Thermal and Magnetic Study of Bonding in CsCuCl3

摘要

The heat capacity and magnetic susceptibility of CsCuCl3powder have been measured in the ranges 5deg;ndash;300deg; and 2deg;ndash;230deg;K, respectively. The susceptibility deviates from Curiendash;Weiss behavior below 55deg;K and the heat capacity exhibits a sharp peak, characteristic of cooperative behavior, in the neighborhood of 10.4deg;K. The behavior of this system is interpreted using a molecular orbital picture in which square planar coordinated copper atoms interact via a linear antiferromagnetic exchange above 10.4deg;K and order three dimensionally below this temperature. The following values are found for the thermodynamic functions:Sdeg;298.15thinsp;equals;thinsp;213.401Jlpar;gfwmiddot;degrpar;minus;1rpar;, minus;thinsp;lpar;Gdeg;298.15thinsp;minus;thinsp;H0deg;rpar;thinsp;sol;thinsp;Tthinsp;equals;thinsp;120.544Jlpar;gfwmiddot;degrpar;minus;1. A leasthyphen;squares analysis ofkhgr;Mvs1thinsp;sol;thinsp;lpar;Tthinsp;plus;thinsp;thgr;rpar;for all data above 77deg;K was performed. It was found thatCthinsp;equals;thinsp;0.458thinsp;plusmn;thinsp;0.003,emumiddot;degsol;mole, lpar;khgr;Dthinsp;plus;thinsp;khgr;TIPthinsp;equals;thinsp;minus;thinsp;0.000058thinsp;plusmn;thinsp;0.00003,emusol;moleandthgr;thinsp;equals;thinsp;minus;thinsp;3.50deg;K. The quoted limits of accuracy are the standard deviations.