title: Applications of in situ Raman spectroscopy for identifying nickel hydroxide materials and surface layers during chemical aging.
abstract: The applications of in situ vibrational spectroscopy for identifying bulk and surface Ni(OH)2 are discussed. Raman spectra from α- and β-Ni(OH)2 samples immersed in water are generally similar to those collected from comparable dry samples. However, the Raman scattering intensities vary, and dry β-Ni(OH)2 additionally exhibits a surface O-H stretching mode at 3690 cm(-1). Using in situ Raman spectroscopy, the spontaneous transformation of α-Ni(OH)2 to β-Ni(OH)2 in room-temperature water was monitored. Such transformations are conventionally performed in high-temperature alkaline media. An intralayer OH-diffusion model is proposed. Internal stresses at the α/β-phase boundary caused shifted peaks, higher order vibrational modes, and a new water peak at 3520 cm(-1). We conclude that Raman spectroscopy may be applied to observe Ni(OH)2 materials in situ during chemical and electrochemical treatments. Such measurements provide information on the proportions of α- and β-Ni(OH)2 and their fine structural details with high sensitivity.
authors: Department of Chemistry, University of Ottawa , D'Iorio Hall, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors: David S
authors: DS
authors: Hall
authors: David J
authors: DJ
authors: Lockwood
authors: Shawn
authors: S
authors: Poirier
authors: Christina
authors: C
authors: Bock
authors: Barry R
authors: BR
authors: MacDougall