The head wear scare and licensing issues with DuPont kept chrome 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. 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-earth elements such as iridium onto the crystal matrix or by improving the axial length-to-width 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 playback equalization setting (70 microseconds) that traded some of the extended high-frequency response for lower noise resulting in a 4–5 dB improvement in signal-to-noise ratio over ferric-oxide audio tapes. Chrome tapes did, however, require a new generation of audiocassette recorders equipped with a higher bias current capability (roughly 50% greater) than that used by iron oxide to properly magnetize the tape particles. Unlike the spongy looking ferric oxides used in common tape, the chromium dioxide crystals were perfectly formed and could be evenly and densely dispersed in a magnetic coating and that led to unparalleled low noise in audio tapes. The crystal's magnetic properties, derived from its ideal shape 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 the standard audio cassette for which treble response and tape hiss were always problems. When commercialized in the late 1960s as a recording medium, DuPont assigned it the tradename of Crolyn. The magnetic crystal that forms is a long, slender glass-like rod - perfect as a magnetic pigment for recording tape. DuPont, by decomposing chromium trioxide in the presence of water at a temperature of 900 ° F. It is still considered today by many oxide and tape manufacturers to have been the most perfect magnetic recording particulate ever invented.Īcicular chromium dioxide was first synthesized in 1956 by Norman L.
However, it is still used in data tape applications for enterprise-class storage systems. With the increasing popularity of CDs and DVDs, the use of chromium(IV) oxide has declined. Except where noted otherwise, data are given for materials in their standard state (at 25 ☌, 100 kPa) Infobox disclaimer and referencesĬhromium dioxide or chromium(IV) oxide is a synthetic magnetic substance once widely used in magnetic tape emulsion.
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