CONDUCTIVITY WITHOUT SPIN-SIGNAL, SPIN SIGNAL WITHOUT CONDUCTIVITY SWITCHABLE RADICAL-ION SALTS OF DEUTERATED CU(DCNQI)(2)

Cu(DCNQI)(2) can be switched from a metallic state to an insulating on e by external pressure or internal (chemical) pressure in a very abrup t manner. We have used the pronounced anticoincidence of the ESR-inten sity and the conductivity to study the processes at the phase transiti ons in detail by measuring simultaneously the ESR and conductivity as a function of T and under pressure. We have a break down of the conduc tivity if 20% of the total volume is switched into ESR-active areas. T his is interpreted by a percolation Limit between the still conducting (ESR-silent) domains. Including individual internal pressure values f or differently deuterated Cu(DCNQI)(2) salts and alloys between deuter ated and undeuterated DCNQI, a general phase diagram can be given.