CrO2 was first prepared by Friedrich Wöhler by decomposition
of chromyl chloride. Acicular chromium dioxide was first
synthesized in 1956 by Norman L. Cox, a chemist at E.I. DuPont.
The magnetic crystal that forms is a long, slender glass-like
rod-perfect as a magnetic pigment for recording tape. When
commercialized in the late 1960s as recording medium, DuPont
assigned it the tradename of Magtrieve.
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. 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.
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.
DuPont licensed the product to Sony in Japan and BASF in Germany
in the early 1970s for regional production and distribution.
Chromdioxid cassettes have the following advantages compared
with low noise ferric oxide cassettes:
- A substantially improved high frequency response. The response is
6 to 10 dB higher at 10 KHz and 8 to 12 dB higher at 15 KHz.
- The undistorted output at low frequencies is 1 to 3 dB better.
- Print-through is 4 to 8 dB less and the stability of high frequency
signals is insured.
- The particles of chromium dioxide are as small as the smallest
low-noise ferric oxide particles, but considerably more needle
shaped.
- The particles are single crystals rather than being made of
many crystals as is the case in ferric oxide. Also they are free
from defects common to all ferric oxides. such as porosity and
the formation of branches.
| Brand: | SKC |
| Model: | QX |
| Tape Length: | C - 46 |
| Country: |  South Korea |
| Magnetic Layer: | Chromdioxid (CrO2) |
| Release Year: | 1990 |
| Timeline: | 1990 |
| Sort: | QX |
| Series: | Complete series in catalog |
| Position: | Chrom |
| Tape Type: | Type II |
