Effect of Particle Size on Magnetic Phase Coexistence in Nanocrystalline La0.4Bi0.3Sr0.3MnO3

AbstractMagnetic phase coexistence in the substituted perovskite compound, La0.4Bi0.3Sr0.3MnO3, is attributed to the spontaneous moment and a step-like metamagnetic transition observed in the magnetization measurements in its magnetically order state. The magnetism of samples reduced to nanometer sizes by the “top down” approach exhibits interesting changes with respect to the bulk, thus giving a handle in influencing the physical properties by reducing the particle size. The bulk sample orders ferromagnetically at TC = 295 K, whereas in nano-sized samples with particle sizes in the range of 21–30 nm, even though TC does not change, the transitions are suppressed. The nano-sized powder samples show a broad hump in the plot of magnetic susceptibility, signifying the possible disordered antiferromagnetic state. A systematic decrease in the magnitude of magnetization in nano-sized samples shows that the reduction in magnetic interaction could be attributed to the formation of a magnetic dead layer around the magnetic core.

Download Full-text

Effect of ZrB2 Particle Size on Pressureless Sintering of ZrB2 - ß-Sic Composites

Journal of Aerospace Technology and Management ◽

10.5028/jatm.v11.1049 ◽

2019 ◽

Cited By ~ 3

Author(s):

Rosa Maria da Rocha ◽

Frank Ferrer Sene ◽

Mariah de Oliveira Juliani ◽

Caroline Oliveira Davi

Keyword(s):

Particle Size ◽

Flexural Strength ◽

Average Particle Size ◽

Theoretical Density ◽

Average Particle ◽

Pressureless Sintering ◽

High Melting Temperature ◽

Powder Samples ◽

Effect Of Particle Size ◽

Sic Composites

Zirconium diboride is an ultra high temperature ceramic material that leads this emerging class of materials because of its distinct combination of properties, including high melting temperature (> 3000 °C) and the lowest theoretical density (6.09 g·cm-3) among the borides. This combination of properties makes ZrB2 candidate for airframe leading edges on sharp-bodied reentry vehicles. In this work, the effect of particle size of ZrB2 on the pressureless sintering of ZrB2-SiC composites was studied, using ZrB2 powder with average particle size of 2.6 and 14.2µm. Four different vol% concentration of ß-SiC (0, 10, 20 and 30 vol%) were added to as-received and planetary milled ZrB2 powder. Samples were pressureless sintered at 2050 °C/1h in argon atmosphere. The reduction of initial ZrB2 particle size led to composites with better results of densification, mechanical properties and oxidation resistance regardless ß-SiC addition, showing relative densities around 92.5 %Theoretical Density (Td) and flexural strength and microhardness around 260 MPa and 17.5 GPa, respectively. Composites processed with as-received ZrB2 powder showed increasing in densification and flexural strength with the SiC content increasing. Relative density varied from 74.7 to 90.8 %TD and flexural strength from 102 to 241 MPa, for 0 and 30 vol% of SiC, respectively.

Download Full-text

INDUCTANCE TECHNIQUE FOR MEASURING TRANSITION TEMPERATURES OF SUPERCONDUCTING POWDERS

International Journal of Modern Physics B ◽

10.1142/s0217979289000579 ◽

1989 ◽

Vol 03 (05) ◽

pp. 763-772 ◽

Cited By ~ 3

Author(s):

T. K. VETHANAYAGAM ◽

W. A. SCHULZE ◽

J. A. T. TAYLOR ◽

R. L. SNYDER

Keyword(s):

Particle Size ◽

Critical Current Density ◽

Sample Size ◽

Critical Current ◽

Current Density ◽

Superconducting State ◽

Simple Technique ◽

Electrical Contacts ◽

Powder Samples ◽

Effect Of Particle Size

A simple technique to measure T c of superconducting powder samples is evaluated. Inductance of the sample is used as the indicator to determine the behavior of the material as it goes to the superconducting state. The effect of particle size and sample size on the measured parameters has been investigated. The main advantages of this technique are the absence of electrical contacts and the elimination of the need for sintered bars. The technique has the potential to measure the amount of superconducting phases as well as the critical current density.

Download Full-text