Rapid alloying of tetrahedral diamagnetic semiconductors in microwave H field

• Published in: Journal of alloys and compounds 2013-09, Vol.571, p.75-78
• Main Authors: Dube, Charu Lata, Kashyap, Subhash C., Dube, D.C., Agrawal, D.K.
• Format: Article
• Language: English
• Subjects: Alloying; Alloying elements; Alloys; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Diamagnetism; Exact sciences and technology; Germanium; Materials science; Materials synthesis; materials processing; Microwave and radio-frequency interactions (excluding resonances); Microwaves; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other interactions of matter with particles and radiation; Phase transitions; Physics; Powder metallurgy; Semiconductors; Silicon; Transmission electron microscopy; X-ray Diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.03.212

•Manuscript deals with heating of diamagnetic semiconductors in microwave H-field.•A model has been proposed to understand heating mechanism.•The induced dipolar losses and magnetic reorientation have been found responsible. Silicon germanium alloy has successfully been synthesized in a 2.45GHz, single mode microwave H field at 900°C in 5min in the Microwave Laboratory. The phase formation occurs at a temperature which is lower by 400°C than its equilibrium temperature. In the present paper an attempt has been made to understand the mechanism of rapid alloying of Si and Ge at a much lower temperature in microwave H field. The shape and size of starting particles play a significant role in microwave absorption. It is proposed that the interaction of H field at 2.45GHz first induces B-field in the irregular shaped precursor powder particles of different sizes; the gradient in induced magnetic flux generates circulating electric field. Consequently, dipolar losses are induced by local electric field in the pellet, which generate heat and culminate into rapid alloying of Si and Ge (nonferric diamagnetic elements). Furthermore, magnetic reorientation of diamagnetic fine particles by H-field at 2.45GHz assists in an efficient heating of the Si and Ge powders and results in alloy formation at a much lower temperature.