The influence of Fe, Cu, Al -doping on the crystal structure, thermal and electrical properties of calcium titanate

Enhanced O2 Flux of CaTi0.85Fe0.15O3−δ Based Membranes by Mn Doping

“…The apparent discrepancy between the TEC values from dilatometry and SR‐XPD may be ascribed to differences in experimental parameters (temperature range and heating rate of the measurements), the thermal history of the samples [see Section ], and influence of porosity on the dilatometry measurements. Comparable results from the literature are scarce, however, the TEC for CTF (CaTi 0.85 Fe 0.15 O 3−δ ), 12.4 × 10 −1 K −1 , is in agreement with reported values for CaTi 0.85 Fe 0.10 O 3−δ , which are in the range of 10.6 to 14.5 × 10 −1 K −1 , and measured by the same procedure (3 temperature cycles) by Paulsen to 12.7 × 10 −1 K −1 …”

The effect of nickel doping on the microstructure and conductivity of Ca(Ti,Al)O3–δ for solid oxide fuel cells

“…Interestingly, the Ni-containing samples are found to be strongly pO 2 dependent and with similar dependencies, while the undoped CTAN00 sample shows a much lower pO 2 dependence across the measured range. This observation agrees with that of the literature where the Al-doped compositions were shown to be predominately ionic conductors across this range of pO 2 16 . In contrast, the higher D grain , may promote the filling of oxygen vacancies and the formation of p-type defects.…”

“…The electrical properties were also studied as a function of oxygen partial pressure (pO 2 ) by mixing O 2 and N 2 at various concentrations, using a dwell time of 1 h under each condition; stability was once again confirmed by repeated measurements after an additional dwell time of 1 h. It has been reported by Iwahara 10 and Murashkina 17 that the maximum solubility limit of Ni, Cu, and Co is significantly lower, x ≤ 0.1, than that of Al, Al x ≤ 0.30, in B-site of CaTiO 3 . 16 At this juncture, it is to be highlighted that the solubility limit of Ni content in Ca(Ti, Al)O 3-δ perovskite is beyond the solid solution limit when x > 0.1, Figure 1. The respective lattice parameters and unit cell volume of all the compositions are listed in Table 1, which is determined by Rietveld refinement and obtained acceptable global goodness of fit parameters.…”

“…For example, for the material CaTi 1−x M x O 3−δ (M=Fe, Al, Cu), the maximum solubilities of Fe x ≤ 0.5, Al x ≤ 0.3 at Ti-site have been reported. 15,16 In contrast, Ni and Cu additions show much lower solubilities x ≤ 0.1. 17,18 In the Fe-substituted case, an increasing p-type electronic conductivity is shown with increasing Fe content.…”

“…Thus, these doped calcium titanates have been shown to offer different behaviors depending on the oxygen partial pressure (pO 2 ), 1,4,[10][11][12][13][14][15] with predominant p-type, ionic, and n-type conductivities shown to be possible in the high, middle, and low pO 2 regions, respectively. 16 Moreover, each dopant exhibits its specific solubility limit in the base perovskite material. For example, for the material CaTi 1−x M x O 3−δ (M=Fe, Al, Cu), the maximum solubilities of Fe x ≤ 0.5, Al x ≤ 0.3 at Ti-site have been reported.…”