Magnetic Properties and Magnetocaloric Effect in Layered NdMn1.9Ti0.1Si2

The structural and magnetic properties of the NdMn1.9Ti0.1Si2 compund have been studied by high-intensity x-ray and high-resolution neutron powder diffraction, specific heat, dc magnetization, and differential scanning calorimetry measurements over the temperature range of 3-450 K. The Curie temperature and Néel temperature of layered NdMn1.9Ti0.1Si2 are indicated as TC ~ 22 K and TN ~ 374 K respectively. The first order magnetic transition from antiferromagnetic [AFil-type] to ferromagnetic [F(Nd)+Fmc] around TC is found in layered NdMn1.9Ti0.1Si2and is associated with large magnetocaloric effect. This behavior has been confirmed as a contribution of the magnetostructural coupling by using neutron and x-ray powder diffraction. The magnetic entropy change –ΔSM ~ 15.3 J kg-1 K-1 and adiabatic temperature change ΔTad ~ 4.7 K have been determined using magnetization and specific heat measurement under 0-5 T applied fields. This compound exhibits almost no thermal and magnetic hysteresis, thus potentially applicable in low temperature region for magnetic refrigerator material.Received: 31 December 2013; Revised:10 February 2014; Accepted: 24 February 201

Phase Analysis and Magnetic Properties of Bafe12o19/nd2fe14b Composite by Mechanical Milling Product

The synthesis and characterization of BaFe12O19/Nd2Fe14B composite by use mechanical milling has been performed. The result of refinement of X-ray diffractions showed that the sample consist of two phases namely BaFe12O19 and Nd2Fe14B phase with fraction mass were 79.89 and 20.11 wt%, respectively. The BaFe12O19 system magnetic materials have been formed with the crystal structure of hexagonal (space group P 63/m m c), lattice parameter are a = 5.9033(5) Å, b = 5. 9033(5) Å and c = 23.239(2) Å, α = β = 90o and γ = 120o, V = 701.3(1) Å3 and ρ = 5.7172 g.cm-3. The Nd2Fe14B system magnetic materials have been formed with the crystal structure of tetragonal (space group P 42/m n m), lattice parameter are a = 8.865(8) Å, b = 8.865(8) Å and c = 12.269(1) Å, α = β = γ = 90o, V = 964.3(1) Å3 and ρ = 7.7508 g.cm-3. The magnetic properties result of Nd2Fe14B shown that the sample has the coercive field and remanence magnetization are 7984 Oe and 5250 Gauss, respectively. The BaFe12O19 are 1625 Oe and 1190 Gauss, respectively. And the BaFe12O19- Nd2Fe14B composite increase to become 2650 Oe and 1580 Gauss, respectively. We conclude that the process of mixing between BaFe12O19 and Nd2Fe14B is not affect the change of each phase. The BaFe12O19 particle can be use as the shielding of the Nd2Fe14B particle from it's the corrosion properties. The BaFe12O19 magnetic material has a stable structure at room temperature, so that this structure was not easy of change after mix with the Nd2Fe14B particles

Investigation on Co-Cr micro-strips for VBLM

Hard magnetic strips can be used for bit stabilization in a VBLM. For this stabilization the magnetic strayfield of the strips induce potential wells for the bits. However, by dimensioning a material into strips the magnetic properties and therefore the potential wells change. In this paper the relation between magnetic properties and shape of Co-Cr micro-strips is investigated. Furthermore the influence of both magnetic properties and shape of the strips on the magnetic strayfield is simulated