Effect of Different Ca2+ and Zr4+ Contents on Microstructure and Electrical Properties of (Ba,Ca)(Zr,Ti)O3 Lead-Free Piezoelectric Ceramics
, Long Qiu 1,†, Cong Yang 1, Yuansheng Chen 1, Kongjun Zhu 2,* and Luming Wang 1,*
Round 1
Reviewer 1 Report
In Introduction, the paper Y. Bai, A. Matousek, P. Tofel, V. Bijalwan, B. Nan, H. Hughes, T.W. Button, (Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric ceramics—The critical role of processing on properties, Journal of the European Ceramic Society, 35 (13), 2015, 3445-3456, https://doi.org/10.1016/j.jeurceramsoc.2015.05.010 can be mentioned.
Though in the Introduction the authors mentioned the compositions of their ceramics, i.e., (Ba1−xCax)(Zr0.1Ti0.9)O3 (BCxZT, x = 0, 0.06, 0.12, and 0.18) 71 and (Ba0.85Ca0.15)(ZryTi1−y)O3 (BCZyT, y = 0, 0.08, 0.1, and 0.12), later on, they used the different designation of their composition, i.e., BCxZT ceramics with x = 0, 0.06, 0.12, and 0.18 as well as BCZyT ceramics with y = 0, 78 0.08, 0.1, and 0.12 were chosen for this study. This designation used in the text, in figure captions, etc. can mislead the reader.
While discussing the XRD patterns of their ceramics, the authors mention that “all samples show single perovskite structure suggesting that the Ca and Zr ions diffuse into the BT lattice to form a new solid solution.” This discussion sounds strange because in many papers the structure of similar ceramics is discussed, and the presented result seems not to be a new one. The patterns presented in Fig. 1 (a,b) are not informative. I recommend to show them in a different scale so that to be able to see the peaks details. It seem that not only the peak at around 2theta =45o is split.
The authors state that the phase structure of BCxZT transforms from orthogonal to tetragonal near room temperature at 0.12 ≤ x ≤ 0.18 via dielectric temperature curve. Is it possible to confirm this tranformation using XRD analysis data?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors have studied the effect of the Ca and Zr content variation in the (Ba1−xCax)(Zr0.1Ti0.9)O3 (BCxZT, x = 0, 0.06, 0.12, and 0.18) and (Ba0.85Ca0.15)(ZryTi1−y)O3 (BCZyT, y = 0, 0.08, 0.1, and 0.12) ceramics on their piezoelectric properties. The contribution of the phase structure, microstructure, dielectric and ferroelectric properties to the piezoelectric properties of the (Ba,Ca)(Zr,Ti)O3 ceramics have been explored. The manuscript is interesting, but some deficiencies need to be corrected to make it acceptable for publication.
(1) Lines 91-93: The part on microstructural characterization should be expanded. It should contain a description of sample preparation including etching etc.
(2) Fig. 2: How the authors can explain such a distinct difference in grain morphology for the cases (c) and (g) having close stoichiometry? This question also relates to grain sizes given in Fig. 3 and values of the Tc given in Table 1.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Revision of “Effect of different Ca2+ and Zr4+ contents on microstructure and 2 electrical properties of (Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric 3 ceramics”
The manuscript under review devoted the effects of Ca and Zr contents on the phase transition and electrical properties of BCxZT (x = 0, 0.06, 0.12, and 0.18) ceramics and BCZyT (y = 0, 0.08, 0.1, and 0.12) ceramics. Providing of such investigations is very important from an academic and economic points of view.
XRD shows that all samples have pure perovskite phase structure, and the BCZyT ceramics morphotropic phase boundary region from tetragonal phase to rhombohedral phase near 0.08 ≤ y ≤ 0.1. From the dielectric temperature curve, the phase transition temperature (TO-T) was found near room temperature at 0.12 ≤ x ≤ 0.18 for the BCxZT ceramics. Both Ca and Zr increase have a significant decrease on the Curie temperature Tc. All samples were found to be relaxors with a diffusivity in the range 1.29 ≤ γ ≤ 1.82. Variations in both the Ca and Zr content have a significant effect on the density and grain size of the ceramics, which are closely related to their piezoelectricity. Different from the undoped ceramics, ceramics doped with Ca and Zr ions exhibit saturated P–E hysteresis loops, and their ferroelectric properties are significantly optimized. In particular, the (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic exhibits optimal properties, namely d33 = 330 pC/N, kp = 0.41, εr = 25 4069, Pr = 4.8 μC/cm2, and Ec = 3.1 kV/cm, which are promising as a lead-free piezoelectric candidate.
In manuscript all necessary information is captured by 7 figures and 1 tables. There are 26 references.
After getting acquainted with the presented manuscript, a few small questions remained:
1. Page 2 line 80 the authors did not present reagent- grade of starting materials.
2. Page 3 line 98 not presented reference to IEEE standards.
3. Page 4 line 140 the authors can describes why the Zr substitution can help improving the grain growth of the materials, due to what.
4. Sections 3.3, 3.4 the authors did not discuss the possible reasonы for the decrease in electrical characteristics compared to the data given in ref. 21.
Obtained results are important both for understanding the physical processes that occur in real objects and for the development of new devices. It corresponds to the field of the Journal «Crystals». It may be accepted after minor revision.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Revision of “Effect of different Ca2+ and Zr4+ contents on microstructure and 2 electrical properties of (Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric ceramics”
The manuscript under review devoted the effects of Ca and Zr contents on the phase transition and electrical properties of BCxZT (x = 0, 0.06, 0.12, and 0.18) ceramics and BCZyT (y = 0, 0.08, 0.1, and 0.12) ceramics. Providing of such investigations is very important from an academic and economic points of view.
XRD shows that all samples have pure perovskite phase structure, and the BCZyT ceramics morphotropic phase boundary region from tetragonal phase to rhombohedral phase near 0.08 ≤ y ≤ 0.1. From the dielectric temperature curve, the phase transition temperature (TO-T) was found near room temperature at 0.12 ≤ x ≤ 0.18 for the BCxZT ceramics. Both Ca and Zr increase have a significant decrease on the Curie temperature Tc. All samples were found to be relaxors with a diffusivity in the range 1.29 ≤ γ ≤ 1.82. Variations in both the Ca and Zr content have a significant effect on the density and grain size of the ceramics, which are closely related to their piezoelectricity. Different from the undoped ceramics, ceramics doped with Ca and Zr ions exhibit saturated P–E hysteresis loops, and their ferroelectric properties are significantly optimized. In particular, the (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic exhibits optimal properties, namely d33 = 330 pC/N, kp = 0.41, εr = 25 4069, Pr = 4.8 μC/cm2, and Ec = 3.1 kV/cm, which are promising as a lead-free piezoelectric candidate.
In manuscript all necessary information is captured by 7 figures and 1 tables. There are 28 references.
Obtained results are important both for understanding the physical processes that occur in real objects and for the development of new devices. It corresponds to the field of the Journal «Crystals».
