High-Temperature Studies of the Thermal Expansion of FeNb2O6

Abstract

High-temperature X-ray diffraction is used to study structural changes and thermal expansion of the synthesized iron niobate sample FeNb₂O₆ of the orthorhombic modification. It is demonstrated that no phase transformations are observed in the temperature range 30–1230 °C; there are only anisotropic changes in unit cell parameters. The temperature dependences of the unit cell parameters are approximated by third order polynomials. Tensor coefficients of the thermal expansion are calculated based on the obtained data. The Schneider-Eberhard formalism is used for the quantitative estimation of thermal expansion anisotropy.