Structural study on YCu1.8O4 by X-ray rietveld refinement

A nearly single-phase sample of the recently discovered new magnetic material with a nominal composition of Y:Cu = 1:1.8 is prepared by a high pressure synthesis technique. Energy dispersive X-ray (EDX) analysis confirms that the composition ratio of Y to Cu is quite close to 1:1.8. The crystal structure of this sample was determined by means of X-ray powder diffraction Rietveld refinement. According to the refinement results, this structure has a monoclinic symmetry with a space group of I2/a (or C2/c, No. 15) and the lattice parameters a = 5.690 (5) Å, b = 9.580 (9) Å, c = 5.609 (5) Å, and β = 92.470 (6) °. It is found that about 10% Cu sites are vacancies in this phase. Electron diffraction analysis indicates that the Cu vacancies do not form any ordering arrangement.