Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Reexamination Certificate
2007-10-02
2007-10-02
Vanoy, Timothy C. (Department: 1754)
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
C423S053000, C252S06251C
Reexamination Certificate
active
10525939
ABSTRACT:
A novel process for preparing chromium dioxide of substantially high purity as well as composites of CrO2/Cr2O3and CrO2/Cr2O5following a sequence of simple steps. The process does not require pressure as a control parameter during the process of synthesis. No chemical modifier has been used to bring down the working pressure during synthesis. Fairly hard sintered pellets of CrO2can be obtained without introducing any detectable impurity phase that usually appears during the process of sintering. Further, CrO2/Cr2O3and CrO2/Cr2O5composites have also been prepared where the fraction of insulating Cr2O3or Cr2O5in metallic CrO2can be easily controlled. Significant negative magnetoresistance is found in pure CrO2(5% MR) as well as CrO2/Cr2O3(33% MR) composites near room temperature. The MR studies on the CrO2/Cr2O5composites have been done and significant negative MR (22%) has been found in CrO2/Cr2O5composites near room temperature.
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P. G. Ivanov et al. “Epitaxial growth of CrO2 thin films by chemical-vapor deposition from a Cr8O21 precursor” Journal of Applied Physics, vol. 89, No. 2 (Jan. 15, 2001), pp. 1035-1040.
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Bajpai Ashna
Nigam Arun Kumar
Akerman & Senterfitt
Pendorf Stephen A.
Tata Institute of Fundamental Research
Vanoy Timothy C.
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