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Vertical Interface Induced Dielectric Relaxation in Nanocomposite (BaTiO3)1-x:(Sm2O3)x Thin Films.

Li W, Zhang W, Wang L, Gu J, Chen A, Zhao R, Liang Y, Guo H, Tang R, Wang C, Jin K, Wang H, Yang H - Sci Rep (2015)

Bottom Line: Vertical interfaces in vertically aligned nanocomposite thin films have been approved to be an effective method to manipulate functionalities.However, several challenges with regard to the understanding on the physical process underlying the manipulation still remain.The movement of oxygen vacancies is confined at the interfaces and hampered by the misfit dislocations, which contributed to a relaxation behavior in (BaTiO3)1-x:(Sm2O3)x thin films.

View Article: PubMed Central - PubMed

Affiliation: 1] College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China [2] College of Physics, Optoelectronics and Energy &Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China.

ABSTRACT
Vertical interfaces in vertically aligned nanocomposite thin films have been approved to be an effective method to manipulate functionalities. However, several challenges with regard to the understanding on the physical process underlying the manipulation still remain. In this work, because of the ordered interfaces and large interfacial area, heteroepitaxial (BaTiO3)1-x:(Sm2O3)x thin films have been fabricated and used as a model system to investigate the relationship between vertical interfaces and dielectric properties. Due to a relatively large strain generated at the interfaces, vertical interfaces between BaTiO3 and Sm2O3 are revealed to become the sinks to attract oxygen vacancies. The movement of oxygen vacancies is confined at the interfaces and hampered by the misfit dislocations, which contributed to a relaxation behavior in (BaTiO3)1-x:(Sm2O3)x thin films. This work represents an approach to further understand that how interfaces influence on dielectric properties in oxide thin films.

No MeSH data available.


Related in: MedlinePlus

High-resolution TEM images of BTO:Sm2O3 thin films with (a) x = 0.5 and (c) x = 0.62. Corresponding Fourier-filtered (FFT) images along column boundaries are shown as (b) and (d), respectively. The FFT images are enlarged to show misfit dislocations clearly.
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f2: High-resolution TEM images of BTO:Sm2O3 thin films with (a) x = 0.5 and (c) x = 0.62. Corresponding Fourier-filtered (FFT) images along column boundaries are shown as (b) and (d), respectively. The FFT images are enlarged to show misfit dislocations clearly.

Mentions: In previous works, we have revealed that the BTO and Sm2O3 phases grow alternatively and spontaneously and form a vertically aligned columnar structure in the BTO:Sm2O3 thin films242526. Fig. 2(a) show high resolution TEM images of the BTO:Sm2O3 thin films with compositions of x = 0.5 and 0.62 respectively, which demonstrate the excellent heteroepitaxial growth of the BTO and Sm2O3 on the STO substrates. Combined with previous results242526, these images indicate that self-assembled Sm2O3 nanocolumns are evenly sized, distributed, and embedded in a BTO matrix. And the diameter of single Sm2O3 nanocolumn is about 10 nm. So, the density of interfaces is estimated to be about 108/m. More than this, a periodic arrangement of misfit dislocations is found along the vertical interfaces, as shown in the corresponding Fourier-filtered images in Fig. 2(b). The density of misfit dislocations along the interfaces is estimated to be about 4.0 × 108/m for x = 0.5, and about 5.0 × 108/m for x = 0.62. Considering the density of interfaces, the areal density of misfit dislocations is estimated to be about 4.0 × 1016/m2 for x = 0.5, and about 5.0 × 1016/m2 for x = 0.62. In other words, the density of misfit dislocations is very high in the BTO:Sm2O3 thin films, which may originate from the large lattice mismatch between the BTO and Sm2O3. Besides, the density of misfit dislocations for x = 0.5 is lower than that for x = 0.62. All these results suggest that self-assembled vertical heteroepitaxial nanostructures of BTO:Sm2O3 are synthesized as expected and can be used as model system to explore the relationship between the vertical interfaces and dielectric properties in oxide thin films.


Vertical Interface Induced Dielectric Relaxation in Nanocomposite (BaTiO3)1-x:(Sm2O3)x Thin Films.

Li W, Zhang W, Wang L, Gu J, Chen A, Zhao R, Liang Y, Guo H, Tang R, Wang C, Jin K, Wang H, Yang H - Sci Rep (2015)

High-resolution TEM images of BTO:Sm2O3 thin films with (a) x = 0.5 and (c) x = 0.62. Corresponding Fourier-filtered (FFT) images along column boundaries are shown as (b) and (d), respectively. The FFT images are enlarged to show misfit dislocations clearly.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4462142&req=5

f2: High-resolution TEM images of BTO:Sm2O3 thin films with (a) x = 0.5 and (c) x = 0.62. Corresponding Fourier-filtered (FFT) images along column boundaries are shown as (b) and (d), respectively. The FFT images are enlarged to show misfit dislocations clearly.
Mentions: In previous works, we have revealed that the BTO and Sm2O3 phases grow alternatively and spontaneously and form a vertically aligned columnar structure in the BTO:Sm2O3 thin films242526. Fig. 2(a) show high resolution TEM images of the BTO:Sm2O3 thin films with compositions of x = 0.5 and 0.62 respectively, which demonstrate the excellent heteroepitaxial growth of the BTO and Sm2O3 on the STO substrates. Combined with previous results242526, these images indicate that self-assembled Sm2O3 nanocolumns are evenly sized, distributed, and embedded in a BTO matrix. And the diameter of single Sm2O3 nanocolumn is about 10 nm. So, the density of interfaces is estimated to be about 108/m. More than this, a periodic arrangement of misfit dislocations is found along the vertical interfaces, as shown in the corresponding Fourier-filtered images in Fig. 2(b). The density of misfit dislocations along the interfaces is estimated to be about 4.0 × 108/m for x = 0.5, and about 5.0 × 108/m for x = 0.62. Considering the density of interfaces, the areal density of misfit dislocations is estimated to be about 4.0 × 1016/m2 for x = 0.5, and about 5.0 × 1016/m2 for x = 0.62. In other words, the density of misfit dislocations is very high in the BTO:Sm2O3 thin films, which may originate from the large lattice mismatch between the BTO and Sm2O3. Besides, the density of misfit dislocations for x = 0.5 is lower than that for x = 0.62. All these results suggest that self-assembled vertical heteroepitaxial nanostructures of BTO:Sm2O3 are synthesized as expected and can be used as model system to explore the relationship between the vertical interfaces and dielectric properties in oxide thin films.

Bottom Line: Vertical interfaces in vertically aligned nanocomposite thin films have been approved to be an effective method to manipulate functionalities.However, several challenges with regard to the understanding on the physical process underlying the manipulation still remain.The movement of oxygen vacancies is confined at the interfaces and hampered by the misfit dislocations, which contributed to a relaxation behavior in (BaTiO3)1-x:(Sm2O3)x thin films.

View Article: PubMed Central - PubMed

Affiliation: 1] College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China [2] College of Physics, Optoelectronics and Energy &Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China.

ABSTRACT
Vertical interfaces in vertically aligned nanocomposite thin films have been approved to be an effective method to manipulate functionalities. However, several challenges with regard to the understanding on the physical process underlying the manipulation still remain. In this work, because of the ordered interfaces and large interfacial area, heteroepitaxial (BaTiO3)1-x:(Sm2O3)x thin films have been fabricated and used as a model system to investigate the relationship between vertical interfaces and dielectric properties. Due to a relatively large strain generated at the interfaces, vertical interfaces between BaTiO3 and Sm2O3 are revealed to become the sinks to attract oxygen vacancies. The movement of oxygen vacancies is confined at the interfaces and hampered by the misfit dislocations, which contributed to a relaxation behavior in (BaTiO3)1-x:(Sm2O3)x thin films. This work represents an approach to further understand that how interfaces influence on dielectric properties in oxide thin films.

No MeSH data available.


Related in: MedlinePlus