Thermostructural and elastic properties of Ni 3 V 2 O 8 , exhibiting a kagome layer arrangement: experimental study in the range 15–1323 K

Thermal expansion of the kagome-structured nickel orthovanadate (Ni 3 V 2 O 8 ) is studied over a wide temperature range (15–1323 K). Using powder X–ray diffraction, we demonstrate that the material retains its orthorhombic symmetry ( Cmca ) throughout the entire temperature range, while exhibiting pronounced structural anisotropy. Our analysis reveals a striking contrast in the thermal response of the crystal's building blocks: while the VO 4 tetrahedra remain nearly rigid, the nickel-centered octahedra (Ni1O 6 and Ni2O 6 ) undergo significant expansion (∼6%). This disparity highlights complex lattice dynamics in which the expansion trend (α a > α c > α b ) directly mirrors the material's compressibility. These findings provide critical insights into the stability and structural behavior of kagome-type oxides under extreme thermal conditions.