Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. Th...Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.展开更多
The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techni...The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completly interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.展开更多
Insertion of species A into species B forms a product P through two kinetic processes, namely, （1） the chemical reaction between A and B that occurs at the B-P interface, and （2） the diffusion of species A in prod...Insertion of species A into species B forms a product P through two kinetic processes, namely, （1） the chemical reaction between A and B that occurs at the B-P interface, and （2） the diffusion of species A in product P. These two processes are symbiotic in that the chemical reaction provides the driving force for the diffusion, while the diffusion sustains the chemical reaction by providing sufficient reactant to the reactive interface. In this paper, a math- ematical framework is developed for the coupled reaction- diffusion processes. The resulting system of boundary and initial value problem is solved analytically for the case of interface-reaction controlled diffusion, i.e., the rate of diffu- sion is much faster than the rate of chemical reaction at the interface so that the final kinetics are limited by the interface chemical reaction. Asymptotic expressions are given for the velocity of the reactive interface and the concentration of diffusing species under two different boundary conditions.展开更多
The interface diffusion and chemical reaction between a PZT (PbZrxTi1-xO3) layer and a Si(111) substrate during the annealing treatment in air have been studied by using XPS (X-Ray Photoelectron Spectroscopy) and AES ...The interface diffusion and chemical reaction between a PZT (PbZrxTi1-xO3) layer and a Si(111) substrate during the annealing treatment in air have been studied by using XPS (X-Ray Photoelectron Spectroscopy) and AES (Auger Electron Spectroscopy). The results indicate that the Ti element in the PZT precursor reacted with residual carbon and silicon, diffused from the Si substrate, to form TiCx, TiSix species in the PZT layer during the thermal treatment. A great interface diffusion and chemical reaction took place on the interface of PZT/Si also. The silicon atoms diffused from silicon substrate onto the surface of PZT layer. The oxygen atoms, which came from air, diffused into silicon substrate also and reacted with Si atoms to form a SiO2 interlayer between the PZT layer and the Si (111) substrate. The thickness of SiO2, interlayer was proportional to the square root of treatment time. The formation of the SiO2 interlayer was governed by the diffusion of oxygen in the PZT layer at low annealing temperature, and governed by the diffusion of oxygen in SiO2 interlayer at high annealing temperature. The apparent activation energy of the interface oxidation reaction was about 39.1 kJ/mol.展开更多
The microstructure together with the formation and growth ofreaction phases in the interfacial diffusion zone of the explosive cladding TA2/A3 has been investigated by means of OM, SEM, AES and XRD techniques. When th...The microstructure together with the formation and growth ofreaction phases in the interfacial diffusion zone of the explosive cladding TA2/A3 has been investigated by means of OM, SEM, AES and XRD techniques. When the specimen annealed at temperature under the βTi→αTi transformation, i. e. below 1173 K, only TiC forms along TA2 side of interface and hinders the interdiffusion of Fe and Ti atoms, thus Fe2Ti or FeTi is unable to occur. While heated up to the transformation temperature of βTi, e. g, over 1223 K, the parabolic growth of intermetallic compounds of Fe2Ti and FeTi with layer structure may form intergranularly and the formation of βTi or βTi+αTi structure at the Fe enriched side of TA2 and the martensitic transformation products at the Fedepleted side are observed owing to the diffusion of Fe. Furthermore, the growth of βTi transformation layer is revealed to follow the parabolic rule.展开更多
Cu thin films are deposited on p-type Si （100） substrates by magnetron sputtering at room temperature. The interface reaction and atomic diffusion of Cu/SiO2/Si （100） systems are studied by x-ray diffraction （XRD...Cu thin films are deposited on p-type Si （100） substrates by magnetron sputtering at room temperature. The interface reaction and atomic diffusion of Cu/SiO2/Si （100） systems are studied by x-ray diffraction （XRD） and Rutherford backscattering spectrometry （RBS）. Some significant results can be obtained. The onset temperature of interdiffusion for Cu/SiO2/Si（100） is 350~℃. With the annealing temperature increasing, the interdiffusion becomes more apparent. The calculated diffusion activation energy is about 0.91 eV. For the Cu/SiO2/Si （100） systems copper silicides are not formed below an annealing temperature of 350~℃. The formation of the copper silicides phase is observed when the annealing temperature arrives at 450~℃.展开更多
基金Project (ZR2011EL023) supported by the Natural Science Foundation of Shandong Province,ChinaProject (12CX04057A) supported by the Fundamental Research Funds for the Central Universities,China
文摘Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.
基金Project supported by the 1997 Grant-in Aid for Scientific Fundament Research of Tsinghua University and by State Key Laboratory of Rare Earth Materials Chemistry and Application.
文摘The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completly interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.
基金supported in part by an ISEN Booster Award at Northwestern Universityin part by NSF(CMMI-1200075)
文摘Insertion of species A into species B forms a product P through two kinetic processes, namely, （1） the chemical reaction between A and B that occurs at the B-P interface, and （2） the diffusion of species A in product P. These two processes are symbiotic in that the chemical reaction provides the driving force for the diffusion, while the diffusion sustains the chemical reaction by providing sufficient reactant to the reactive interface. In this paper, a math- ematical framework is developed for the coupled reaction- diffusion processes. The resulting system of boundary and initial value problem is solved analytically for the case of interface-reaction controlled diffusion, i.e., the rate of diffu- sion is much faster than the rate of chemical reaction at the interface so that the final kinetics are limited by the interface chemical reaction. Asymptotic expressions are given for the velocity of the reactive interface and the concentration of diffusing species under two different boundary conditions.
基金Project supported by the Grant-in Aid for Scientific Fundament Research of Tsinghua University and by State Key Laboratory of Rare Earth Materials Chemistry and Application.
文摘The interface diffusion and chemical reaction between a PZT (PbZrxTi1-xO3) layer and a Si(111) substrate during the annealing treatment in air have been studied by using XPS (X-Ray Photoelectron Spectroscopy) and AES (Auger Electron Spectroscopy). The results indicate that the Ti element in the PZT precursor reacted with residual carbon and silicon, diffused from the Si substrate, to form TiCx, TiSix species in the PZT layer during the thermal treatment. A great interface diffusion and chemical reaction took place on the interface of PZT/Si also. The silicon atoms diffused from silicon substrate onto the surface of PZT layer. The oxygen atoms, which came from air, diffused into silicon substrate also and reacted with Si atoms to form a SiO2 interlayer between the PZT layer and the Si (111) substrate. The thickness of SiO2, interlayer was proportional to the square root of treatment time. The formation of the SiO2 interlayer was governed by the diffusion of oxygen in the PZT layer at low annealing temperature, and governed by the diffusion of oxygen in SiO2 interlayer at high annealing temperature. The apparent activation energy of the interface oxidation reaction was about 39.1 kJ/mol.
基金the+6 种基金Non-ferrousMetal Industry Corperation of China
文摘The microstructure together with the formation and growth ofreaction phases in the interfacial diffusion zone of the explosive cladding TA2/A3 has been investigated by means of OM, SEM, AES and XRD techniques. When the specimen annealed at temperature under the βTi→αTi transformation, i. e. below 1173 K, only TiC forms along TA2 side of interface and hinders the interdiffusion of Fe and Ti atoms, thus Fe2Ti or FeTi is unable to occur. While heated up to the transformation temperature of βTi, e. g, over 1223 K, the parabolic growth of intermetallic compounds of Fe2Ti and FeTi with layer structure may form intergranularly and the formation of βTi or βTi+αTi structure at the Fe enriched side of TA2 and the martensitic transformation products at the Fedepleted side are observed owing to the diffusion of Fe. Furthermore, the growth of βTi transformation layer is revealed to follow the parabolic rule.
基金supported by the National Natural Science Foundation of China (Grant No. 10375028)
文摘Cu thin films are deposited on p-type Si （100） substrates by magnetron sputtering at room temperature. The interface reaction and atomic diffusion of Cu/SiO2/Si （100） systems are studied by x-ray diffraction （XRD） and Rutherford backscattering spectrometry （RBS）. Some significant results can be obtained. The onset temperature of interdiffusion for Cu/SiO2/Si（100） is 350~℃. With the annealing temperature increasing, the interdiffusion becomes more apparent. The calculated diffusion activation energy is about 0.91 eV. For the Cu/SiO2/Si （100） systems copper silicides are not formed below an annealing temperature of 350~℃. The formation of the copper silicides phase is observed when the annealing temperature arrives at 450~℃.
