Centimeter Wave Absorption in Molecular Crystals
Abstract
Molecular dynamics calculations performed at the University of Nebraska predict that temperature-dependent microwave activity is present in some ionic molecular crystals. This activity is due to the excitation of 'hindered rotations' or thermally activated 'hopping' modes for the molecular ions. Microwave reflectometer measurements performed at the BRL show temperature-dependent microwave losses occur in several ionic molecular crystals at or near the calculated order/disorder transition temperatures. These measurements, performed from 2 to 20 GHz from room temperature to about 300 deg C on the BRL 'arch,' were made on powder samples of the nitrates and nitrites of potassium, sodium, and other materials. Potassium nitrate displays an interesting temperature dependence with the absorption 'turning on' at about 1200 C, near the calculated order/disorder transition temperature. Measurements were also performed on selected ionic salts which uniformly show small microwave losses at any of the temperatures measured.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1992
- Accession Number
- ADA257453
Entities
People
- Arthur Gauss Jr.
- H. M. Lu
- J. R. Hardy
- Robert B. Bossoli
- Steve G. Cornelison
Organizations
- Ballistic Research Laboratory