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Physical Chemistry

Iowa State University

Cobalt compounds

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Resistivity, Thermopower And The Correlation To Infrared Active Vibrations Of Mn1.56co0.96ni0.48o4 Spinel Films Sputtered In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor Jan 1999

Resistivity, Thermopower And The Correlation To Infrared Active Vibrations Of Mn1.56co0.96ni0.48o4 Spinel Films Sputtered In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor

Alexander H. King

Mn1.56Co0.96Ni0.48O4 spinel was sputter deposited using a series of oxygen partial pressures. Electrical resistivity versus temperature and thermopower versus temperature measurements at each oxygen partial pressure were made. The variations of the thermopower and resistivity with oxygen partial pressure are consistent with a change in the ratio of Mn3+ to Mn4+ cations, which occurs due to changes of oxygen content of the material. The weak temperature dependence of the thermopower indicates small polaron hopping is the charge transport mechanism. Combining the models of Mott and Schnakenberg to analyze the transport data, we find that the Debye temperature (or frequency) is …


Infrared Optical Properties Of Mn1.56co0.96ni0.48o4 Spinel Films Sputter Deposited In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor Jan 1999

Infrared Optical Properties Of Mn1.56co0.96ni0.48o4 Spinel Films Sputter Deposited In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor

Alexander H. King

Mn1.56Co0.96Ni0.48O4 spinel films were sputter deposited onto silicon substrates using a series of oxygen partial pressures. Fourier transform infrared transmission and reflectance, and Raman scattering measurements were made. The 1–25 μm wavelength range was examined using these optical techniques. The complex index of refraction was calculated for this entire wavelength range. Infrared active vibrations were analyzed using multiple oscillator analysis, Kramers–Kronig analysis, and derivative reflectance spectroscopy. The Raman and infrared active lattice vibrations were observed to shift with increasing oxygen partial pressure during film deposition, and were consistent with the earlier published shift in Debye frequency calculated from resistivity data. …