Rare earth chromium oxides revisited, special case: Structural, magnetic and thermal studies of Ce1−xEuxCrO3 nano-powders

Due to their high chemical stability at elevated temperatures combined with interesting electric and magnetic properties, perovskite-type rare earth orthochromites of composition RCrO3 (R = rare earth element) have potential applications as catalysts, electrolytes, fuel cells, spin valve materials, multiferroics, refractory ceramics, thermoelectric materials as well as gas-sensor devices. In this work, we present a short review of the electric and magnetic properties of rare earth orthochromites with light rare earths. Especially, we focus on recent results we obtained by investigating mixed phases Ce1−xEuxCrO3 (0  ≤ x ≤  1) which were prepared as phase pure nano-powders (particle size 50-100 nm) employing the solution combustion method. Substitution with europium as an ion with the smaller radius size and a magnetic configuration different from that of Ce3+ has essential consequences for the structural and magnetic properties. CeCrO3 exhibits one of the highest antiferromagnetic ordering temperatures ( ∼ 257 K) among the rare earth orthochromite series. By substituting Ce with Eu the Néel temperature is continuously lowered, reaching  ∼ 182 K for EuCrO3. EuCrO3 orders itself with a G-type antiferromagnetic structure which we determined for the first time by elastic neutron scattering. The mixed phases Ce1−xEuxCrO3 exhibit puzzling electric and magnetic properties including magnetization reversal, exchange bias effect, and relaxor-type dielectric properties.