Abstract: | The System KCl/ErCl3 and the Modifications of Compounds K3LnCl6 (Ln = Ce–Lu, Y) The phase diagram of the system KCl/ErCl3 was investigated by DTA and XRD. Two compounds exist: KEr2Cl7 incongruently and K3ErCl6 congruently melting. Their thermodynamic functions for the formation from KCl and ErCl3 were determined by solution calorimetry and emf vs T measurements in a galvanic cell for solid electrolytes. Both compounds are stable down to 0 K. – K3ErCl3 exists in three modifications. The structure of T–K3ErCl6 was determined by single crystal measurements: S.G. P21/c; Z = 4; a = 1309.8(5), b = 767.1(3), c = 1252.6(4) pm, β = 109.94(2)°. – A survey of all known results on compounds K3LnCl6 reveals, that from Ln = Ce to Ln = Ho they only are stable at higher temperatures, > 521 °C (Ce) and > –27 °C (Ho), resp. |