Structural and Magnetic Characterization of La_1+xSr_1-xCo_0.5M_0.5O_4±δ (M=Cr, Mn)

Hany El Shinawi (1) , Colin Greaves (2)

1 School of Chemistry
2 School of Chemistry [Birmingham]

The K₂NiF₄ phases La_1+xSr_1-xCo_0.5Cr_0.5O_4±δ (x=0, 0.15) and La_1+xSr_1-xCo_0.5Mn_0.5O_4±δ (x=0, 0.2) have been synthesised and examined by X-ray powder diffraction, thermal analysis, neutron powder diffraction and magnetic susceptibility measurements. Mn³⁺/Co³⁺ and Cr³⁺/Co³⁺ states predominate in the oxidised forms. Structural stability and crystal symmetry are retained under reducing conditions which cause reduction of Co³⁺ into Co²⁺ and the creation of oxide ion vacancies within the equatorial planes of the K₂NiF₄ structure. Excess oxygen in La_1.2Sr_0.8Co_0.5Mn_0.5O_4.1 is accommodated in the ideal interstitial positions (0, 0.5, 0.25) of the tetragonal structure. these materials depending upon the atmosphere applied. No long-range magnetic order has been observed because of competing AFM and FM interactions in these B-site disordered materials.

Mots clés: Physical Sciences

Hany El Shinawi, Colin Greaves. Structural and Magnetic Characterization of La_1+xSr_1-xCo_0.5M_0.5O_4±δ (M=Cr, Mn). Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (12), pp.1856. ⟨10.1002/zaac.200900202⟩. ⟨hal-00508909⟩