Formation of the core–shell microstructure in lead-free Bi1/2Na1/2TiO3-SrTiO3 piezoceramics and its influence on the electromechanical properties

Pure hydroxyapatite (HA) is brittle and it cannot be directly used for the load-bearing biomedical applications. Aim of this paper was to present a new iron-containing hydroxyapatite/titanium composites synthesized via pressureless sintering at a relatively low temperature of 1000°C using nano-sized HA powders and Ti-33%Fe mixed powders. The microstructure and composition of the new type composites were evaluated. The results showed that the uniformly distributed reinforcing particles had a unique and favorable core/shell microstructure after sintering that consisted of outer titanium and inner iron. The mechanism for the formation of the core/shell structure was discussed. The addition of iron reduced the decomposition rate of HA and the interaction between HA and titanium.

Download Full-text

Modeling of the core-shell microstructure of temperature-stable BaTiO3 based dielectrics for multilayer ceramic capacitors

Journal of Electroceramics ◽

10.1007/s10832-007-9240-1 ◽

2007 ◽

Vol 21 (1-4) ◽

pp. 545-548 ◽

Cited By ~ 13

Author(s):

Hai Wen ◽

Xiaohui Wang ◽

Zhilun Gui ◽

Longtu Li

Keyword(s):

Core Shell ◽

Shell Microstructure ◽

Multilayer Ceramic Capacitors ◽

The Core ◽

Ceramic Capacitors ◽

Multilayer Ceramic

Download Full-text

Synthesis Chemistry and Properties of Ni Catalysts Fabricated on SiC@Al2O3 Core-Shell Microstructure for Methane Steam Reforming

Catalysts ◽

10.3390/catal10040391 ◽

2020 ◽

Vol 10 (4) ◽

pp. 391

Author(s):

Hyunju Lee ◽

Doohwan Lee

Keyword(s):

Mass Transport ◽

Metal Oxide ◽

Al2o3 Content ◽

Oxide Shell ◽

Core Shell ◽

High Heat Flux ◽

Shell Microstructure ◽

The Core ◽

Supported Ni Catalyst ◽

Reaction Processes

Heat and mass transport properties of heterogeneous catalysts have significant effects on their overall performance in many industrial chemical reaction processes. In this work, a new catalyst micro-architecture consisting of a highly thermally conductive SiC core with a high-surface-area metal-oxide shell is prepared through a charge-interaction-induced heterogeneous hydrothermal construction of SiC@NiAl-LDH core-shell microstructures. Calcination and reduction of the SiC@NiAl-LDH core-shell results in the formation of Ni nanoparticles (NPs) dispersed on SiC@Al2O3, referred to as Ni/SiC@Al2O3 core-shell catalyst. The Ni/SiC@Al2O3 exhibit petal-like shell morphology consisting of a number of Al2O3 platelets with their planes oriented perpendicular to the surface, which is beneficial for improved mass transfer. For an extended period of methane-stream-reforming reaction, the Ni/SiC@Al2O3 core-shell structure remained stable without any significant degradation at the core/shell interface. However, the catalyst suffered from coking and sintering likely associated with the relatively large Ni particle sizes and the low Al2O3 content. The synthesis procedure and chemistry for construction of supported Ni catalyst on the core-shell microstructure of the highly thermal conductive SiC core, and the morphology-controlled metal-oxide shell, could provide new opportunities for various catalytic reaction processes that require high heat flux and enhanced mass transport.

Download Full-text

New Low Temperature Alloy Core-Shell Structures for Joining Applications

International Symposium on Microelectronics ◽

10.4071/isom-2016-wp42 ◽

2016 ◽

Vol 2016 (1) ◽

pp. 000705-000710

Author(s):

Richard Stephenson ◽

Kyle Bandaccari ◽

Howard Imhof

Keyword(s):

Low Temperature ◽

Lead Free ◽

Shell Structures ◽

Process Conditions ◽

Core Shell ◽

Powder Materials ◽

Application Process ◽

The Core ◽

Fracture Area ◽

Shell Powder

Abstract Silver and copper core-shell powder materials are introduced and discussed in low temperature joining applications. Properties of the core-shell powders are reviewed and suggested process conditions are shown. Examination of ductile fracture area corroborate bonding strength results for both silver and copper core-shell materials. Selectable materials sets are presented to address different application process needs for lead-free systems.

Download Full-text

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

Ukrainian Journal of Physics ◽

10.15407/ujpe65.10.904 ◽

2020 ◽

Vol 65 (10) ◽

pp. 904

Author(s):

V. O. Zamorskyi ◽

Ya. M. Lytvynenko ◽

A. M. Pogorily ◽

A. I. Tovstolytkin ◽

S. O. Solopan ◽

...

Keyword(s):

Magnetic Properties ◽

Spinel Ferrite ◽

Composite Nanoparticles ◽

Core Shell ◽

Cofe2o4 Nanoparticles ◽

Core Diameter ◽

The Core ◽

Shell Particles ◽

Interface Parameters ◽

Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

Download Full-text

Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽

10.3390/catal11010072 ◽

2021 ◽

Vol 11 (1) ◽

pp. 72

Author(s):

Christian Zambrzycki ◽

Runbang Shao ◽

Archismita Misra ◽

Carsten Streb ◽

Ulrich Herr ◽

...

Keyword(s):

Water Purification ◽

Functional Materials ◽

Core Material ◽

Solid Catalyst ◽

Core Shell ◽

Shell Nanoparticles ◽

The Core ◽

Shell Nanostructures ◽

Sio2 Shell ◽

Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

Download Full-text

Light-Scattering Simulations from Spherical Bimetallic Core–Shell Nanoparticles

Micromachines ◽

10.3390/mi12040359 ◽

2021 ◽

Vol 12 (4) ◽

pp. 359

Author(s):

Francesco Ruffino

Keyword(s):

Optical Properties ◽

Light Scattering ◽

Bimetallic Nanoparticles ◽

Dominant Role ◽

Scattered Light ◽

Specific Interaction ◽

Surface Enhanced Raman Spectroscopy ◽

Localized Surface Plasmon ◽

Core Shell ◽

The Core

Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.

Download Full-text

Tuning and understanding the electronic effect of Co-Mo-O sties in bifunctional electrocatalysts for ultralong-lasting rechargable zinc-air battery

Journal of Materials Chemistry A ◽

10.1039/d1ta04408g ◽

2021 ◽

Author(s):

Yi Guan ◽

Nan Li ◽

Jiao He ◽

Yongliang Li ◽

Lei Zhang ◽

...

Keyword(s):

Electronic Effect ◽

Metal Organic Frameworks ◽

Core Shell ◽

Zeolitic Imidazolate Frameworks ◽

Assembly Strategy ◽

The Core ◽

Bifunctional Electrocatalysts ◽

Metal Organic ◽

Air Battery

Herein, we report a post-assembly strategy by growing the bimetallic Co/Zn zeolitic imidazolate frameworks (BIMZIF) on the surface of the customized Mo metal-organic frameworks (MOFs) (Mo-MOF) to prepare the core-shell...

Download Full-text

Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

Polymers ◽

10.3390/polym13040502 ◽

2021 ◽

Vol 13 (4) ◽

pp. 502

Author(s):

Karel Šindelka ◽

Zuzana Limpouchová ◽

Karel Procházka

Keyword(s):

Dissipative Particle Dynamics ◽

Water Soluble ◽

Coarse Grained ◽

Core Shell ◽

Computer Study ◽

Interpolyelectrolyte Complex ◽

The Core ◽

Porphyrin Derivatives ◽

Oppositely Charged ◽

Positively Charged

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P+) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A10+B25 and 137 A10−B25 chains with moderately hydrophobic A blocks (DPD interaction parameter aAS=35) and hydrophilic B blocks (aBS=25) with 10 to 120 P+ added (aPS=39). The P+ interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P+ molecules easily solubilize in IPEC cores, where they partly replace PE+ and electrostatically crosslink PE− blocks. As the large P+ rings are apt to aggregate, P+ molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P+ in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P+ in the mixture and on their association number, AS. If AS is lower than the ensemble average ⟨AS⟩n, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing AS, which approaches ⟨AS⟩n. If AS>⟨AS⟩n, they escape into the bulk solvent.

Download Full-text