Perpendicular orientation of acicular γ-Fe2O3in recording discs

This experimental work has demonstrated that acicular gamma-ferric oxide particles can be perpendicularly oriented in rigid discs. The technique of vertical orientation was similar to that reported previously for horizontal (in-plane) orientation. Perpendicularly oriented discs visually appear optically active and demonstrate an improved surface smoothness over both non-oriented and horizontally oriented coatings. SEM studies support the presence of individual particles in the vertical direction. VSM data, reported as Orientation Ratio, also confirms the increased significance of the vertical component.