Structural phase transition in cobalt oxyfluoride Co
Sb
O
F
observed by high-resolution synchrotron and neutron diffraction
Shimono, Seiya*; Ishibashi, Hiroki*; Nagayoshi, Yusuke*; Ikeno, Hidekazu*; Kawaguchi, Shogo*; Hagihara, Masato
; Torii, Shuki*; Kamiyama, Takashi*; Ichihashi, Katsuya*; Nishihara, Sadafumi*; Inoue, Katsuya*; Ishii, Yui*; Kubota, Yoshiki*
The structural phase transition from cubic (
) to a
tetragonal (
) at
180 K was found in non-centrosymmetric oxyfluoride Co
Sb
O
F
by high-resolution neutron and synchrotron powder diffraction. To investigate this phase transition, specific heat, magnetization, and dielectric measurements were performed. Although the specific heat and dielectric constant showed anomalies at
, a phase transition to ferroelectricity was not observed in the polarization hysteresis loop down to 30 K. The rotation of the CoO
F
octahedron was observed at
from the structural analysis using synchrotron and neutron powder diffraction data. It was found that the magnetic phase transition from paramagnetic to G-type antiferromagnetic occurred at
67 K, at which a peak was observed in the specific heat measurements, via magnetic structure analysis using neutron powder diffraction data. The magnetic moments of Co
were aligned along the tetragonal
-axis direction with a Co
moment of 2.80(1)
at 13 K.