  The compound CaV2O4 contains V^{+3} cations with spin S = 1 and has an
orthorhombic structure at room temperature containing zigzag chains of V atoms
running along the c-axis. We have grown single crystals of CaV2O4 and report
crystallography, static magnetization, magnetic susceptibility \chi, ac
magnetic susceptibility, heat capacity Cp, and thermal expansion measurements
in the temperature T range of 1.8-350 K on the single crystals and on
polycrystalline samples. An orthorhombic to monoclinic structural distortion
and a long-range antiferromagnetic (AF) transition were found at
sample-dependent temperatures T_S \approx 108-145 K and T_N \approx 51-76 K,
respectively. In two annealed single crystals, another transition was found at
\approx 200 K. In one of the crystals, this transition is mostly due to V2O3
impurity phase that grows coherently in the crystals during annealing. However,
in the other crystal the origin of this transition at 200 K is unknown. The
\chi(T) shows a broad maximum at \approx 300 K associated with short-range AF
ordering and the anisotropy of \chi above T_N is small. The anisotropic \chi(T
\to 0) data below T_N show that the (average) easy axis of the AF magnetic
structure is the b-axis. The Cp(T) data indicate strong short-range AF ordering
above T_N, consistent with the \chi(T) data. We fitted our \chi(T) data near
room temperature by a J1-J2 S = 1 Heisenberg chain model, where J1(J2) is the
(next)-nearest-neighbor exchange interaction. We find J1 \approx 230 K, and
surprisingly, J2/J1 \approx 0 (or J1/J2 \approx 0). The interaction J_\perp
between these S = 1 chains leading to long-range AF ordering at T_N is
estimated to be J_\perp/J_1 \gtrsim 0.04.
