Phase Composition and Physical Properties of the MnBiCr Films, Obtained by Ion-Plasma Sputtering

Abstract

The paper presents the results of investigations of phase composition and physical properties of the pure Mn, MnCr and MnBiCr films, thickness d 150-550 nm, obtained by a modernized three-electrode ion-plasma sputtering. X-ray analysis and estimation of the size (L) of coherent-scattering regions (CSR) showed that in the pure Mn as-deposited films is formed the nanocrystalline cubic phase of manganese, the size of the CSR which L 7,4 nm. There is a formation of solid solution nanocrystalline -Mn phase in the original MnCr films (L 7,5 nm). In the original state MnBiCr films is a mixture of rhombohedral Bi phase (L 10,5 nm) and Mn cubic, which decays by heat treatment at 703 K. Heat treatment of Mn and MnCr films at 773 K leads to the formation of MnO oxide. Analysis of displacement temperature of the initial phase transitions with increasing heating rate in the films allowed for the calculation of the activation energy (Ea) of phase transformations by the Kissinger method. For the MnCr films the activation energy is 3500-4800 K. In the MnBiCr films first phase transition ( 573 K) is related with melting of Bi, the second, probably due to the collapse of the cubic Mn ( 653 K, Ea 7000 K). When the film is heated above 673 K and subsequently cooling it, at a temperature of 423 K there is an abrupt increase in resistance of about two-fold. Analysis of the demagnetization curves of the MnBiCr films showed the manifestation of hard magnetic properties in a perpendicular field Hc 16 103 А/m. Study has shown that the addition of Cr in small amounts prevents oxidation of Mn and leads to an increase of the films thermal stability. Thus, the thermostable magnetically hard material in a film form was obtained. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35396