The observation of electron density distribution of thermally excited states in CeB6 at 430 and 535K

Graduate School of Materials Science & Engineering, Nagoya Institute of Technology* Omohi College, Graduate School of Materials Science & Engineering, Nagoya Institute of Technology, Japan** Graduate School of Science, Osaka University, Japan*** Graduate School of Natural Science, Nagoya City University, Japan****
â—‹Ryoko Makita* Shiro Funahashi* Kiyoaki Tanaka** Yoshichika Onuki*** Hiroshi Tatewaki****

Most of the properties of materials are determined by electrons.
The electron density distribution (EDD) of excited states have not yet been observed. The observation of EDD is useful for revealing relations between physical properties and electronic states and will help control physical properties.
CeB6 crystal has 4f(j=5/2) γ7 andγ8 (ground state). In the previous study[1], just significant amount of electrons exist inγ7 orbital of CeB6 at 298K.The excitation energy between γ7 andγ8 is reported to be 530K - 560K[2].
Therefore the aim of present study is to observe EDD of excited states of CeB6 and to pioneer accurate measurements of EDD at high temperature.
X-ray intensity measurement is performed by 4-circle diffractmeter keeping multiple diffraction effect minimum and CeB6 single-crystal is heated by furnace up to 430K and 535K. The furnace equipped with a brass cylinder and a spiral Pt wire is put on chi circle of our diffractometer keeping the N2-gas flow rate constant by KOFLOC 8300.
The reflection data are refined by the least-squares method (QNTAO by K.Tanaka). Spin-orbital interaction was taken into account and scattering factors calculated from relativistic atomic orbital ware used. The EDD was divided into sub-shells and electron-population and expansion/contraction of each orbital were refined keeping the unit cell electrically neutral together with anharmonic vibration parameters.
We investigate states of electron occupiedγ7 and γ8 orbital at 430K and 535K, and verify EDD of thermally excited states of CeB6 are observed at 430K and 535K.
[1] K.Tanaka and Y.Onuki, Acta Cryst, B58, 423-436(2002)
[2] E.Zirngiebl et al, Phys.Rev.B30, 4052-4054(1984)