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科学家发现碳在地球深部新的赋存状态 New host for carbon in the deep Earth 最近法国科学家在研究中发现一种新的含C高压相，这种含C高压相具有相当的稳定性，与理论计算所预测的结构非常一致，这对于认识C在地球深部的赋存状态以及地球内部的碳循环具有一定的意义。这一成果发表在2011年3月29日美国科学院院报PNAS上： http://www.pnas.org/content/108/13/5184 PDF下载： 2011-PNAS-New host for carbon in the deep Earth.pdf 以下是全文翻译：（原文中有太多的化学式，难于在编辑器中一一编辑，请见谅；所有化学式以公式请参考原文。） 全球地球化学碳循环包含地球内部和表层碳的交换。碳通过俯冲作用主要以碳酸盐形式再循环进入地幔中，通过火山作用主要以 CO2 形式释放到大气中。所以碳酸盐的稳定性以及脱碳酸盐化作用和熔融作用对于认识全球碳循环具有重要意义。由此，我们需要认识一直到核幔边界条件下这些矿物的热动力学性质和相图。但是含 C 矿物在这些条件下的性质仍然不太清楚。本文我们报道了在 1800km 以下条件下存在一种新的 Mg-Fe 含 C 化合物。它具有由共角 (CO4)4- 四面体所构成的三元环结构，与第一性原理量子计算所预测的结构 (Oganov et al.,2008) 非常接近。该碳酸盐高压相可以通过如下 Fe(II) 和 (CO3)2- 的晶内反应： 4FeO + CO2 → 2Fe2O3 + C ，来聚集大量的 Fe(III) 。这将会形成由新的高压相 + 磁铁矿 + 纳米金刚石所组成的矿物组合。 关键词： diamond, Earth mantle, phase transition, experimental petrology, redox interaction 碳酸盐是主要的含 C 矿物，能够通过大洋岩石圈深俯冲作用进入到地幔中 (1) 。俯冲下去的成分与原始的 C 一同被认为对下地幔 C 储库具有重要作用 (2,3) 。因为在深部地幔矿物中 C 的溶解度极低 (4,5) ，因此 C 有可能以单独的相存在，如碳酸盐或者金刚石。有些研究表明碳酸镁 ( 菱镁矿 ) 是方解石和白云石消失之后 C 在深部的主要赋存方式 (6-8) 。另外一些模型认为与橄榄岩达到平衡以后的碳酸盐将会在下地幔被还原成金刚石 (9) 。但是，如同在上地幔所观测到的，下地幔氧化还原状态的不均匀性很有可能也存在：例如，俯冲带是由能够在很长时间尺度都保持稳定的更加氧化的矿物所组成的 (10) 。也有观点认为氧化和还原矿物可以在地球深部共存，如富 CO2 的金伯利岩浆可以将金刚石携带至地表来 (11,12) ，并且在来自下地幔的金刚石中发现了碳酸盐包裹体 (13,14) 。有关碳酸盐稳定性的高压实验表明菱形结构的 MgCO3 菱镁矿可以稳定至 115 GPa 、 2000-3000K ，而它在高压下会形成一种新的结构 (8) 。但是，第一性原理计算预测菱镁矿在 82 GPa 会转变成由 (CO4)4- 四面体所构成的新相，在 160 GPa 会转变成类似辉石的结构。考虑到地幔中平均 Fe/Mg 摩尔比为 0.12 ，那么碳酸盐的成分可能是介于菱镁矿和 FeCO3 菱铁矿之间，这两相可以形成连续的固熔体。目前含铁碳酸盐的相变研究很少。菱铁矿可以稳定至至少 47 GPa 和 2000K(18) ，在常温下可以稳定至 90 GPa(19) 。总之，菱铁矿和菱镁矿端元的结构特征是相似的，因为 Fe(II) 和 Mg 原子之间大小不匹配可以由 Fe(II) 中的自旋态转换来补偿 (19,20) 。 结果 Result 对于 MgCO3 和 MgO+CO2 组合，高压含 C 化合物的稳定性是一致的。在两种情况下，在类似温压条件下 ( 大约 80 GPa ， 2400K) 所获取的 X 光衍射 (XRD) 图像中出现了新的峰，这些峰并不是已知的 MgO 和 CO2 氧化物或者菱镁矿结构的峰。这些峰指示在该压力范围内一种新的稳定结构。 MgO+CO2 组合在 82 GPa 、 2350 ± 150K 条件下典型的 XRD 图像如图 1A 所示。淬火到室温之后该高压相会转变回低压菱镁矿结构。对回收样品的 EELS (Electron energy loss spectroscopy) 分析结果与原位 (in situ) 观测结果是一致的。图 1B 显示自 MgO+CO2 组合回收样品在碳 K-edge 所获取的 EELS 图谱。 290.3 eV 处尖锐的峰指示 (CO3)2-(21) 。另外，根据 EELS 分析所得出的化学成分指示为 MgCO3 成分。所以，该高压相是菱镁矿的一种等化学多晶体。 图 1. (A) X-ray diffraction pattern of a sample obtained from the transformation of periclase in CO2 confining medium at 82 GPa and 2,350 ± 150 K. Crosses represent observed data after subtraction of the background and the solid line represents the profile refinement. For this refinement we used an assemblage of untransformed periclase (Upper), platinum (Middle), and the new high-pressure phase (Lower). Residual between observations and fit is shown below the spectrum. (B) C K-edge EELS spectrum done on the recovered sample. 大于 80 GPa 时，天然富菱铁矿样品在 1850-2300 K 会发生相变，生成与上述 MgCO3 样品类似的 XRD 图像，同时还有一种铁氧化物 ( 图 2A) 。这表示形成了一种 Mg-Fe 系列的含 C 高压相。与 MgCO3 端元不同地是，该高压含铁结构是可淬火的 (quenchable) 。随后对回收样品的 TEM 分析显示有三种不同相对存在：未相变的 (Fe0.75Mg0.25)CO3 菱铁矿、高压相和一种铁氧化物 ( 图 2B) 。图 2C 中显示在铁 L2,3 dege 所获取的 EELS 图像；部分图谱与残余菱铁矿晶体结构比较吻合，与在相同能量分辨率条件下所获取的含 Fe(II) 相的图谱比较相似 (22) 。菱镁矿的出现同样也由 EELS 分析所确认。该高压相 Fe L2,3 edge 处的结构显示处理含 Fe(III) 矿物的明显结构 (22,23) ，并且根据参考文献 24 所作的定量分析表明至少 3/4 的铁是以 Fe(III) 氧化态形式存在的。根据碳 K-edge 的 EELS 数据 ( 图 2D) 确认残余菱铁矿的存在，并显示未相变的碳酸盐的峰偏移到 290.7 eV 处的特征。 287.5 eV 处的小峰指示一氧化碳 (CO)(25) 可能以包裹体 / 纳米泡形式存在，形成了该高压相的独特显微结构 ( 图 2B) 。如下面所讨论的，这些包裹体是在碳酸盐高压相形成过程中生成的。 EELS 测量表明元素比值与初始碳酸盐有所不同： Fe/C ~0.61 ± 0.07 ， Fe/O ~0.22 ± 0.02 。 图 2. (A) X-ray diffraction pattern collected at 80 GPa and room temperature of siderite transformed at 1,850–2,300 K. Crosses represent observed diffraction data after subtraction of the background and solid line the profile refinement. For the refinement we used an assemblage of high-pressure polymorph of magnetite (37) (Upper), untransformed siderite (space group R-3c) (Middle), and the new high-pressure phase (Lower). Residual between observations and fit is shown below the spectrum. (B) STEM high-angle annular dark field showing the untransformed siderite (Sid), the iron oxide (Mt for magnetite), and the transformed carbonate (HP carb.) appearing as a dark gray uniform matrix in the left side of the image. (C) EELS spectra collected on the recovered sample. These spectra provide qualitative information on the Fe(III)/ Σ Fe ratio of each phase (23, 24) and noticeable features have been indicated by small bars and can be compared with reference siderite, magnetite, and Fe(III) oxide (22). Spectrum collected on the untransformed carbonate shows a high intensity peak of 707.7 eV that indicates the main iron speciation to be Fe(II). In the case of the iron oxide, the broad L3 peak at 707–709 eV with no splitting is characteristic of magnetite, whereas the L2 shows many subsplitting and an intermediate energy position between pure ferric and ferrous iron that is typical of a mixed valence of magnetite (23). The spectrum collected in the new phase shows a L3 line at higher energy loss than in carbonate groups with a fine structure indicating the main iron speciation to be Fe(III). (D) C K-edge spectra collected in the untransformed and transformed carbonate phases. In the case of siderite relic, the peak at 290.3 eV corresponds to planar (CO3)2- carbonate groups. In the spectrum collected in the transformed carbonate, the slightly broader peak at 290.7 eV is attributed to the tetrahedral (CO4)4- forming rings of (C3O9)6-. Presence of CO can also be detected in intimate association with the new phase. (Mg0.6,Fe0.4)O+CO2 在 105 GPa 、 ~2850 K 条件下的相变会形成一个由未反应的 (Mg0.6,Fe0.4)O 、菱镁矿的高压相和相同的新高压相所组成的组合。这一组合已经由 XRD 所观测到并进一步由 ATEM 所确认 ( 图 3A) 。纳米金刚石也由电子衍射和碳 K-edge EELS 图谱所鉴别出来 ( 图 3B) 图 3. (A) TEM image of the recovered sample from the ferropericlase + CO2 experiment. Magnetite (Mt), high-pressure carbon-bearing phase (HP carb.), ferropericlase (FP), and nanodiamonds (D) are present. (B) C K-edge EELS spectrum of nanodiamonds observed in the recovered sample. The spectrum presents the absorption edge at 289 eV and the dip at 303 eV is characteristic of diamond C K-edge (38, 39). 讨论 Discussion 对高温高压下 XRD 图像分析可以鉴定高压含 C 结构。 XRD 图像与在该压力范围内理论计算所得到的菱镁矿的 phase II 相 ( 空间群为 C2/m) 是一致的 (15) 。但是当使用另一个晶体对称性更低一些的 P21/c 空间群时，拟合的质量会得到明显提高。这一结构见图 4 所示，它由共角的三个 (CO4)4- 四面体组所构成，这样组成了 (C3O9)6- 环。晶格常数为： MgO+CO2 在 P=82 GPa 、 T=2350 ±150K 条件下： a=8.39 , b=6.41 , c=6.82 , β =105.49 (V=354.7 3 ) ； MgCO3 在 P=85 GPa 、 T=2400 ±150K 条件下： a=8.37 , b=6.37 , c=6.80 , β =104.57 (V=351.7 3 ) 。对于后者，假设每个晶胞化学式单位为 12 (15) ，得到的密度为 4.76 g/cm3 ，与相同 P-T 条件下的低压结构具有 +10% 的密度差异。因为有相对较小的 Fe(III) 原子的加入，这种新的含铁相的晶格体积比富镁端元的要小 10% ： (Mg0.6Fe0.4)O+CO2 在 P=105 GPa 、 T=2850 ±150K 条件下： a=7.72 , b=6.41 , c=6.57 , β =101.31 (V=319.0 3 ) ； (Mg0.25Fe0.75)CO3 在 P=80 GPa 、室温 条件下： a=7.83 , b=6.37 , c=6.73 , β =101.97 (V=328.9 3 ) 。 图 4. Structure of the new high-pressure phase in space group P21/c related to phase II of magnesite proposed by theoretical calculation (15). (CO4)4- tetrahedra appear in green and magnesium atoms are shown as violet spheres. 对于这种新的高压相由于没有现成的 EELS 图谱做参考，我们对该未知的电子态密度进行了密度泛函理论 (DFT) 计算。 Mg 态密度显示在大约 5 eV 费米能级之上有个很窄的峰，对应着碳的 K-edge 以及它的“分子”类型 (CO3)2-( 图 5) 。由这种高压含 C 新相所得到的态密度并没有任何 (CO3)2- 峰，但是在高能区 (7-11 eV) 有一个很宽的带 (band) 。晶体密度在 80 GPa 时为 4.79 g/cm3 。 (C3O9)6- 环的几何形态见图 5 右边所示。 为了解四面体 (C3O9)6- 环在减压时是如何变化的，在常温常压条件下该结构得到松弛。结果如下图所示 ( 密度为 3.60 g/cm3),C-O 键会变长。从 80 GPa 到 0 GPa C-O-C 角从大约 10-112 变到 115-118 ，这些值与已知的四面体的畸变 (distortion) 是一致得 (15) 。这些结构变化对于态密度具有重要影响。的确，正如对低密度结构的预测，整体态密度会向低能方向偏移。这些出现的窄峰对应着四面体 (C3O9)6- 环，其分子结构特征与高压实验样品的 EELS 分析结果非常相似 ( 即 290.7 eV 附近的峰 ) 图 5. DFT calculations for electronic density of state of the carbon atoms (p orbital symmetry). This unoccupied density of state roughly corresponds to the excitation probed by EELS at the C K-edge (excitonic effects are neglected in the calculation). 在含铁实验中，大量的 Fe(III) 进入到这种新结构中。实验中未见 Pt 的出现，因此 Pt 对该氧化还原反应没有影响。 Fe(III) 形成的氧化还原配对 (partner) 最终可能是 Fe(0) ，就像在高压硅酸盐如钙钛矿中观测到的一样 (9) 。但是 Fe(0) 可能只是一个过渡配对，因为在回收样品中并未观测到 Fe(0) 的存在证据。我们认为 Fe(III) 的加入更可能是由于一个氧化碳配对。我们由此认为铁的氧化是通过下面的化学反应由如 (CO3)2- 或 CO2 这样的含 C 分子结构的部分还原作用来平衡的： 20(Mg0.25Fe(II)0.75)CO3 = 20Mg0.25Fe(III)0.3(C3O9)0.2333 + 3Fe3O4 + 6CO 该反应指示含 Fe(III) 新相中的元素比值为 Fe/C ~0.43 ， Fe/O ~0.14 ，与对回收样品的 EELS 估算值非常吻合。 结论 Conclusion 我们的研究证明，在近于下地幔地温 P-T 条件下 CO2 和其他氧化物的重新作用可以形成一种新的高压含 C 相。这表明这种新相具有较高的稳定性而不会分解为简单氧化物。同样，新高压相中 Fe(III) 的出现指示部分 C 的还原，如以上化学反应。这表明在下地幔条件下 C 的氧化态和还原态可以共存。这种性质可能是由于该含 C 相具有较强的热动力学稳定性。但是若这种新相真在下地幔深部存在的话，那么碳酸盐必须能够在深俯冲中保存下来。尽管根据下地幔矿物组合推测下地幔为还原条件 (9) ，但是如果与周围地幔隔离开来碳酸盐是可以在深部保持稳定的，例如在相对低温的俯冲板片中，由局部矿物组合所控制的氧逸度会相对较高一些 (10,26) 。残留的部分碳酸盐可以被搬运到 1800 km 深度以下，并转变成这种新的含 Fe(III) 相。 参考文献： ↵ Sleep NH, Zahnle K (2001) Carbon dioxide cycling and implications for climate on ancient Earth. 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本文最后有关于微波设备的联系方式，关于微波CVD金刚石膜产业化的问题，可以看我的博客文章： http://www.sciencenet.cn/blog/user_content.aspx?id=402561 （ 关于（微波法）CVD金刚石膜产业化的看法 ） 看看老外用微波设备作材料研究的视频： http://bbs.sciencenet.cn/forum.php?mod=viewthreadtid=201615extra = AX5010 Microwave Plasma CVD Reactor (1.5 kW) The AX5010 Microwave Plasma CVD Reactor is used for growth of high quality diamond films. Intended as a low cost system for basic film research in RD laboratories. It produces a wide range polycrystalline and single crystal diamond films on a variety of substrates with properties equal to or better than those made by any other method. The AX5010 is easy to use, small in size, and gives reproducible results. Model AX5010 AX5200 1.5kW Microwave Plasma CVD Integrated System he model AX5200 Microwave Plasma CVD system incorporates a 1.5kW at 2.45GHz microwave generator for high power and high temperature plasma deposition. System can also be equipped with optional electromagnets to become an Electron Cyclotron Resonance (ECR) system for operations at low pressure and low temperature. Both systems are: Capable of depositing high quality CVD diamond films for a wide variety of applications Flexible reactor design supports high pressure microwave and magnetized microwave CVD Development time minimized with supplied CVD diamond process recipes Reliable, stable, reproducible, versatile operation Modular approach to suit a wide range of budgets Manual operations or Computer controlled GUI for ease of operation Up to 6 different gas inlets Pressures from 10 to 150 Torr (1 to 150 Torr optional) Substrate Stage Temperature control – heated stage Extensive after-sales support AX5200 1.5kw Integrated Systems AX5250 5kW Microwave Plasma CVD System The AX5250 microwave plasma reactor incorporates a 5kW at 2.45GHz microwave generator to produce plasma at high power densities. Such operation allows a new regime of plasma chemistries. In this microwave cavity configuration, liner growth rates on axis up to 15 micro meter an hour for diamond have been demonstrated. Total mass deposition rates of 60mg/hour have been achieved. The process recipe for thick, high growth films is included with the system. Features: Film or thick CVD diamond at deposition rates up to 15 micro meter per hour White transparent diamond at growth rates up to 2 to 5 micro meter per hour. Accommodates substrates up to 4 inch diameter Produce CVD diamond with high thermal conductivity - 10 to 20 W/cm-K Operation at 10 to 100 Torr (1 to 100 Torr optional) Fully automated for CVD diamond growth for multi-recipe, multi-day operation AX5250 5kW Integrated Systems Comparison between 1.5kW and 5kW Microwave Diamond CVD Microwave Power 1.5kW 5kW Appropriate applications Semiconductor device (doping), Homo Hetero epitaxial films, FED* Thermal management (Heat Sink), Optical, Tools coating, FED*, SAW filters** Typical Growth rate 0.1 - 0.5 or 1 micron/hr 2 - 5 or 6 micron/hr Substrate Stage Heated Stage Water Cooled Stage Substrate Temp. Control Digital Setting Need shim replacement BEN*** OK OK Grain Size Small Small - large Sample size 50mm (2 inch)±15% uniformity (Guaranteed) 50mm (2 inch) ±15% uniformity (Guaranteed) Accommodating substrate 90mm (4 inch) 100mm (4 inch) Stage Option: No Yes (changeable to heating stage) Field Emission Display*, Surface Acoustic Wave**, Biased Enhanced Nucleation*** AX6500 8kW Microwave Plasma CVD System The AX6500 produces CVD diamond substrates suitable for most heat-spreading applications. Thick CVD diamond films, to over 3.5 inches in area, enable and expand applications such as laser diode mounts, multi-chip modules, surface acoustic wave devices, and high-power GaAs-based circuits. The AX6500 is designed for a production environment, with features including: easy loading, push-button operation, low maintenance and high uptime. The AX6500 high deposition rates allow relatively short deposition runs which increases manufacturing flexibility and response time. The AX6500 combines the most advanced microwave reactor design and high growth rate diamond deposition process into a turnkey system for pilot production of CVD diamond-coated tool inserts. In addition, the AX6500 is ideally suited for robotic tool handling in a production environment. Features: Deposits CVD diamond films at growth rates and uniformity necessary for practical, cost effective tooling applications Enables pilot production of CVD diamond-coated tools Provides a path to full-scale production Includes proprietary process knowledge which significantly shorten the user's learning curve. Easy to use Available with extensive after-sales service and support for high reliability and uptime AX6500 8kw Semi-Production Model AX6600 Microwave Plasma CVD System The AX6600 microwave plasma system is designed to operate with plasma at high power densities for large area, high deposition rate processes to meet the scale-up needs for diamond coated tool insert manufacturers. This complete turnkey system incorporates the latest microwave technology with computer control for ease of use. A large batch size, covering an area of 8 inches in diameter, can be processed all at once. It is a highly flexible design which can be operated in a wide range of power from 15kW to 100kW. Features: Large throughput Easy to use Production capability Computer-controlled, turnkey operation Reliable, stable reproducible,versatile operation Extensive after-sales process support and training Specifications of different models System Model AX5200 AX5250 AX6500 AX6600 Reactor Type Plasma Immersion Plasma Immersion Plasma Immersion Plasma Immersion Usage RD RD Production Production Stage Heated or Cooled Heated Cooled Cooled Cooled RF Power 1.5kW 5kW 8kW 60 - 100kW RF Frequency 2.45GHz 2.45GHz 2.45GHz 915MHz Typical Diameter 50mm 50mm 64mm dia. Thermal 100mm dia. Tools 200mm Max Diameter 100mm 100mm 125mm 300mm Typical Growth Rate 0.1-0.5μm/hr Up to 7μm/hr Up to 7μm/hr Up to 15μm/hr Typical Mass Rate 1-4mg/hr 60mg/hr 90mg/hr 1g/hr MPCVD FOR DIAMONDS PECVD system with reliable and versatile base and many options will solve almost any your RD problem. DIFS-ST10 system for MPCVD diamond film growth. Applications: tool coatings IR optical components heat spreaders for electronic devices surface acoustic waves devices biosensors, biocompatible coatings conductive diamond electrodes for electrochemistry ionizing radiation detectors (UV, X-ray, particles) MEMS The DIFS-ST10 microwave plasma CVD reactor is designed for polycrystalline diamond film and wafers deposition on large area substrates of various materials. Smooth nanocrystalline diamond films can be deposited as well. B asic parameters of the CVD system: Microwave power source: 5kW at 2.45 GHz. Number of feed gas channels: 4. Reaction gases: CH4, H2 (main); O2, Ar, N2, CO2 optional. Gas process pressure: 20-150 Torr. Gas consumption: 1000 sccm (typical). Substrate diameter: 3 inches. Substrate temperature: 700 – 1000°С (control with a pyrometer). Growth rate: 1-7 microns/hour. Diagnostic ports: 5 quartz windows. Vacuum chamber: stainless steel, water cooled. Full computer control. 5KW microwave plasma CVD system Reactor Parameters MW Power - 30 kW MW Frequency - 915 MHz Bell Jar Diameter – 10” (25 cm) Sample Holder Diameter – 6” (15 cm) Water Cooled Stage Optional Bias Voltage Temperature Control by IR-Pyrometer Optical Emission Spectroscopy Control Capable for long deposition hours Microwave plasma chemical vapor deposition chamber shown in action growing ultrananocrystalline diamond films at Argonne's Center for Nanoscale Materials. AsTex MWCVD MicroWave Plasma Chemical Vapour Deposition - Process gases: methane(CH4), hydrogen(H2), nitrogen(N2), argon(Ar), oxygen(O2) - Materials: Poly- and nanocrystalline diamond films (PCD and NCD) A Lamda Technologies microwave plasma-enhanced chemical vapor deposition (PECVD) instrument for the growth of nanocrystalline diamond is available in the cleanroom facility This system is an Electron-Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition (ECR-PECVD) chamber which we have used in research related to diamond and other carbon-based thin films, low-K dielectrics, and other thin films. This system uses a 2.45 GHz microwave source and a ring of rare earth magnets to create a plasma which is used to break down gaseous precursors and deposit films onto a variety of substrates. A 2.45 GHz, 1.5 kW, Microwave Electron Cyclotron Resonance (ECR) plasma processing facility has been set up to give a uniform deposition on a substrate area of around 100 mm, with features like substrate rotation, substrate heating, deposition under RF bias / pulse bias condition etc. The photo on the left shows the system undergoing tests. Diamond is grown from a plasma generated by a gaseous absorption of high power microwave energy Plasma Quest ECR Etch Tool 如果需要CVD金刚石膜设备，可以与我联系，可以根据要求进行配置，从而满足不同的科研，教学的要求。 热丝CVD或者各种功率大小的微波CVD均可以与我联系！喜欢CVD金刚石膜的朋友，可以看我博客中的其他文章。 --Options-- * Optical Emission Spectrometer * Remote Raman Spectrometer * Additional Gas Channels * Biasing capabilities * Temperature Measurement System (In-situ nucleation monitoring) * Turbo Pump ------------------------------------------------------------- 欢迎看看我的其他的博客内容： 金刚石薄膜的性质、制备及应用 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=231983 微波等离子体化学气相沉积 —— 一种制备金刚石膜的理想方法 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=232233 微波 CVD 金刚石膜产品及应用分析 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=402659 关于（微波法） CVD 金刚石膜产业化的看法 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=402561 Carnegie-Made Diamonds on Exhibit(CVD 金刚石产品展示） http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=386101 国外先进的微波等离子体 CVD 制备金刚石膜设备介绍 (Diamond) http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=384330 微波等离子体 CVD 制备金刚石膜 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=384313 Synthetic Diamonds http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=351296 微波等离子体同质外延修复金刚石的研究 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=232229 微波 CVD 金刚石薄膜用作 LED 散热片的制备 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=232213 提高金刚石薄膜与硬质合金基底之间附着力工艺的研究进展 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=231988 国外微波法制备金刚石膜设备介绍（ microwave plasma CVD diamond system introduction) http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogview=mefrom=spacepage=2 等离子体技术 —— 一种处理废弃物的理想方法 http://bbs.sciencenet.cn/home.php?mod=spaceuid=257140do=blogid=259594
据MIT新闻办公室报道，MIT经济学家Peter Diamond 与西北大学的Dale T. Mortensen 和伦敦经济学校的Christopher A. Pissarides共同赢得2010诺贝尔经济学奖。1963年Diamond在MIT获得博士学位。他的导师Robert M. Solow 1987也获得过诺贝尔经济学奖。Diamond毕业于Yele大学，进入MIT数学研究生学习后，转入攻读经济学博士学位。 Diamond是MIT经济学获得诺贝尔奖的第四人 另外3人是Paul A. Samuelson (1970), Franco Modigliani (1985) and Solow.还有8位在MIT获得博士学位的校友获得过诺贝尔经济学奖，他们是 George Akerlof PhD 66; Robert Aumann Phd 55 (in mathematics); Lawrence Klein PhD 44; Paul Krugman PhD 77; Robert Merton PhD 69; Robert Mundell PhD 56; Joseph Stiglitz PhD 66; and Oliver Williamson 55。.还有4位曾经在MIT任教过的教授获得过诺贝尔经济学奖，他们是: Robert Engle, Eric Maskin, Daniel McFadden and John Nash。 In an initial announcement Monday morning , the Nobel Foundation cited the three scholars in part for their analysis of markets with search frictions. Among many other avenues of research he has pursued in his career, Diamond helped develop studies from the late 1970s onward that examined the ways markets function over a period of time. This aspect of economic research search theory has been frequently applied to labor markets in the years since, in an attempt to see how the needs of individuals and employers are met. Diamond received his PhD from MIT in 1963 (his thesis adviser, Robert M. Solow, also won the Nobel Prize in Economic Sciences, in 1987). He returned to the Institute in 1966 and has remained a member of its faculty ever since. I am delighted and elated, Diamond told MIT News in a phone call Monday morning. He found out the news while bring driven home from the Boston airport an hour earlier by his wife and one of his two sons, having arrived on an overnight flight from San Francisco, the last leg of a long journey from New Zealand. Fortunately, I was sitting down, and I wasnt behind the wheel, Diamond joked in a press conference on the MIT campus Monday. Remarkably broad range of research MIT President Susan Hockfield heralded Diamonds accomplishments in introductory remarks at the press conference. As a professional economist, Peter has embraced the role of public citizen, conducting highly influential research over five decades on a remarkably diverse range of subjects, she said. In addition to his work on markets, Diamonds career has covered topics from public finance to taxation, Social Security, labor markets and behavior economics. By his own account, his career has had several phases. I think of myself as finding something interesting and important to work on, and working on it until, if youll excuse my economists expression, diminishing returns sets it, he said at the press conference. Then I look for some other area where I have the possibility of working something out that would be useful. Diamonds work modeling the uncertainties and imperfections (or frictions) of markets has been used in many ways, but his co-winners this year, Mortensen and Pissarides, are among the many economists who have applied it to labor markets, to see how individuals and prospective employers search for matches to their own needs. The aim of his studies of markets, Diamond said, was to pay much closer attention to how the economy plays out in real time than in the simplest abstractions of how markets work. In the labor market, it takes time for workers to find suitable jobs, it takes time for employees to find suitable workers, and that dynamic has a feedback into how wages are determined and how efficient the economy is. This subject, Diamond noted, is particularly relevant in the current economic situation. Its very important that people get back to work, because if theyre out of work too long, it breaks the connection to the labor market, and the economy functions more poorly thereafter, he said at his press conference. Diamonds fellow economists at MIT were delighted about his selection. It shows that sometimes the good guys do win, said a beaming Solow after Diamonds press conference, where he was one of many MIT economists who arrived on very short notice to attend the event. This is great day not only for Peter but for economics, and our department in particular, said Ricardo Caballero, the head of MITs Department of Economics. Peter is an economists economist. He was awarded the Nobel for his seminal work on search theory, the theory of the frictions and incentives involved in the process of matching, but he could have won it for his work on public debt and the overlapping generations model, or on optimal taxation with private information. One paper Diamond wrote in the 1960s, National Debt in a Neoclassical Growth Model, became a widely used model of public debt. In the early 1970s, Diamond published widely influential work on taxation, including a pair of 1971 papers on Optimal Taxation and Public Production, co-written with economist James Mirrlees that outlined what kind of tax regime leads to the highest production efficiency available in an economy. The research is part of a body of work that led to Mirrlees being awarded a 1996 Nobel Prize in economics. By the late 1970s, Diamond had begun long-running research into Social Security, when he first served on a government panel analyzing the topic. Since then Diamond has written many papers on social insurance and co-authored a 2005 book, Saving Social Security: A Balanced Approach , with Peter Orszag, the Obama administrations first director of the Office of Management and Budget. In Diamonds analysis, Social Security is hardly rushing toward imminent insolvency, but will likely need some increased taxes and some reduced benefits to maintain stability a few decades down the road. Diamond also refers to himself as a card-carrying behavioral economist and edited a recent book on the subject. The economy, the Fed and policy This spring, Diamond was nominated by President Barack Obama to serve on the Board of Governors of the Federal Reserve, the central bank of the United States. The nomination is still pending confirmation by the full U.S. Senate. At his press conference this morning, Diamond reaffirmed his interest in serving as a Fed governor, and in response to media questions, allowed himself a few comments on the current economic situation. Diamond believes the current unemployment rate more than 9 percent is not necessarily due to long-term structural shifts in the economy, as some observers have suggested. To discover that something is indeed structural would take time, Diamond said. I dont think that, with suitable macro policies, theres any reason to think that in time we wont go back to more normal levels of employment when the economy is doing well. Many of the policy actions of the current government, Diamond believes, have helped prevent a worse downturn. Were fortunate the Fed and the Treasury acted so dramatically to prevent our sliding into something as bad as the Great Depression, he said. The bailout of the large banks, as unpleasant as it is in contemplating, was absolutely essential for getting the economy going. The economic stimulus package of 2009, he said, has also helped reduce unemployment levels. Still, Diamond added, there are limits to the extent of necessary policy intervention. Im a believer in markets, Im a believer in capitalism, he said. I think the economy is very adaptive. Workers and employers adapt to what will work to help the economy function. A math student turns to economics After receiving his undergraduate degree from Yale, Diamond entered MIT as a graduate student in mathematics. He decided to switch to economics and completed his PhD thesis under the supervision of Solow. After beginning his teaching career at the University of California, Berkeley, Diamond returned to the MIT faculty in 1966 and has remained at the Institute ever since. He was promoted to full professor in 1970, and was named Institute Professor the highest honor awarded by MIT's faculty and administration in 1997. The MIT economics department has just been a perfect place for me, said Diamond. I stayed around because I couldnt imagine a better job. Diamond is held in high regard by other colleagues on campus. Of course Peter is an incredibly distinguished economist, said Deborah Fitzgerald, Kenan Sahin Dean of MITs School of Humanities, Arts, and Social Sciences. But people should know hes a dedicated member of the MIT community who has often worked behind the scenes to make this a better place. Diamond served on the Institute-wide search committee that selected Hockfield, and has lent his expertise to committees analyzing topics such as the Institutes employee retirement plan. Diamond has received numerous awards and honors, including Guggenheim and Fulbright fellowships. He is a fellow of the National Academy of Arts and Sciences, and a member of the National Academy of Sciences. Diamond has been a visiting scholar at Cambridge University, Oxford University and Harvard University, among other institutions. Diamond has served as chair of MITs Department of Economics, and had a term as president of the American Economic Association in 2003. Diamond is the fourth person to win the Nobel while a member of MITs Department of Economics. The others are Paul A. Samuelson (1970), Franco Modigliani (1985) and Solow. Eight other scholars have won the Nobel Prize in Economics having received a degree from MIT, six of whom have received doctorates from MITs Department of Economics: George Akerlof PhD 66; Robert Aumann Phd 55 (in mathematics); Lawrence Klein PhD 44; Paul Krugman PhD 77; Robert Merton PhD 69; Robert Mundell PhD 56; Joseph Stiglitz PhD 66; and Oliver Williamson 55. An additional four people have gone on to win the Nobel in economics having previously taught at MIT: Robert Engle, Eric Maskin, Daniel McFadden and John Nash. http://web.mit.edu/newsoffice/2010/nobel-diamond.html
标签: Diamond
