Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use ...Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use them in constellations of small spacecraft for remote sensing of various regions of the magnetosphere. They require a payload with specific size, weight and power consumption. In order to respond to this demand, new instruments have to be developed. Those instruments should exhibit at least the same performances as those used in larger satellites while fulfilling the specific requirements imposed by the satellites size. For this reason, the authors currently develop a xylophone bar magnetometer （XBM） based on micro-electromechanical systems （MEMS） with integrated detector electronics. The principle of this magnetometer is based on a classical resonating xylophone bar. A sinnsoidal current oscillating at the fundamental bending resonant frequency of the bar is applied through the device, and when an external magnetic field is present, the resulting Lorentz force yields the bar to vibrate at its fundamental mode with a displacement directly proportional to the amplitude in one direction of the ambient magnetic field. When designing a MEMS XBM, the detection method is a crucial aspect. The measurement method largely influences the geometry of the magnetometer as well as the manufacturing technology. Due to the constraints in terms of size, weight and power consumption, the two most promising measurement methods are capacitive and piezoelectric ones. Several designs including these measurement techniques are presented and simulated under realistic conditions. First, designs including lateral electrodes for capacitive measurement are tackled based on Silicon-On-Insulator （SOI） process. For the piezoelectric detection, a new configuration based on Lead Zirconate Titanate （PZT）/Pt structure is introduced and leads to much better sensitivity than the traditional Pt/PZT/Pt sandwich structure. Finally, the principle of electronic circuits enabling high sensitivity and low power consumption are proposed.展开更多
微波烧结是一种新型、高效的陶瓷烧结工艺,具有升温速度快、节能省时、改善微观结构、降低烧结温度等特点。本文采用微波烧结工艺制备了Fe2O3掺杂的0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3(简写为0.55PNN-0.45PZT)压电陶瓷,烧结温度...微波烧结是一种新型、高效的陶瓷烧结工艺,具有升温速度快、节能省时、改善微观结构、降低烧结温度等特点。本文采用微波烧结工艺制备了Fe2O3掺杂的0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3(简写为0.55PNN-0.45PZT)压电陶瓷,烧结温度为1200℃、保温时间为2h。利用X射线衍射(X-Ray Diffraction,XRD)、扫描电子显微镜(Scanning Electron Microscope,SEM)、阻抗分析仪及铁电分析仪等测试表征方法,研究了Fe2O3掺杂对陶瓷的结构、介电以及压电性能的影响。结果表明,所有陶瓷样品均为钙钛矿结构,随着Fe2O3掺杂量的增加,压电和介电性能呈先增加后减小趋势。当Fe2O3掺杂量为0.8%(质量分数)时,陶瓷达到最优电学性能:压电常数d33、平面机电耦合系数kp、相对介电常数εr和介电损耗tanδ分别为d33=520pC/N,kp=0.51,εr=4768,tanδ=0.026。展开更多
文摘Initially studied and developed by students in universities, the very small pico satellites （with a mass lower than 1 kg） are more and more considered for science applications. In particular, there are plans to use them in constellations of small spacecraft for remote sensing of various regions of the magnetosphere. They require a payload with specific size, weight and power consumption. In order to respond to this demand, new instruments have to be developed. Those instruments should exhibit at least the same performances as those used in larger satellites while fulfilling the specific requirements imposed by the satellites size. For this reason, the authors currently develop a xylophone bar magnetometer （XBM） based on micro-electromechanical systems （MEMS） with integrated detector electronics. The principle of this magnetometer is based on a classical resonating xylophone bar. A sinnsoidal current oscillating at the fundamental bending resonant frequency of the bar is applied through the device, and when an external magnetic field is present, the resulting Lorentz force yields the bar to vibrate at its fundamental mode with a displacement directly proportional to the amplitude in one direction of the ambient magnetic field. When designing a MEMS XBM, the detection method is a crucial aspect. The measurement method largely influences the geometry of the magnetometer as well as the manufacturing technology. Due to the constraints in terms of size, weight and power consumption, the two most promising measurement methods are capacitive and piezoelectric ones. Several designs including these measurement techniques are presented and simulated under realistic conditions. First, designs including lateral electrodes for capacitive measurement are tackled based on Silicon-On-Insulator （SOI） process. For the piezoelectric detection, a new configuration based on Lead Zirconate Titanate （PZT）/Pt structure is introduced and leads to much better sensitivity than the traditional Pt/PZT/Pt sandwich structure. Finally, the principle of electronic circuits enabling high sensitivity and low power consumption are proposed.
文摘微波烧结是一种新型、高效的陶瓷烧结工艺,具有升温速度快、节能省时、改善微观结构、降低烧结温度等特点。本文采用微波烧结工艺制备了Fe2O3掺杂的0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3(简写为0.55PNN-0.45PZT)压电陶瓷,烧结温度为1200℃、保温时间为2h。利用X射线衍射(X-Ray Diffraction,XRD)、扫描电子显微镜(Scanning Electron Microscope,SEM)、阻抗分析仪及铁电分析仪等测试表征方法,研究了Fe2O3掺杂对陶瓷的结构、介电以及压电性能的影响。结果表明,所有陶瓷样品均为钙钛矿结构,随着Fe2O3掺杂量的增加,压电和介电性能呈先增加后减小趋势。当Fe2O3掺杂量为0.8%(质量分数)时,陶瓷达到最优电学性能:压电常数d33、平面机电耦合系数kp、相对介电常数εr和介电损耗tanδ分别为d33=520pC/N,kp=0.51,εr=4768,tanδ=0.026。
