e precursor (e.g., a salt such as a metal nitrate, a metal acetate salt, a metal citrate salt, a metal formate salt, a metal formate salt, a metal chloride salt, and hydoxy iron polymer) that converts to a metal oxide upon decomposition by heating, and/or particles of metal oxide which may have been added as a particulate (preferably having a particle size (i.e., the longest dimension) of less tha