Growth of a Single MnCr2O4 Spinel on Ni–25Cr–1.5Mn Alloy by the Rhines Pack Method and Photoelectrochemical and Raman Signatures of MnCr2O4 Spinel

A single thin MnCr 2 O 4 spinel layer was synthesized on a Ni–25Cr–1.5Mn alloy by a fine control of oxygen partial pressure using the Rhines-pack method, a technique that utilized an appropriate buffering powder mixture. The spinel was characterized using X-Ray diffraction, Raman spectroscopy and photoelectrochemistry. The cubic spinel MnCr 2 O 4 was formed under the oxygen partial pressure close to 5 × 10 –21 atm at 1050 °C controlled by the buffering Ni–25Cr/Cr 2 O 3 powder mixture. Raman MnCr 2 O 4 spectrum is characterized by five vibrational modes, whereas photoelectrochemical characterization revealed the MnCr 2 O 4 band gap measurement at 3.7 eV with an n-type conductivity.