Xiaojing Ma

Biography

Abstract: The Mn₅Si₃ structure is an attractive structure type in which chemical versatilities through the incorporation of interstitials allow the subtle exploration of the composition-property-electronic structure relationships in intermetallic compounds. Our studies on the oxygen interstitial chemistry of Ce₅Ge₃, with the Mn₅Si₃-type, led to the interstitial phase, Ce₅Ge₃O_x (0 ≤ x ≤ 1).  Ce₅Ge₃O_x were synthesized by arc-melting, under controlled dilute-oxygen gas flow.  Phase relationships were analyzed by powder X-ray diffraction, and chemical analysis were done by ICP-MS. The crystal structures of Ce₅Ge₃ and Ce₅Ge₃O were determined by single crystal X-ray diffraction. Fourier map analysis and Raman spectroscopy confirm the absence of any oxygen in the binary Ce₅Ge₃. Contrary to previously published results magnetic measurements on Ce₅Ge₃O_x (x = 0, 0.2, 0.5, 0.8, 1) indicate that Ce₅Ge₃ exhibits Curie-Weiss paramagnetism with no anomalous behavior. However, upon incorporation of oxygen in Ce₅Ge₃O_x (x > 0), a Kondo-like magnetic behavior arises at low temperatures (2K -10K). This is consistent with previous reports on Ce₅Ge₃. The Kondo-like effect appears to increase with oxygen content; an optimum effect is observed with x = 0.8; it is suppressed with increasing magnetic field. Details of our studies will be presented.