Improved structural and magnetic properties of Polypyrrole substituted spinel ferrites composites

Highlights

• The spinel ferrites Mg_0.96Pr_0.04Fe₂O₄ were synthesized by co-precipitate route.

• The XRD data confirmed the incorporation of praseodymium in spinel nanoferrites.

• The hysteresis loop discloses the ferromagnetic nature of Nano-composites.

• The magnetic parameters like coercivity and saturation magnetization show variation with increase of ferrite additives.

• Two Nano-composites FP1 = 25% and FP2 = 50% may be recommended for hyperthermia of cancer treatment.

Abstract

The spinel ferrites Mg_0.96Pr_0.04Fe₂O₄ were synthesized by co-precipitate route. The in-situ polymerization technique is employed to prepare Polypyrrole. In present work, nanocomposites were manufactured by intermixing of Polypyrrole polymers and Mg-Pr-ferrites Mg_0.96Pr_0.04Fe₂O₄. The nanocomposites were subjected to characterization techniques like XRD (X-ray diffraction), SEM (scanning electron microscope) and VSM (vibrating sample magneto-meter). The XRD data confirmed the incorporation of praseodymium in spinel nanoferrites. Non-homogeneous particle size distribution will be seen in SEM micrographs and core shell structure of prepared Nano-composites estimated. The hysteresis loop discloses the ferromagnetic nature of Nano-composites. The magnetic parameters like coercivity and saturation magnetization show variation with increase of ferrite additives. So, by controlling the amount of additives, one can acquire the desired properties. Two Nano-composites FP1 = 25% and FP2 = 50% may be recommended for hyperthermia of cancer treatment.

Introduction

Nano-ferrites are researched by many investigators due to their potential uses in many fields. They are widely used in medical field for drug delivery, protein detection, as contrast agent in MRI etc. These nanoparticles act as good receptors and capsules for drugs [1], [2]. The substances obtained from combination of conducting polymers and ferromagnetic materials. Now a day, a lot of literature is available on the examination of conducting polymers with ferrites materials [3]. The soft ferrites materials are employed by lodging magnetic grains in the non-magnetic matrix. Thus, these substances can be modified into distinct shapes and can be utilized in required applications [4]. The semicrystalline materials such as polyvinylidene fluoride (PVDF) possess transparency and elasticity like characteristics. Also, these materials are easily manufactured and show strong piezo- and pyro-electric behavior [5]. The functional materials like polymer-magnetic nanocomposites are obtained by simply mixing polymers with nanomaterials. The resulting combined materials can be used in many technological areas like electromagnetic interference control system, drug targeting and in immunoassay. The mechanical properties of these materials are modified by addition of metal oxides [6]. The technologies in which larger noise control is needed, high quality materials are required so that to work at gigahertz frequency range. The simultaneous presence of conducting and dielectric nature in these substances enables them to use in electromagnetic interference [7]. These are suitable in low eddy current and larger resistivity devices. Their in-homogeneous dielectric nature make them good candidate in the microwave devices and used as a cathode in batteries [8].

In ferrites materials, Mg-ferrites are extensively used in technical industry [9]. Today, ferrite coatings are used as microwave absorbing substances in wars to prevent recognize of plane by radar. Similarly, many parameters such as skin depth, frequency, complex permeability and complex permittivity are employed to govern the absorbing properties [10]. Many types of Nano-composites are widely prepared all over the world in Polypyrrole form. Their magnetic behavior is dependent on grain size, grains interactions and annealing temperature. Recently, a lot of work has been done on the synthesis of pure and doped ferrites as reported in literature [3], [6]. The behavior of ferrites and dielectrics is explored by many scientists on composite materials while researches on composites and performance as interface are under-examination [7]. Substitution of rare earth ion in spinel ferrites results distortion of structure which lead to alteration in electromagnetic behavior. Also, the desired structural and magnetic characteristics were found by employing these types of suitable replacements [8].

Co-precipitation method is adopted to prepare ferrite sample with formula Mg_0.96Pr_0.04Fe₂O₄.

The raw materials as metal chlorides like MgCl₂·4H₂O (Aldrich, 98%), FeCl₃·6H₂O (Merck, 99%), PrCl₃·6H₂O (Aldrich, 99.9%), NH₃ (BDH, 35%) in aqueous form were used in preparation. The stoichiometric amounts of these metal chlorides were mixed in appropriate amount of de-ionized water. The resulting solutions are subjected to continuous stirring at 333 K temperature. Drop wise 2 M ammonia solution is added in order to keep the pH up to 11–12. Precipitates were formed and then filtered and washed by de-ionized water many times to remove undesired impurities. Then the precipitates were dried at 383 K temperature in oven. The annealing treatment of precipitate were done in the muffle furnace Vulcan Model A-550 under 973 K temperature for 7 h.

To make Polypyrrole, iron chloride is added in 10 ml of distilled water. The pyrole is gradually added in resulting solution while continuously stirred in the absence of light at the temperature of 51 °C. The 1:2 ratio of monomer to oxidant is maintained during preparation. The prepared suspension is left free for 24 h to make polymers. These polymers are then filtered and washed many times with distilled water in order to remove unwanted impurities. Polypyrrole powder in greenish black color obtained which was dried at 90 °C temperature for 24 h by using vacuum oven [12]. The nanosized composites were achieved by mixing Mg-Pr-ferrites with these polymers through solid state reaction method as shown in Table 1.

Philips X’Pert Model: PRO 3040/60 X-ray Diffractometer having Cu Kα radiation source with wavelength 1.54 Å is used for phase studying of nano-materials. The XRD peak broadening examined and Scherer’s formula is used to calculate the average crystallite size which is given as;

$$D=\frac{B\lambda }{\beta cos\theta }$$

where “D” is the average crystallite size, “λ” represents wavelength of radiation of source CuKα, “B” represents the Scherer’s constant (B = 0.89), “β” is full width half maxima of peaks and the “θ” indicates Bragg’s angle.

To measure the magnetic properties of all these samples, hysteresis loops were used which was obtained from vibrating sample magnetometer at room temperature. The sample is vibrated in the vicinity of coil which produces the changing magnetic flux in this coil. For this purpose, sample should be fixed with the tail of non-magnetic rod while the head of this non-magnetic rod is attached with mechanical vibrator. By using the piezoelectric materials, prepared sample was rotated physically. Due to sinusoidal vibration of the sample, emf is induced in the oscillating sample due to changing magnetic field. The quantity of induced emf is very minute, which was amplified by using lock in amplifier.

The magnetic behavior investigated by vibrating sample magnetometer (VSM) Model: Lakeshore 74071 under the field of 10 kOe. Different parameters like coercivity (H_c), saturation magnetization M_s and remanence magnetization M_r were calculated from M vs H graph.