We present Si-29-NMR relaxation and spectral data in URu2Si2. Our echo-deca
y experiments detect slowly fluctuating magnetic field gradients. In additi
on, we find that the echo-decay shape (time dependence) varies with tempera
ture T and its rate behaves critically near T-N indicating a correlation be
tween the gradient fluctuations and the transition to small-moment order. T
-dependent broadening contributions become visible below similar to 100 K a
nd saturate somewhat above T-N, remaining saturated at lower temperatures.
Together, the line width and shift suggest partial lattice distortions belo
w T-N We propose an intrinsic minority phase below T-N and compare our resu
lts with one of the current theoretical models. (C) 2000 Elsevier Science B
.V. All rights reserved.