In this experiment, we selleck kinase inhibitor explore the role of ethylenediamine (EDA or en in ligand form) on the phases of iron oxide in hydrothermal condition. EDA is usually considered to be the chelating agent or to function as a ligand to facilitate the growth of particles under hydrothermal reaction [36, 37]. However, phase transformation of iron oxide was observed when
EDA was added into the alkaline solution. Thus, a special low-temperature route for the transformation of α-Fe2O3 to Fe3O4 was provided. The phase and shape variations with the addition of potassium hydroxide (KOH), EDA, and KOH and EDA were investigated and compared. Methods Ferric nitrate (Fe(NO3)3 · 9H2O), 1 mmol, was dissolved in 10 ml of distilled water to form a transparent yellow solution. Next, three different mineralizing agents were added into the ferric solution. First is 5 ml of 10.67 M KOH aqueous MK-4827 solution. The solution was added dropwisely into the ferric solution. Second is 1 ml of EDA. The EDA was added gradually into the ferric solution. Third is the combination of KOH and EDA. The 10.67 M KOH solution, 5 ml, was added first followed by the addition of 1 ml of EDA. After adding these mineralizing agents, a brown Fe(OH)3 suspension was obtained. Then, these
solutions were all stirred for 30 min before transferring the mixture into a Teflon-lined stainless steel autoclave (DuPont, Wilmington, DE, USA) of 40-ml capacity and followed by heat treatments at 200°C for 9 h. After that, the autoclave was cooled down to room temperature in air. The precipitates were collected by centrifugation, washed Amoxicillin with deionized water and ethanol several times to remove organic and impurities, and finally dried in air at 80°C for 12 h. The as-synthesized powder was characterized by X-ray diffraction (XRD) with Cu-Kα radiation, field emission
scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The magnetic properties were measured by a vibrating sample magnetometer (VSM) with a maximum magnetic field of 1.5 kOe. Results and discussion Figure 1 shows the iron oxide particles synthesized with three different reducing agents, KOH, EDA, and KOH/EDA, under a hydrothermal condition of 200°C for 9 h in the ferric solution. Figure 1a shows the α-Fe2O3 hexagonal plates which were obtained with the addition of KOH, and Figure 1b shows the α-Fe2O3 hexagonal bipyramid particles obtained when EDA was added into the system. Figure 1c shows the Fe3O4 polyhedral particles obtained with the addition of both KOH and EDA into the reaction system. (When NaOH substitutes for KOH, a similar reaction would occur.) The crystal structure of these iron oxide particles was analyzed by XRD and is shown in Figure 1d. The phase can be identified to be α-Fe2O3 when either KOH or EDA alone was added to the reaction system despite different morphologies. The diffraction peaks match the JCPDS card no.