The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from c...The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of products.LiCo1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen atmosphere.LiNiOz and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.展开更多
A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high ca...A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high capacitance ratio needed for wideband tuning filter requires the three-terminal varactor diode (TTVD) to be biased up pinch-off voltage or positive bias. Therefore a variable-capacitance model is applied to analyzing C-V characteristics of this TTVD. The earlier capacitance model for GaAs MESFET did not consider the free carrier move in active region which can cause varying the C-V characteristic, but only depletion layer model approximation. The new model described here takes into account the free carrier move for contributing to gate capacitance. The model analytical results agree well with experiment.展开更多
文摘The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of products.LiCo1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen atmosphere.LiNiOz and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.
文摘A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high capacitance ratio needed for wideband tuning filter requires the three-terminal varactor diode (TTVD) to be biased up pinch-off voltage or positive bias. Therefore a variable-capacitance model is applied to analyzing C-V characteristics of this TTVD. The earlier capacitance model for GaAs MESFET did not consider the free carrier move in active region which can cause varying the C-V characteristic, but only depletion layer model approximation. The new model described here takes into account the free carrier move for contributing to gate capacitance. The model analytical results agree well with experiment.
