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Study of the perovskite-type manganites Ca1 - x Ce x MnO3 (0.00 ≤ x ≤ 0.25) has been carried out. The electrical resistivity values for these samples were measured in the temperature range from 300 up to 900 K and show that the doping of the phase CaMnO3 with cerium induces simultaneously a marked decrease in the electrical resistivity and a metal-to-insulator transition. This behavior is exceptional since such a transition has not been observed to date in these compounds for these experimental conditions and can be attributed to the formation of Mn3+ ions as a result of charge compensation. The values of metal-to-insulator transition temperature, T MI, change with Mn3+ amount. Further the carrier doping tends to suppress the semiconductor behavior of CaMnO3 and the T MI is attributed to charge ordering observed in these compounds around 255 K.

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The use of inorganic species as assisting materials in matrix-assisted laser desorption/ionization (MALDI) analysis is an alternative approach to avoid interfering matrix ions in the low-mass region of the mass spectra. Reports of the application of inorganic species as matrices in MALDI analysis of small molecules are, however, scarce. Nevertheless, titanium dioxide (TiO(2)) powder has been reported to be a promising matrix medium. In this study we further explore the use of TiO(2) as a matrix for the MALDI analysis of low molecular weight compounds. We present results showing that nanosized TiO(2) anatase and TiO(2) rutile perform better as MALDI matrices than a commercial TiO(2) anatase/rutile mixture. Moreover, when using nanosized TiO(2) anatase as a matrix, high-quality mass spectra can be obtained with strong analyte signals and weak or non-existing matrix interference ions. Furthermore, our results show that the phase type plays an important role in the application of TiO(2) as a MALDI matrix.

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