Electron paramagnetic resonance of Gd3+ in praseodymium triacetate monohydrate

X-band( similar to 9.6 GHz) electron paramagnetic resonance measurements we re carried out on a Gd3+-doped praseodymrum triacetate monohydrate, Pr(CH3C OO)(3). H2O, single crystal in the temperature range 4.2-295 K. The spin-Ha miltonian parameters were estimated at room, liquid-nitrogen and liquid-hel ium temperatures by the use of a rigorous least-squares fitting technique. The absolute sign of the zero-field splitting parameter, b(2)(0), was deter mined to be negative by comparison of the intensities of the high- and low- field EPR lines at room and liquid-helium temperatures. The behaviour of EP R spectrum was studied as a function of temperature; the variation of the l inewidth and line positions indicated a significant reordering of acetate a nd water molecules at about 240 K. The present Gd3+ EPR results in praseody mium triacetate monohydrate are compared with those in the rare-earth triac etate tetrahydrate hosts with Sm, Nd, Er, Y, Yb and Dy ions. (C) 1999 Elsev ier Science B.V. All rights reserved.