Mpms 7

Diverse methods were implemented for material characterization, permitting a detailed comparison of the iron oxides before and after the propagation of combustion waves. These included scanning electron microscopy (SEM) images, energy dispersive X-ray spectroscopy (EDX) line profile data from a field-emission SEM (FEI, Model Quanta 250 FEG; Jeol, Model JSM-6701F), transmission electron microscope (TEM) images and EDX mapping (FEI, Talos F200 X), Raman spectroscopy (Horiba Jobin Yvon, LabRAM ARAMIS IR² spectrometer), and X-ray diffraction (XRD) patterns (Rigaku, SmartLab). Raman spectra were measured with a 532-nm diode laser as an excitation source. XRD patterns were measured in the 2θ mode at a scan speed of 2°/min. The magnetic properties were measured through the B–H curve for magnetic flux and magnetic field strength (MPMS–7, Quantum Design, USA).

The superparamagnetic properties of the fabricated LMWHA-Fe₃O₄ NPs were determined using a superconducting quantum interference device (SQUID) (MPMS7, Quantum Design, San Diego, CA, USA). The hysteresis loops of the LMWHA-Fe₃O₄ NPs were measured at temperatures of 5 K and 300 K. The saturation magnetizations of the oleic acid-coated Fe₃O₄ NPs and LMWHA-Fe₃O₄ NPs were also tested and compared.
The dynamic viscosities of the LMWHA and LMWHA-Fe₃O₄ NPs were measured at 25 °C using a viscometer (X-420, Cannon Instrument Co., State College, PA, USA). As described in a previous study [26 (link)], the samples were added to pure water to form solutions with a concentration of 0.5 mg/mL. The solutions were then stirred magnetically for 2 h and the dynamic viscosity was read with units of centistokes (cSt) using DD water as a control.
The thermal stabilities of the oleic acid-coated Fe₃O₄ NPs, neat LMWHA, and LMWHA-Fe₃O₄ NPs were measured using a thermogravimeter (TGA, TG 209 F3 Tarsus, Netzsch, Gerätebau GmbH, Bavarian, Germany). An amount of 5 mg of each sample was heated from room temperature to 700 °C at a rate of 10 °C/min in a chamber filled with nitrogen. The decomposition temperatures (T_d) and residual weights of the various samples at 700 °C were then measured and compared.

Pure MgB₂ and (Fe, Ti) particle-doped MgB₂ specimens were synthesized using the nonspecial atmosphere synthesis (NAS) method¹⁶ . Briefly, NAS method needs Mg (99.9% powder), B (96.6% amorphous powder), (Fe, Ti) particles and stainless steel tube. Mixed Mg and B stoichiometry, and (Fe, Ti) particles were added by weight. They were finely ground and pressed into 10 mm diameter pellets. (Fe, Ti) particles were ball-milled for several days, and average radius of (Fe, Ti) particles was approximately 0.163 μm¹⁰ . On the other hand, an 8 m-long stainless-steel (304) tube was cut into 10 cm pieces. Insert holed Fe plate into stainless- steel (304) tube. One side of the 10 cm-long tube was forged and welded. The pellets and pelletized excess Mg were placed at uplayer and downlayer in the stainless-steel tube, respectively. The pellets were annealed at 300 °C for 1 hour to make them hard before inserting them into the stainless-steel tube. The other side of the stainless-steel tube was also forged. High-purity Ar gas was put into the stainless-steel tube, and which was then welded. Specimens had been synthesized at 920 °C for 1 hour. They are cooled in air and quenched in water respectively. The field and temperature dependence of magnetization were measured using a MPMS-7 (Quantum Design).

The magnetic properties of wafer pieces with FePt helices (annealed) and Janus particles (as-deposited, annealed, and aged) were characterized via superconducting quantum interference device (SQUID, MPMS-7, quantum design) magnetometry. The field-dependent magnetization measurements were conducted at room temperature and the field was varied from 7 T to $-7$ T. For the M–H hysteresis loop measurements, the external magnetic field H has been applied in the out-of-plane and the in-plane directions where in-plane denotes a measurement perpendicular to the wafer surface’s normal while out-of-plane is defined as parallel to it. The contribution of the substrate and the ${\text{SiO}}_2$ was subtracted via linear fitting at high field ranges.

(Fe, Ti) particle-doped ${\text{MgB}}_2$ specimens were synthesized using the non-special atmosphere synthesis (NAS) method²¹ . The starting materials were Mg (99.9% powder) and B (96.6% amorphous powder) and (Fe, Ti) particles. Mixed Mg and B stoichiometry, and (Fe, Ti) particles were added by weight. They were finely ground and pressed into 10 mm diameter pellets. (Fe, Ti) particles were ball-milled for several days, and average radius of (Fe, Ti) particles was about 0.163 $\mathrm{\mu }$ m. On the other hand, an 8 m-long stainless- steel (304) tube was cut into 10 cm pieces. One side of the 10 cm-long tube was forged and welded. The pellets and excess Mg were placed in the stainless-steel tube. The pellets were annealed at 300 °C for 1 h to make them hard before inserting them into the stainless-steel tube. The other side of the stainless-steel tube was also forged. High-purity Ar gas was put into the stainless-steel tube, and which was then welded. Specimens had been synthesized at 920 °C for 1 hour and cooled in air. Field dependences of magnetization were measured using a MPMS-7 (Quantum Design). During the measurement, sweeping rates of all specimens were made equal for the same flux-penetrating condition.