Layered niobate KNb ₃ O ₈ synthesized by the polymeric precursor method

Niobato lamelar KNb ₃ O ₈ sintetizado pelo método dos precursores poliméricos

Abstract

The polymeric precursor method was used for the synthesis of KNb₃O₈ and compared to the solid-state method. The materials were characterized by X-ray diffraction (XRD), infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and determination of surface area and total pore volume by nitrogen isotherms at 77 K. The material prepared by the polymeric precursor method was single-phase while K₂Nb₄O₁₁ was obtained as secondary phase when the solid-state method was used, as evidenced by the XRD patterns and the Raman spectra. The morphology of the materials was significantly altered by the synthesis method, as the KNb₃O₈ prepared by the polymeric precursor method presented a more porous morphology leading to a higher surface area and pore volume.

Keywords:
KNb₃O₈; polymeric precursor method; Raman spectroscopy; K₂Nb₄O₁₁