  The crystal structure and magnetic properties of the spin-1
triangular-lattice antiferromagnet Ba$_2$La$_2$NiTe$_2$O$_{12}$ are reported.
Its crystal structure is trigonal $R\bar{3}$, which is the same as that of
Ba$_2$La$_2$NiW$_2$O$_{12}$ [Y. Doi et al., J. Phys.: Condens. Matter 29,
365802 (2017)]. However, the exchange interaction $J/k_{\mathrm{B}}\simeq19$ K
is much greater than that observed in the tungsten system. At zero magnetic
field, Ba$_2$La$_2$NiTe$_2$O$_{12}$ undergoes successive magnetic phase
transitions at $T_{\mathrm{N}1}=9.8$ K and $T_{\mathrm{N}2}=8.9$ K. The ground
state is accompanied by a weak ferromagnetic moment. These results indicate
that the ground-state spin structure is a triangular structure in a plane
perpendicular to the triangular lattice owing to the small easy-axis-type
anisotropy. The magnetization curve exhibits the one-third plateau
characteristic of a two-dimensional triangular-lattice Heisenberg-like
antiferromagnet. Exchange constants are also evaluated using density functional
theory (DFT). The DFT results demonstrate the large difference in the exchange
constants between tellurium and tungsten systems and the good
two-dimensionality of the tellurium system.
