Vol.:(0123456789) 1 3 Applied Physics A (2020) 126:959 https://doi.org/10.1007/s00339-020-04138-5 Magnetic, electrical and gas sensing properties of poly(o‑phenylenediamine)/MnCoFe 2 O 4 nanocomposites Nagarajan Kannapiran 1  · Athianna Muthusamy 2  · B. Renganathan 3  · A. R. Ganesan 3  · Sher Singh Meena 4 Received: 27 June 2020 / Accepted: 9 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract A series of poly(o-phenylenediamine)/MnCoFe 2 O 4 nanocomposites containing varying concentrations of MnCoFe 2 O 4 were synthesized by in situ oxidative polymerization method. These nanocomposites were characterized by thermal, spectro- scopic, microscopic techniques and dielectric properties analyzed at diferent temperature and frequency. X-ray difraction and Fourier-transform infrared spectra are confrming the formation of poly(o-phenylenediamine)/MnCoFe 2 O 4 nanocom- posites. The Mössbauer spectral data are indicating the inverse nature of MnCoFe 2 O 4 nanoparticles. The ferromagnetic behavior of nanocomposites is ascertained with the hysteresis loops of MnCoFe 2 O 4 . Transmission electron microscopy results are giving good evidences for the deposition of MnCoFe 2 O 4 nanoparticles on the poly(o-phenylenediamine) matrix and the modifcation of spherical morphology of poly(o-phenylenediamine) by MnCoFe 2 O 4 . The thermal stability of poly(o- phenylenediamine)/MnCoFe 2 O 4 nanocomposites is increasing with increase in the concentration of MnCoFe 2 O 4 nanopar- ticles. Dielectric constant and AC conductivity of nanocomposites are varying with applied frequency, temperature and concentration of MnCoFe 2 O 4 nanoparticles. The ethanol gas sensing ability of MnCoFe 2 O 4 has been improved by poly(o- phenylenediamine) matrix. Keywords MnCoFe 2 O 4  · Dielectric constant · AC conductivity · Ethanol gas sensing 1 Introduction In the past decades, huge numbers of researchers have focused their attention on magnetic polymer nanocomposites because of their easy synthesis, tunable properties, fexibil- ity and exceptional applications [1]. The composites made by the incorporation of magnetic materials into conducting polymer matrix enhancing the magnetic, chemical, structural and electric properties and are called as magneto-polymeric materials [2]. The miniaturizations of electric and electronic instruments like mobile phone and portable computers need materials with high dielectric constant [3]. The crystalline size infuences the properties of magneto-polymeric nano- composites such as catalytic efects, drug delivery, electri- cal and magnetic behavior [46]. Generally, the conduct- ing polymers have many attractive properties such as high mechanical strength, light weight, non-corrosiveness, sen- sor and tunable dielectric property. Among the conducting polymer, polyaniline is an extensively studied conducting polymer due to its thermal stability, easy preparation and electrical properties. The o-phenylenediamine is an aniline derivative and its polymer has large number of –NH 2 , which is easily bonded with inorganic materials to have efective interaction [7]. Spinel ferrite nanoparticles are one of the most important kinds of magnetic nanoparticles because of their amazing applications in various felds. Generally, the spinel ferrites have been analyzed for biomedical applica- tions and surface functionalized ferrite nanoparticles used for drug targeting [8]. Among the spinel ferrite, cobalt fer- rite nanoparticles have high stability, mechanical hardness, high saturation magnetization and coercivity [9, 10]. The nanocomposites made by the combination two or more * Athianna Muthusamy muthusrkv@gmail.com 1 Department of Chemistry, Karpagam Academy of Higher Education, Coimbatore 641021, Tamil Nadu, India 2 PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu, India 3 Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India 4 Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India