Quarternary Gd3Ti2MnSi3 compound in the GdMn1-xTixSi (x=0...1) section of Gd-Mn-Ti-Si system at 1073 K

Investigations made by powder X-ray diffraction and metallographic analysis of the GdMn1-xTixSi section (x=0...1) in the Gd-Mn-Ti-Si system at 1073 K are reported. The GdMn1-xTixSi isothermal section includes the a and a' pha ses with CeFeSi-type structure, and the beta phase with Ti5Ga4 type structu re. A single alpha phase is present in the GdMn1-xTixSi section for 0 less than or equal to x less than or equal to 0.3. The alpha and beta phases are present for 0.3<x<0.66. A single beta phase is present for 0.66 less than or equal to x less than or equal to 0.7, and the a' and beta phases are pre sent for 0.7<x<1. A single a' phase is present for x approximate to 1. The Gd3Ti2MnSi3 quarternary compound (a=0.8508(2) nm, c=0.6418(2), space group P6(3)/mcm) forms as a result of ordering of the Ti5Ga4-type solid solutions . The Gd3Ti2MnSi3-type structure is a superstructure of the Ti5Ga4-type str ucture. The cell parameters of the ct and a' phases monotonously increase w ith increasing Ti content, as a rule, but the cell parameters of the beta p hase have a maximum near the Gd3Ti2MnSi3 composition in the GdMn1-xTixSi se ction. (C) 1999 Elsevier Science S.A. All rights reserved.