Method for preparing nanometer chromium dioxide

A technology of chromium dioxide and chromium hydroxide, applied in the direction of chromium dioxide, chromium oxide/hydrate, etc., can solve the problems of Cr6+ pollution reaction temperature, harsh reaction conditions, long reaction time, etc., and meet the requirements of green process and sealing Low, the effect of shortening the reaction time

Inactive Publication Date: 2010-03-31
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] The purpose of the invention is to solve the current CrO 2 Cr present in preparation 6+ Pollution problems and harsh reaction conditions such as high reaction temperature, high pressure, and long reaction time in the existing process, to achieve milder reaction conditions

Method used

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  • Method for preparing nanometer chromium dioxide

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Experimental program
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Effect test

Embodiment 1

[0025] Take 0.2 g of dry chromium hydroxide hydrate after ball milling for 2-3 hours, put it into a corundum crucible, and then add 0.4 g of deionized water. Put the crucible in the high-pressure reactor, seal it, then feed oxygen, evacuate and ventilate until the air pressure in the reactor is lower than the original 1 / 1000, and then adjust O 2 pressure, so that the initial pressure of oxygen is 7MPa. Close the valve, program temperature rise in a closed system, set the reaction temperature at 390°C, keep it at 390°C for 6h, and then cool down to room temperature. Then, the kettle was opened, and the reactant was taken out to obtain 69.1nm nano-chromium dioxide.

Embodiment 2

[0027] Take 0.2 g of dry chromium hydroxide hydrate after ball milling for 2-3 hours, put it into a corundum crucible, and then add 0.4 g of deionized water. Put the crucible in the high-pressure reactor, seal it, then feed oxygen, evacuate and ventilate until the air pressure in the reactor is lower than the original 1 / 1000, and then adjust O 2 pressure, so that the initial pressure of oxygen is 6MPa. Close the valve, program temperature rise in a closed system, set the reaction temperature at 350°C, keep it at 350°C for 10min, and then cool down to room temperature. Then, the kettle was opened, and the reactant was taken out to obtain 76.75nm nano-chromium dioxide.

Embodiment 3

[0029] Take 0.4 g of dry chromium hydroxide hydrate after ball milling for 2-3 hours, put it into a corundum crucible, and then add 0.4 g of deionized water. Put the crucible in the high-pressure reactor, seal it, then feed oxygen, evacuate and ventilate until the air pressure in the reactor is lower than the original 1 / 1000, and then adjust O 2 pressure, so that the initial pressure of oxygen is 4MPa. Close the valve, program temperature rise in a closed system, set the reaction temperature at 370°C, keep it at 370°C for 3 hours, and then cool down to room temperature. Then open the kettle, take out the reactants, and obtain 60.81nm nano-CrO 2 .

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Abstract

The invention relates to a method for preparing nanometer chromium dioxide, belonging to the preparation field of inorganic materials, in particular to a method for preparing the nanometer chromium dioxide with an oxidation process; the method is characterized in that: chromium hydroxide hydrate is taken as raw material and is mixed with water according to the proportion that water/ chromium hydroxide hydrate (w/w) is 0.001-5 after being crushed by a ball-milling method or other ways, the initial oxygen pressure is 0.001-7MPa, constant reaction temperature with 350-390 DEG C generally is kept, and the mixture is reacted for less than 60min, so as to obtain purified nanometer CrO2. The method has simple process and the reaction condition is mild compared with the existing process, thereby having promotional value.

Description

field of invention [0001] The invention relates to a method for preparing nano chromium dioxide (CrO 2 ) method, particularly a method for preparing nano-chromium dioxide by an oxidation method. Background technique [0002] CrO 2 It is a tetravalent metastable chromium oxide with a relative molecular weight of 83.995. It is dark brown or black powder, insoluble in water but soluble in nitric acid. Its Curie temperature is 390-400K, and its coercive force is high; the temperature difference electromotive force is very small, about 10μv / K; the room temperature resistivity is 0.1-0.9Ω·cm. Its saturation magnetization and r-Fe 2 o 3 Comparable, but due to CrO 2 The shape is very regular, almost no holes, and it is easy to obtain a coercive force of 35-50Ka / m. In addition, in recent years it has been discovered that CrO 2 Semi-metallic and almost 100% rotational polarization, this special property means that CrO 2 Thin films have low-field channel magnetization resistan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/027
Inventor 徐红彬裴振昭郑诗礼张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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