Behavior of Sm in the boron cage of Sm-doped B ( =Yb, La) observed by multiple-wavelength neutron holography

Uechi, Shoichi*; Oyama, Kenji*; Fukumoto, Yohei*; Kanazawa, Yuki*; Happo, Naohisa*; Harada, Masahide   ; Inamura, Yasuhiro  ; Oikawa, Kenichi   ; Matsuhra, Wataru*; Iga, Fumitoshi*; Kevin, A.*; Hayashi, Koichi*

We have succeeded in visualizing the local atomic structures around Sm in B ( =Yb, La), in which a rareearth atom is located in the boron cage, using the newly developed technique for local structure investigations, multiple-wavelength neutron holography in a pulsed neutron facility. From the local atomic structures, we were able to clarify the behavior of Sm in the boron cage. Doped Sm in YbB fluctuates within the boron cage with a mean displacement of 0.25(4) , while that of Sm in LaB is approximately 0.15 . The Sm doping causes the fluctuation of the first-nearest-neighbor B with a mean displacement of 0.28 , while its effect on La, Yb, and the rest of the boron atoms is negligible. These are the first observations of the local behavior of doped rare-earth atoms and B in rare-earth borides with boron cages.