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Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature.

Qi JQ, Peng T, Hu YM, Sun L, Wang Y, Chen WP, Li LT, Nan CW, Chan HL - Nanoscale Res Lett (2011)

Bottom Line: The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized.The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials.It is confirmed that the nanoparticles have tetragonal phase at room temperature.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Sciences and Engineering, Northeastern University at Qinhuangdao Branch, Qinhuangdao, Hebei Province, 066004, Peoples Republic of China. jianquanqi@mail.tsinghua.edu.cn.

ABSTRACT
A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature.

No MeSH data available.


Temperature-dependent Raman spectra.
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Figure 3: Temperature-dependent Raman spectra.

Mentions: The phase transition of BaTiO3 is related to its ferroelectricity because a net displacement of Ti4+ with respect to the O6-octahedron in the distortion directions results in the spontaneous polarization in the ferroelectric phases [16]. For the non-ferroelectric cubic phase of BaTiO3 nanoparticles that are synthesized in aqueous systems mostly, the study of phase transition is important to check if the nanoparticles have tetragonal phase at room temperature and have ferroelectricity. The tetragonal distortion of BaTiO3, δ = (c - a)/a, is only 1% in bulk materials and thus is quite difficult to be measured with XRD in nanoparticles for the line broadening effect. The vibrational spectroscopy as Raman spectroscopy is sensitive to the structural transformation, and thus, the local lattice distortions and crystallographic defects at the molecular level can be detected [17]. In our experiment, the sample is found to be pseudo-cubic by XRD. In order to observe the phase transition in BaTiO3 nanoparticles, temperature-dependent Raman spectroscopy is used as shown in Figure 3. The detailed phonon assignments for each active modes are: 720 cm-1(E(4LO) + A1(3LO)), 515 cm-1 (E(4TO) + A1(3TO)), 305 cm-1 (E(3TO) + E(2LO) + B1), 260 cm-1 (A1(2TO)), and 185 cm-1 (E(2TO) + E(1LO) + A1(1TO) + A1(1LO)) [18,19].


Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature.

Qi JQ, Peng T, Hu YM, Sun L, Wang Y, Chen WP, Li LT, Nan CW, Chan HL - Nanoscale Res Lett (2011)

Temperature-dependent Raman spectra.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211978&req=5

Figure 3: Temperature-dependent Raman spectra.
Mentions: The phase transition of BaTiO3 is related to its ferroelectricity because a net displacement of Ti4+ with respect to the O6-octahedron in the distortion directions results in the spontaneous polarization in the ferroelectric phases [16]. For the non-ferroelectric cubic phase of BaTiO3 nanoparticles that are synthesized in aqueous systems mostly, the study of phase transition is important to check if the nanoparticles have tetragonal phase at room temperature and have ferroelectricity. The tetragonal distortion of BaTiO3, δ = (c - a)/a, is only 1% in bulk materials and thus is quite difficult to be measured with XRD in nanoparticles for the line broadening effect. The vibrational spectroscopy as Raman spectroscopy is sensitive to the structural transformation, and thus, the local lattice distortions and crystallographic defects at the molecular level can be detected [17]. In our experiment, the sample is found to be pseudo-cubic by XRD. In order to observe the phase transition in BaTiO3 nanoparticles, temperature-dependent Raman spectroscopy is used as shown in Figure 3. The detailed phonon assignments for each active modes are: 720 cm-1(E(4LO) + A1(3LO)), 515 cm-1 (E(4TO) + A1(3TO)), 305 cm-1 (E(3TO) + E(2LO) + B1), 260 cm-1 (A1(2TO)), and 185 cm-1 (E(2TO) + E(1LO) + A1(1TO) + A1(1LO)) [18,19].

Bottom Line: The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized.The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials.It is confirmed that the nanoparticles have tetragonal phase at room temperature.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Sciences and Engineering, Northeastern University at Qinhuangdao Branch, Qinhuangdao, Hebei Province, 066004, Peoples Republic of China. jianquanqi@mail.tsinghua.edu.cn.

ABSTRACT
A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature.

No MeSH data available.