La_1−xCe_xCrO₃ (0.0 ≤ x ≤ 1.0): A New Series of Solid Solutions with Tunable Magnetic and Optical Properties

A new series of La_1−xCe_xCrO₃ (0.0 ≤ x ≤1.0) compounds in nanocrystalline form were synthesized using a two-step synthesis route, involving an initial combustion reaction followed by vacuum heating in the presence of a Zr sponge, which acted as an oxygen getter. For the first time, a homogeneous solid solution formation throughout the entire range was obtained in this series. These compounds were characterized using X-ray diffraction, diffuse reflectance UV visible spectrophotometry, and superconducting quantum interference device magnetometry. The crystallite size for the phase-pure products was confirmed to be ∼42−44 nm by high-resolution transmission electron microscopy. All compounds (nanocrystalline) in this series are found to be predominantly antiferromagnetic in nature with a remarkable linear increasing trend in Neel temperature from 257 to 281.5 K as a function of decreasing Ce³⁺ content. Interestingly, the band gap also shows a linear decrease from 3.21 to 3.02 eV as a function of increasing Ce³⁺ concentration in the La_1−xCe_xCrO₃ series.