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Grain size-dependent magnetic and electric properties in nanosized YMnO3 multiferroic ceramics.

Han TC, Hsu WL, Lee WD - Nanoscale Res Lett (2011)

Bottom Line: The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K.Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters.Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2).PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan. tchan@nuk.edu.tw.

ABSTRACT
Magnetic and electric properties are investigated for the nanosized YMnO3 samples with different grain sizes (25 nm to 200 nm) synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K. A corresponding shift of the dielectric anomaly is observed, indicating a strong correlation between the electric polarization and the magnetic ordering. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2).PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s.

No MeSH data available.


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The evolution of lattice parameters for YMnO3 samples sintered at different temperatures. The uncertainty is contained within the area of the suitable mark.
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Figure 2: The evolution of lattice parameters for YMnO3 samples sintered at different temperatures. The uncertainty is contained within the area of the suitable mark.

Mentions: Figure 1 shows the XRD patterns of the YMnO3 samples sintered at different temperatures from 800°C to 1,050°C. Based on the standard reference, all the observed peaks can be indexed on the basis of a hexagonal unit cell of space group P63cm (JCPDS:25-1079), suggesting that all samples are pure phases without any impurity. In addition, with the increase in sintering temperature, there is a gradual intensity increasing and narrowing of the diffraction peaks, indicative of better crystallization and the grain growth. The lattice parameters were determined by Rietveld refinement method and shown in Figure 2. With increasing of sintering temperature, the value of c lattice parameter is slightly expanded, while the value of a lattice parameter decreased. The typical scanning electron microscopy (SEM) images of the YMnO3 samples sintered at different temperatures are shown in Figure 3. From the images, it can be found that the grain size becomes larger as the sintering temperature increases. The estimated average grain size is about 25, 45, 95, and 200 nm for the samples sintered at 800°C, 850°C, 900°C, and 1,050°C, respectively.


Grain size-dependent magnetic and electric properties in nanosized YMnO3 multiferroic ceramics.

Han TC, Hsu WL, Lee WD - Nanoscale Res Lett (2011)

The evolution of lattice parameters for YMnO3 samples sintered at different temperatures. The uncertainty is contained within the area of the suitable mark.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211257&req=5

Figure 2: The evolution of lattice parameters for YMnO3 samples sintered at different temperatures. The uncertainty is contained within the area of the suitable mark.
Mentions: Figure 1 shows the XRD patterns of the YMnO3 samples sintered at different temperatures from 800°C to 1,050°C. Based on the standard reference, all the observed peaks can be indexed on the basis of a hexagonal unit cell of space group P63cm (JCPDS:25-1079), suggesting that all samples are pure phases without any impurity. In addition, with the increase in sintering temperature, there is a gradual intensity increasing and narrowing of the diffraction peaks, indicative of better crystallization and the grain growth. The lattice parameters were determined by Rietveld refinement method and shown in Figure 2. With increasing of sintering temperature, the value of c lattice parameter is slightly expanded, while the value of a lattice parameter decreased. The typical scanning electron microscopy (SEM) images of the YMnO3 samples sintered at different temperatures are shown in Figure 3. From the images, it can be found that the grain size becomes larger as the sintering temperature increases. The estimated average grain size is about 25, 45, 95, and 200 nm for the samples sintered at 800°C, 850°C, 900°C, and 1,050°C, respectively.

Bottom Line: The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K.Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters.Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2).PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan. tchan@nuk.edu.tw.

ABSTRACT
Magnetic and electric properties are investigated for the nanosized YMnO3 samples with different grain sizes (25 nm to 200 nm) synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K. A corresponding shift of the dielectric anomaly is observed, indicating a strong correlation between the electric polarization and the magnetic ordering. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2).PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s.

No MeSH data available.


Related in: MedlinePlus