Microtwinning in HoFe6Ge6 studied by high-resolution electron microscopy and electron diffraction

The microdomain structure of the HoFe6Ge6 phase has been studied by transmission electron microscopy (TEM) and electron diffraction. The main features of electron diffraction patterns and high-resolution TEM images confirmed the orthorhombic superstructure (Cmcm; a(1) = 2c(h); b(1) = 2 x 3(1/2)3a(h) and c(1) = b(h), where (a,c)(h) are the dimensions of the average YCo6Ge6 structure). Direct evidence of multiple microtwinning has been obtained. The submicroscopic twin domains are extended along the [46 (1) over bar]-[4 (6) over bar 1) directions and are 30-50 Angstrom wide in the [021] direction.