A-Site Doping Effect on PLZT Relaxor Ferroelectric Glass-Free Medium-Temperature Sintering Ceramics

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article investigated the polarization characteristics of Pb₀.₉₇₋ₓLa₀.₀₃Ndₓ(Mg₀.₈Mo₀.₂Zr₀.₉₅Ti₀.₀₅)O₃ (x = 0.01, 0.03, 0.05, and 0.07) ceramics sintered at low temperature. The development of this type of material is crucial for the manufacturing of multilayer ceramic capacitors (MLCCs). Therefore, this research is highly relevant, and the manuscript can be considered for publication. However, several questions need to be addressed before a final decision can be made.

• Introduction: The problem of high-temperature sintering is not sufficiently explained. Why does high-temperature sintering lead to incompatibility with Nickel (Ni) and Copper (Cu) electrodes? What should the sintering temperature be for ceramics to be suitable for manufacturing MLCCs with Base-Metal Electrodes (BME)?

• The review of current literature on methods for reducing sintering temperature should be expanded. What are their drawbacks?

• In the "Experimental procedures" section, it is stated that sintering was conducted at 1030 °C. How was such a low temperature achieved? Why was this specific ceramic composition chosen? What guarantees the low sintering temperature?

• What is the scientific novelty of this research? Has the investigated ceramic composition not been studied before? This should be discussed in more detail in the introduction.

• The manuscript does not present results confirming successful low-temperature sintering. What was the density of the obtained ceramics relative to the theoretical density?

• It would be useful to study the ceramic powder using Differential Scanning Calorimetry (DSC) to demonstrate the feasibility of low-temperature sintering.

• Fig. 2: The shift in the diffraction peaks should be commented on. What is it associated with?

• This article lacks the dielectric characteristics of the fabricated ceramics. The frequency dependencies of the dielectric permittivity and the dielectric loss tangent (tan δ) should be provided. This is necessary to assess the technical parameters of the dielectric material. Furthermore, the frequency-dependent behavior of the dielectric response would allow for an evaluation of the quality of the sintered ceramics.

Author Response

Dear Editor and Reviewer,

First, we would like to express our thanks to the Reviewers for their instructive comments concerning our manuscript entitled ‘A-site doping effect on PLZT relaxor ferroelectric glass-free medium-temperature sintering ceramics’(coatings-3849391). We have studied the comments carefully, and then revised the whole manuscript. The revisions/explanation corresponding to comment are shown in the attached file.

Qingwei Liao

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents interesting work on Nd³⁺ A-site doping in PLZT relaxor ferroelectric ceramics prepared by a glass-free medium-temperature sintering process. The topic is important for energy storage applications and the results are promising, especially regarding energy density, efficiency, and fast discharge behavior. The experiments are well conducted, and the paper is generally clear. I believe the manuscript could be accepted after some revisions. I list below several questions and suggestions that I hope the authors can consider to improve the quality and impact of the work.

1. The novelty compared with other rare-earth-doped PLZT works is not very clear. Beyond the medium-temperature sintering, what is the main new contribution? Please compare your results directly with the best reported values in literature, possibly in a summary table.
2. The SEM images are discussed in a qualitative way. Could the authors provide grain size distribution histograms with average values and standard deviations, and also quantify porosity? How do these microstructural parameters affect breakdown strength and energy storage density?
3. The XRD analysis only states that no secondary phases are observed. Could the authors provide Rietveld refinement or lattice parameter analysis to confirm A-site substitution of Nd³⁺ and to quantify strain or crystallite size changes?
4. The Raman red shift of 2.7 cm⁻¹ is small. What is the spectral resolution of the instrument, and is the shift statistically significant across multiple samples? Would temperature-dependent Raman help confirm the link to cation disorder and polar nanoregion formation?
5. The hysteresis loop data show that η is maximized at x = 0.05, while Wrec peaks at x = 0.07. Could this discrepancy be related to leakage current, defect dipoles, or oxygen vacancy dynamics? Please provide dielectric loss (tan δ vs. frequency) or leakage current density data to support the interpretation.
6. The discharge performance (τ0.9 ~ 9–11 ns) is very good. Could the authors report reproducibility and error margins over several cycles? How stable are these parameters under repeated charging/discharging (fatigue test)?
7. The XPS discussion suggests that Nd³⁺ doping reduces oxygen vacancies. Could the authors quantify the O1s peak area ratios (lattice O / adsorbed O / oxygen vacancies) and include error margins? Also, could the Nd 3d binding energy shift be partly due to changes in local bonding or electronic shielding, not only lattice contraction?
8. Have the authors checked temperature-dependent dielectric or energy storage properties? Since capacitors often work under heating, data of Wrec and η vs. temperature would make the application perspective stronger.
9. Could the authors comment on the scalability of this process? The sintering temperature of 1030 °C is lower than standard PLZT, but is it fully compatible with industrial multilayer capacitor fabrication using Ni electrodes?
10. Figures of XRD, Raman, and XPS are not very clear. Higher-resolution plots with better annotations would improve readability.
11. When mentioning “104% increase,” please also indicate the baseline value to avoid ambiguity.
12. Some references appear only loosely related (e.g., refs. [23], [25], [27]). Please refine the citations so that every reference directly supports the corresponding statement.

the study is strong and interesting, and only minor improvements are required. I recommend acceptance after revision.

Author Response

Dear Editor and Reviewer,

First, we would like to express our thanks to the Reviewers for their instructive comments concerning our manuscript entitled ‘A-site doping effect on PLZT relaxor ferroelectric glass-free medium-temperature sintering ceramics’(coatings-3849391). We have studied the comments carefully, and then revised the whole manuscript. The revisions/explanation corresponding to comment are shown in the attached file.

Qingwei Liao

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have made the necessary revisions to improve the quality of the submitted manuscript. The manuscript can now be accepted for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks to the authors for their corrections and addressing almost all of the comments. Now, the paper can be accepted for publication in the Coatings journal.