by Claudio P. Sanniti
Abstract:
Ceramic samples of CuNbO3 were made by solid state reaction method. The X-ray spectra of powdered CuNbO3 corresponded to that given by previously published data. Within the ceramic, cherry-red crystals were identified under microscopic examination. The samples were found to be insulators. Crystal size varied from 0.5-1.0 mm in diameter, with lengths of 1-2 mm. Attempts to dope CuNb1-xAxO3 with various dopants were made, where x ranged from 0.02 to 0.1. CuNbO3 doped with tungsten of concentration x = 0.05 formed into navy blue needles that were metallic conductors. At x=0.1 concentration, this material formed into golden yellow needles with brownish flat feather-like crystals that were insulators. Both the blue and yellow needles were not identified. There is a possibility that some type of complex tungsten bronze structure was formed instead. It was not possible to reproduce the growth of these structures. Phases formed by solid state reactions in the copper niobium oxygen system revealed a number of ceramic compounds previously reported and some not previously reported. CuNb1-xAxO3 doped with A=Co, Cr, Ge, Sb, Sn, Ti did not form the CuNbO3 structure, but did form some type of insulator. CuNb2(1-x)A2xO6 doped with A=Pd, W of concentration x=0, 0.02,0.05 produced oxidizing metals. The powdered X-ray spectra matched with literature values. Substitution for niobium was made with vanadium in the CuNb2O3 structure which was doped with A=Ge, W of concentration x=0.05. Germanium doped produced a semiconductor with a small band gap. As well substitutions were made with tantalum, which was doped with A=Cr. Both doped and undoped samples produced ceramic insulators.
Reference:
Claudio P. Sanniti, "Doping copper niobium oxygen CuNb1-xAxO3", 1998.
Bibtex Entry:
@bachelorsthesis{1998S,
title={Doping copper niobium oxygen CuNb<sub>1-x</sub>A<sub>x</sub>O<sub>3</sub>},
author={Claudio P. Sanniti},
month={June},
year={1998},
abstract={Ceramic samples of CuNbO<sub>3</sub> were made by solid state reaction method. The X-ray spectra of
powdered CuNbO<sub>3</sub> corresponded to that given by previously published data. Within the ceramic,
cherry-red crystals were identified under microscopic examination. The samples were found to be
insulators. Crystal size varied from 0.5-1.0 mm in diameter, with lengths of 1-2 mm. Attempts
to dope CuNb<sub>1-x</sub>A<sub>x</sub>O<sub>3</sub> with various dopants were made, where x ranged
from 0.02 to 0.1. CuNbO<sub>3</sub> doped with tungsten of concentration x = 0.05 formed into navy
blue needles that were metallic conductors. At x=0.1 concentration, this material formed into golden
yellow needles with brownish flat feather-like crystals that were insulators. Both the blue and yellow
needles were not identified. There is a possibility that some type of complex tungsten bronze
structure was formed instead. It was not possible to reproduce the growth of these structures. Phases
formed by solid state reactions in the copper niobium oxygen system revealed a number of ceramic
compounds previously reported and some not previously reported. CuNb<sub>1-x</sub>A<sub>x</sub>O<sub>3</sub>
doped with A=Co, Cr, Ge, Sb, Sn, Ti did not form the CuNbO<sub>3</sub> structure, but did form some
type of insulator. CuNb<sub>2(1-x)</sub>A<sub>2x</sub>O<sub>6</sub> doped with A=Pd, W of concentration
x=0, 0.02,0.05 produced oxidizing metals. The powdered X-ray spectra matched with literature values.
Substitution for niobium was made with vanadium in the CuNb<sub>2</sub>O<sub>3</sub> structure which
was doped with A=Ge, W of concentration x=0.05. Germanium doped produced a semiconductor with a small
band gap. As well substitutions were made with tantalum, which was doped with A=Cr. Both doped and
undoped samples produced ceramic insulators.},
note={Supervised by F.S. Razavi}
}