![]() BASF eventually became the largest producer of both the chromium dioxide pigment and chrome tapes, basing its VHS & S-VHS video tape, audio cassettes, and 3480 data cartridges on this formulation. Added to that was the problem that the production of CrO 2 yielded toxic by-products of which Japanese manufacturers had great difficulty properly disposing. Japanese competitors developed cobalt-adsorbed (TDK: Avilyn) and cobalt ferrite (Maxell: Epitaxial) "chrome equivalent" Type II audio cassettes and various videotape formats as substitutes. Producers ĭuPont licensed the product to Sony in Japan and BASF in Germany in the early 1970s for regional production and distribution. Because of its low Curie temperature of approximately 386 K (113 ☌ 235 ☏), chrome tape lent itself to high-speed thermomagnetic duplication of audio and video cassettes for pre-recorded product sales to the consumer and industrial markets. The head wear scare and licensing issues with DuPont kept blank consumer chrome tapes at a great disadvantage versus the eventually more popular Type II tapes that used cobalt-modified iron oxide, but chrome was the tape of choice for the music industry's cassette releases. Although the tape wore hard ferrite heads faster than oxide-based tapes, it actually wore softer permalloy heads at a slower rate and head wear was more a problem for permalloy heads than for ferrite heads. The chrome coating was harder than competitive coatings, and that led to accusations of excessive head wear. Although the decrease was uniform across the frequency range and noise also dropped the same amount, preserving the dynamic range, the decrease misaligned Dolby noise reduction decoders that were sensitive to level settings. Output from a tape could drop about 1 dB or so in a year's time. Until manufacturers developed new ways to mill the oxide, the crystals could easily be broken in the manufacturing process, and this led to excessive print-through (echo). The resulting product was potentially a competitor to metallic iron pigments but apparently achieved little market penetration. Later research significantly increased the coercivity of the particle by doping or adsorbing rare elements such as iridium onto the crystal matrix or by improving the axial length-to-deprecated ratios. ![]() These bias and EQ settings were later carried over to "chrome-equivalent" cobalt-modified tapes introduced in the mid-1970s by TDK, Maxell, and others. Also introduced was a new equalization (70 μs) that traded some of the extended high-frequency response for lower noise, resulting in a 5–6 dB improvement in signal-to-noise ratio over ferric oxide audio tapes. Chrome tapes did, however, require audio cassette recorders to be equipped with a higher- bias current capability (roughly 50% greater) than that used by ferric oxide to properly magnetize the tape particles. ![]() Unlike the imperfectly formed ferric oxide coating commonly used, the chromium dioxide crystals were perfectly formed and could be evenly and densely dispersed in a magnetic coating leading to higher signal-to-noise ratios in audio recordings. The crystal's magnetic properties, derived from its ideal shape such as anisotropy which imparted high coercivity and remanent magnetization intensities, resulted in exceptional stability and efficiency for short wavelengths, and it almost immediately appeared in high performance audio tape used in audio cassettes for which treble response and hiss were always problems.
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