Accession Number : AD0673525

Title :   THE PRODUCTION OF TEMPERATURES BELOW 1 DEGREE K BY THE ADIABATIC DEMAGNETIZATION OF 50% CE(PO3)3-BA(PO3)2 GLASS.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Althouse,Edwin Lewis

Report Date : 15 JUL 1968

Pagination or Media Count : 47

Abstract : It was the object of the investigation to determine whether cerium metaphosphate glass (specifically 50% by weight Ce(PO3)3-Ba(PO3)2) is a suitable coolant material for adiabatic demagnetization experiments. Cerium glass is not susceptible to dehydration and attack by glycerine (used for thermal contact) as are many of the hydrated salts. In addition, the concentration of magnetic atoms can be varied over a wide range by diluting the magnetic glass Ce(PO3)3 with the nonmagnetic glass Ba(PO3)2. The principal results of this investigation are: (a) the 50% Ce(PO3)3-Ba(PO3)2 glass was successfully cooled many times by adiabatic demagnetization, and 'magnetic' temperatures as low as 0.0069K were reached, (b) using a cerium magnesium nitrate paramagnetic salt as a thermometer, absolute temperatures as low as 0.02K were observed, and (c) within experimental error, the measured Curie constant for the cerium glass (density 3.57) agrees with that calculated from the Brillouin function for J = 1/2 and 1.97 < or = g < or = 2.00. (Author)

Descriptors :   (*CRYOGENICS, *GLASS), COOLING, PARAMAGNETIC MATERIALS, CERIUM COMPOUNDS, BARIUM COMPOUNDS, PHOSPHATES, MAGNETIC PROPERTIES, TRANSITION TEMPERATURE

Subject Categories : Solid State Physics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE