FTIR, DC electrical measurements of Mg Nano-ferrite and their composites with reduced graphene oxide (rGO) and polypyrrole (PPy)

Mg ferrite nanoparticles have been synthesized using the citrate-nitrate auto-combustion technique. Also, polypyrrole (PPy) has been synthesized using a chemical polymerization technique. Physically blending ferrite with PPy and/or rGO in various ratios has produced composite samples. The XRD indicates that the ferrite nanoparticles are in a crystalline state with lattice constant 0.845 A and crystallite size 40 nm, and the composite samples contain PPy and rGO as intended. FTIR analyses indicate vibrational modes of octahedral at 405cm -1 and tetrahedral mode at 565 cm -1 of spinel structure. The EDX analysis of Fe, Mg, O, C


Introduction
The dynamic performance of spinel ferrite makes it a very appealing ferrite material (Mulushoa et al., 2018).

XRD
The X-ray diffraction method confirmed the crystalline nature of the synthesized nanoparticles.

FT-IR spectra
As demonstrated in Fig. 2 (a-f), the absorption bands below 600 cm -1 indicate the presence of pure ferrite.
Specifically, the higher band υ 1 at 565
has been added drop by drop to the nitrate-citrate solution to change the pH to 6.0.This made the solution darker and thicker.The water was then evaporated on a hot plate, resulting in the formation of a viscous gel.With much more heating, a self-propagating combustion event began within the gel.The combustion continued until the entire gel was transformed into a charred ash-like powder.The rough powder was then ground in an agate mortar to produce a fine powder.The fine powder was sintered for 6 hours at 900 °C then left into the furnace until being cooled to room temperature.The pure PPY sample was created via chemical polymerization of pyrrole monomer with apurity (99.5%), which have been purchased from Sisco Research laboratories, (with FeCl 3 .6H 2 O as an oxidizing agent) with a ratio of pyrrole: FeCl 3 equals 1:2.33.A solution of 1.21 mole of ferric chloride was added drop by drop to 0.52 mole of pyrrole monomers.The resultant precipitate was obtained after 24 hours by filtering and washing with distilled water until it became clear (Diauudin et al., 2020).The reduced graphene oxide was bought from Nano-Gate-Cairo -Egypt.We prepared the composites by physically mixing weight ratios carried out by the sonication process and grinding them into fine powders in an agate mortar for three hours.All composites have been prepared in the same conditions.Characterization Fourier transform infrared (FTIR) spectra for all samples have been recorded by Bruker FT-IR in the range of 400-2000 cm -1 at room temperature.Also, the prepared sample's structure has been investigated by XRD (German Bruker D8 advance diffractometer, Ultima IV-XRD) (10 • ≤ 2θ ≥ 80 • , Cu-Kα, λ = 1.5405Å).Energy-dispersive X-ray spectroscopy (EDXS) has also been used to study the element compositions of the prepared samples.Electrical properties have been evaluated using a four-probe methodology with a programmable electrometer for DC measurements.The DC conductivity of the samples was analyzed as a function of temperature, encompassing a range from 303 K to 423 K.
Fig. 1 (a-f) shows the XRD patterns.The obtained peaks of magnesium ferrite particles are matched with the standard JCPDS card (no.790416).The observed diffractogram patterns of all the samples verified the existence of a single-phase spinel ferrite with no additional unwanted peaks.The 2θ values of 30.74•, 36.1•,43.74•, 54.11•, 57.62•, and 63.27• are the characteristic angles for the standard peaks of spinel cubic ferrites.These values correspond to the reflection from the (220), (311), (222), (400), (422), (511), and (440) planes (JCPDS no.790416) (Swati et al., 2021), as shown in the MgFe 2 O 4 standard card.Also, the peaks characteristic of PPy and rGO are not obviously seen in Fig. 1.This could be because the ratios of the polymer and reduced graphene oxide in the studied composites aren't very high compared to the ratios of the ferrite, along with the much higher intensity of the ferrite peaks making them much more noticeable than the peaks of PPy and rGO.
Fig. 3 (a-f), confirming the proper chemical compositions of the prepared ferrite sample and their composite samples with their intended elemental ratios.It is evident from Fig. 3 (a-f) that only elemental contents of Mg, C, N, Fe, and O are present in the EDX spectra of nanoparticles.Furthermore, the absence of impurity peaks in the EDX spectra of samples showed that there is no impurity atom present in these nanoparticles, confirming the high purity of the synthesized nanoparticles.
Fig. (4): (a-f) The temperature dependence of DC conductivity of the samples with linear fit.