Low temperature specific heat of metalhyphen;rich alkali metal oxides

摘要

The specific heats of the metallic oxidesCs11O3,Cs7Othinsp;( =circ;Cs10Cs11O3)andRb7Cs11O3have been measured in the temperature range of0.50les;Tles;100thinsp;K.The results are in agreement with a bond model of ionic clusters of the compositionCs11O3which are weakly coupled to one another and to the matrix of additional alkali metal atoms via metallic bonding. The Debye temperatures are extremely lowlsqb;thgr;0(Cs11O3) = 41thinsp;K,thgr;0thinsp;(Cs7O) = 45thinsp;K,andthgr;0thinsp;(Rb7Cs11O3) = 47thinsp;Krsqb;.Anomalies in the lattice specific heat at low temperatures(Tles;5thinsp;K)are interpreted as due to low frequency vibrations of the heavyCs11O3clusters (molecular weightm=1510thinsp;gthinsp;molminus;1),corresponding to a characteristic Debye temperature ofthgr;Dsime;4thinsp;K.