Talos f200s g2 microscope

The procedures for synthesis of Cu₅FeS₄ core-shell icosahedral nanoparticles were described in detail in our previous work [27 ]. Morphology of nanoparticles was characterized by a field-emission environmental scanning electron microscope (SEM, Thermoscientific Quattro S, Brno, Czech) at 5 kV. TEM-related studies, including high-resolution TEM (HRTEM), selected area electron diffraction (SAED), high-angle annular dark field (HAADF), and energy-dispersive X-ray spectroscopy (EDS) mapping, were conducted on a Thermoscientific Talos F200S G2 microscope (Brno, Czech) at 200 kV. Two kinds of TEM samples were prepared. First, the icosahedral nanoparticles were dispersed in ethanol and directly deposited on copper grids. Second, ultramicrotomy was applied to section nanoparticles into thin slices (ca. 30 nm) for HRTEM observation and composition determination for cores and shells, since the nanoparticles with a size of 100–200 nm were too large/thick for these studies. The nanoparticles were firstly embedded in resin (Epon 812, West Chester, PA, USA) after 80 °C heating/solidification for 48 h in vacuum and then sectioned to thin slices via ultramicrotome (Leica EM UC7, Vienna, Austria). The icosahedral nanoparticles and thin slices were transformed to TEM grids for ex situ studies and to heating MEMS chips for further in situ heating TEM studies by using a FEI NanoEx-w/v MEMS holder.

Transmission electron microscopy (TEM) investigations were carried out using a Talos F200S G2 microscope (Thermo Fisher Scientific, Waltham, USA), equipped with an S-FEG Schottky field emitter operating at 200 kV and two large-area energy-dispersive X-ray (EDX) spectrometers with silicon drift detectors. The investigated samples were suspended with 1 ml of acetone in a test tube, sonicated for 20 min (using a low-power sonic bath) and left to set for 5 min. Then, a drop of the suspension was transferred onto a 300-mesh carbon copper TEM grid (Ted Pella Inc., Redding, USA) and left to dry. Observations were made both in TEM and scanning TEM (STEM) mode.

TEM was used to describe the shape and size of CNCs. The experiments were carried out using a Talos F200S G2 microscope (Thermo Scientific, Brno, Czech Republic), running at an acceleration voltage of 200 kV. Briefly, 0.2 g of CNCs were mixed with 5 mL of double-distilled water with ultrasonication (28 kHz, 180 W, 20 min) (Argo Lab, Carpi, Italy). A drop of CNCs suspension was pipetted onto a formvar/carbon-coated copper grid (200 mesh). TEM micrographs were analyzed by means of ImageJ software (v. 1.53a, National Institutes of Health, Bethesda, Maryland, MD, USA). The average width and length of 100 randomly chosen CNCs were measured.
Pure orange CNCs and films were subjected to Cu-Kα radiation at 40 kV and 40 mA in an X-ray diffractometer (X’Pert Pro, PANalytical, Eindhoven, The Netherlands) to capture the XRD patterns. At room temperature, each sample was inspected with a scanning angle of 2θ from 5 to 110 at a rate of 2.45°/min. According to Nam et al. [36 (link)], Equation (1) was used to calculate the crystallinity index (CI):
where I_cry is the peak’s greatest intensity of diffraction in the crystalline region, which occurs at an angle of 2θ∼22.5° for cellulose I and ∼21.7° for cellulose II. At an angle of 2θ∼18° for cellulose I and ∼16° for cellulose II, I_am is the minimal intensity in the amorphous region [37 (link),38 (link)].