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Reconstructing phase diagrams from local measurements via Gaussian processes:mapping the temperature-composition space toconfidence

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npj Computational Materials 2018年第1期4卷 451-461页

作者： Dhiren K.Pradhan Shalini Kumari Evgheni Strelcov Dillip K.Pradhan Ram S.Katiyar Sergei V.Kalinin Nouamane Laanait Rama K.Vasudevan Department of Physics and Institute of Functional Nanomaterials University of Puerto Rico San Juan PR 00936 USA Institute for Research in Electronics and Applied Physics University of MarylandCollege ParkMD 207425USA Department of Physics&Astronomy National Institute of TechnologyRourkela 769008India Center for Nanophase Materials Sciences Oak Ridge National laboratory Oak Ridge TN 37831 USA Institute for Functional Imaging of Materials Oak Ridge National LaboratoryOak RidgeTN 37831USA geophysical laboratory Carnegie Institution for ScienceWashingtonDC 20015USA Department of Physics and Astronomy West Virginia UniversityMorgantownWV 26506USA

We show the ability to map the phase diagram of a relaxor-ferroelectric system as a function of temperature and composition through local hysteresis curve acquisition,with the voltage spectroscopy data being used as a proxy for the(unknown)microscopic state or thermodynamic parameters of *** the discrete nature of the measurement points,we use Gaussian processes to reconstruct hysteresis loops in temperature and voltage space,and compare the results with the raw data and bulk dielectric spectroscopy *** results indicate that the surface transition temperature is similar for all but one composition with respect to the *** clustering algorithms,we recreate the main features of the bulk diagram,and provide statistical confidence estimates for the reconstructed phase transition *** validate the method by using Gaussian processes to predict hysteresis loops for a given temperature for a composition unseen by the algorithm,and compare with *** techniques can be used to map phase diagrams from functional materials in an automated fashion,and provide a method for uncertainty quantification and model selection.

关键词： materials hysteresis phase

FeH_(x)的稳定性以及氢在地球核-幔边界的传输

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Science Bulletin 2023年第14期68卷 1567-1573,M0004页

作者：何宇 Duck Young Kim Viktor V.Struzhkin Zachary M.Geballe Vitali Prakapenka 毛河光 Key laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China Center for High Pressure Science and Technology Advanced Research Shanghai 201203China Division of Advanced Nuclear Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea geophysical laboratory Carnegie InstitutionWashington DC 20015USA Center for Advanced Radiation Sources University of ChicagoChicago IL 60637USA

地球内部水和铁的反应可以生成铁-氢合金.研究铁-氢合金可以增进对地球内部氢传输的认知.我们通过高压实验和第一性原理计算的方法,对高温高压下具有面心立方结构(fcc)FeH_(x)(x≤1)的相稳定性、密度、氢的输运性质和熔点进行了系统研究... 详细信息

地球内部水和铁的反应可以生成铁-氢合金.研究铁-氢合金可以增进对地球内部氢传输的认知.我们通过高压实验和第一性原理计算的方法,对高温高压下具有面心立方结构(fcc)FeH_(x)(x≤1)的相稳定性、密度、氢的输运性质和熔点进行了系统研究,证实了FeH_(x)在165 GPa时的稳定性.通过高温的分子动力学模拟,发现FeH_(x)在下地幔温压下转变为超离子态.在超离子态FeH_(x)中,氢离子快速扩散表现出类似流体的性质,扩散系数高达3.710^(-4)cm~2s^(-1).与超离子态冰类似,氢离子的快速扩散可以导致体系的熵增,使其的熔化温度增加.FeH_(x)可以将氢从地幔传输到外地核,使得外核成为H的潜在储库,并在核-幔边界上方留下了富氧的块状结构.

关键词：离子态第一性原理计算氢离子相稳定性地球内部熔化温度高压实验分子动力学模拟

PRECURSOR DYNAMICS OF Pb(B_(1/2)B0_(1/2))O_(3)-TYPE RELAXOR FERROELECTRICS STUDIED BY BROADBAND MICRO-BRILLOUIN SCATTERING

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Journal of Advanced Dielectrics 2012年第2期2卷 74-84页

作者： SEIJI KOJIMA MUHTAR AHART VENKATASUBRAMANIAN SIVASUBRAMANIAN ALEXEI.A.BOKOV ZUO-GUANG.YE PAS University of Tsukuba TsukubaIbaraki 305-8573Japan geophysical laboratory carnegie institution of washington washington dc 20015 USA Indira Gandhi Centre for Atomic Research Kalpakkam-603102 India Department of Chemistry and 4D LABS Simon Fraser University Burnaby BCCanada V5A 1S6

This paper reviews the recent progress in the understanding of the dynamics of Pb(B_(1/2)B0_(1/2))O_(3)-type relaxor ferroelectrics using of broadband micro-Brillouin scattering spectroscopy,which covers a large frequency range from 1 to 1000 GHz by a tandem multi-pass FabryPerot inter*** contrast to Pb(B_(1/3)B0_(2/3))O_(3)-type relaxors,there is no frustration on the B-site of perovskite structure and the degree of order of B-site cations depends on heat *** softening of sound velocity and an intense central peak are observed above the Curie temperature TC owing to the polarization°uctuations in polar nanoregions(PNRs).Unlike the Pb(B_(1/3)B0_(2/3))O_(3)relaxors,Pb(B_(1/2)B'_(1/2))O_(3)does not undergoes a typical diffuse phase transition without lead vacancies on A-site which enhances *** the(1-x)Pb(B_(1/2)B'_(1/2))O_(3-x)PbTiO_(3)solid solutions,the long range polar order increases as the PbTiO_(3)content ***,a central peak owing to dynamic PNRs still remains even for the composition near the MPB,and a critical slowing down is clearly observed in the vicinity of TC.

关键词： Ferroelectric relaxor elastic anomaly central peak Brillouin scattering

Superconductivity in La and Y hydrides: Remaining questions to experiment and theory

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Matter and Radiation at Extremes 2020年第2期5卷 62-72页

作者： Viktor Struzhkin Bing Li Cheng Ji Xiao-Jia Chen Vitali Prakapenka Eran Greenberg Ivan Troyan Alexander Gavriliuk Ho-kwang Mao Center for High Pressure Science and Technology Advanced Research ShanghaiChina geophysical laboratory Carnegie Institution of WashingtonWashingtonDC 20015USA Center for Advanced Radiation Sources The University of Chicago5640 South Ellis AvenueChicagoIllinois 60637USA Federal Scientific Research Center Crystallography and Photonics Russian Academy of Sciences59 Leninskii Pr-tMoscow 119333Russia Institute for Nuclear Research Russian Academy of SciencesMoscowTroitsk 108840Russia

Recent reports of the superconductivity in hydrides of two different families(covalent lattice,as in SH3 and clathrate-type H-cages containing La and Y atoms,as in LaH10 and YH6)have revealed new families of high-Tc materials with Tc’s near room temperature *** findings confirm earlier expectations that hydrides may have very high Tc’s due to the fact that light H atoms have very high vibrational frequencies,leading to high Tc values within the conventional Bardeen–Cooper–Schrieffer phonon mechanism of ***,as is pointed out by Ashcroft,it is important to have the metallic hydrogen“alloyed”with the elements added to *** concept of a metallic alloy containing a high concentration of metal-like hydrogen atoms has been instrumental in finding new high-Tc *** new superhydride“roomtemperature”superconductors are stabilized only at very high pressures above 100 GPa,making the experimental search for their superconducting properties very *** will review the current experimental and theoretical results for LaH10−x and YH6−x superhydrides.

关键词： hydrides alloy metallic

铅铝硅酸盐锰钡矿的晶体化学——一种新型的含八面体硅的高压合成相

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地质科学译丛 1996年第4期13卷 1-3页

作者： RobertT.Downs 王福盛 geophysical laboratory and Center for High Pressure Research Carnegie Institution of Washington.5251 Broad Branch Road NW Washington.DC 20015-1305 USA

在压力16.5GPa和温度1450℃条件下合成了Pb_(0.8)Al_(1.6)Si_(2.4)O_8铅铝硅酸盐锰钡矿的单晶。晶体属四方晶东[空间群:I4,Z=2,a=9.414(3)A,c=2.750(3)A,V=243.7(3)A^3]。Si和Al无序地占据八面体位置。在结构模型中,Pb占据两个原子位置,一个原子位置在四次轴上,另一个原子的分布脱离了四次轴。Post和Burnham(1986)已预测过这一特征,但在此之前尚未观察到。

关键词：铅铝硅酸盐锰矿钡矿八面体硅晶体化学

Elastic properties of Fe-bearing Akimotoite at mantle conditions: Implications for composition and temperature in lower mantle transition zone

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Fundamental Research 2022年第4期2卷 570-577页

作者： Yajie Zhao Zhongqing Wu Shangqin Hao Wenzhong Wang Xin Deng Jian Song laboratory of Seismic and Physics of Earth's Interior School of Earth and Space SciencesUniversity of Seience and Technology of ChinaHefei 230026China National geophysical Observatory at Mengcheng University of Science and Technology of ChinaHefeiChina CAS Center for Excllence in Comparative Planetology UsTcHefei 230026China Institute of Geophysics and Planetary Physics Scripps Institution of OeanographyUniversiy of California San DiegoLa Jolla 92092CAUSA Departnent of Earth Sciences University CollegeLondonLondon WCIE6BTUnited Kingdom Earth and Planets laboratory Carnegie Instution for ScienceWashingtonDC 20015UsA

The pyrolite model,which can reproduce the upper-mantle seismic velocity and density profiles,was suggested to have significantly lower velocities and density than seismic models in the lower mantle transition zone(MTZ).This argument has been taken as mineral-physics evidence for a compositionally distinct lower ***,previous studies only estimated the pyrolite velocities and density along a one-dimension(1D)geotherm and never considered the effect of lateral temperature *** the majorite-perovskite-akimotoite triple point is close to the normal mantle geotherm in the lower MTz,the lateral low-temperature anomaly can result in the presence of a significant fraction of akimotoite in pyrolitic lower *** this study,we reported the elastic properties of Fe-bearing akimotoite based on first-principles *** with literature data,we found that the seismic velocities and density of the pyrolite model can match well those in the lower MTZ when the lateral temperature heterogeneity is modeled by a Gaussian distribution with a standard deviation of~10o K and an average temperature of dozens of K higher than the triple point of *** suggest that a harzburgite-rich lower MTZ is not required and the whole mantle convection is expected to be more favorable globally.

关键词： Akimotoite Pyrolite Elasticmoduli Temperature heterogeneity Gaussian distribution

Two-temperature warm dense hydrogen as a test of quantum protons driven by orbital-free density functional theory electronic forces

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Matter and Radiation at Extremes 2020年第6期5卷 48-59页

作者： Dongdong Kang Kai Luo Keith Runge S.B.Trickey Department of Physics National University of Defense TechnologyChangshaHunan 410073People’s Republic of China Earth and Planets laboratory Carnegie Institution of Washington5251 Broad Branch Rd.NWWashingtonDC 20015USA Department of Materials Science and Engineering University of ArizonaTucsonArizona 85721USA Quantum Theory Project Department of Physics and Department of ChemistryUniversity of FloridaGainesvilleFlorida 32611USA

We consider a steady-state(but transient)situation in which a warm dense aggregate is a two-temperature system with equilibrium electrons at temperature T_(e),ions at T_(i),and T_(e)≠T_(i).Such states are achievable by pump–probe *** warm dense hydrogen in such a twotemperature situation,we investigate nuclear quantum effects(NQEs)on structure and thermodynamic properties,thereby delineating the limitations of ordinary ab initio molecular *** use path integral molecular dynamics(PIMD)simulations driven by orbital-free density functional theory(OFDFT)calculations with state-of-the-art noninteracting free-energy and exchange-correlation functionals for the explicit temperature *** calibrate the OFDFT calculations against conventional(explicit orbitals)Kohn–Sham *** find that when the ratio of the ionic thermal de Broglie wavelength to the mean interionic distance is larger than about 0.30,the ionic radial distribution function is meaningfully affected by the inclusion of ***,NQEs induce a substantial increase in both the ionic and electronic *** confirms the importance of NQEs for highly accurate equation-of-state data on highly driven *** Te>20 kK,increasing Te in the warm dense hydrogen has slight effects on the ionic radial distribution function and equation of state in the range of densities *** addition,we confirm that compared with thermostatted ring-polymer molecular dynamics,the primitive PIMD algorithm overestimates electronic pressures,a consequence of the overly localized ionic description from the primitive scheme.

关键词： orbital quantum electronic

Disproportionation of(Mg,Fe)SiO3 in Earth's deep lower mantle

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Disproportionation of(Mg,Fe)SiO3 in Earth's deep lower mantl...

How Depth is the Tibetan Chromite: Experimental Study

2014年中国地球科学联合学术年会——专题9：深部地幔物质成分与结构探测

作者： Li Zhang Yue Meng Wenge Yang Lin Wang Wendy L.Mao Qiao-Shi Zeng Jong Seok Jeong Andrew J.Wagner K.Andre Mkhoyan Wenjun Liu Ruqing Xu Ho-kwang Mao Center for High Pressure Science and Technology Advanced Research geophysical laboratory Carnegie InstitutionWashington DC 20015 USA High Pressure Collaborative Access Team Geophysical Laboratory Carnegie InstitutionArgonne IL 60439 USA High Pressure Synergetic Consortium Geophysical Laboratory Carnegie InstitutionArgonne IL 60439 USA Geological and Environmental Sciences Stanford UniversityStanford CA 94305 USA Photon Science SLAC National Accelerator LaboratoryMenlo Park CA 94025 USA Department of Chemical Engineering and Materials Science University of MinnesotaMinneapolis MN 55455 USA Advanced Photon Source Argonne National LaboratoryArgonne IL 60439 USA

The lower mantle extends over the enormous pressure(P)-temperature(T)range from the bottom of the transition zone at 670 km depth(24 GPa)to the core-mantle boundary(CMB)at 2900km(136 GPa).Seismic observations suggested a discontinuity beyond000 kilometers depth(1).Our recent study using laser-heated diamond anvil cell(DAC)technology coupled with synchrotron x-ray diffraction(XRD)has demonstrated the disproportionation reaction of(Mg,Fe)SiO3 perovskite(pv)to a nearly Fe-free pv and an Fe-rich H-phase at95 to 101 GPa and 2200 to 2400 K(2).Therefore,we suggest that(Mg,Fe)SiO3 pv may not be the major silicate throughout the lower mantle down to the top of the D″*** have studied the P-T-x relations of pv,ppv,and the H-phase to the core mantle boundary *** a two-phase or three-phase mixed XRD

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Acta Geologica Sinica(English Edition) 2015年第A2期89卷 35-35页

作者： JIN Zhenmin WU Yao XU Mengjing FEI Yingwei Paul T. ROBINSON State Key Lab of Geological Processes and Mineral Resources China University ofGeosciences Wuhan 430074China geophysical laboratory Carnegie Institution of Washington Washington DC 20015 USA Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

Podiform chromitites are generally lenticular bodies of massive to disseminated chromite typically hosted in mantle peridotites in ophiolites. Most such chromitites are surrounded by envelopes of dunite, a few centimeters to a few meters wide. Based on their textures and compositions, podiform chromitites have been interpreted as magmatic rocks formed as partial melting of mantle peridotite under low-pressure conditions in the upper mantle or by magma mingling and melt-rock reaction.

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