STUDY OF MAGNETIC-SUSCEPTIBILITIES AND ANISOTROPY OF TB3+ DIGLYCOLLATE CRYSTAL

Magnetic susceptibilities (K-parallel to, K-perpendicular to) and thei r anisotropy of single crystal of Na-3[Tb(oxydiacetate)(3)]. 2NaClO(4) . 6H(2)O (Tb diglycollate or TbDG) between 300 and 23 K are reported here for the first time. The room-temperature value of the anisotropy Delta K = K-parallel to-K-perpendicular to was found to be 2900 x 10(- 6) emu/mol, being only 6.6% of (K) over bar, which is quite low compar ed to other Tb3+ crystals studied. On cooling, the anisotropy value de creased to zero at 94 K. Below this temperature, AK changed sign and i ncreased rapidly till 23 K. These special characteristics provided add itional experimental constraints for fitting the results using crystal field (CF) theory, so that it was posible to determine accurately the CF parameters, which were found as B-20 = -310, B-40 = -800, B-60 = 3 00, B-43 = -1400, B-63 = 1950, B-66 = 200 (all in cm(-1)). Using these values, the emisson spectra reported earlier and the absorption lines for F-7(6) --> D-5(4) transition studied by us, were fitted reasonabl y well. (C) 1998 Elsevier Science B.V. All rights reserved.