ABSTRACT The exploration of novel double perovskite (DP) oxides with advanced and tunable properties continues to expand, owing to their potential to host distinctive electronic and magnetic ground states. This study demonstrates the first‐ever synthesis of the theoretically predicted 3 d –5 d DP oxide La 2 NiHfO 6 (LNHO), via sol‐gel auto‐combustion technique. At ambient conditions, LNHO crystallizes in the orthorhombic ( Pbnm ) structure. An optical band gap of 3.15 eV and a refractive index of 2.38 obtained from the UV‐Vis spectroscopy reveal the semiconducting behavior. Thermomagnetic studies propose an antiferromagnetic ordering with uncompensated spins leading to ferrimagnetism below T c ∼ 101 K. The presence of such uncompensated spin contributions from the multivalent Ni ions (Ni 2+ and Ni 3+ ), as confirmed from XPS, further demonstrates a conventional exchange bias of 600 Oe at 5 K. Low‐temperature structural analysis indicates subtle changes in the cell parameters, octahedral tilting, and modulations in bond angle, suggesting a magneto‐structural coupling below 100 K in LNHO. Further, high‐pressure structural investigation reveals an anisotropic lattice compression and a reversible isostructural phase transition at 8.6 GPa. The presence of LNHO is found to improve the degradation efficiency of methylene blue under ultraviolet irradiation by 73.7%, suggesting its potential application as a photocatalyst. In addition, LNHO may be a potential material for other applications, such as spintronics and pressure‐sensing devices.
Das et al. (Fri,) studied this question.