  Astrophysical scenarios for the formation and evolution of intermediate-mass
black holes (IMBHs) in the mass range $10^2 M_\odot \lesssim M \lesssim 10^6
M_\odot$ remain uncertain, but future ground-based gravitational-wave (GW)
interferometers will probe the lower end of the IMBH mass range. We study the
detectability of IMBH binary mergers and the measurability of their parameters
with next-generation ground-based detector networks consisting of various
combinations of Cosmic Explorer (CE) and Einstein Telescope (ET)
interferometers. We find that, for binaries with component masses $m_{1,2}\sim
1000\,M_\odot$, an optimal 3-detector network can constrain the masses with
errors $\lesssim 0.1\%$ ($\lesssim 1\%$) at $z=0.5$ ($z=2$), and the source
redshift can be measured with percent-level accuracy or better at $z\lesssim
2$. The redshift of lighter binaries ($m_{1,2}\lesssim 300\,M_\odot$) can still
be measured with $O(10)\%$ accuracy even at $z=10$. Binaries with $z\lesssim
0.5$ can be localized within $1\,\rm{deg}^2$ for $m_{1,2}\lesssim
1000\,M_\odot$, and within $0.1\,\rm{deg}^2$ for comparable mass systems. The
sky localization is good enough that it may be possible to cross-correlate GW
searches with galaxy catalogs and to search for electromagnetic counterparts to
IMBH mergers. We also point out that the low-frequency sensitivity of the
detectors is crucial for IMBH detection and parameter estimation. It will be
interesting to use our results in conjunction with population synthesis codes
to constrain astrophysical IMBH formation models.
