We prepared the Nano-sized bismuth titanate Bi4Ti3O12 (BIT) powders, through a high-energy ball milling process from their oxides Bi2O3 and TiO2. This BIT phase can be formed after a milling process for 40 min. With a...We prepared the Nano-sized bismuth titanate Bi4Ti3O12 (BIT) powders, through a high-energy ball milling process from their oxides Bi2O3 and TiO2. This BIT phase can be formed after a milling process for 40 min. With an increasing milling time, this particle size of mixture is gradually reduced, thus, we have mostly an amorphous phase. The BIT ceramics were duly obtained by sintering the synthesized powders at temperatures ranging from 850°C to 1000°C. The BIT ceramics sintered at 1020°C for 1 h, exhibiting a density with 7.52 g/cm3 of a crystaline phase and a dielectric of K = 288.11 (100 Hz), as well as a dielectric loss of 0.05 (100 kHz). The High-energy ball milling process is a promising way to prepare BIT ceramics. After the preparation of the BIT, we doped it with the Multi-Walled Carbon Nanotubes which are properly obtained by a chemical vapour deposition (CVD), using nickel as a catalyst, as well as using acetilene at 720°C, and then proceeded with the dielectric and optical measurements.展开更多
Temperature dependence of the dielectric constant of oleic acid with different degrees of puritywas measured in the 233-313 K range.It was observed that the presence of impurities(palmiticand linolenic acids)strongly ...Temperature dependence of the dielectric constant of oleic acid with different degrees of puritywas measured in the 233-313 K range.It was observed that the presence of impurities(palmiticand linolenic acids)strongly influences the dielectric constant,melting point and dipole moment of the oleic acid.The values of apparent dipole moment and the Kirkwood correlation parameterswere evaluated using the Kirkwood's model and were estimated to be about 1.20,1.61 and 2.27 D,respectively for 60,90 and 97 wt%oleic acid.展开更多
基金We would like to thank to the institution below:UFC,LOCEM,UECE,CNPq,CAPES,FUNCAP,G.D.Saraiva acknowledges the support from MCT/CNPqEdital 14/2010(process 476569/2010-9)FUNCAP/Edital 02/2010(process 10293648-0)+1 种基金 FUNCAP/Edital 05/2009(process 186.01.00/09)The other authors acknowledge CNPq and FUNCAP for partial financial support.
文摘We prepared the Nano-sized bismuth titanate Bi4Ti3O12 (BIT) powders, through a high-energy ball milling process from their oxides Bi2O3 and TiO2. This BIT phase can be formed after a milling process for 40 min. With an increasing milling time, this particle size of mixture is gradually reduced, thus, we have mostly an amorphous phase. The BIT ceramics were duly obtained by sintering the synthesized powders at temperatures ranging from 850°C to 1000°C. The BIT ceramics sintered at 1020°C for 1 h, exhibiting a density with 7.52 g/cm3 of a crystaline phase and a dielectric of K = 288.11 (100 Hz), as well as a dielectric loss of 0.05 (100 kHz). The High-energy ball milling process is a promising way to prepare BIT ceramics. After the preparation of the BIT, we doped it with the Multi-Walled Carbon Nanotubes which are properly obtained by a chemical vapour deposition (CVD), using nickel as a catalyst, as well as using acetilene at 720°C, and then proceeded with the dielectric and optical measurements.
基金FFS acknowledges the support from MCT/CNPqEdital 14/2011(process.482495/2011-1)and theauthors thank the Brazilian institutions CAPES,FUNCAP,FAPESPA and CNPq for financial sup-port.Authors also acknowledge Dr.Jeanlex Sousafor a critical reading of the manuscript.
文摘Temperature dependence of the dielectric constant of oleic acid with different degrees of puritywas measured in the 233-313 K range.It was observed that the presence of impurities(palmiticand linolenic acids)strongly influences the dielectric constant,melting point and dipole moment of the oleic acid.The values of apparent dipole moment and the Kirkwood correlation parameterswere evaluated using the Kirkwood's model and were estimated to be about 1.20,1.61 and 2.27 D,respectively for 60,90 and 97 wt%oleic acid.