이산화 크롬

한글명:이산화 크롬

카스 번호12018-01-8

상품명:chromium dioxide

CBNumberCB0721172

분자식CrO2

포뮬러 무게83.99

MOL 파일12018-01-8.mol

동의어(한글)

이산화크롬

화학적 성질

녹는점	>375 °C (dec.)(lit.)
끓는 점	decomposes to Cr2O3℃ [KIR78]
밀도	4.85 g/mL at 25 °C(lit.)
용해도	insoluble in H2O; soluble in acid solutions
물리적 상태	갈색-검정색 정사각형 분말
색상	brown-black tetragonal powder
수용성	물에 불용성, Cr+++ 및 중크롬산염을 제공하는 수용성 산 [KIR78]
Merck	13,2254
CAS 데이터베이스	12018-01-8
EPA	Chromium oxide (CrO2) (12018-01-8)

위험 및 안전 성명

위험품 표기	Xi
위험 카페고리 넘버	36
안전지침서	26-36
WGK 독일	3
RTECS 번호	GB6400000
유해 물질 데이터	12018-01-8(Hazardous Substances Data)

그림문자(GHS)

이산화 크롬 화학적 특성, 용도, 생산

화학적 성질
dark brown or black powder(s); tetr; used in magnetic tapes [KIR78]; ferromagnetic; rutile structure [MER06]
물리적 성질
Chromium dioxide [12018-01-8], chromium(IV)oxide, CrO2, is a ferromagnetic material with a specific saturation magnetization Ms/? of 132 A m2 kg?1 at 0 K, corresponding to the spin of two unpaired electrons per Cr4+ ion. TheMs/n value of CrO2 at room temperature is ca. 100 A m2 kg?1; CrO2 magnetic pigments reach values of 77–92 A m2 kg?1. The material crystallizes with a tetragonal rutile lattice in the form of small needles, which have the desired magnetic shape anisotropy. The morphology of the particles can be varied with several dopants, particularly antimony and tellurium. The coercive field strength can be controlled between ca. 30 and 75 kA m?1 (in addition to shape) by doping with transition metal ions, which modify the magneto-crystalline anisotropy of the material; the Fe3+ ion being industrially important.
용도
Chromium dioxide is used exclusively for magnetic recording media. It may also be used in combination with cobalt-modified iron oxides in the production of magnetic recording media. The world consumption of CrO2 is decreasing continuously as compact disc and digital videodisc are taking over the audio and video market. The sole producer is DuPont.
In the course of the development of pigments for magnetic information storage, CrO2 was the first widely used pigment material that gave a higher recording density than ã-Fe2O3. In the field of audio recording this led to the IEC II standard or “chrome position”.
생산 방법
The conversion of an intimate mixture of Cr(III) and Cr(VI) compounds into CrO2 under hydrothermal conditions has been developed into an industrial process in autoclaves at ca. 350 °C and 300 bar.
Pure CrO2 slowly disproportionates in the presence of water. The CrO2 crystal surface of commercial pigments is therefore topotactically converted to â-CrOOH, which serves as a protection layer. In the absence of moisture, CrO2 is stable up to ca. 400 °C, above this temperature it decomposes to form Cr2O3 and oxygen.

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