X-ray,electrical conductivity,magnetic and infrared studies of the system Co2?x Ge1?x Fe2x O4

X-ray, electrical conductivity, magnetic hysteresis and IR studies for the system Co_2−x Ge_1−x Fe_2x O₄ were carried out. All the compounds, 0⩽x⩽1, showed cubic symmetry. X-ray intensity calculations, magnetic hysteresis measurements and IR studies indicated the presence of Ge⁴⁺ at tetrahedral, Co²⁺ at octahedral and Fe³⁺ at both the sites. The activation energy and threshold frequency decreased with increasing value ofx. The compounds withx⩽0.5 arep-type and those withx⩾0.75 aren-type semiconductors. Magnetic hysteresis indicated that all the compounds are ferrimagnetic except forx=0 which is antiferromagnetic. The shapes of χ/χ _i vsT plots, highH _c values andJ _R/J_s ratios showed that all the compounds exceptx=0 exhibit single-domain behaviour. Curie temperature,T _c increased with increasing Fe³⁺ ions. The probable ionic configuration for the system is suggested as Ge _1−x ⁴⁺ Fe _x ³⁺ co _2−x ²⁺ Fe _x ³⁺ ]O ₄ ²⁻ .