Full Antiferroelectric Performance and GMR Effect in Multiferroic La_0.75Ba_0.25Fe₁₂O₁₉ Ceramic

Round 1

Reviewer 1 Report

This manuscript reports on the investigation of Multiferroic ceramic M-type lanthanum-doped barium ferrite (La_0.75Ba_0.25Fe₁₂O₁₉), in particular on their properties of structures, magnetization, and magnetoelectricity. In general, it is a well-planned work containing many new and interesting results. However, some minor corrections must be done before its publication.

 -       Throughout the manuscript, several references were not inserted, e.g., “the powders structure was identified by X-ray diffraction spectroscopy. Error! Reference source not found.(A) shows the X-ray diffraction (XRD) spectrum of the as-prepared La0.75Ba0.25Fe12O19 powders, the discrete red lines is corresponding to the standard diffraction pattern of BaFe12O19 (PDF#84-0757). It can be seen from Error! Reference source not found.(A)”

-       In the structure identification report, the fitting of Rietveld refinement in Figure 1 is necessary.

-       What is the charge compensation mechanism after the doping process?

-       The authors describe them as nano-powders, I believe after the synthesis process, but do not report the size “… Therefore, it is certain that lanthanum has successfully replaced part of the barium and successfully made pure La0.75Ba0.25Fe12O19 nano-powders in single magnetoplumbite-5H phase.”

-       In the following paragraph, “… It can be seen that sintering the ceramic at 1400℃ resulted in a high densification, most grains take long plate-like shape.” report the densification value and average grain size.

-       Improve the following paragraph “. It can be seen from Error! Reference source not found. that most of the crystal grains of La0.75Ba0.25Fe12O19 are irregular hexagonal plate-like structures, after the substitution of lanthanum with barium, which leads to the destruction of the hexagonal symmetry in the crystal lattice of BaFe12O19”.

-       Discussion is required around the effects of grain size and grain boundary interdiffusion on dielectric [ https://doi.org/10.1007/s40145-015-0130-8; https://doi.org/10.1016/j.jmmm.2016.01.082; https://doi.org/10.1016/j.materresbull.2012.11.085] and magnetoelectric [https://doi.org/10.1186/1556-276X-6-201; https://doi.org/10.1016/j.jmmm.2014.04.014; https://doi.org/10.1016/B978-0-323-90586-2.00003-6] properties which have been demonstrated in the literature.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

In this article the authors decided to dope BaFe12O19 with lanthanum, aiming to reduce the Curie temperature of BaFe12O19 down to low temperature region, thereby realizing the FE-AFE transition at low temperature and thus achieving pure AFE phase at room temperature in LBFO (LaBaFe12O19) system. Thus, it can expand multiferroics to a new candidate type that combines both antiferroelectrics (AFE) and ferromagnetism (FM), in addition to traditional multiferroics demonstrating a combination of FE+FM or FE+ AFM.

The authors have done a great and scientifically interesting work, obtained new interesting results, including in the priority direction of the physics of magnetic materials "composition-structure-properties".

The powder produced by doping lanthanum in BaFe12O19 was examined by XRD to demonstrate that La0.75Ba0.25Fe12O19 was successfully prepared. The behavior of the La0.75Ba0.25Fe12O19 ceramic was examined in an electric field at room temperature, and a double P-E hysteresis loops diagram without macroscopic polarization in the AFE region was successfully obtained. The UV-vis-NIR optical spectrum of La0.75Ba0.25Fe12O19 proved it to be a direct bandgap semiconductor with an ?? of 1.753eV. The maximum MR ratio reaches - 110.6% when the magnetic field is 1.1T.

Remarks:

A part of the References in the text of the article are very poorly designed: Error! Reference source not found.

I didn't find the file with the Supplementary information on the article. So in Figure 6 (B), the authors draw a tangent to the graph. What program did they use? I know that OriginPro does it very well.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

1. It is necessary to fix problems with links inside the text, after the introduction, each link looks like 'Error! Reference source not found'

2. The text says: "The specific calculation process for this method is described in section 3 of the Supplementary file"

I have not found supplementary files for this work.

3. I have no questions regarding magnetochemical studies, the result is presented well and is, in some way, a breakthrough.

However, I have big questions regarding the identification of the structure of the resulting material. XRD is a good, solid method, but it cannot be the main to proving the structure of this type of material. SEM is also good, but in the presented form, a very large number of materials can look same in this way (without the presence of EDX-SEM at least). And in the case of a material with such significant magnetic properties, XPS and/or TEM/HR-TEM are necessary for indisputable proof of the structural features of such material

This work is written in a good, understandable language, I did not experience any difficulties in interpreting the results of the study, the narrative is clearly traced in the article. A few typos need to be corrected, but they do not affect the overall impression of the text.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have responded to all my comments. The article can be accepted for publication.

Reviewer 3 Report

The authors correctly responded to the comments on the manuscript, the article can be accepted for publication in Applied Sciences in present form