The 9.355 GHz Complex Permittivity of Light and Heavy Water from 1to 90 .degree.C Using an Improved High-Precision Instrumentation System

Abstract

Recent improvements to a high-precision instrumentation system for measuring the complex permittivity of high loss liquids using a variable-length transmission sample cell at microwave frequencies are described. An error analysis for this system is given. These improvements have enabled the complex permittivity of heavy water and of double-distilled, deionized light water to be measured with a typical accuracy of &0.1% for 6' and f0.2% for 6'' and a precision of about 0.02% at 9.355 GHz in the temperature interval from approximately 1 to 90 C in increments of about 2.5 C. The values of ~'(t) and ~(t) have been fitted to empirical quintic polynomials in the temperature t (0. For light water ~'(t) = 44.628(3) + (13.929(8) x 10-l)t - (3.222(6) x 10-2)t2 + (3.165(17) x 10-4)t3 - (1.503(21) x + (2.67(9) x 10-9)t5 and ~(t) = 40.573(3) - (1.475(6) x 10-l)t - (2.477(4) x 10-2)t2 + (6.092(12) x 10-4)t3 - (6.000(15) x 10-6)t4 + (2.213(7) x 10-8)t5 and for heavy water ~'(t) = 31.452(17) + (16.630(28) x 10-l)t - (2.796(17) x 10-2)t2 + (1.141(45) x 10-4)t3 + (0.920(54) x 10-6)t4 - (7.16(23) x 10-9)t5 and ~(t) = 37.610(9) + (4.952(16) x 10-1)t - (4.749(10) x 10-2)tZ + (9.659(26) x 10-4)t3 - (8.609(30) x 10-6)t4 + (2.913(13) x 10-8)t5. The temperature dependences of the Gibbs free energy, enthalpy, and entropy of activation parameters for the relaxation process as well as the relaxation time have been calculated from both the ~'(t) and ~(t) data sets for both light and heavy water.