Synthesis, Characterization And Application Of Vanadium Family Metal Nitrides And Carbides

Group V B metal (V, Nb, and Ta) nitrides and carbides were synthesized by using a mild temperature. The mechanism of the reactions were studied according the experiment data combined the reported essays. The uses of niobium nitride and niobium carbide in rechargeable lithium ion battery also were studied. The main content was concluded as:1.To synthesize metal nitride (VN, NbN, and (Ta, O)) nanometer materialsNH4VO3, Nb2O5, and Ta2O5 were used as vanadium source, niobium source, and tantalum source, with NaN3 as N source and Mg as reduce agent were loaded into stainless autoclave and heated at 300℃. Nanometer particles of VN, NbN, and (Ta, N) were successfully produced. The X-ray diffraction test results are listed as follows.VN sample can be indexed as cubic Fm-3m structure. And the crystal constant calculated (a=4.126) is consist with the reported value (a= 4.124, JCPDS card No. 65-9409). NbN sample can be indexed as cubic Fm-3m structure. And the crystal constant calculated (a=4.388) is consist with the reported value (a= 4.389, JCPDS card No.65-5011). (Ta, N) sample contains TaN, which can be indexed as cubic Fm3m structure, and Ta2N which can be indexed as hexagonal P(?)eTEM and SEM images show that VN sample with a diameter ranges from 300 nm to 1μm. NbN sample with a diameter ranges from 30 nm to 300 nm. The average diameter of Tantalum was about 80 nm.TGA curves show that all the nitride we produced has good stability before 400℃. And as temperature rise, the products get oxidized. Vanadium nitride can be completely oxidized, while Niobium nitride and Tantalum nitride were protected from the further oxidized by the oxidization on surface of the nitride.2.To synthesize metal carbide (VC, NbC, TaC)NH4VO3, Nb2O5 and Ta2O5 were used as vanadium source, niobium source, and tantalum source, with C2H5OH as C source and Mg as reduce agent were loaded into stainless autoclave and heated at 300℃. Nanometer particles of VC. NbC. and TaC were successfully produced.The X-ray diffraction test results are listed as follows.VC sample can be indexed as cubic Fm-3m structure. And the crystal constant calculated (a=4.163) is consist with the reported value (a= 4.167, JCPDS card No. 65-8825). NbC sample can be indexed as cubic Fm-3m structure. And the crystal constant calculated (a=4.388) is consist with the reported value (a= 4.389, JCPDS card No.65-7964). TaC sample can be indexed as cubic Fm-3m structure. And the crystal constant calculated (a=4.445) is consist with the reported value (a= 4.47, JCPDS card No.65-8784).3.Use of Nb, NbC/C composite in Li-ion coin cellsNbN, NbC/C as work electrode with lithium sheet as counter electrode and reference electrode were assembled into CR2032 coin cells. The galvanostatic cell cycling and cyclic voltammetry between 0.01 V and 3.5 V. The mechanism of the discharge and charge process was studied. The first discharge specific capacity is 447 mAh/g. The specific capacity stable at 122 mAh/g after cycled 50 times.