Influence of the Defects on Magnetic Properties of Glass-Coated Microwires

Using magnetic characterization, electronic and optical microscopy we studied magnetic properties and different kind of defects in glass-coated microwires containing Co. We observed that Co addition allows improvement of magnetic softness. We also observed the oxygen presence in “defective” regions on the metallic nucleus surface and indications of chemical interaction between the glass-coating and the metallic nucleus.

Fabrication and First Characterization of Ni2MnGa Glass-Coated Microwires

In this paper we report on fabrication and characterization of a novel glass coated Ni2MnGa glass coated microwires with metallic nucleus diameter of 44 μm prepared the modified Taylor-Ulitovsky method. First magnetic and structural characterization have been performed.

Magnetic and Mechanical Properties of Magnetic Glass-Coated Microwires with Different Glass Coating

Glass coated microwires with two metallic nucleus compositions Co57Fe 6.1Ni10B15.9Si11 and Fe36,4Co41,7B11,8Si10,1 with 3 different glass coating compositions (Pyrex – 74.5% SiO2, 15% - B2O3, 3%- Na2O, 2%- Al2O3 1.5% -K2O; Nonex – 73% SiO2, 16.5% - B2O3, 6% - PbO 3 %-Na2O, 1.5% -K2O; and F1 – 70.2% SiO2, 27% - B2O3, 0.8 %-Na2O, 2%- LiO2 1% -K2O;) with very similar geometry (metallic nucleus diameter 7 µm, total diameter 19 µm) have been successfully fabricated and studied. Ferich microwires in as-prepared state show rectangular hysteresis loops, which is connected with the strong internal stresses induced by the fabrication process. Co-rich compositions show inclined hysteresis loop with smaller value of coercive field. The coercivity, Hc, of Co-rich microwires is the highest and of Ferich samples is the lowest in the case of Pyrex coated microwires. The Nonex coated microwires are in the intermediate position while the F1 coated Co-rich microwires have the lowest Hc while the Fe-rich samples have the highest Hc. The mechanical tests show that the best tensile strain yield is observed in samples coated by Nonex glass followed by Pyrex and F1. In this way the variation of the glass coating material allows to tailor both magnetic and mechanical properties of glass coated tiny microwires.