Structural characterization of Y2Pd14B5

Y2Pd14B5 is the major phase in as-cast and annealed multiphase alloys with nominal compositions near YPd5B3C0.3. Its crystal structure determined the first time here by single crystal X-ray diffraction is body-centered tetrag onal (space group I 4(1)/amd). Transmission electron microscopy (TEM) revea ls that in as-cast specimens the tetragonal phase has a modulated structure and is oriented intergrown with a face-centered cubic phase of similar com position, namely YPd7B2. According to Rietveld analyses of the multiphase s ystem the structure of this phase can be well-described by space group Fm ( 3) over bar m. Annealing the sample for 150 hrs at 973 K results in a coars ening and enrichment of the tetragonal phase as well as a disappearance of the modulations allowing a detailed structure analysis by single crystal di ffractometry.