A comparative study on effects of magnesium substitution at Nd and Fe-sites on the structural, optical, magnetic, and dielectric properties of neodymium orthoferrite

IF 4.6 2区物理与天体物理 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Results in Physics Pub Date : 2025-10-22 DOI:10.1016/j.rinp.2025.108496

Mansoureh Pourjafar, Davoud Sanavi Khoshnoud

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Abstract

Tailoring optical, electrical and magnetic behaviour of orthoferrites is vital for their application in advanced devices. In this study comparatively investigated the effects of magnesium ion substitution on structural, optical, magnetic, and dielectric properties of Nd_1-xMg_xFeO₃ and NdFe_1-yMg_yO₃ (x, y = 0.0, 0.05, 0.10, 0.15, and 0.20). X-ray photoelectron spectroscopy analysis revealed that Mg doping at the Fe site induces a higher concentration of oxygen vacancies compared to that of Nd-site. Rietveld refinement and XRD patterns confirmed that the samples crystalized in an orthorhombic structure with space group Pbnm. The unit cell volume (V) decreases overall due to magnesium doping in the Nd and Fe-sites. The FE-SEM images revealed homogenous, spherical nanoparticles ranging in size from 70 nm to 108 nm, depending on the Mg concentration. The optical band gap energy (E_g) was investigated by diffuse reflectance spectroscopy analysis. While E_g decreases from 2.15 eV for the pure sample to 1.87 eV for the y = 0 sample, in Nd_1-xMg_xFeO₃ samples is found to decrease at first until x = 0.10 sample, and then increase monotonically with increasing Mg content. The nature of the magnetic hysteresis loops for Nd_1-xMg_xFeO₃ compounds show a soft ferromagnetic behavior. Notably, the remanent magnetization in the Nd_1-xMg_xFeO₃ samples was found to be more than five times higher than that of the NdFe_1-yMg_yO₃ compounds. By contrast, H_c in NdFe_1-yMg_yO₃ nanoparticles increases significantly from y > 0.05 and reaches 1300 Oe for the sample with y = 0.2 while the H_c decreases slightly with Mg doping in Nd_1-xMg_xFeO₃ samples. A substantial increase in the dielectric constant was observed in all the Mg-substituted samples at room temperature, regardless of the substitution site. However, this increase was considerably more pronounced in the samples in which Mg was substituted at the Fe-site. Finally, the presence of an anomaly in the temperature dependence of the dielectric constant for the studied samples around the antiferromagnetic-paramagnetic transition implies the existence of magnetoelectric coupling in our compounds due to strong spin-phonon coupling.

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Nd和fe位置的镁取代对钕正铁氧体结构、光学、磁性和介电性能影响的比较研究

调整正铁氧体的光学、电学和磁学行为对其在先进器件中的应用至关重要。本研究对比研究了镁离子取代对Nd1-xMgxFeO3和NdFe1-yMgyO3 （x, y = 0.0, 0.05, 0.10, 0.15和0.20）结构、光学、磁性和介电性能的影响。x射线光电子能谱分析表明，与nd位点相比，在Fe位点掺杂Mg会产生更高浓度的氧空位。Rietveld细化和XRD图谱证实，样品结晶为具有空间基团Pbnm的正交结构。由于镁在Nd和fe位点的掺杂，使单元胞体积(V)整体减小。FE-SEM图像显示了均匀的球形纳米颗粒，大小从70 nm到108 nm不等，取决于Mg的浓度。用漫反射光谱法研究了光学带隙能（Eg）。纯样品的Eg从2.15 eV下降到y = 0样品的1.87 eV，而Nd1-xMgxFeO3样品的Eg先下降到x = 0.10样品，然后随着Mg含量的增加单调增加。Nd1-xMgxFeO3化合物的磁滞回线性质表现为软铁磁性。值得注意的是，Nd1-xMgxFeO3样品的剩余磁化强度比NdFe1-yMgyO3化合物高5倍以上。相比之下，纳米NdFe1-yMgyO3中的Hc从y >； 0.05显著增加，当y = 0.2时达到1300 Oe，而在掺杂Mg的Nd1-xMgxFeO3中Hc略有下降。在室温下，无论取代位置如何，所有mg取代样品的介电常数都显著增加。然而，这种增加是相当明显的，在样品中，Mg取代了铁的位置。最后，在所研究的样品中，介电常数在反铁磁-顺磁转变周围的温度依赖性异常的存在意味着由于强自旋-声子耦合，我们的化合物中存在磁电耦合。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Results in Physics MATERIALS SCIENCE, MULTIDISCIPLINARYPHYSIC-PHYSICS, MULTIDISCIPLINARY

CiteScore

8.70

自引率

9.40%

发文量

754

审稿时长

50 days

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