Crystal structure and magnetism of novel compounds U{sub 3}(M{prime}, M{double_prime}){sub 5}, M{prime} = Al,Ga, M{double_prime} = Si,Ge
- Universitaet Wien (Germany)
- Universite de Rennes I (France); and others
Compounds with the formula U{sub 3}M{sub 2}{prime}M{sub 3}{double_prime} have been synthesized for M{prime} = Al,Ga and M{double_prime} = Si,Ge. The crystal structures of U{sub 3}Al{sub 2}Si{sub 3} and U{sub 3}Al{sub 2}Ge{sub 3} have been determined from single crystal X-ray counter data and were found to be isopointal with the Cr{sub 5}B{sub 3} type. Atom order has been refined for U{sub 3}Al{sub 2}Ge{sub 3} (a = 0.77579(13) nm, c = 1.10357(28) nm), revealing a random occupation for 8Ge + 8Al in the 16l sites and 4 Ge in the 4c sites (space group I4/mcm-D{sub 4h}{sup 18}, No. 140, Z = 4). For 317 (276) reflections ({vert_bar}F{sub o}{vert_bar}>3{sigma}) the obtained residual values, R{sub x} = {Sigma}{vert_bar}{Delta}F{vert_bar}/{Sigma}{vert_bar}F{sub o}{vert_bar}, were R{sub x} = 0.057 for U{sub 3}(Al,Si){sub 5} and R{sub x} = 0.074 for U{sub 3}Al{sub 2}Ge{sub 3}, respectively. Isotypism with the crystal structure of U{sub 3}Al{sub 2}Ge{sub 3} (Cr{sub 5}B{sub 3}-type derivative) was confirmed from X-ray powder diffraction analysis for the novel compounds U{sub 3}Ga{sub 2}Si{sub 3} and U{sub 3}Ga{sub 2}Ge{sub 3}. Whereas the compounds U{sub 3}Al{sub 2}Ge{sub 3} and U{sub 3}Ga{sub 2}(Si, Ge){sub 3} were obtained at the given stoichiometry, a small homogeneous range was observed for U{sub 3+y}(Al{sub 1-x} Si{sub x}){sub 5-y} ranging in as-cast alloys from x = 0.64 to x = 0.68 and 0 {le} y {le} 0.04. U{sub 3}(Al,Si){sub 5} is a high-temperature compound only observed in as-cast alloys and transforms on annealing at temperatures below {approximately} 1000{degrees}C. For the homologous phases U{sub 3}Al{sub 2}Ge{sub 3} and U{sub 3}Ga{sub 2}(Si,Ge){sub 3} no transformation has been observed in the range from 600{degrees}C to the melting.
- OSTI ID:
- 508653
- Journal Information:
- Journal of Solid State Chemistry, Vol. 111, Issue 2; Other Information: PBD: Aug 1994
- Country of Publication:
- United States
- Language:
- English
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