  High-field neutron diffraction studies of the new quantum-disordered S=1
linear-chain antiferromagnet Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(ClO$_4$) (NDMAZ)
are reported. At T=70 mK, at a critical field $H_c=13.4$ T applied along the
(013) direction, a phase transition to a commensurate N\'{e}el-like ordered
state is observed. The results are discussed in the context of existing
theories of quantum phase transitions in Haldane-gap antiferromagnets, and in
comparions with previous studies of the related system
Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(PF$_6$).
