To obtain a stable amplified spontaneous emission(ASE) source for complex environment applications, we design an ASE source and study the output power and spectral characteristics under different ambient temperature...To obtain a stable amplified spontaneous emission(ASE) source for complex environment applications, we design an ASE source and study the output power and spectral characteristics under different ambient temperatures.We optimize the structure of the ASE source to flatten the ASE spectrum, and study the output characteristics in terms of output power and optical spectrum under different pump powers. Then the performance of the ASE source is investigated in the temperature range from-18.9°C to 50°C. A stable-power and flat-spectrum ASE source can be obtained by structural optimization and pump control.展开更多
With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing material...With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing materials(MAMs).Since both the electromagnetic response and energy conversion character vary with temperature,to achieve temperature insensitive microwave absorption behaviour in wide temperature range has become extremely challenging.In this work,structured metacomposites containing sub-wavelength reduced graphene oxide(RGO)@carbon spheres were fabricated,and the microwave absorption was further improved through structural and composition design of the RGO@carbon units.Due to the unique anti-reflection effect on microwave of the metacomposites,the temperature-insensitive electromagnetic performance at elevated temperature could be exhibited.Moreover,both the dielectric relaxation behaviour and microwave absorption proformance of the system could be further increased.As a result,the effective absorption bandwidth(reflection loss(RL)<−10 dB)of the metacomposites with only 3.0 wt.%filler content could cover the entire X-band(8.2–12.4 GHz)frequency ranging from 298 to 473K.The metacomposite proposed in this work provides a“de-correlating”strategy to break the linkage between microwave absorption behaviour and temperature,which offers an interesting plateau for fabricating efficient high-temperature microwave absorption structures with tunable and designable advantages.展开更多
High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adop...High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11504320
文摘To obtain a stable amplified spontaneous emission(ASE) source for complex environment applications, we design an ASE source and study the output power and spectral characteristics under different ambient temperatures.We optimize the structure of the ASE source to flatten the ASE spectrum, and study the output characteristics in terms of output power and optical spectrum under different pump powers. Then the performance of the ASE source is investigated in the temperature range from-18.9°C to 50°C. A stable-power and flat-spectrum ASE source can be obtained by structural optimization and pump control.
基金the National Natural Science Foundation of China(Nos.U1704253 and 21671057).
文摘With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing materials(MAMs).Since both the electromagnetic response and energy conversion character vary with temperature,to achieve temperature insensitive microwave absorption behaviour in wide temperature range has become extremely challenging.In this work,structured metacomposites containing sub-wavelength reduced graphene oxide(RGO)@carbon spheres were fabricated,and the microwave absorption was further improved through structural and composition design of the RGO@carbon units.Due to the unique anti-reflection effect on microwave of the metacomposites,the temperature-insensitive electromagnetic performance at elevated temperature could be exhibited.Moreover,both the dielectric relaxation behaviour and microwave absorption proformance of the system could be further increased.As a result,the effective absorption bandwidth(reflection loss(RL)<−10 dB)of the metacomposites with only 3.0 wt.%filler content could cover the entire X-band(8.2–12.4 GHz)frequency ranging from 298 to 473K.The metacomposite proposed in this work provides a“de-correlating”strategy to break the linkage between microwave absorption behaviour and temperature,which offers an interesting plateau for fabricating efficient high-temperature microwave absorption structures with tunable and designable advantages.
基金the National Key Research and Development Program of China(Grant No.2022YFB3807404)the Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents (Grant No. BX2021377 ).
文摘High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.