![]() Although the tape initially 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. ![]() As such, each Cr(IV) center has octahedral coordination geometry and each oxide is trigonal planar. When commercialized in the late 1960s as a recording medium, DuPont assigned it the tradename of Magtrieve.ĬrO 2 adopts the rutile structure (as do many metal dioxides). The magnetic crystal that forms is a long, slender glass-like rod - perfect as a magnetic pigment for recording tape. The balanced equation for the hydrothermal synthesis is: DuPont, by decomposing chromium trioxide in the presence of water at a temperature of 800 K (527 ☌ 980 ☏) and a pressure of 200 MPa. Acicular chromium dioxide was first synthesized in 1956 by Norman L. Preparation and basic properties ĬrO 2 was first prepared by Friedrich Wöhler by decomposition of chromyl chloride. It is still considered by many oxide and tape manufacturers to have been one of the best magnetic recording particulates ever invented. 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. It once was widely used in magnetic tape emulsion. Chromium dioxide or chromium(IV) oxide is an inorganic compound with the formula CrO 2.
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