Shane Harstad

Enhancement of 𝜷-phase in PVDF films embedded with ferromagnetic Gd5Si4 nanoparticles for piezoelectric energy harvesting

Self-polarized Gd5Si4-polyvinylidene fluoride (PVDF) nanocomposite films have been synthesized via a facile phase-inversion technique. For the 5 wt% Gd5Si4-PVDF films, the enhancement of the piezoelectric β-phase and crystallinity are confirmed using Fourier transform infrared (FTIR) spectroscopy (phase fraction, Fβ, of 81% as compared to 49% for pristine PVDF) and differential scanning calorimetry (crystallinity, ΔXc, of 58% as compared to 46% for pristine PVDF), respectively. The Gd5Si4 magnetic nanoparticles, prepared using high-energy ball milling were characterized using Dynamic Light Scattering and Vibrating Sample Magnetometry (VSM) to reveal a particle size of ∼470 nm with a high magnetization of 11 emu/g. The VSM analysis of free-standing Gd5Si4-PVDF films revealed that while the pristine PVDF membrane shows weak diamagnetic behavior, the Gd5Si4-PVDF films loaded at 2.5 wt% and 5 wt% Gd5Si4 show enhanced ferromagnetic behavior with paramagnetic contribution from Gd5Si3 phase. The interfacial inte...

Gd-Based Magnetic Nanoparticles for Biomedical Applications

Abstract Magnetic micro- and nano-sized particles have important biomedical applications and are therefore extensively researched. The optimum particle size varies depending on the application. Magnetic nanoparticles (NPs) exhibit properties different than their corresponding bulk materials due to finite size effects, composition, crystal structure, etc. These NPs could be synthesized by several methods using either top-down or bottom-up approaches. The optimization of size, shape, and structure of these NPs leads to interesting magnetic properties that have diverse applications. Gadolinium silicide (Gd5Si4) NPs are ferromagnetic at room temperature and have the potential to serve both as an agent for diagnostics (e.g., as magnetic resonance imaging (MRI) contrast agent) and treatment (hyperthermia therapy for cancer treatment). In this chapter, we give an overview of size-dependent magnetic properties such as magnetization, Curie temperature, and coercivity of Gd5Si4 NPs.

Investigating phase transition temperatures of size separated gadolinium silicide magnetic nanoparticles

Gadolinium silicide (Gd5Si4) nanoparticles (NPs) exhibit different properties compared to their parent bulk materials due to finite size, shape, and surface effects. NPs were prepared by high energy ball-milling of the as-cast Gd5Si4 ingot and size separated into eight fractions using time sensitive sedimentation in an applied dc magnetic field with average particle sizes ranging from 700 nm to 82 nm. The largest Gd5Si4 NPs order ferromagnetically at 316 K. A second anomaly observed at 110 K can be ascribed to a Gd5Si3 impurity. As the particle sizes decrease, the volume fraction of Gd5Si3 phase increases at the expense of the Gd5Si4 phase, and the ferromagnetic transition temperature of Gd5Si4 is reduced from 316 K to 310 K, while the ordering of the minor phase is independent of the particle size, remaining at 110 K.

Gd 5 Si 4 particles for magnetic hyperthermia

One developing application of nanomedicine is magnetic hyperthermia (MH) cancer treatment.