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Pressure- and temperature-induced insertion of N₂, O₂, and CH₄ to Ag-natrolite
Donghoon Seoung,Hyeonsu Kim,Pyosang Kim,Yongmoon Lee 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
This paper aimed to investigate the structural and chemical changes of Ag-natrolite in the presence of different pressure transmitting mediums (PTMs), such as N₂, O₂, and CH₄, up to ca. 8 GPa and 250℃ using in-situ synchrotron X-ray powder diffraction and Rietveld refinement. Pressure-induced insertion occurs in two stages in the case of N₂ and O₂ runs, as opposed to the CH4 run. First changes of the unit cell volume in N₂, O₂ and CH4 runs are observed at 0.88(5) GPa, 1.05(5) GPa and 1.84(5) GPa with increase of 5.7(1)%, 5.5(1)% and 5.7(1)%, respectively. Subsequent volume changes of Ag-natrolite in the presence of N2 and O2 appear at 2.15(5) GPa and 5.24(5) GPa with a volume increase of 0.8(1)% and a decrease of 3.0(1)%, respectively. The bulk moduli of the Ag-NAT change from 42(1) to 49(7), from 38(1) to 227(1), and from 49(3) to 79(2) in the case of N₂, O₂, and CH₄ runs, respectively, revealing that the Ag-NAT becomes more incompressible after each insertion of PTM molecules. The shape of the channel window of the Ag-NAT changes from elliptical to more circular after the uptake of N₂, O₂, and CH₄. Overall, the experimental results of Ag-NAT from our previous data and this work establishes that the onset pressure exponentially increases with the molecular size. The unit cell volumes of the expanded (or contracted) phases of the Ag-NAT have a linear relationship and limit to maximally expand and contract upon pressure-induced insertion.
Seoung, Donghoon,Lee, Yongmoon,Kao, Chi-Chang,Vogt, Thomas,Lee, Yongjae American Chemical Society 2015 Chemistry of materials Vol.27 No.11
<P>In situ high pressure X-ray powder diffraction studies of natrolite (NAT) containing the divalent extra-framework cations (EFC) Sr<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Pb<SUP>2+</SUP>, and Cd<SUP>2+</SUP> reveal that they can be superhydrated in the presence of water. In the case of Ca-NAT, Sr-NAT, and Pb-NAT pressure-induced hydration (PIH) inserts 40 H<SUB>2</SUB>O/unit cell into the zeolite compared to 32 in superhydrated natrolites containing monovalent EFC. Cd-NAT is superhydrated in one step to a zeolite containing 32 H<SUB>2</SUB>O/unit cell. PIH of Ca-NAT and Sr-NAT occurs in two steps. During PIH of Pb-NAT three distinct steps have been observed. The excess H<SUB>2</SUB>O in natrolites with divalent EFC are accommodated on sites no longer required for charge compensation. Two distinct families with ordered and disordered EFC–water topologies have been found. Our work established the importance of both size and charge of the EFC in PIH.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-11/acs.chemmater.5b00506/production/images/medium/cm-2015-00506p_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b00506'>ACS Electronic Supporting Info</A></P>
성동훈(Donghoon Seoung),김표상(Pyosang Kim),김현수(Hyeonsu Kim),이용문(Yongmoon Lee) 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
압력은 열역학의 중요 요소 중 하나로, 온도와 마찬가지로 물질의 물리적, 화학적 속성을 변화시키고 상전이를 유도한다. 지구내부 모사를 통한 실험적 접근을 위해 압력과 온도는 동시에 고려되어야 하며, 다이아몬드 고압기와 방사광가속기의 발전은 이를 실시간으로 관측할 수 있는 실험적 조건을 제공하고 있다. 국내의 포항 가속기 연구소는 고온/고압 실험용 전용빔라인을 구축하고 있지는 않으나, 약 4개의 빔라인에서 고압 X-선 회절 실험이 가능한 상태이다. 하지만, 실시간 고온/고압 동시 수반 실험은 장치개발의 한계와 검출기 분해능의 제한으로 인해 낮은 대칭의 결정계를 가지거나 격자상수가 큰 광물 및 다종의 광물이 섞인 암석시료에 대해 실시간 관측이 힘든 상태이다. 본 연구진은 실시간 온도/압력 변화 실험을 위해 다이아몬드 고압기에 장착될 소형 가속기를 자체 개발하여, 상압 – 약 100 혬(약 10,000 bar) 까지의 압력과 상온 – 약 1200 K까지 온도를 동시에 원격으로 조절하며 실험이 가능하게 하였으며, 방사광 가속기 빔라인 내부의 검출기를 대체, 변형하여 기존까지 약 0.05°의 반치폭과 회절 peak당 5개 이내의 관측점을 나타내던 회절 데이터를 약 0.02°의 반치폭과 10개 이내의 관측점으로 약 2배 이상 향상시킬 수 있음을 확인하였다. 이러한 새로운 장치개발을 통해 기존장비로 불가능 하던 복잡한 광물 및 암석에 대한 실시간 연구가 가능할 것으로 생각되며, 이러한 장치들을 차세대가속기와 전용빔 라인 구축을 통해 새로운 실험적 접근이 가능할 것으로 생각된다.
A role for subducted super-hydrated kaolinite in Earth’s deep water cycle
Hwang, Huijeong,Seoung, Donghoon,Lee, Yongjae,Liu, Zhenxian,Liermann, Hanns-Peter,Cynn, Hyunchae,Vogt, Thomas,Kao, Chi-Chang,Mao, Ho-Kwang Nature Publishing Group UK 2017 Nature geoscience Vol.10 No.12
Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H<SUB>2</SUB>O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.
Pressure-induced metathesis reaction to sequester Cs.
Im, Junhyuck,Seoung, Donghoon,Lee, Seung Yeop,Blom, Douglas A,Vogt, Thomas,Kao, Chi-Chang,Lee, Yongjae American Chemical Society 2015 Environmental science & technology Vol.49 No.1
<P>We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag(+) by Cs(+) in the natrolite framework forming Cs16Al16Si24O80·16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6·H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic (137)Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.</P>
Im, Junhyuck,Seoung, Donghoon,Hwang, Gil Chan,Jun, Jong Won,Jhung, Sung Hwa,Kao, Chi-Chang,Vogt, Thomas,Lee, Yongjae American Chemical Society 2016 Chemistry of materials Vol.28 No.15
<P>Pressure-dependent structural and chemical changes of the metal organic framework (MOF) compound MIL-47(V) have been investigated up to 3 GPa using different pore-penetrating liquids as pressure transmitting media (PTM). We find that at 0.3(1) GPa the terephthalic acid (TPA) template molecules located in the narrow channels of the as synthesized MIL-47(V) are selectively replaced by methanol molecules from a methanol ethanol water mixture and form a methanol inclusion complex. Further pressure increase leads to a gradual narrowing of the channels up to 1.9(1) GPa, where a second irreversible insertion of methanol molecules leads to more methanol molecules being inserted into the pores. After pressure release methanol molecules remain within the pores and can be removed only after heating to 400 degrees C. In contrast, when MIL-47(V) is compressed in water, a reversible replacement of the TPA by H2O molecules takes place near 1 GPa. The observed structural and chemical changes observed in MIL-47(V) demonstrate unique high pressure chemistry depending on the size and type of molecules present in the liquid PTM. This allows postsynthetic nonthermal pressure-induced removal and insertion of organic molecules in MOFs forming novel and stable phases at ambient conditions.</P>