SciELO - Scientific Electronic Library Online

 
vol.64Preparation of CNx/carbon nanotube intramolecular junctions by switching gas sources in continuous chemical vapour depositionSimultaneous determination of metals in coal with low-resolution continuum source atomic absorption spectrometer and filter furnace atomizer índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Artigo

Indicadores

Links relacionados

  • Em processo de indexaçãoCitado por Google
  • Em processo de indexaçãoSimilares em Google

Compartilhar


South African Journal of Chemistry

versão On-line ISSN 1996-840X
versão impressa ISSN 0379-4350

Resumo

YAZDANBAKHSH, Mohammad; TAVAKKOLI, Haman  e  HOSSEINI, Seyed Mohammad. Electrical and optical properties of nanosized perovskite-type La0.5Ca0.5MO3 (M=Co,Ni) prepared using a sol-gel method. S.Afr.j.chem. (Online) [online]. 2011, vol.64, pp.71-78. ISSN 1996-840X.

In this paper the uniform nanopowders of La0.5Ca0.5CoO3-δ and La0.5Ca0.5NiO3-δ (LCCO and LCNO) were synthesized from nitrates of the constituent metal ion, citric acid (CA), and ethylene glycol (EG) by the combined citrate-ethylene glycol (EG) method. These nanopowders were also characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), SEM-EDX analysis and Brunauer-Emmett-Teller (BET) method XRD results show that single perovskite phase was completely formed after calcination at 750 °C. Fourier transform infrared (FTIR) spectra were measured for the xerogels and powder samples after calcination. In addition, the TEM images show that the average particle size of nanoparticles is approximately 25-32 nm in diameter. The ultraviolet (UV) spectrum was used to calculate the absorption coefficient (a) as a function of photon energy (hv) and the obtained results indicate that the optical band gap energy (Eg) for LCNO sample is smaller than that of LCCO. Finally, the temperature dependence of the specific resistivity of LCCO and LCNO sintered at 1100 °C was compared and revealed that the resistivity of both compounds decreases exponentially by increasing the temperature.

Palavras-chave : La0.5Ca0.5MO3; perovskite; sol-gel process; nanopowder; optical properties.

        · texto em Inglês     · Inglês ( pdf )

 

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons