MICROTWINNING IN HOFE6GE6 STUDIED BY HIGH-RESOLUTION ELECTRON-MICROSCOPY AND ELECTRON-DIFFRACTION

The microdomain structure of the HoFe6Ge6 phase has been studied by tr ansmission electron microscopy (TEM) and electron diffraction. The mai n features of electron diffraction patterns and high-resolution TEM im ages 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 dimension s of the average YCo6Ge6 structure). Direct evidence of multiple micro twinning has been obtained. The submicroscopic twin domains are extend ed along the [46 (1) over bar]-[4 (6) over bar 1) directions and are 3 0-50 Angstrom wide in the [021] direction.