We have investigated the incommensurate crystal structure of the spinel CuV
2S
4, which exhibits incommensurate charge-density wave at 90 K, using the synchrotron powder diffraction technique. It is found that the crystal structure at 70 K has an orthorhombic unit cell with the superspace-group
Imm2(0
β0)with a modulation vector
q=0.7391(5)
b*. By Rietveld analysis including the incommensurate modulation along the
b-axis, large static atomic displacements were found at the positions of V atoms, suggesting that V atoms play an important role in a charge-density wave transition. We have found the formation of V clusters, and arrangements of the clusters form a gradation pattern along the
b-axis.
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