Morphology and band gap variations of oxynitride LaTaON2 depending on the ammonolysis temperature and precursor

Title
Morphology and band gap variations of oxynitride LaTaON2 depending on the ammonolysis temperature and precursor
Author(s)
박나영[박나영]김영일
Keywords
VISIBLE-LIGHT; DIELECTRIC-PROPERTIES; SR; DIFFRACTION; NEUTRON; BATAO2N; OXIDES; SYSTEM; LAYERS; CA
Issue Date
201207
Publisher
SPRINGER
Citation
JOURNAL OF MATERIALS SCIENCE, v.47, no.13, pp.5333 - 5340
Abstract
Polycrystalline LaTaON2 samples were prepared by the ammonolysis of LaTaO4, where the oxide preparation temperatures (700, 900, and 1,400 A degrees C) and ammonolysis temperatures (850, 950, and 1,000 A degrees C) were varied to control the specific surface area and porosity. The resulting LaTaON2 samples had a surface area of 15-20 m(2)/g and a pore volume of 0.045-0.059 cm(3)/g, as determined from the nitrogen adsorption-desorption isotherms. In particular, the ammonolysis of crystalline LaTaO4 (prepared at 1,400 A degrees C) can be described as a condensation from layered perovskite to three-dimensional perovskite, where mesoporous LaTaON2 were produced with pore diameters of 5-50 nm and particle sizes of a parts per thousand 1 mu m. Diffuse-reflectance measurements demonstrated that these ammonolysis parameters also affected the optical band gap energy of LaTaON2, which varied from 1.93 to 2.07 eV. Increasing the LaTaO4 preparation temperature and/or ammonolysis temperature tended to decrease the band gap of LaTaON2.
URI
http://hdl.handle.net/YU.REPOSITORY/27657http://dx.doi.org/10.1007/s10853-012-6420-4
ISSN
0022-2461
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이과대학 > 화학생화학부 > Articles
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