Impact of silica environment on hyperfine interactions in ε-Fe2O3 nanoparticles

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F16%3A10332324" target="_blank" >RIV/00216208:11320/16:10332324 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68378271:_____/16:00469997 RIV/61388980:_____/16:00469997

Výsledek na webu

<a href="http://dx.doi.org/10.1007/s10751-016-1356-8" target="_blank" >http://dx.doi.org/10.1007/s10751-016-1356-8</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s10751-016-1356-8" target="_blank" >10.1007/s10751-016-1356-8</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Impact of silica environment on hyperfine interactions in ε-Fe2O3 nanoparticles

Popis výsledku v původním jazyce

Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of ε-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distribution of particle sizes was determined from the TEM pictures giving the average size 20 nm and the thickness of silica coating ~5; 8; 12; 19 nm. The particles were further characterized by the XRPD and DC magnetic measurements. The nanoparticles consisted mainly of ε-Fe2O3 with admixtures of ~1%of the α-phase and less than 1% of the γ-phase. The hysteresis loops displayed coercivities of ~2 T at room temperature. The parameters of hyperfine interactions were derived from transmission Mossbauer spectra. Observed differences of hyperfine fields for nanoparticles in the matrix and the bare ones are ascribed to strains produced during cooling of the composite. This interpretation is supported by slight changes of their lattice parameters and increase of the elementary cell volume deduced from XRD. The temperature dependence of the magnetization indicated a two-step magnetic transition of the ε-Fe2O3 nanoparticles spread between ~85 K and ~150 K, which is slightly modified by remanent tensile stresses in the case of nanoparticles in the matrix. The subsequent coating of the bare particles by silica produced no further change in hyperfine parameters, which indicates that this procedure does not modify magnetic properties of nanoparticles.

Název v anglickém jazyce

Impact of silica environment on hyperfine interactions in ε-Fe2O3 nanoparticles

Popis výsledku anglicky

Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of ε-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distribution of particle sizes was determined from the TEM pictures giving the average size 20 nm and the thickness of silica coating ~5; 8; 12; 19 nm. The particles were further characterized by the XRPD and DC magnetic measurements. The nanoparticles consisted mainly of ε-Fe2O3 with admixtures of ~1%of the α-phase and less than 1% of the γ-phase. The hysteresis loops displayed coercivities of ~2 T at room temperature. The parameters of hyperfine interactions were derived from transmission Mossbauer spectra. Observed differences of hyperfine fields for nanoparticles in the matrix and the bare ones are ascribed to strains produced during cooling of the composite. This interpretation is supported by slight changes of their lattice parameters and increase of the elementary cell volume deduced from XRD. The temperature dependence of the magnetization indicated a two-step magnetic transition of the ε-Fe2O3 nanoparticles spread between ~85 K and ~150 K, which is slightly modified by remanent tensile stresses in the case of nanoparticles in the matrix. The subsequent coating of the bare particles by silica produced no further change in hyperfine parameters, which indicates that this procedure does not modify magnetic properties of nanoparticles.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BM - Fyzika pevných látek a magnetismus

OECD FORD obor

—

Projekt

<a href="/cs/project/GA16-04340S" target="_blank" >GA16-04340S: Oxidové nanomagnety, jejich vlastnosti a interakce s biologickými systémy</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Hyperfine Interaction

ISSN

0304-3843

e-ISSN

—

Svazek periodika

2016

Číslo periodika v rámci svazku

237

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

1-10

Kód UT WoS článku

—

EID výsledku v databázi Scopus

2-s2.0-84995543338