Evolution of the magnetic properties during the thermal treatment of barium hexaferrite precursors obtained by coprecipitation from barium ferrate (VI) solutions

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

Download Full-text

Magnetic Study on Divalent Ion Substituted Barium Hexaferrites

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.410.714 ◽

2021 ◽

Vol 410 ◽

pp. 714-719

Author(s):

Denis Vinnik ◽

Santhoshkumar Mahadevan ◽

Puneet Sharma

Keyword(s):

Magnetic Properties ◽

Solid State ◽

Barium Hexaferrite ◽

Anisotropy Field ◽

Magnetic Interaction ◽

Ceramic Method ◽

Saturation Magnetisation ◽

State Ceramic ◽

Saturation Remanence ◽

Substituted Barium Hexaferrite

Magnetic properties of Co, Ni and Zn substituted barium hexaferrite (BaM) samples prepared by solid state ceramic method were studied. Saturation magnetisation were found higher for Zn-substituted BaM, whereas, coercivity is higher for Co2+ and Ni2+ ion substituted samples. Anisotropy field for all substituted samples was calculated by the law of approaching saturation. Remanence, squareness and thermomagnetic plot suggest Zn2+ ions restricts the magnetic interaction of various sites in BaM.

Download Full-text

Evolution of microstructure, mechanical and magnetic properties of electrodeposited 50% Ni-Fe alloy foil after thermal treatment

Journal of Iron and Steel Research International ◽

10.1016/s1006-706x(17)30125-5 ◽

2017 ◽

Vol 24 (8) ◽

pp. 844-851 ◽

Cited By ~ 3

Author(s):

Hong-ru Ren ◽

Jin-tao Gao ◽

Zhe Wang ◽

Chong Li ◽

Fu-qiang Wang ◽

...

Keyword(s):

Magnetic Properties ◽

Thermal Treatment ◽

Alloy Foil ◽

Evolution Of Microstructure

Download Full-text

Electrical and Magnetic Properties of Barium Hexaferrite Modified Barium Zirconium Titanate Lead-Free Ceramics

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16165 ◽

2019 ◽

Vol 19 (3) ◽

pp. 1276-1282

Author(s):

Pakpoom Jarupoom ◽

Pharatree Jaita ◽

Supalak Manotham ◽

Thanatep Phatungthane ◽

Komsanti Chokethawai ◽

...

Keyword(s):

Magnetic Properties ◽

Barium Hexaferrite ◽

Lead Free ◽

Zirconium Titanate ◽

Electrical And Magnetic Properties ◽

Lead Free Ceramics ◽

Barium Zirconium Titanate ◽

Titanate Lead

Download Full-text

Influence of mechanical activation and heat treatment on magnetic properties of nanostructured mixture Ni85.8Fe10.6Cu2.2W1.4

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb180809004v ◽

2019 ◽

Vol 55 (1) ◽

pp. 85-93 ◽

Cited By ~ 2

Author(s):

M.M. Vasic ◽

A.S. Kalezic-Glisovic ◽

R. Milincic ◽

Lj. Radovic ◽

D.M. Minic ◽

...

Keyword(s):

Magnetic Properties ◽

Thermal Treatment ◽

Mechanical Activation ◽

Powder Mixture ◽

Structural Characteristics ◽

Volume Density ◽

Magnetic Domains ◽

Microstructural Changes ◽

Mass Magnetization ◽

Stress Relieving

The mechanical activation of the Ni85.8Fe10.6Cu2.2W1.4 powder mixture in the time intervals of 30-210 min in combination with thermal treatment at 393-873 K resulted in microstructural changes, forming the nanostructured mixture of the same composition but improved magnetic properties. The best result were achieved for mechanical activation during 120 min and thermal treatment at temperatures close to the Curie temperature (693K), enhancing the mass magnetization of the starting powder mixture by about 57%. The microstructural changes, which include the structural relaxation, decrease in free volume, density of dislocation and microstrain, improve structural characteristics of material, enabling better mobility of walls of magnetic domains and their better orientation in applied magnetic field and consequently enabling better mass magnetization of the material. With longer time of milling, the growing stress introduced in the sample undergoes easier relief, relocating stress-relieving processes toward lower temperatures.

Download Full-text