  We report the results of measurements of the dc magnetic susceptibility
chi(T) and of the 23Na nuclear magnetic resonance (NMR) response of NaVGe2O6, a
material in which the V ions form a network of interacting one-dimensional spin
S=1 chains. The experiments were made at temperatures between 2.5 and 300 K.
The chi(T) data suggest that the formation of the expected low-temperature
Haldane phase is intercepted by an antiferromagnetic phase transition at 18 K.
The transition is also reflected in the 23Na NMR spectra and the corresponding
spin-lattice relaxation rate 1/T1(T). In the ordered phase, 1/T1(T) decreases
by orders of magnitude with decreasing temperature, indicating the formation of
a gap of the order of 12 K in the magnetic excitation spectrum.
