Thin films of silicon carbide nitride （SiCN） were prepared on （111） oriented silicon substrates by pulsed high-energy density plasma （PHEDP）. The evolution of the chemical bonding states between silicon, nitroge...Thin films of silicon carbide nitride （SiCN） were prepared on （111） oriented silicon substrates by pulsed high-energy density plasma （PHEDP）. The evolution of the chemical bonding states between silicon, nitrogen and carbon was investigated as a function of discharge voltage using X-ray photoelectron spectroscopy. With an increase in discharge voltage both the C 1s and N 1s spectra shift to lower binding energy due to the formation of C--Si and N--Si bonds. The Si--C--N bonds were observed in the deconvolved C ls and N ls spectra. The X-ray diffractometer （XRD） results show that there were no crystals in the films. The thickness of the films was approximately 1-2 μm with scanning electron microscopy （SEM）.展开更多
To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current ...To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.展开更多
We demonstrate a novel picosecond optical parametric preamplification to generate high-stability, high-energy and high-contrast seed pulses. The 5ps seed pulse is amplified from 60pJ to 300μJ with an 8.6ps/ 3mJ pump ...We demonstrate a novel picosecond optical parametric preamplification to generate high-stability, high-energy and high-contrast seed pulses. The 5ps seed pulse is amplified from 60pJ to 300μJ with an 8.6ps/ 3mJ pump laser in a signal stage of short pulse non-collinear optical parametric chirped pulse amplification. The total gain is more than 106 and the rms energy stability is under 1.35%. The contrast ratio is higher than 10s within a scale of 20ps before the main pulse. Consequently, the improvement factor of the signal contrast is approximately equal to the gain 106 outside the pump window.展开更多
The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing t...The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary.展开更多
The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-indu...The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.展开更多
A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification（CPA） technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillat...A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification（CPA） technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied.We find that the compressed pulse duration is dependent on the amplified energy,the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ,while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ.The measured energy fluctuation is approximately 0.46% root mean square（RMS） over 2 h.The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines,medical therapy,and scientific studies.展开更多
We present a high-energy,hundred-picosecond(ps)pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation(SHG)in a barium borate(BaB_(2)O_(4),BBO)nonlinear crystal.The green pump source ...We present a high-energy,hundred-picosecond(ps)pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation(SHG)in a barium borate(BaB_(2)O_(4),BBO)nonlinear crystal.The green pump source is a 710 mJ,330 ps pulsed laser at a wavelength of 532 nm with a repetition rate of 1 Hz.Under a green pump energy of 710 mJ,a maximum output energy of 253.3 mJ at 266 nm is achieved with 250 ps pulse duration resulting in a peak power of more than 1 GW,corresponding to an SHG conversion efficiency of 35.7%from 532 to 266 nm.The experimental data were well consistent with the theoretical prediction.To the best of our knowledge,this laser exhibits both the highest output energy and highest peak power ever achieved in a hundred-ps/ps regime at 266 nm for BBO-SHG.展开更多
To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light source...To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light sources. Using the High Energy Photon Source as an example, we numerically test the feasibility of implementing one coherent harmonic generation technology, i.e.,the echo-enabled harmonic generation(EEHG) scheme, in a diffraction-limited storage ring(DLSR). Two different EEHG element layouts are considered, and the effect of the EEHG process on the electron beam quality is also analyzed. Studies suggest that soft X-ray pulses, with pulse lengths of a few femtoseconds and peak powers of up to1 MW, can be generated by using the EEHG scheme, while causing little perturbation to the regular operation of a DLSR.展开更多
We demonstrate a passively mode-locked all-fiber laser incorporating a piece of graded-index multimode fiber as a mode-locking modulator based on a nonlinear multimodal interference technique, which generates two type...We demonstrate a passively mode-locked all-fiber laser incorporating a piece of graded-index multimode fiber as a mode-locking modulator based on a nonlinear multimodal interference technique, which generates two types of coexisting high-energy ultrashort pulses [i.e., the conventional soliton(CS) and the stretched pulse(SP)]. The CS with pulse energy as high as 0.38 n J is obtained at the pump level of 130 mW. When the pump increases to175 mW, the high-energy SP occurs at a suitable nonlinear phase bias and its pulse energy can reach 4 n J at a 610 mW pump. The pulse durations of the generated CS and SP are 2.3 ps and 387 fs, respectively. The theory of nonlinear fiber optics, single-shot spectral measurement by the dispersive Fourier-transform technique, and simulation methods based on the Ginzburg–Landau equation are provided to characterize the laser physics and reveal the underlying principles of the generated CS and SP. A rogue wave, observed between the CS and SP regions, mirrors the laser physics behind the dynamics of generating a high-energy SP from a CS. The proposed all-fiber laser is versatile, cost-effective and easy to integrate, which provides a promising solution for high-energy pulse generation.展开更多
A novel method to prepare ceramic coatings has been developed by making use of plasma energy produced from the pulsed discharge between electric conductor and aqueous electrolyte. A ZrO2-8%Y2O3 coating was obtained by...A novel method to prepare ceramic coatings has been developed by making use of plasma energy produced from the pulsed discharge between electric conductor and aqueous electrolyte. A ZrO2-8%Y2O3 coating was obtained by this method, which had excellent adhesion with substrate, smooth surface and good resistance to high temperature oxidation.展开更多
In this work, new plain and composite high-energy solitons of the cubic–quintic Swift–Hohenberg equation were numerically found. Starting from a composite pulse found by Soto-Crespo and Akhmediev and changing some p...In this work, new plain and composite high-energy solitons of the cubic–quintic Swift–Hohenberg equation were numerically found. Starting from a composite pulse found by Soto-Crespo and Akhmediev and changing some parameter values allowed us to find these high energy pulses. We also found the region in the parameter space in which these solutions exist. Some pulse characteristics, namely, temporal and spectral profiles and chirp, are presented. The study of the pulse energy shows its independence of the dispersion parameter but its dependence on the nonlinear gain. An extreme amplitude pulse has also been found.展开更多
In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core nume...In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250µm at the thin end and 56/400μm at the thick end.With a backward-pumping confguration,a maximum single pulse energy of 177.9μJ at a repetition rate of 504 kHz is realized,corresponding to an average power of 89.7 W.Through partially compensating for the accumulated nonlinear phase during the amplifcation process via adjusting the high order dispersion of the stretching chirped fber Bragg grating,the duration of the amplifed pulse is compressed to 401 fs with a pulse energy of 126.3μJ and a peak power of 207 MW,which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fber laser.At the highest energy,the polarization extinction ratio and the M2 factor were respectively measured to be~19 dB and 1.20.In addition,the corresponding intensity noise properties as well as the short-and long-term stability were also examined,verifying a stable operation of the system.It is believed that the demonstrated laser source could fnd important applications in,for example,advanced manufacturing and photomedicine.展开更多
Dissipative soliton resonance (DSR) is a phenomenon where the energy of a soliton in a dissipative system increases without limit at certain values of the system parameters. Using the method of collective variable app...Dissipative soliton resonance (DSR) is a phenomenon where the energy of a soliton in a dissipative system increases without limit at certain values of the system parameters. Using the method of collective variable approach, we have found an approximate relation between the parameters of the normalized complex cubic-quintic Ginzburg-Landau equation where the resonance manifests itself. Comparisons between the results obtained by collective variable approach, and those obtained by the method of moments show good qualitative agreement. This choice also helps to see the influence of the active terms on the resonance curve, so can be very useful in constructing passively mode-locked laser that generate solitons with the highest possible energies.展开更多
The development of laser performance models having real-time prediction capability for the OMEGA EP laser system has been essential in meeting requests from its user community for increasingly complex pulse shapes tha...The development of laser performance models having real-time prediction capability for the OMEGA EP laser system has been essential in meeting requests from its user community for increasingly complex pulse shapes that span a wide range of energies. The laser operations model PSOPS provides rapid and accurate predictions of OMEGA EP lasersystem performance in both forward and backward directions, a user-friendly interface and rapid optimization capability between shots. We describe the model’s features and show how PSOPS has allowed real-time optimization of the lasersystem configuration in order to satisfy the demands of rapidly evolving experimental campaign needs. We also discuss several enhancements to laser-system performance accuracy and flexibility enabled by PSOPS.展开更多
Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transp...Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.展开更多
文摘Thin films of silicon carbide nitride （SiCN） were prepared on （111） oriented silicon substrates by pulsed high-energy density plasma （PHEDP）. The evolution of the chemical bonding states between silicon, nitrogen and carbon was investigated as a function of discharge voltage using X-ray photoelectron spectroscopy. With an increase in discharge voltage both the C 1s and N 1s spectra shift to lower binding energy due to the formation of C--Si and N--Si bonds. The Si--C--N bonds were observed in the deconvolved C ls and N ls spectra. The X-ray diffractometer （XRD） results show that there were no crystals in the films. The thickness of the films was approximately 1-2 μm with scanning electron microscopy （SEM）.
基金supported by the National Natural Science Foundation of China(Nos.51974196,52275361,and 52105390)Open Research Fund from National Key Laboratory of Metal Forming Technology and Heavy Equipment(S2308100.W01)+1 种基金Natural Science Foundation of Shanxi Province(No.20210302124426)Special Funds for the Central Government to Guide Local Science and Technology Development(No.YDZX20191400002149).
文摘To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11604350 and 61405211
文摘We demonstrate a novel picosecond optical parametric preamplification to generate high-stability, high-energy and high-contrast seed pulses. The 5ps seed pulse is amplified from 60pJ to 300μJ with an 8.6ps/ 3mJ pump laser in a signal stage of short pulse non-collinear optical parametric chirped pulse amplification. The total gain is more than 106 and the rms energy stability is under 1.35%. The contrast ratio is higher than 10s within a scale of 20ps before the main pulse. Consequently, the improvement factor of the signal contrast is approximately equal to the gain 106 outside the pump window.
文摘The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary.
基金supported by the National Natural Science Foundation of China(Grant Nos.11074078,61378036,61307058,11304101,and 61177077)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)the Ph.D.Start-up Fund of the Natural Science Foundation of Guangdong Province,China(Grant No.S2013040016320)
文摘The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.
基金Project supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2012BAC23B03)the National Key Basic Research Program of China(Grant No.2013CB922401)the National Natural Science Foundation of China(Grant No.11474002)
文摘A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification（CPA） technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied.We find that the compressed pulse duration is dependent on the amplified energy,the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ,while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ.The measured energy fluctuation is approximately 0.46% root mean square（RMS） over 2 h.The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines,medical therapy,and scientific studies.
基金This work was supported by the Instrument Developing Project of the Chinese Academy of Sciences(CAS)(No.GJJSTD2020007)。
文摘We present a high-energy,hundred-picosecond(ps)pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation(SHG)in a barium borate(BaB_(2)O_(4),BBO)nonlinear crystal.The green pump source is a 710 mJ,330 ps pulsed laser at a wavelength of 532 nm with a repetition rate of 1 Hz.Under a green pump energy of 710 mJ,a maximum output energy of 253.3 mJ at 266 nm is achieved with 250 ps pulse duration resulting in a peak power of more than 1 GW,corresponding to an SHG conversion efficiency of 35.7%from 532 to 266 nm.The experimental data were well consistent with the theoretical prediction.To the best of our knowledge,this laser exhibits both the highest output energy and highest peak power ever achieved in a hundred-ps/ps regime at 266 nm for BBO-SHG.
基金supported by National Natural Science Foundation of China(No.11475202,11405187)the Youth Innovation Association of Chinese Academy of SciencesKey Research Program of Frontier Sciences,CAS(No.QYZDJ-SSW-SLH001)
文摘To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light sources. Using the High Energy Photon Source as an example, we numerically test the feasibility of implementing one coherent harmonic generation technology, i.e.,the echo-enabled harmonic generation(EEHG) scheme, in a diffraction-limited storage ring(DLSR). Two different EEHG element layouts are considered, and the effect of the EEHG process on the electron beam quality is also analyzed. Studies suggest that soft X-ray pulses, with pulse lengths of a few femtoseconds and peak powers of up to1 MW, can be generated by using the EEHG scheme, while causing little perturbation to the regular operation of a DLSR.
基金National Natural Science Foundation of China(NSFC)(61475188,61635013,61805277)Chinese Academy of Sciences(CAS)Strategic Priority Research Program and Light of West China Program(XDB24030600,XAB2017A09)
文摘We demonstrate a passively mode-locked all-fiber laser incorporating a piece of graded-index multimode fiber as a mode-locking modulator based on a nonlinear multimodal interference technique, which generates two types of coexisting high-energy ultrashort pulses [i.e., the conventional soliton(CS) and the stretched pulse(SP)]. The CS with pulse energy as high as 0.38 n J is obtained at the pump level of 130 mW. When the pump increases to175 mW, the high-energy SP occurs at a suitable nonlinear phase bias and its pulse energy can reach 4 n J at a 610 mW pump. The pulse durations of the generated CS and SP are 2.3 ps and 387 fs, respectively. The theory of nonlinear fiber optics, single-shot spectral measurement by the dispersive Fourier-transform technique, and simulation methods based on the Ginzburg–Landau equation are provided to characterize the laser physics and reveal the underlying principles of the generated CS and SP. A rogue wave, observed between the CS and SP regions, mirrors the laser physics behind the dynamics of generating a high-energy SP from a CS. The proposed all-fiber laser is versatile, cost-effective and easy to integrate, which provides a promising solution for high-energy pulse generation.
文摘A novel method to prepare ceramic coatings has been developed by making use of plasma energy produced from the pulsed discharge between electric conductor and aqueous electrolyte. A ZrO2-8%Y2O3 coating was obtained by this method, which had excellent adhesion with substrate, smooth surface and good resistance to high temperature oxidation.
基金FCT(Fundacao para a Ciência e Tecnologia)for supporting this work through the Project UID/CTM/50025/2013
文摘In this work, new plain and composite high-energy solitons of the cubic–quintic Swift–Hohenberg equation were numerically found. Starting from a composite pulse found by Soto-Crespo and Akhmediev and changing some parameter values allowed us to find these high energy pulses. We also found the region in the parameter space in which these solutions exist. Some pulse characteristics, namely, temporal and spectral profiles and chirp, are presented. The study of the pulse energy shows its independence of the dispersion parameter but its dependence on the nonlinear gain. An extreme amplitude pulse has also been found.
基金the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2020ZR02)the Postgraduate Scientifc Research Innovation Project of Hunan Province(No.QL20220007).
文摘In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250µm at the thin end and 56/400μm at the thick end.With a backward-pumping confguration,a maximum single pulse energy of 177.9μJ at a repetition rate of 504 kHz is realized,corresponding to an average power of 89.7 W.Through partially compensating for the accumulated nonlinear phase during the amplifcation process via adjusting the high order dispersion of the stretching chirped fber Bragg grating,the duration of the amplifed pulse is compressed to 401 fs with a pulse energy of 126.3μJ and a peak power of 207 MW,which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fber laser.At the highest energy,the polarization extinction ratio and the M2 factor were respectively measured to be~19 dB and 1.20.In addition,the corresponding intensity noise properties as well as the short-and long-term stability were also examined,verifying a stable operation of the system.It is believed that the demonstrated laser source could fnd important applications in,for example,advanced manufacturing and photomedicine.
文摘Dissipative soliton resonance (DSR) is a phenomenon where the energy of a soliton in a dissipative system increases without limit at certain values of the system parameters. Using the method of collective variable approach, we have found an approximate relation between the parameters of the normalized complex cubic-quintic Ginzburg-Landau equation where the resonance manifests itself. Comparisons between the results obtained by collective variable approach, and those obtained by the method of moments show good qualitative agreement. This choice also helps to see the influence of the active terms on the resonance curve, so can be very useful in constructing passively mode-locked laser that generate solitons with the highest possible energies.
基金based on work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856the University of Rochesterthe New York State Energy Research and Development Authority。
文摘The development of laser performance models having real-time prediction capability for the OMEGA EP laser system has been essential in meeting requests from its user community for increasingly complex pulse shapes that span a wide range of energies. The laser operations model PSOPS provides rapid and accurate predictions of OMEGA EP lasersystem performance in both forward and backward directions, a user-friendly interface and rapid optimization capability between shots. We describe the model’s features and show how PSOPS has allowed real-time optimization of the lasersystem configuration in order to satisfy the demands of rapidly evolving experimental campaign needs. We also discuss several enhancements to laser-system performance accuracy and flexibility enabled by PSOPS.
基金the Project of Hubei Polytechnic University (No.12xjz01R)The Natural Science Foundation of Hubei Province(No.2012FFB01001)the Program of Ministry of Education of China(for New Century Excellent Talents in University, No.NCET-08-0674)for their financial supports
文摘Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.
