Quaternary alumogermanides in the Er-{Co,Ni}-Al-Ge systems

 

Chem. Met. Alloys 1 (2008) 254-260

 

Grygorii DEMCHENKO, Joanna KOŃCZYK, Pavlo DEMCHENKO, Roman GLADYSHEVSKII, Wiesław MAJZNER, Liliya MURATOVA

 

The crystal structures of two new quaternary alumogermanides have been determined from X-ray single crystal and powder diffraction data. Er2CoAl4Ge2 crystallizes with a Tb2NiAl4Ge2-type structure: space group I4/mmm, Pearson symbol tI18, cell parameters a = 4.0970(6), c = 19.343(4) Å, R1 = 0.0492, wR2 = 0.1195, Goof = 1.115, whereas the structure of ErNiAl4Ge2 adopts the YNiAl4Ge2 type: space group R-3m, Pearson symbol hR24, cell parameters a = 4.07160(8), c = 30.7027(9) Å, Rp = 0.0550, Rwp = 0.0708, RB = 0.0523, RF = 0.0402, c2 = 3.88. The structures are ordered and built up from structural slabs characteristic of binary and ternary compounds via intergrowth.

 

 

Environment of the Ni atoms in the structure of ErNiAl4Ge2: presentation as a deformed cube (left) and Al2 atoms in cyclohexane chair conformation (right).

 

Keywords

Rare-earth alumogermanides / Crystal structure / X-ray diffraction