CHROMIUM DIOXIDE RECORDING TAPE WITH AN EXTREMELY NARROW SWITCHING FIELD DISTRIBUTION

An improved process has made possible the laboratory scale preparation of highly uniform particles of chromium dioxide. Video tapes have bee n coated with remanence curve switching field distributions as low as 0.17, a value which has not been achieved with any other acicular mate rial, and which approaches values reported for barium ferrite. Althoug h the uniformity of the product is visible in the external particle ge ometry, this alone is not enough to explain the exceptionally narrow S FD, which is due to a more effective incorporation of iron dopant into the CrO2.