Synthetically tuned structural variations in CePdxGe2−x (x = 0.21, 0.32, 0.69) towards diverse physical properties. Issue 2 (9th December 2016)

• Record Type: Journal Article
• Authors: Sarkar, Sumanta; Banerjee, Swastika; Halappa, Pramod; Kalsi, Deepti; Mumbaraddi, Dundappa; Ghara, Somnath; Pati, Swapan K.; Sundaresan, A.; da Silva, Ivan; Rayaprol, Sudhindra; Joseph, Boby; Peter, Sebastian C.
• Is Part Of: Inorganic chemistry frontiers. Volume 4:Issue 2(2017)
• Page Start: 241
• Page End: 255
• Publication Date: 2016-12-09
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6qi00366d
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Three structural variations of CePd x Ge2− x with versatile properties were synthesized by varying the Pd : Ge ratio. Abstract : In this work, we have studied the structure and physical properties of a series of intermetallic compounds with the general formula CePd x Ge2− x (where, x = 0.21, 0.32, 0.69). It was found that the compound crystallizes in three different phases with stoichiometries: CePd0.32 Ge1.68, CePd0.21 Ge1.79 and CePd0.69 Ge1.31 by varying the Pd to Ge ratio. While CePd0.32 Ge1.68 and CePd0.69 Ge1.31 crystallize in the hexagonal AlB2 structure type with the space group P 6/ mmm, CePd0.21 Ge1.79 crystallizes in the tetragonal α-ThSi2 structure type with the space group I 41 / amd . CePd0.69 Ge1.31 is in fact an ordered superstructure of CePd0.32 Ge1.68 with tripling of the c -lattice. Relative changes in the Pd/Ge ratio also impart substantial variation in their magnetic properties, although Ce is in the trivalent state in both the phases. CePd0.21 Ge1.79 shows metamagnetic behavior below 10 K whereas CePd0.69 Ge1.31 showed ferromagnetic behavior in the same temperature range. In addition to the metamagnetic behavior, CePd0.21 Ge1.79 also shows spin glass behavior at low temperature. DFT calculations were used to obtain ulterior information on the CePd0.69 Ge1.31 phase. Self-consistent calculations revealed that the ferromagnetic ordering of the ground state arises from the spins at the Ce and Pd sites. The observed sharp rise in the low temperature resistivity of CePd0.69 Ge1.31 is an indication of a pseudo-gap formation or possible Kondo behavior in the electronic density of states, enhancing the scattering of the charge carriers. Heat capacity measurements on CePd0.69 Ge1.31 suggest that it falls in the category of medium heavy fermion compounds.