Yang Dexin,Yang Tao,Chen Yulong,Liang Yu,Liu Yan’gai
Double perovskite La 2 CoMnO 6 is an attractive spintronics with magnetoelectric, magnetodielectric, and magnetoresistive effects, which are related, at least in part, to combined structural and magnetic instabilities. To explore its magnetoelastic coupling behaviour, a conventional analysis of lattice parameter data in terms of spontaneous strain shows that the ferromagnetic ordering process is accompanied by significant volume ( e aM ) and shear ( e tM ) strains. The DC and AC magnetic data reveal the antisite defects with antiphase regions, and the ferromagnetic transition is at ~ 230 K with a small antiferromagnetic ordering at about 170 K. In addition, the Rietveld refinement of the in situ variation X-ray diffraction from 120 to 1400 K, scanning electron microscopy, and differential scanning calorimetry were used to confirm the crystal structure, microstructure, magnetic, and structural anomalies of the sample synthesised in pure oxygen atmosphere. This study, and in particular the strain analysis, of La 2 CoMnO 6 will facilitate its potential application in the field of spin electronics and thin-film engineering.
Shu-Fang Li,Jie Zheng,Liang Hu,Yao Ma,Shuang Zhao,Chuan-Hui Zhu,Dong Yan
Graphical Substitute A-site : The effect of Sr-doping on the performance of double perovskite La 2 CoMnO 6 for catalyzing oxygen evolution reaction (OER) has been studied. The A-site partially substituted compounds, which were obtained via a facile sol-gel method, have proved to have better OER performances compared with La 2 CoMnO 6 . A higher content of oxygen vacancies together with the optimized e g orbit filling make contribution to the enhanced OER activity. Developing effective electrocatalysts for oxygen evolution reaction (OER) is crucial for exploring clean fuels. Owing to the flexible structure and unique 3d electron structure, perovskite has been considered as a promising candidate for OER electrocatalyst. Here, we report a range of A-site partially substituted perovskite obtained via a facile sol-gel method, La 2- x Sr x CoMnO 6 ( x =0.2, 0.4, 0.6, 0.8, and 1.0, LSCMO- x ). LSCMO- x has been proved to have better OER performances. Therein, LSCMO-0.8 shows the best OER catalytic performance among these A-site partially substituted perovskites. The OER overpotential of LSCMO-0.8 catalyst is 0.39 V, which is reduced by 80 mV compared to parent perovskite La 2 CoMnO 6 (LCMO, 0.47 V). The experimental studies have shown that LSCMO-0.8 exhibits a higher content of oxygen vacancies compared with LCMO, which may be the factor for the enhanced OER activity. Meanwhile, it is revealed that Sr doped in the A site can efficiently optimize the e g orbit filling. This work manifests that doping Sr into perovskites appropriately is an effective strategy for the improvement of OER activity.
The growing concern over electromagnetic pollution has intensified attention on the double perovskite La 2 CoMnO 6 (LCMO) microwave absorbing material with high dielectric constant. However, its practical microwave absorption is constrained by inherent impedance mismatch and attenuation capability. To overcome these limitations, we propose a simple interface engineering strategy based on a polydopamine-derived nitrogen-doped carbon (NC) layer on LCMO surface. The NC layer not only enhances conductive loss by constructing a conductive network but also induces the generation of oxygen vacancies to enrich polarization centers, and induces the exchange coupling of Mn 4 + , Mn 3+ , Co 3+ , Co 2+ to increase magnetic loss. The controlled thickness of the NC layer makes it possible to construct heterointerfaces with good impedance matching. The optimal NC layer on LCMO (LCMO@NC‑5) achieved a minimum reflection loss (RL min ) of −56.15 dB and an effective absorption bandwidth (EAB) of 3.55 GHz at a matched thickness of 3.8 mm. This study confirms that precise interface engineering using ultrathin NC coatings provides an effective route and design strategy to unleash the potential of perovskite-based absorbing materials.
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