Heat capacities of three magnetic salts near their critical points

Low temperature heat capacity measurements have been made near the . 6H20. A method of determining the critical point TA from a welldefined physical event has been found. For Mn(NH4)2(S04)2 . 6H20, TA = 0.1763°K, the width of the transition is known to +2 ~oK, and data have been obtained to T-T -4 A = +10 TA. The precision in the differences, T-T A , is a few microdegrees near Td A structured peak 5 mOK in width has been found in the heat capacity of K3Fe(CN)6 at about 0.130 oK. TA could not be defined uniquely for this salt. For CuK2(S04)2 . 6H20, TA = 0.0295°K, the width of the transition -2 is known to ±0.2 mOK, and data have been obtained to T-TA = ±3 x 10 TA The magnetic entropy has been found for the latter two salts. The results of these measurements are compared with the work of others on magnetic phase transitions and liquid-vapor phase transitions. Agreement with existing theories is discussed. These results will be published by the author, 0. E. Vilches, and J. C. Wheatley.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Rayl, Martin

Contributors dc:contributor

• Wheatley, J.C.

• low temperature heat capacity
• magnetic salts
• critical point
• magnetic entropy

Statement dc:rights

• 1966 Martin Rayl

Language dc:language

en

Identifier

6117609

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25068