Size-dependent critical transition in the origin of light emission from core–shell Si–SiO2 nanoparticles

2020 ◽  
Vol 8 (26) ◽  
pp. 9012-9023
Author(s):  
Bruno P. Falcão ◽  
Joaquim P. Leitão ◽  
Maria R. Soares ◽  
Joana Rodrigues ◽  
Lídia Ricardo ◽  
...  
Keyword(s):  
Light Emission ◽  
Sio2 Nanoparticles ◽  
Core Shell ◽  
Critical Transition ◽  
Shell Nanoparticles ◽  
Size Dependent ◽  
The Core ◽  
Core Shell Nanoparticles ◽  
Small Nanoparticles

Here, it is established that the origin of the photoluminescence of Si–SiO2 core–shell nanoparticles is strongly size-dependent, with large nanoparticles emitting mostly from the core, whereas small nanoparticles emit predominantly from the shell.

Size-dependent thermal stresses in the core—shell nanoparticles

2013 ◽  
Vol 22 (12) ◽  
pp. 128102 ◽  
Author(s):  
I Astefanoaei ◽  
I Dumitru ◽  
Al Stancu
Keyword(s):  
Thermal Stresses ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Size Dependent ◽  
The Core ◽  
Core Shell Nanoparticles

Aromatic thiol-modulated Ag overgrowth on gold nanoparticles: tracking the thiol's position in the core–shell nanoparticles

Nanoscale ◽  
2019 ◽  
Vol 11 (37) ◽  
pp. 17471-17477 ◽  
Author(s):  
Jiaqi Chen ◽  
Dejing Meng ◽  
Hui Wang ◽  
Haiyun Li ◽  
Yinglu Ji ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Growth Process ◽  
Shell Growth ◽  
Core Shell ◽  
Internal Reference ◽  
Shell Nanoparticles ◽  
Aromatic Thiol ◽  
The Core ◽  
Spatial Trajectory ◽  
Core Shell Nanoparticles

Using DMAB as the Raman internal reference, the spatial trajectory of modulating 4-ATP molecules was tracked during the shell growth process.

Frequency- and Temperature-Dependent Ferromagnetic Resonance of Co/CoO Core-Shell Nanoparticles

2004 ◽  
Vol 818 ◽  
Author(s):  
U. Wiedwald ◽  
J. Lindner ◽  
M. Spasova ◽  
Z. Frait ◽  
M. Hilgendorff ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Field ◽  
Core Shell ◽  
Direct Measure ◽  
Temperature Dependent ◽  
Spin Magnetic Moment ◽  
Shell Nanoparticles ◽  
The Core ◽  
G Value ◽  
Core Shell Nanoparticles

AbstractFerromagnetic Resonance experiments are used to investigate the magnetic properties of monodisperse Co/CoO core-shell nanoparticles with diameters of about 10nm. From frequency- dependent measurements at various frequencies of 9-80 GHz the g-value is determined to be 2.13 which suggests an fcc bulk-like environment of the Co atoms within the core of the particles. This result yields a direct measure of the ratio of orbital to spin magnetic moment νL/νS=0.065. Moreover, from temperature-dependent measurements of the resonance field the anisotropy energy is extracted and found much lower than the hcp bulk value.

PREPARATION AND CHARACTERIZATION OF SURFACE-FUNCTIONALIZATION OF SILICA-COATED MAGNETITE NANOPARTICLES FOR DRUG DELIVERY

NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450042 ◽  
Author(s):  
CONG-WANG ZHANG ◽  
CHANG-CHUN ZENG ◽  
YING XU
Keyword(s):  
Drug Delivery ◽  
Shell Structure ◽  
Drug Carrier ◽  
Point Of View ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Application Potential ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

Fe 3 O 4– SiO 2 core–shell structure nanoparticles containing magnetic properties were investigated for their potential use in drug delivery. The Fe 3 O 4– SiO 2 core–shell structure nanoparticles were successfully synthesized by a simple and convenient way. The Fe 3 O 4– SiO 2 nanoparticles showed superparamagnetic behavior, indicating a great application potential in separation technologies. From the application point of view, the prepared nanoparticles were found to act as an efficient drug carrier. Specifically, the surface of the core–shell nanoparticles was modified with amino groups by use of silane coupling agent 3-aminopropyltriethoxysilane (APTS). Doxorubicin (DOX) was successfully grafted to the surface of the core–shell nanoparticles after the decoration with the carboxyl acid groups on the surface of amino-modified core–shell structure nanoparticles. Moreover, the nanocomposite showed a good drug delivery performance in the DOX-loading efficiency and drug release experiments, confirming that the materials had a great application potential in drug delivery. It is envisioned that the prepared materials are the ideal agent for application in medical diagnosis and therapy.

Colloidal Preparation of γ-Fe2O3@Au [core@shell] Nanoparticles

2003 ◽  
Vol 774 ◽  
Author(s):  
Jiye Fang ◽  
Jibao He ◽  
Eun Young Shin ◽  
Deborah Grimm ◽  
Charles J. O'Connor ◽  
...  
Keyword(s):  
Magnetic Core ◽  
Core Shell ◽  
Medical Systems ◽  
Solution Synthesis ◽  
Organic Solution ◽  
Shell Nanoparticles ◽  
The Core ◽  
Promising Application ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

Abstractγ-Fe2O3@Au core-shell nanoparticles were prepared through a combined route, in which high temperature organic solution synthesis and colloidal microemulsion techniques were successively applied. High magnification of TEM reveals the core-shell structure. The presence of Au on the surface of as-prepared particles is also confirmed by UV-Vis absorption. The magnetic core-shell nanoparticles offer a promising application in bio- and medical systems.

Enhanced Emission from Single Component Organic Core–Shell Nanoparticles

2007 ◽  
Vol 7 (12) ◽  
pp. 4311-4317 ◽  
Author(s):  
Koushik Dhara ◽  
Krishanu Sarkar ◽  
Partha Roy ◽  
Asim Bhaumik ◽  
Pradyot Banerjee
Keyword(s):  
Rate Constant ◽  
Mixed Solvent ◽  
Condensation Reaction ◽  
Single Component ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Remarkable Feature ◽  
Packing Factor ◽  
The Core ◽  
Core Shell Nanoparticles

By one-step mixed-solvent mediated approach, we have prepared fluorescent organic core–shell nanoparticles with an oligomer (1) derived from the Schiff base condensation reaction of 2,6-diformyl-4-methylphenol and o-phenylenediamine at room temperature. The core and shell structures are generated by the same oligomer (1) featuring the aggregation structure in core different from that in shell. The radial packing factor distribution of oligomer cluster depending on the solvent interaction in the time of nucleation is mainly responsible for the single component core–shell formation. Different morphologies of the core–shell nanospheres (CSNS) and core–shell nanohemispheres (CSNHS) were generated simply by changing the concentration of 1 in chloroform-methanol mixed solvent (1:2). We observed that fluorescent emission from those core–shell nanoparticles is intense whereas as-synthesized oligomer (1) itself is non-fluorescent in dilute solution. The enhanced emission in the core–shell form with more than 50 times increase in fluorescent quantum yield vis-à-vis 1 is a remarkable feature of the study. As UV absorption spectra of nanoparticles are blue-shifted relative to their properties in solution, the observed strong emission in the solid state makes the oligomer an outstanding exception to a well-established rule based on the molecular exciton model. The core–shell nanoparticles have been characterized by FE-SEM, TEM, XRD, nanosecond (ns) time-resolved fluorescence dynamics, UV-Vis and fluorescence spectroscopy. The longer fluorescence lifetimes (τ) of core–shell nanoparticles (3.50 ns and 3.52 ns for CSNS and CSNHS respectively) than 1 as-synthesized (1.28 ns) implies that the formation of the nanoparticles restricts the rotation and vibration of the groups in the molecules. The factor that induces fluorescent enhancement of nanoparticles is mainly ascribed to the increase of radiative rate constant (kr) and simultaneous decrease of nonradiative rate constant (knr).

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