V2Te2O: A Two-Dimensional van der Waals Correlated Metal.

A metastable vanadium oxytelluride V2Te2O is prepared via a topochemical deintercalation of interlayer Rb+ cations in Rb1-δV2Te2O. The new ternary mixed-anion compound crystallizes in a body-centered tetragonal lattice with a = 3.9282(1) Å and c = 13.277(5) Å, containing V2O square nets that are sandwiched by Te-atomic sheets. The charge-neutral [V2OTe2] block layers stack along the c axis with van der Waals forces, which shows a metallic behavior with a dominant T2 dependence for resistivity at low temperatures. The electronic specific-heat coefficient reaches 33.9 mJ K-2 mol-1, ∼4 times that of the electronic structure calculations, suggesting a significant electron-mass renormalization. The electron correlation effect is concurrently demonstrated by the Wilson and Kadowaki-Woods ratios. Neither charge/spin-density wave nor superconductivity was observed down to 0.03 K.