Mo2C was prepared by microwave plasma chemical vapor deposition(MPCVD)technique with the power of 800 W and pressure of 18 kPa.Compared with traditional preparation methods,MPCVD has faster growth rate and higher puri...Mo2C was prepared by microwave plasma chemical vapor deposition(MPCVD)technique with the power of 800 W and pressure of 18 kPa.Compared with traditional preparation methods,MPCVD has faster growth rate and higher purity of the products.The influence of growth time on the morphology and structure of Mo_(2)C was characterized by X-ray diffraction and Scanning Electron Microscopy.The photocatalytic performance of Mo_(2)C was tested.It was found that Mo_(2)C had good photocatalytic performance and the 6 h sample had the highest photodegradation rate,indicating the great potential of Mo_(2)C as photocatalyst.展开更多
Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important prope...Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important properties,usually deteriorates with inhibitors.Here,(Cr,Mo,Ta)_(2)(C,N) synthesized by carbothermal reductionnitridation was used as a novel inhibitor,and its effects on the microstructure and mechanical properties of the cemented carbides were investigated.The results showed that the cemented carbides containing(Cr,Mo,Ta)_(2)(C,N)outperformed its counterpart comprising the traditional inhibitors in comprehensive mechanical properties,which was mainly attributed to the better inhibition performance provided by the(Cr,Mo,Ta)_(2)(C,N) solid-solution powders.With the content of(Cr,Mo,Ta)_(2)(C,N) increasing from 0 wt% to 1.25 wt%,the average grain size of WC in the cemented carbides decreased from 0.85 to 0.60 μm firstly,and then increased to 0.64 μm.With 1.00 wt%(Cr,Mo,-Ta)_(2)(C,N) addition,the cemented carbides with the best performance of hardness(HV_(30)) of 15.55 GPa,transverse rupture strength of 4272 MPa,fracture toughness of13.91 MPa·m1/2 were obtained.The electron backscattered diffraction(EBSD) measurements showed that cemented carbides with(Cr,Mo,Ta)_(2)(C,N) processed more amount of∑2 boundary compared with the other specimens,which contributed to better fracture resistance.展开更多
Title compound,Mr=1273.16,was synthesized by a substitution reaction and its crystal' is triclinic belonging to space group P1 with cell parameters:a=13.944(2),b=14.143(7),c=14.233(3), A,a=77.35(3)°,β=69.94(...Title compound,Mr=1273.16,was synthesized by a substitution reaction and its crystal' is triclinic belonging to space group P1 with cell parameters:a=13.944(2),b=14.143(7),c=14.233(3), A,a=77.35(3)°,β=69.94(2)°,γ=63.50(3)°,V=2351(1)A^3,Z=2,D_c=1.799g cm^(-3).Room tem- perature,graphite-filtered Mo K_α,radiation(λ=0.71073A)was used for data collection.μ=14.988 cm^(-1),F(000)=1280,R=0.051 for 7025 observed reflections.The crystal consists of decrete cluster molecules containing a duster core[Mo_3(μ_3-S)]^(10+)with three μ-S,one μ-dtp(dtp=[S_2P(OC_2H_5)]^(2-), three x-dtp and one allylthioureo to form a local six-coordinated sphere around each Mo atom.The bónds of cluster skeleton[Mo_3(μ_3-S)(μ-S)_3]^(4+),Mo—Mo 2.744～2.766,Mo—(μ_3-S)2.340～2.342 and Mo—(μ-S)2.272～2.296 A,are comparable with those found in the related analogues.展开更多
Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7...Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.展开更多
基金Hubei Provincial Department of Education(Q20201512)。
文摘Mo2C was prepared by microwave plasma chemical vapor deposition(MPCVD)technique with the power of 800 W and pressure of 18 kPa.Compared with traditional preparation methods,MPCVD has faster growth rate and higher purity of the products.The influence of growth time on the morphology and structure of Mo_(2)C was characterized by X-ray diffraction and Scanning Electron Microscopy.The photocatalytic performance of Mo_(2)C was tested.It was found that Mo_(2)C had good photocatalytic performance and the 6 h sample had the highest photodegradation rate,indicating the great potential of Mo_(2)C as photocatalyst.
基金financially supported by the National Key Research and Development Plan of China(No.2017YFB0305900)the Sichuan Provincial Science Research Program of China(No.2017GZ0120)the Zigong/Sichuan University Science and Technology Cooperation Special Project(No.2018CDZG-14)。
文摘Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important properties,usually deteriorates with inhibitors.Here,(Cr,Mo,Ta)_(2)(C,N) synthesized by carbothermal reductionnitridation was used as a novel inhibitor,and its effects on the microstructure and mechanical properties of the cemented carbides were investigated.The results showed that the cemented carbides containing(Cr,Mo,Ta)_(2)(C,N)outperformed its counterpart comprising the traditional inhibitors in comprehensive mechanical properties,which was mainly attributed to the better inhibition performance provided by the(Cr,Mo,Ta)_(2)(C,N) solid-solution powders.With the content of(Cr,Mo,Ta)_(2)(C,N) increasing from 0 wt% to 1.25 wt%,the average grain size of WC in the cemented carbides decreased from 0.85 to 0.60 μm firstly,and then increased to 0.64 μm.With 1.00 wt%(Cr,Mo,-Ta)_(2)(C,N) addition,the cemented carbides with the best performance of hardness(HV_(30)) of 15.55 GPa,transverse rupture strength of 4272 MPa,fracture toughness of13.91 MPa·m1/2 were obtained.The electron backscattered diffraction(EBSD) measurements showed that cemented carbides with(Cr,Mo,Ta)_(2)(C,N) processed more amount of∑2 boundary compared with the other specimens,which contributed to better fracture resistance.
文摘Title compound,Mr=1273.16,was synthesized by a substitution reaction and its crystal' is triclinic belonging to space group P1 with cell parameters:a=13.944(2),b=14.143(7),c=14.233(3), A,a=77.35(3)°,β=69.94(2)°,γ=63.50(3)°,V=2351(1)A^3,Z=2,D_c=1.799g cm^(-3).Room tem- perature,graphite-filtered Mo K_α,radiation(λ=0.71073A)was used for data collection.μ=14.988 cm^(-1),F(000)=1280,R=0.051 for 7025 observed reflections.The crystal consists of decrete cluster molecules containing a duster core[Mo_3(μ_3-S)]^(10+)with three μ-S,one μ-dtp(dtp=[S_2P(OC_2H_5)]^(2-), three x-dtp and one allylthioureo to form a local six-coordinated sphere around each Mo atom.The bónds of cluster skeleton[Mo_3(μ_3-S)(μ-S)_3]^(4+),Mo—Mo 2.744～2.766,Mo—(μ_3-S)2.340～2.342 and Mo—(μ-S)2.272～2.296 A,are comparable with those found in the related analogues.
文摘Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.
