ИСТИНА

The structural and magnetic properties of the CePt5-xAlx system at 800 °C have been studied in [1]. It was found that platinum in CePt5 can be replaced by aluminum up to the composition of CePt2Al3. However, at 700°C we found several ternary compounds with structures related to CePt5 in mentioned concentration interval of this system. Ternary intermetallic CePt3.43Al1.57 is one of them. The crystal structure of CePt3.43Al1.57 was determined from single-crystal X-ray diffraction data: a = 9.312(2) Å, b = 26.200(6) Å, c = 4.4158(9) Å; space group Cmmm, Z = 10; RF = 0.054. X-ray single crystal and powder data (STOE STADI P diffractometer) are in fine agreement. The composition was confirmed by EMPA (Carl Zeiss LEO EVO 50XVP instrument with a Link EDX INCA Energy 450 system). The architecture of the crystal structure of CePt3.43Al1.57 is based on CePt5 units with hexagonal CaCu5-type (P6/mmm, a1 = 5.366 Å, c1 = 4.377 Å): unit cell parameters are related by equations: a = a1, b = 5a1, c = c1. The structure can be presented as a construction of two types of networks similar to the layers in CePt5. The first one consists of Ce, Pt and (Pt,Al) atoms similar to Ce,Pt layer (z=0) in CePt5. 1/5 part of the Ce-atoms in these networks is absent and 3/5 of Pt-positions are statistically occupied by Pt and Al atoms. The second network contains Ce-atoms in contrast to Pt layer in CePt5, 1/15 and 4/15 part of Pt positions (z = 0.5) are occupied by Al and (Pt,Al) atoms. The compound exists in the region from CePt3.56Al1.44 to CePt.3.22Al1.78. The work was supported by the Russian Foundation for Basic Research under research grants No. 11-03-00957a and No. 11-03-01191a. [1] Z. Blazina, S.M. Westwood, J. Alloys and Compd. 201 (1993) 151-155