EPR STUDY OF MONOCLINIC RBD(2)PO(4) MONOCRYSTAL DOPED WITH CR5+ ION

Deuterated monoclinic RbD2PO4 (DRDP) doped with chromium Cr5+ is studi ed by EPR in 90 K to 400 K temperature range. EPR reveals two types of paramagnetic centers: single Cr5+ (S = 1/2) complex and Cr5+ - Cr5+ c oupled pairs with effective spin S = 1. The EPR line splitting of sing le Cr5+ complex in DRDP versus temperature agrees with the unit cell m ultiplication. The splitting of EPR line of pair spectrum appears at T = 160 K, far below the phase transition temperatures and is due to t he anisotropy of the exchange interaction. The clustering effect in th e low-dimensional DRDP is suggested.