Crystallographic and Magnetic Properties of KFeO$_2$

Abstract

The crystallographic and magnetic properties of KFeO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_2$</tex> powder prepared by ball-mill method, have been studied by X-ray diffraction (XRD), MÖssbauer spectroscopy, and vibrating sample magnetometer (VSM) measurements. The crystal structure of KFeO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_2$</tex> powder at room temperature is determined to be an orthorhombic structure of Pbca with its lattice constants <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$a_0 = 5.594, b_0 =11.247$</tex> , and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$c_0=15.863$</tex> Å by Reitveld refinement. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex> - <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$H$</tex> curves show antiferromagnetic behavior at 34 K and room temperature. MÖssbauer spectra of KFeO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_2$</tex> were taken at various temperatures ranging from 4.2 to 600 K. And the NÉel temperature <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(T_N)$</tex> was determined to be 930 K. The magnetic hyperfine field and isomer shift value at 4.2 K were 519 kOe and 0.19 mm/s, respectively.