%0 Journal Article
%A Suemoto, Yuya
%A Masubuchi, Yuji
%A Nagamine, Yuki
%A Matsutani, Atsuo
%A Shibahara, Takeshi
%A Yamazaki, Kumiko
%A Kikkawa, Shinichi
%D 2018
%T Intergrowth between the Oxynitride Perovskite SrTaO2N and the Ruddlesden–Popper Phase Sr2TaO3N
%U https://acs.figshare.com/articles/journal_contribution/Intergrowth_between_the_Oxynitride_Perovskite_SrTaO_sub_2_sub_N_and_the_Ruddlesden_Popper_Phase_Sr_sub_2_sub_TaO_sub_3_sub_N/6820604
%R 10.1021/acs.inorgchem.8b01079.s001
%2 https://acs.figshare.com/ndownloader/files/12404423
%K 0.2 MPa
%K oxynitride perovskite
%K single-phase perovskite
%K ambient conditions
%K ambient air
%K stoichiometric composition
%K XRD
%K oxide perovskites
%K Thermal analysis
%K perovskite-type structure
%K Ruddlesden
%K Oxynitride Perovskite SrTaO 2 N
%K dielectric behavior
%K SrTaO 2 N perovskite
%K perovskite lattice
%K composition range
%K moisture sensitivity
%K Sr 2 TaO 3 N
%K perovskite SrTaO 2 N
%K crystal lattice
%K 10 days
%K perovskite crystal lattice
%K SrCO 3
%K Partial substitution
%K Sr 2 TaO 3 N ceramics
%K X-ray diffraction analyses
%K perovskite intergrown
%K SrO content
%X Strontium
tantalum oxynitrides were prepared within the nominal composition
range of 1.0 ≤ x ≤ 2.0, where x = Sr/Ta atomic ratio. A gradual structural transition
was observed between the perovskite SrTaO2N and the Ruddlesden–Popper
phase Sr2TaO3N with increasing SrO content.
X-ray diffraction analyses showed that a single-phase perovskite was
obtained up to x = 1.1, after which Sr2TaO3N gradually appeared at x ≥
1.25. High-resolution scanning transmission electron microscopy observations
identified the gradual intergrowth of a Ruddlesden–Popper Sr2TaO3N type planar structure interwoven with the
perovskite crystal lattice upon increasing x. The
crystal lattice at x = 1.4 was highly defective and
consisted primarily of perovskite intergrown with a large amount of
the Ruddlesden–Popper phase structure. This Ruddlesden–Popper
phase layer intergrowth is a characteristic of an oxynitride perovskite
rather than the Ruddlesden–Popper defects previously reported
in oxide perovskites. Partial substitution of Ta with Sr was also
evident in this perovskite lattice. Just below x =
2, a perovskite-type structure was intergrown as defects in the Ruddlesden–Popper
Sr2TaO3N. Characterization of Sr2TaO3N in ambient air was challenging due to its moisture
sensitivity. Thermal analysis demonstrated that this material was
relatively stable up to approximately 1400 °C in comparison with
SrTaO2N perovskite, especially under nitrogen. Sr2TaO3N could keep its structure in a sealed tube, and some
amount of SrCO3 was observed in XRD after 10 days of exposure
to 75% relative humidity under prior ambient conditions. A compact
of this material had a relative density of 96% after sintering at
1400 °C under 0.2 MPa of nitrogen, even though a drastic loss
of nitrogen was previously reported for a SrTaO2N perovskite
under these same conditions. Postammonolysis of the Sr2TaO3N ceramics was not required prior to studying its
dielectric behavior. This is in contrast to the SrTaO2N
perovskite, which requires postammonolysis to recover its stoichiometric
composition and electrical insulating properties.
%I ACS Publications