The measurement of internal strain in core–shell Ni₃Si(Al)–SiO_xnanoparticles

Abstract

Internal defects and strain in nanoparticles can influence their properties and therefore measuring these values is relevant. Powder diffraction techniques (neutron and synchrotron) are successfully used to characterize internal strain in the core-shell Ni(3)Si(Al)-SiO(x) nanoparticles having mean diameters of approximately 80 nm. The nanoparticles, which are strain-free after extraction from the bulk alloys, develop internal strain on heating. Both micro- and macro-strains can be measured from the analysis of Bragg peak shift and broadening. It is identified that differences in thermal expansion coefficient of the metallic core and the amorphous shell of the nanoparticles, as well as partial disordering of the L1(2) ordered core phase, are the main causes of strain evolution. Synchrotron measurements also detected partial crystallization of the amorphous silica shell.

Depletion gels from dense soft colloids: Rheology and thermoreversible melting

“…In the current system, we rationalized this conformational change by the chemically different nature of the Si-containing core and the polybutadiene arms of the stars, with different thermal expansion coefficients: j core % 10 À4 K À1 [Mazo et al (1999)], j PBD ¼ 6:6 Á 10 À4 K À1 . The internal strain generated by this mismatch may be non-negligible and likewise its influence on the macroscopic properties of the materials [Pigozzi et al (2009);Astefanoaei et al (2011)]. We estimated this strain from the increase in temperature DT and the thermal expansion mismatch Dj ¼ j PBD À j Si , as DeðDTÞ ¼ DjDT.…”

Thermal-Induced Stress of Plasmonic Magnetic Nanocomposites

“…Consequently, the stress strains can be substantially strengthened using both external fields and laser light exposure. The strain fields can be measured by neutron powder diffraction techniques, 29) geometric phase analysis, 28,30) and digital correlation analysis of scanning electron microscope (SEM) images. For water medium, Young's modulus E m is supposed to be zero, we enable to measure the spatial displacement both stress strains outside nanoflowers.…”

Thermal-induced stress of plasmonic magnetic nanocomposites

“…Consequently, the stress strains can be substantially strengthened using both external fields and laser light exposure. The strain fields can be measured by neutron powder diffraction techniques, 29) geometric phase analysis, 28,30) and digital correlation analysis of scanning electron microscope (SEM) images. 31) For water medium, Young's modulus E m is supposed to be zero, we enable to measure the spatial displacement both stress strains outside nanoflowers.…”