The magnetic properties required by a potential pigment for magnetic recording tapes are discussed from the point of view of high intrinsic sensitivity. It is pointed out that a high maximum slope of the remanence curve of the pigment is synonymous with high sensitivity, and the respective roles of the coercive force and the saturation remanence in determining this slope are discussed. The geometric characteristics of commercial pigments of (symbol)-Fe2O3, which govern these properties, are demonstrated. These characteristics are summed up by the statement that the individual particles of the pigment must behave like single-domain particles. This is achieved in most American pigments with particles which approximate prolate ellipsoids of revolution measuring about 0.5 x 0.1 micron. Discussed, too, is a German pigment which possesses particles that are roughly spherical and measure about 0.06 micron in diameter. The influence of the manufacturing processes on the sensitivity of the final product is examined, and data correlating tape sensitivity with all of these factors are given. The factors included in this correlation are the maximum slope of the remanence curve of the pigment, the density of the particles in the tape coating, the coating thickness, and the degree of pigment orientation.
Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.