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S. Saxena
Center for the Study of Matter at Extreme Conditions, Department of Mechanical and Materials Engineering, College of Engineering and Computing, Florida International University, Miami, FL 33199, USA

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Journal article
Published: 14 October 2019 in Processes
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Iron ore was studied as a CO2 absorbent. Carbonation was carried out by mechanochemical and high temperature–high pressure (HTHP) reactions. Kinetics of the carbonation reactions was studied for the two methods. In the mechanochemical process, it was analyzed as a function of the CO2 pressure and the rotation speed of the planetary ball mill, while in the HTHP process, the kinetics was studied as a function of pressure and temperature. The highest CO2 capture capacities achieved were 3.7341 mmol of CO2/g of sorbent in ball milling (30 bar of CO2 pressure, 400 rpm, 20 h) and 5.4392 mmol of CO2/g of absorbent in HTHP (50 bar of CO2 pressure, 100 °C and 4 h). To overcome the kinetics limitations, water was introduced to all carbonation experiments. The calcination reactions were studied in Argon atmosphere using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. Siderite can be decomposed at the same temperature range (100 °C to 420 °C) for the samples produced by both methods. This range reaches higher temperatures compared with pure iron oxides due to decomposition temperature increase with decreasing purity. Calcination reactions yield magnetite and carbon. A comparison of recyclability (use of the same material in several cycles of carbonation–calcination), kinetics, spent energy, and the amounts of initial material needed to capture 1 ton of CO2, revealed the advantages of the mechanochemical process compared with HTHP.

ACS Style

Eduin Yesid Mora Mendoza; Armando Sarmiento Santos; Enrique Vera López; Vadym Drozd; Andriy Durygin; Jiuhua Chen; Surendra K. Saxena. Siderite Formation by Mechanochemical and High Pressure–High Temperature Processes for CO2 Capture Using Iron Ore as the Initial Sorbent. Processes 2019, 7, 735 .

AMA Style

Eduin Yesid Mora Mendoza, Armando Sarmiento Santos, Enrique Vera López, Vadym Drozd, Andriy Durygin, Jiuhua Chen, Surendra K. Saxena. Siderite Formation by Mechanochemical and High Pressure–High Temperature Processes for CO2 Capture Using Iron Ore as the Initial Sorbent. Processes. 2019; 7 (10):735.

Chicago/Turabian Style

Eduin Yesid Mora Mendoza; Armando Sarmiento Santos; Enrique Vera López; Vadym Drozd; Andriy Durygin; Jiuhua Chen; Surendra K. Saxena. 2019. "Siderite Formation by Mechanochemical and High Pressure–High Temperature Processes for CO2 Capture Using Iron Ore as the Initial Sorbent." Processes 7, no. 10: 735.

Original paper
Published: 22 December 2017 in Monatshefte für Chemie - Chemical Monthly
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A potential, environmentally friendly production process for refractory metal carbides is investigated whereby methane is used as the reducing agent for many oxides. Using the most recently available thermodynamic data, the optimum conditions for production of binary and ternary carbides, together with hydrogen-rich gases, have been calculated. Our thermodynamic analysis indicates that methane reduction of the oxides is both economic and helpful in reducing carbon emissions. The investigations show that hot syngas from one reactor may be re-used as input to other reactors to minimize the use of energy in carbide production.

ACS Style

Surendra Saxena; Philip Spencer; Vadym Drozd. An alternative, environmentally friendly production process for refractory metal carbides and syngas using methane reduction of the oxide ores. Monatshefte für Chemie - Chemical Monthly 2017, 149, 411 -422.

AMA Style

Surendra Saxena, Philip Spencer, Vadym Drozd. An alternative, environmentally friendly production process for refractory metal carbides and syngas using methane reduction of the oxide ores. Monatshefte für Chemie - Chemical Monthly. 2017; 149 (2):411-422.

Chicago/Turabian Style

Surendra Saxena; Philip Spencer; Vadym Drozd. 2017. "An alternative, environmentally friendly production process for refractory metal carbides and syngas using methane reduction of the oxide ores." Monatshefte für Chemie - Chemical Monthly 149, no. 2: 411-422.

Original articles
Published: 10 November 2016 in Materials and Manufacturing Processes
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Laser-assisted processing and in-situ characterization of a Ni0.7-Al0.1235-Co0.15-Ti0.0265 alloy were carried out under a range of simultaneous hydrostatic high pressures of ∼30 GPa and high temperature conditions ∼2000°C using a laser-assisted heating in diamond anvil cell with synchrotron X-ray micro-diffraction. The characterization of the microstructure and X-ray diffraction analysis at ambient conditions confirmed the formation of the cuboids of ordered γ′ phase in the disordered γ matrix. The isothermal bulk modulus (B0) and its first-order derivative (B0’) of the alloy were determined to be B0 = 123 ± 9 GPa and B0’ = 5.7 ± 2.8. The in-situ characterization of the alloy at high temperatures under high pressures revealed that the γ′ phase transforms into the tetragonaly distorted D022-type structure. This transformation is similar to the transformation that occurs in the ordered Ni3Al, responsible for the improved strength at high temperatures. High pressure was found to increase the onset temperature of the structural distortion. The pressure–temperature phase diagram of the Ni0.7-Al0.1235-Co0.15-Ti0.0265 up to ∼30 GPa and ∼2000°C was determined and is reported here.

ACS Style

Selva Vennila Raju; Rostislav Hrubiak; Vadym Drozd; Surendra Saxena. Laser-assisted processing of Ni-Al-Co-Ti under high pressure. Materials and Manufacturing Processes 2016, 32, 1606 -1611.

AMA Style

Selva Vennila Raju, Rostislav Hrubiak, Vadym Drozd, Surendra Saxena. Laser-assisted processing of Ni-Al-Co-Ti under high pressure. Materials and Manufacturing Processes. 2016; 32 (14):1606-1611.

Chicago/Turabian Style

Selva Vennila Raju; Rostislav Hrubiak; Vadym Drozd; Surendra Saxena. 2016. "Laser-assisted processing of Ni-Al-Co-Ti under high pressure." Materials and Manufacturing Processes 32, no. 14: 1606-1611.

Journal article
Published: 11 November 2015 in Calphad
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Earth's core is believed to consist of a solid inner core and an outer liquid core. Since the inner core is mostly solid iron, most geophysical work has focused on melting of pure iron at core conditions. The inner core density is well matched with seismological data if some S is added to iron. The available phase equilibrium experimental data in the binary Fe–S system to pressures as high as ~200 GPa is used to create a thermodynamic database extending to core pressures that can be used to calculate the inner core density if S were the only other constituent. Such a calculation gives the maximum temperature of the solid inner core as 4428 (±500) K (363.85 GPa, density=13.09 g/cm3) with a sulfur content of ~15 wt%. To be consistent with the seismically determined density, the outer liquid core requires mixing of yet another light element or elements; both oxygen and carbon are suitable.

ACS Style

S. Saxena; G. Eriksson. Thermodynamics of Fe–S at ultra-high pressure. Calphad 2015, 51, 202 -205.

AMA Style

S. Saxena, G. Eriksson. Thermodynamics of Fe–S at ultra-high pressure. Calphad. 2015; 51 ():202-205.

Chicago/Turabian Style

S. Saxena; G. Eriksson. 2015. "Thermodynamics of Fe–S at ultra-high pressure." Calphad 51, no. : 202-205.

Journal article
Published: 01 September 2015 in Journal of Physics and Chemistry of Solids
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ACS Style

Surendra K. Saxena; Gunnar Eriksson. Thermodynamics of iron at extreme pressures and temperatures. Journal of Physics and Chemistry of Solids 2015, 84, 70 -74.

AMA Style

Surendra K. Saxena, Gunnar Eriksson. Thermodynamics of iron at extreme pressures and temperatures. Journal of Physics and Chemistry of Solids. 2015; 84 ():70-74.

Chicago/Turabian Style

Surendra K. Saxena; Gunnar Eriksson. 2015. "Thermodynamics of iron at extreme pressures and temperatures." Journal of Physics and Chemistry of Solids 84, no. : 70-74.

Journal article
Published: 27 November 2012 in Catalysts
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We have studied the effect of ball milling on alumina mixed nickel, magnetite and Raney nickel on the reaction: 2NaOH(s) + CO (g) = Na2CO3 (s)+ H2 (g) and determined the optimum particle size for the catalysts. The best performance was shown by a 2 h ball milled Raney nickel with average crystallite size of 209 Å. This reaction serves the dual purpose of carbon sequestration and yielding hydrogen gas.

ACS Style

Sushant Kumar; Vadym Drozd; Surendra K. Saxena. Catalytic Studies of Sodium Hydroxide and Carbon Monoxide Reaction. Catalysts 2012, 2, 532 -543.

AMA Style

Sushant Kumar, Vadym Drozd, Surendra K. Saxena. Catalytic Studies of Sodium Hydroxide and Carbon Monoxide Reaction. Catalysts. 2012; 2 (4):532-543.

Chicago/Turabian Style

Sushant Kumar; Vadym Drozd; Surendra K. Saxena. 2012. "Catalytic Studies of Sodium Hydroxide and Carbon Monoxide Reaction." Catalysts 2, no. 4: 532-543.

Journal article
Published: 01 June 2012 in Journal of Applied Physics
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ACS Style

Rostislav Hrubiak; Vadym Drozd; Ali Karbasi; Surendra K. Saxena. High P-T phase transitions and P-V-T equation of state of hafnium. Journal of Applied Physics 2012, 111, 112612 .

AMA Style

Rostislav Hrubiak, Vadym Drozd, Ali Karbasi, Surendra K. Saxena. High P-T phase transitions and P-V-T equation of state of hafnium. Journal of Applied Physics. 2012; 111 (11):112612.

Chicago/Turabian Style

Rostislav Hrubiak; Vadym Drozd; Ali Karbasi; Surendra K. Saxena. 2012. "High P-T phase transitions and P-V-T equation of state of hafnium." Journal of Applied Physics 111, no. 11: 112612.

Journal article
Published: 18 March 2012 in CheM
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ACS Style

Sushant Kumar; Vadym Drozd; Surendra Saxena. A Catalytic Study of the Modified Coal Gasification Process to Produce Clean Hydrogen Gas. CheM 2012, 2, 20 -26.

AMA Style

Sushant Kumar, Vadym Drozd, Surendra Saxena. A Catalytic Study of the Modified Coal Gasification Process to Produce Clean Hydrogen Gas. CheM. 2012; 2 (1):20-26.

Chicago/Turabian Style

Sushant Kumar; Vadym Drozd; Surendra Saxena. 2012. "A Catalytic Study of the Modified Coal Gasification Process to Produce Clean Hydrogen Gas." CheM 2, no. 1: 20-26.

Short communication
Published: 30 April 2011 in International Journal of Hydrogen Energy
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Hydrogen is mostly produced by the Steam Methane Reforming (SMR) reaction which adds many tonnes of carbon emissions to the environment for each tonne of hydrogen. A modified scheme for carbon-emission free production of hydrogen, which involves sodium hydroxide, methane and steam, has been explored here. The modification of the SMR reaction is CH4 + 2NaOH + H2O = Na2CO3 + 4H2 The modified reaction has several advantages: it does not require catalysis, the temperature of reaction is considerably reduced and the products are industrially important. By this process, we can produce hydrogen without any carbon dioxide emission as shown in this theoretical and experimental study. The reaction has been studied in the temperature range of 873–1073 K in an open configuration for 30 min and at various methane and constant water vapor flow. It is determined that at a methane flow rate of 25 ml/min the reaction is 98% complete at 873 K.

ACS Style

Surendra Saxena; Sushant Kumar; Vadym Drozd. A modified steam-methane-reformation reaction for hydrogen production. International Journal of Hydrogen Energy 2011, 36, 4366 -4369.

AMA Style

Surendra Saxena, Sushant Kumar, Vadym Drozd. A modified steam-methane-reformation reaction for hydrogen production. International Journal of Hydrogen Energy. 2011; 36 (7):4366-4369.

Chicago/Turabian Style

Surendra Saxena; Sushant Kumar; Vadym Drozd. 2011. "A modified steam-methane-reformation reaction for hydrogen production." International Journal of Hydrogen Energy 36, no. 7: 4366-4369.

Journal article
Published: 01 October 2010 in Elements
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The validity and usefulness of thermodynamic models commonly used to model the physical and chemical properties of Earth's interior at high to ultrahigh pressures and their associated geophysical databases are discussed. All calorimetric data used in these models must have the quality of fitting to experimental phase diagrams derived from work not only at high temperatures and pressures but also under ambient conditions. The density and temperature profiles calculated for Earth's mantle and core and the phase diagram of iron calculated under core conditions illustrate how thermodynamic modeling helps us understand the physics of Earth's deep interior.

ACS Style

Surendra K. Saxena. Thermodynamic Modeling of the Earth's Interior. Elements 2010, 6, 321 -325.

AMA Style

Surendra K. Saxena. Thermodynamic Modeling of the Earth's Interior. Elements. 2010; 6 (5):321-325.

Chicago/Turabian Style

Surendra K. Saxena. 2010. "Thermodynamic Modeling of the Earth's Interior." Elements 6, no. 5: 321-325.

Journal article
Published: 01 August 2010 in Journal of Physics and Chemistry of Solids
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Two silver samples, coarse grained (c-Ag, grain size 300±30 nm) and nanocrystalline (n-Ag, grain size 55±6 nm), are compressed in a diamond anvil cell in separate experiments. The pressure is increased in steps of ∼3 GPa and the diffraction pattern recorded at each pressure. The grain size and compressive strength are determined from the analysis of the diffraction line-widths. The grain size of c-Ag decreases rapidly from 300±30 nm at ambient pressure to 40±8 nm at 15 GPa, and then gradually to 20±3 nm at 40 GPa. After pressure release to ambient condition, the grain size is 25±4 nm. The strength at ambient pressure is 0.18±0.05 GPa and increases to 1.0±0.3 GPa at 40 GPa. The grain size of n-Ag decreases from 55±6 nm at ambient pressure to 17±4 nm at 15 GPa and to 14±3 nm at 55 GPa. After release of pressure to ambient condition, the grain size is 50±7 nm. The strength increases from 0.51±0.07 GPa at ambient pressure to 3.5±0.4 GPa at 55 GPa. The strength is found to vary as the inverse of the square-root of the grain size. The results of the present measurements agree well with the grain-size dependence of strength derived from the hardness versus grain size data at ambient pressure available in the literature. Keywords C. High pressure C. X-ray diffraction 1 Introduction Diamond anvil cells (DACs) have been extensively used to pressurize samples and study the properties under ultrahigh pressures. On compression in a DAC, the sample–gasket assembly flows radially between the anvils and equilibrium is reached when the frictional forces between the sample–anvil interfaces balance the forces causing the flow. This results in a highly complex stress state in the sample. Two types of stresses, macro and micro, are recognized in such cases. The macro-stresses represent average stresses in a direction that cuts across large number crystallites. These stresses produce strains that cause the diffraction lines to shift. The description of macro-stresses at the center of the sample is considerably simplified by the presence of an axial symmetry about the load axis of the DAC. The stress state is completely described by three principal stresses, one along the symmetry axis and two equal stresses in the plane parallel to the anvil face. The principal stress along the symmetry axis is larger than that parallel to the anvil face and the difference between the two equals the yield strength of the solid sample at a pressure that is given by the mean normal stress [1] . The analyses of the diffraction-line shifts measured in high-pressure X-ray diffraction experiments on polycrystalline samples give information on the mechanical properties like yield strength and elasticity. The development of this subject can be found in a review article [2] . The micro-stresses vary randomly in direction and magnitude in each crystallite [3] , and produce micro-strains that cause the diffraction lines to broaden. The product of micro-strain and an appropriate Young’s modulus is a measure of the compressive yield strength of the solid sample [4–18] . It may be mentioned that the X-ray diffraction measures lattice strains that are elastic even though the sample undergoes considerable plastic deformation during pressurization. In this study, we analyze the line-widths of high-pressure X-ray diffraction patterns of silver to derive the grain size and compressive strength as function of pressure. Two silver samples of different grain sizes, c-Ag (300±30 nm) and n-Ag (55±6 nm), are used. The strength corrected for the pressure effect is found to vary as the inverse of the square-root of the grain size [19,20] . The grain-size dependence of the strength obtained in this study is compared with that derived from the hardness-grain-size data at ambient pressure available in literature [21] . 2 Experimental details The c-Ag sample from Johnson Matthey Chemicals used in the present experiment was of spectroscopic purity containing 1 ppm/wt of palladium as the major impurity. The other impurity elements (calcium, copper, iron, and magnesium) were <1 ppm/wt. The n-Ag sample, dark grey in color, from Sigma-Aldrich was of 99.5% purity based on trace metal analysis. The major impurities were: iron (8.1 ppm), calcium (3.1 ppm), thallium (1.3 ppm), chromium (0.9 ppm), boron (0.6 ppm) and magnesium (0.6 ppm). The initial grain sizes as determined from the line-widths of the high-resolution X-ray diffraction patterns taken at ambient pressure were 300±30 and 55±6 nm for c-Ag and n-Ag, respectively. A diamond anvil cell with diamond-anvil flat faces of 300 μm diameter was used to compress the sample. A stainless steel gasket (44 μm indented region with 130 μm hole) was used to contain a small piece of silver. No pressure transmitting medium was used to maximize the nonhydrostatic compression effects. The diffraction experiments were carried out using the insertion device beam of the High-Pressure Collaboration Access Team (HPCAT) at the Advanced Photon Source (APS), Argonne National Laboratory, Chicago. The incident beam of wavelength 0.036633 nm was collimated to achieve a cross section of 13×13 μm 2 . The pressure was increased in steps of ∼3 GPa and the diffraction pattern recorded online on an image plate at each pressure. The first eight diffraction peaks from silver could be recorded in all the pressure runs with c-Ag and five to eight peaks with n-Ag. After reaching the highest pressure (∼40 GPa with c-Ag and 55 GPa with n-Ag), the pressure was reduced in steps of ∼10 GPa and diffraction patterns were recorded. The pressure on the sample was computed from the measured unit cell volume of silver by using equation HO2 given in Table 2 of Holzapfel [22] with the values of 97.7 GPa and 5.51 for the isothermal bulk modulus and its pressure derivative,...

ACS Style

Hanns-Peter Liermann; Anjana Jain; Anil K. Singh; Surendra K. Saxena. Compression of silver in a diamond anvil cell: Pressure dependences of strength and grain size from X-ray diffraction data. Journal of Physics and Chemistry of Solids 2010, 71, 1088 -1093.

AMA Style

Hanns-Peter Liermann, Anjana Jain, Anil K. Singh, Surendra K. Saxena. Compression of silver in a diamond anvil cell: Pressure dependences of strength and grain size from X-ray diffraction data. Journal of Physics and Chemistry of Solids. 2010; 71 (8):1088-1093.

Chicago/Turabian Style

Hanns-Peter Liermann; Anjana Jain; Anil K. Singh; Surendra K. Saxena. 2010. "Compression of silver in a diamond anvil cell: Pressure dependences of strength and grain size from X-ray diffraction data." Journal of Physics and Chemistry of Solids 71, no. 8: 1088-1093.

Editorial
Published: 21 July 2010 in Journal of Physics and Chemistry of Solids
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ACS Style

N.L. Saini; S.K. Saxena; A. Bansil. Preface. Journal of Physics and Chemistry of Solids 2010, 71, 1031 .

AMA Style

N.L. Saini, S.K. Saxena, A. Bansil. Preface. Journal of Physics and Chemistry of Solids. 2010; 71 (8):1031.

Chicago/Turabian Style

N.L. Saini; S.K. Saxena; A. Bansil. 2010. "Preface." Journal of Physics and Chemistry of Solids 71, no. 8: 1031.

Journal article
Published: 31 May 2009 in International Journal of Hydrogen Energy
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Mg2FeH6 was synthesized by ball milling MgH2 and Fe (2:1 molar ratio) mixture for 72 h followed by heating at 400 °C under H2 pressure. The hydride formation, its structure and homogeneity were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy. High pressure in situ synchrotron X-ray diffraction and Vienna ab initio simulation were used to determine bulk modulus of the sample. The bulk modulus of Mg2FeH6 was found to be 75.4(4) GPa by optimized experiment and 76.3 GPa by theoretical simulation. From high temperature in situ X-ray diffraction study the volumetric thermal expansion coefficient of Mg2FeH6 was found to be αv = 5.85(3) × 10−5 + 7.47(7) × 10−8 (T − To)/°C. Decomposition of Mg2FeH6 was observed at 425 °C and the decomposition products were Mg, Fe and H2.

ACS Style

Lyci George; Vadym Drozd; Andriy Durygin; Jiuhua Chen; Surendra K. Saxena. Bulk modulus and thermal expansion coefficient of mechano-chemically synthesized Mg2FeH6 from high temperature and high pressure studies. International Journal of Hydrogen Energy 2009, 34, 3410 -3416.

AMA Style

Lyci George, Vadym Drozd, Andriy Durygin, Jiuhua Chen, Surendra K. Saxena. Bulk modulus and thermal expansion coefficient of mechano-chemically synthesized Mg2FeH6 from high temperature and high pressure studies. International Journal of Hydrogen Energy. 2009; 34 (8):3410-3416.

Chicago/Turabian Style

Lyci George; Vadym Drozd; Andriy Durygin; Jiuhua Chen; Surendra K. Saxena. 2009. "Bulk modulus and thermal expansion coefficient of mechano-chemically synthesized Mg2FeH6 from high temperature and high pressure studies." International Journal of Hydrogen Energy 34, no. 8: 3410-3416.

Journal article
Published: 31 July 2008 in International Journal of Hydrogen Energy
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A zero-emission process of hydrogen production from fossil fuel through a system of reactions involving hydroxide, carbon, CO, CO2 and water is described here. It provides for a complete sequestration of carbon (CO2 and CO) from coal/natural-gas burning plants. The CO and or CO2 produced in coal or natural gas burning power plants and the heat may be used for producing hydrogen. Economically hydrogen production cost is less than the current price of fossil-fuel produced hydrogen with the added benefit of carbon sequestration. The reduced cost of the hydrogen may aid in making a hydrogen fueled automobile economically viable.

ACS Style

Surendra K Saxena; Vadym Drozd; Andriy Durygin. A fossil-fuel based recipe for clean energy. International Journal of Hydrogen Energy 2008, 33, 3625 -3631.

AMA Style

Surendra K Saxena, Vadym Drozd, Andriy Durygin. A fossil-fuel based recipe for clean energy. International Journal of Hydrogen Energy. 2008; 33 (14):3625-3631.

Chicago/Turabian Style

Surendra K Saxena; Vadym Drozd; Andriy Durygin. 2008. "A fossil-fuel based recipe for clean energy." International Journal of Hydrogen Energy 33, no. 14: 3625-3631.

Text
Published: 15 March 2008 in Journal of Applied Physics
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X-ray diffraction patterns from platinum foil ( ∼ 300 nm grain size) have been recorded up to 330 GPa using a beveled-anvil diamond cell. The compressive strength has been determined from the analysis of the diffractionlinewidths. In a separate set of experiments, coarse-grained platinum powder ( ∼ 300 nm grain size) is compressed up to 64 GPa in a diamond anvil cell with 300 μ m flat-face anvils and diffraction patterns are recorded. The strengths as functions of pressure derived in the two sets of experiments agree well. The strength increases linearly from 0.21 ( 2 ) GPa at zero pressure to 9.8 ( 4 ) GPa at a pressure of 330 GPa . The nanocrystallineplatinum sample ( ∼ 20 nm average grain size) exhibits much higher strength and increases linearly from 3.0 ( 1 ) to 8.0 ( 3 ) GPa as the pressure is increased from zero pressure to 70 GPa . The grain size of nanocrystalline sample decreases with increasing pressure. The effect of nonhydrostatic compression on the pressures determined with platinum as a pressure marker in high-pressurex-ray diffraction studies is discussed.

ACS Style

Anil K. Singh; Hanns-Peter Liermann; Yuichi Akahama; Surendra K. Saxena; Eduardo Menendez Proupin. Strength of polycrystalline coarse-grained platinum to 330GPa and of nanocrystalline platinum to 70GPa from high-pressure x-ray diffraction data. Journal of Applied Physics 2008, 103, 063524 .

AMA Style

Anil K. Singh, Hanns-Peter Liermann, Yuichi Akahama, Surendra K. Saxena, Eduardo Menendez Proupin. Strength of polycrystalline coarse-grained platinum to 330GPa and of nanocrystalline platinum to 70GPa from high-pressure x-ray diffraction data. Journal of Applied Physics. 2008; 103 (6):063524.

Chicago/Turabian Style

Anil K. Singh; Hanns-Peter Liermann; Yuichi Akahama; Surendra K. Saxena; Eduardo Menendez Proupin. 2008. "Strength of polycrystalline coarse-grained platinum to 330GPa and of nanocrystalline platinum to 70GPa from high-pressure x-ray diffraction data." Journal of Applied Physics 103, no. 6: 063524.

Journal article
Published: 30 September 2007 in International Journal of Hydrogen Energy
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A number of hydrides are considered good candidates for hydrogen storage material for various applications in particular for automobile use. A metal hydride is synthesized through the reaction of a metal with hydrogen which is formed on industrial scale either by the electrolysis of water, by heating coke with steam in the water gas shift reaction or using hydrocarbons with steam. This study demonstrates that under certain conditions, it is possible to synthesize a metal hydride by the reaction of a metal with water or with a hydroxide. Such a synthesis route dispenses with the need for separately forming hydrogen by an expensive process and then to synthesize a hydride by metal–hydrogen reaction. If adopted in many of the hydrogen storage projects which plan to use a hydride for producing hydrogen through a chemical reaction or by a reversible dissociation for automobile use, this method could make a significant difference in making them cost-effective.

ACS Style

Surendra K. Saxena; Vadym Drozd; Andriy Durygin. Synthesis of metal hydride from water. International Journal of Hydrogen Energy 2007, 32, 2501 -2503.

AMA Style

Surendra K. Saxena, Vadym Drozd, Andriy Durygin. Synthesis of metal hydride from water. International Journal of Hydrogen Energy. 2007; 32 (13):2501-2503.

Chicago/Turabian Style

Surendra K. Saxena; Vadym Drozd; Andriy Durygin. 2007. "Synthesis of metal hydride from water." International Journal of Hydrogen Energy 32, no. 13: 2501-2503.

Journal article
Published: 16 August 2004 in Physics of the Earth and Planetary Interiors
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Iron hydride (FeHx) is considered as suitable storage for hydrogen in the earth’s interior and possibly in the core [J. Geophys. Res. 91 (B 9) (1986) 9222]. Most experimental data on its stability pertain to low pressures (<10 GPa) and temperatures. We studied the reaction of iron with brucite (water) at pressures 75 GPa and temperatures of ∼2000 K using the double-side laser-heated diamond-anvil cell. A high-pressure phase of magnetite (Fe3O4) (orthorhombic) and iron hydride (double hcp) were found to exist stably under these conditions. The results indicate that at pressures corresponding to the earth’s lower mantle, the hydride phase is stable, and that orthorhombic high-magnetite (h-Fe3O4) may also be stabilized in lieu of or in addition to magnesiowuestite. The stability of these phases open up the possibility that water (as a component of a fluid phase or hydrous solids) may be present not only in the mantle but also in the core (as dissolved hydride and oxide), which helps melting and dynamic movements. The core may have been the reservoir of oceans of fluid. A percent of water (by weight) in the core is equivalent to about 10 times the water in all the oceans. The dissolved water components in the core would depress the melting temperature of iron (or iron–nickel alloy) significantly, reduce the density and effectively promote convection.

ACS Style

Surendra K Saxena; Hanns-Peter Liermann; Guoyin Shen. Formation of iron hydride and high-magnetite at high pressure and temperature. Physics of the Earth and Planetary Interiors 2004, 146, 313 -317.

AMA Style

Surendra K Saxena, Hanns-Peter Liermann, Guoyin Shen. Formation of iron hydride and high-magnetite at high pressure and temperature. Physics of the Earth and Planetary Interiors. 2004; 146 (1):313-317.

Chicago/Turabian Style

Surendra K Saxena; Hanns-Peter Liermann; Guoyin Shen. 2004. "Formation of iron hydride and high-magnetite at high pressure and temperature." Physics of the Earth and Planetary Interiors 146, no. 1: 313-317.

Journal article
Published: 17 May 2002 in International Journal of Hydrogen Energy
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Using thermochemical calculations in the system Na–C–H–O, it is shown that when used in appropriate molar proportions carbon or methane, water and sodium hydroxide react to produce almost pure hydrogen and solid sodium carbonate. At 1atm, the reaction takes place over a wide range of temperatures (100–800°C) producing hydrogen with only traces of other hydrocarbon impurities. Sodium carbonate is the byproduct of the reaction.

ACS Style

Surendra K Saxena. Hydrogen production by chemically reacting species. International Journal of Hydrogen Energy 2002, 28, 49 -53.

AMA Style

Surendra K Saxena. Hydrogen production by chemically reacting species. International Journal of Hydrogen Energy. 2002; 28 (1):49-53.

Chicago/Turabian Style

Surendra K Saxena. 2002. "Hydrogen production by chemically reacting species." International Journal of Hydrogen Energy 28, no. 1: 49-53.

Journal article
Published: 15 July 2001 in Geophysical Research Letters
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The stability of KAISi3O8 hollandite-type structure is investigated in a series of synthesis experiments between 20 and 95 GPa at 650(±50) °C and between 1200 to 2300 °C, using electrically- and laser-heated diamond anvil cells, respectively. Potassium feldspar transformed to a hollandite-type structure in the experimental pressure range from 20 to 95 GPa at temperatures between 1200 to 2300 °C, whereas it remained amorphous at 65(±5) GPa and 650(±50) °C. KAISi3O8 hollandite is, therefore, a stable phase under the pressure and temperature conditions of at least 2200 km deep in the lower mantle and could be an important host for potassium in that region

ACS Style

Faramarz Tutti; Leonid S. Dubrovinsky; Surendra K. Saxena; Stefan Carlson. Stability of KAlSi3O8Hollandite-type structure in the Earth's lower mantle conditions. Geophysical Research Letters 2001, 28, 2735 -2738.

AMA Style

Faramarz Tutti, Leonid S. Dubrovinsky, Surendra K. Saxena, Stefan Carlson. Stability of KAlSi3O8Hollandite-type structure in the Earth's lower mantle conditions. Geophysical Research Letters. 2001; 28 (14):2735-2738.

Chicago/Turabian Style

Faramarz Tutti; Leonid S. Dubrovinsky; Surendra K. Saxena; Stefan Carlson. 2001. "Stability of KAlSi3O8Hollandite-type structure in the Earth's lower mantle conditions." Geophysical Research Letters 28, no. 14: 2735-2738.

Journal article
Published: 15 January 2001 in Geophysical Research Letters
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Experimental values for the vibrational Grüneisen ratio, γυ, for hexagonal close‐packed (hcp) iron, called epsilon (ϵ)‐iron, were obtained over a large compression range corresponding to Earth's inner‐core pressure. This was done by measuring the intensity change in x‐ray diffraction lines under pressure, P. X‐ray structural refinement using the Rietveld method on powder diffraction data yielded information on mean square displacement used to obtain the Debye temperature, Θ, as a function of compression, V/V0. The value of Θ was determined from the measured intensity of the diffraction lines, which arises from the mean squared amplitude < u² > measured in‐situ in the diamond cell. From the Debye relationship, γυ=−(∂ ln Θ/∂ ln V)T, we determined experimental data on γυ versus V of Fe (hcp) up to 330 GPa at 300 K. The measured value of γυ(V) is 1.18 at 330 GPa and 1.41 at 135 GPa.

ACS Style

Orson L. Anderson; Leonid Dubrovinsky; Surendra K. Saxena; T. LeBihan. Experimental vibrational Grüneisen ratio values for ϵ-iron up to 330 GPa at 300 K. Geophysical Research Letters 2001, 28, 399 -402.

AMA Style

Orson L. Anderson, Leonid Dubrovinsky, Surendra K. Saxena, T. LeBihan. Experimental vibrational Grüneisen ratio values for ϵ-iron up to 330 GPa at 300 K. Geophysical Research Letters. 2001; 28 (2):399-402.

Chicago/Turabian Style

Orson L. Anderson; Leonid Dubrovinsky; Surendra K. Saxena; T. LeBihan. 2001. "Experimental vibrational Grüneisen ratio values for ϵ-iron up to 330 GPa at 300 K." Geophysical Research Letters 28, no. 2: 399-402.