The Synthesis, Properties, and Applications of Columbite Niobates (M²⁺Nb₂O₆): A Critical Review

Abstract

A series of ANb 2 O 6 (A=Ca, Mg, Cu, Ni) columbites and 50% Ni doped with CaNb 2 O 6 ,MgNb 2 O 6 and CuNb 2 O 6 has been prepared using sol-gel technique. The samples were sintered at 9000C for 6 hours. Structural characterization of the prepared samples has been done using X-ray diffraction (XRD) method. To study their applicability in low temperature cofired ceramic (LTCC) technology, dielectric and thermal properties have been characterized. Microwave dielectric properties like dielectric constant and Qf values over Ku-band for all the compositions have been measured. Dielectric constant was found to fall between 4.8 to 10. Thermal properties like thermal conductivity and thermal coefficient of expansion (TCE) were measured over a temperature range from room temperature to 900 0C. Thermal conductivity was found to be of the order of 1-2 W/m 0K while TCE was of the order of 5-10 x 10-6/0C. TCE of some of the compositions have shown negative value at 900 0C.

Raman and Infrared Phonon Features in a Designed Cubic Polymorph of CaTa2O6

“…1,2,17,26 Conversely to tantalite perovskites, which have higher Q u than niobate ones, the AB 2 O 6 tantalites (B = Ta, A = divalent cation) have lower Q u than corresponding niobates (B = Nb). 1,27 The polymorphism presented by members the tantalite family 1 could be at the origin of such behavior, since the ANb 2 O 6 compounds with different A 2+ cations have usually the columbite structure.…”

Magnetic behavior of the NixFe1−xNb2OSarvezuk1, Gusmao2, Cunha3 et al. 2012Phys. Rev. B183131View full textAdd to dashboardCite

“…While the tantalites are tetragonal and present quasi-two-dimensional magnetic properties, the niobates are orthorhombic and characterized by quasi-one-dimensional magnetism [1][2][3] besides presenting interesting optical and dielectric properties. [4][5][6][7] The MNb 2 O 6 compounds present the Pbcn orthorhombic space group, 1,2 known as columbite structure. In this structure, the M 2+ and Nb 5+ cations are located at 4c and 8d positions, respectively.…”

A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

“…The synthesis, properties and applications of the columbiteniobates have been recently reviewed by Pullar (2009). He mentioned that the niobates-columbites are also attracting growing interest owing to their potential application as microwave ceramic substitutes for the highly expensive Tacontaining phases.…”