ion batteries and gas sensors. It is also an important catalyst and catalyst support for oxidation reactions. Here, we describe a novel nonaqueous sol–gel synthesis approach to produce tin oxide nanoparticles (NPs) with a low NP size dispersion. The success of this method lies in the nonhydrolytic pathway that involves the reaction between tin chloride and an oxygen donor, 1-hexanol, without the need for a surfactant or subsequent thermal treatment. This one-pot procedure is carried out at relatively low temperatures in the 160–260 °C range, compatible with coating processes on flexible plastic supports. The NP size distribution, shape, and dislocation density were studied by powder X-ray powder diffraction analyzed using the method of whole powder pattern modeling, as well as high-resolution transmission electron microscopy. The SnO 2 NPs were determined to have particle sizes between 3.4 and 7.7 nm. The reaction products were characterized using liquid-state 13 C and 1 H nuclear magnetic resonance (NMR) that confirmed the formation of dihexyl ether and 1-chlorohexane. The NPs were studied by a combination of 13 C, 1 H, and 119 Sn solid-state NMR as well as Fourier transform infrared (FTIR) and Raman spectroscopy. The 13 C SSNMR, FTIR, and Raman data showed the presence of organic species derived from the 1-hexanol reactant remaining within the samples. The optical absorption, studied using UV–visible spectroscopy, indicated that the band gap ( E g ) shifted systematically to lower energy with decreasing NP sizes. This unusual result could be due to mechanical strains present within the smallest NPs perhaps associated with the organic ligands decorating the NP surface. As the size increased, we observed a correlation with an increased density of screw dislocations present within the NPs that could indicate relaxation of the stress. We suggest that this could provide a useful method for band gap control within SnO 2 NPs in the absence of chemical dopants.

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“…The microstructural features were analyzed via the whole powder pattern modeling (WPPM) method, through the PM2K software; this novel technique exploits XRD by describing each observed peak profile as a convolution of instrumental and sample‐related physical effects, and by refining the corresponding model parameters directly on the observed data . Therefore, adopting the WPPM formalism, microstructure information such as crystalline domain shape and size (ie, the size of coherently scattering domains), size distribution, defect type, and content, can be obtained quantitatively . The shape of the crystalline domains was approximated to be spherical, with diameter distributed according to a log‐normal curve.…”

Section: Methodsmentioning

confidence: 99%

Increased UV absorption properties of natural hydroxyapatite‐based sunscreen through laser ablation modification in liquid

et al. 2018

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Sunfilters based on hydroxyapatite (HAp) and iron‐containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe‐containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared, respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser‐treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near‐infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties.

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High dielectric constant and capacitance in ultrasmall (2.5 nm) SrHfO₃ perovskite nanoparticles produced in a low temperature non-aqueous sol–gel route

Abstract: Strontium hafnium oxide (SrHfO3) has great potential as a high-k gate dielectric material, for use in memories, capacitors, CMOS and MOSFETs.

Cited by 22 publications

References 59 publications

Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

One-Step Synthesis, Structure, and Band Gap Properties of SnO₂ Nanoparticles Made by a Low Temperature Nonaqueous Sol–Gel Technique

Increased UV absorption properties of natural hydroxyapatite‐based sunscreen through laser ablation modification in liquid

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High dielectric constant and capacitance in ultrasmall (2.5 nm) SrHfO3 perovskite nanoparticles produced in a low temperature non-aqueous sol–gel route

Abstract: Strontium hafnium oxide (SrHfO3) has great potential as a high-k gate dielectric material, for use in memories, capacitors, CMOS and MOSFETs.

Cited by 22 publications

References 59 publications

Smallest Bimetallic CoPt3 Superparamagnetic Nanoparticles

Smallest Bimetallic CoPt3 Superparamagnetic Nanoparticles

One-Step Synthesis, Structure, and Band Gap Properties of SnO2 Nanoparticles Made by a Low Temperature Nonaqueous Sol–Gel Technique

Increased UV absorption properties of natural hydroxyapatite‐based sunscreen through laser ablation modification in liquid

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High dielectric constant and capacitance in ultrasmall (2.5 nm) SrHfO₃ perovskite nanoparticles produced in a low temperature non-aqueous sol–gel route

Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

Smallest Bimetallic CoPt₃ Superparamagnetic Nanoparticles

One-Step Synthesis, Structure, and Band Gap Properties of SnO₂ Nanoparticles Made by a Low Temperature Nonaqueous Sol–Gel Technique