Comment on "Local lattice distortions vs. structural phase transition in NdFeAsO1-xFx" reported in [Physica C 527 (2016) 55]

In a recent paper Calamiotou et al. [1] analyzed the structural properties of NdFeAs(O0.95F0.05) and NdFeAs(O0.75F0.25) by means of synchrotron X-ray powder diffraction and Raman spectroscopy. In particular no evidence for a tetragonal to orthorhombic structural transition can be detected on cooling for the superconducting NdFeAs(O0.75F0.25) composition. In the present comment, it is suggested that the intrinsically large micro-strain affecting the analyzed sample prevents the detection of the symmetry breaking (if present) even by line-broadening analysis.