Definitive experimental evidence for Microwave Effects: Radically new effects of separated E and H fields, such as decrystallization of oxides in seconds

Rustum Roy, Ramesh Peelamedu, Larry Hurtt, Jiping Cheng, Dinesh Kumar Agrawal

Research output: Contribution to journalArticle

185 Scopus citations

Abstract

Inspite of overwhelming evidence showing that a variety of solid state reactions were radically different when performed in a multimode microwave chamber compared to conventional heating some still question whether there is direct link to the radiation field. The present study has been conducted, for the first time ever, in a single mode TE103 cavity at 2.45 GHz. A large variety of materials have been reacted as ≈ 1 cm φ, 2 mm thick samples within the same cavity, at the positions of the E field and H field maxima. Enormous differences are shown to occur for certain families of common ceramic phases depending only on which of the E or H fields were used. The most extraordinary effects and sharpest differences (noted to date) between reactions at the E and H nodes have been found in ferroic oxides. Phases such as Fe3O4 or binary compounds such as BaFe12O19 are rendered non-crystalline to XRD in a few seconds in the H field, although they show no bulk evidence for melting. The microstructures are unique, showing smooth glass-like regions with regular waves parallel to each other. In the E field node the identical pellet components react completely and form large euhedral crystals of a single phase. The phenomenon of de-crystallization or formation of nano-glasses was confirmed for all the 3d ferrite phases. The magnetic properties of these decrystallized ferro-magnetic phases also show remarkable changes from the original very hard, transforming to very soft, magnets.

Original languageEnglish (US)
Pages (from-to)128-140
Number of pages13
JournalMaterials Research Innovations
Volume6
Issue number3
DOIs
StatePublished - Sep 2002

All Science Journal Classification (ASJC) codes

  • Industrial and Manufacturing Engineering
  • Materials Science (miscellaneous)

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