Mark Paskevicius

Curtin University Australia, Bentley, Western Australia, Australia

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Publications (45)141.97 Total impact

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    ABSTRACT: Rare earth metal borohydrides have been proposed as materials for solid-state hydrogen storage because of their reasonably low temperature of decomposition. New synthesis methods, which provide halide-free yttrium and gadolinium borohydride, are presented using dimethyl sulfide and new solvates as intermediates. The solvates M(BH4)3S(CH3)2 (M = Y or Gd) are transformed to α-Y(BH4)3 or Gd(BH4)3 at ∼140 °C as verified by thermal analysis. The monoclinic structure of Y(BH4)3S(CH3)2, space group P21/c, a = 5.52621(8), b = 22.3255(3), c = 8.0626(1) Å and β = 100.408(1)°, is solved from synchrotron radiation powder X-ray diffraction data and consists of buckled layers of slightly distorted octahedrons of yttrium atoms coordinated to five borohydride groups and one dimethyl sulfide group. Significant hydrogen loss is observed from Y(BH4)3 below 300 °C and rehydrogenation at 300 °C and p(H2) = 1550 bar does not result in the reformation of Y(BH4)3, but instead yields YH3. Moreover, composites systems Y(BH4)3-LiBH4 1 : 1 and Y(BH4)3-LiCl 1 : 1 prepared from as-synthesised Y(BH4)3 are shown to melt at 190 and 220 °C, respectively.
    Dalton Transactions 07/2014; · 3.81 Impact Factor
  • International Journal of Hydrogen Energy 07/2014; 39(21):11103–11109. · 3.55 Impact Factor
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    ABSTRACT: A simplified techno-economic model has been used as a screening tool to explore the factors that have the largest impact on the costs of using metal hydrides for concentrating solar thermal storage. The installed costs of a number of paired metal hydride concentrating solar thermal storage systems were assessed. These comprised of magnesium-based (MgH2, Mg2FeH6, NaMgH3, NaMgH2F) high-temperature metal hydrides (HTMH) for solar thermal storage and Ti1.2Mn1.8H3.0 as the low-temperature metal hydride (LTMH) for hydrogen storage. A factored method approach was used for a 200 MWel power plant operating at a plant capacity factor (PCF) of 50% with 7 hours of thermal storage capacity at full-load. In addition, the hydrogen desorption properties of NaMgH2F have been measured for the first time. It has a practical hydrogen capacity of 2.5 wt% (2.95 wt% theoretical) and desorbs hydrogen in a single-step process above 478 oC and in a two-step process below 478 oC. In both cases the final decomposition products are NaMgF3, Na and Mg. Only the single-step desorption is suitable for concentrating solar thermal storage applications and has an enthalpy of 96.8 kJ mol-1 H2 at the midpoint of the hydrogen desorption plateau. The techno-economic model showed that the cost of the LTMH, Ti1.2Mn1.8H3.0, is the most significant component of the system and that its cost can be reduced by increasing the operating temperature and enthalpy of hydrogen absorption in the HTMH that, in turn, reduces the quantity of hydrogen required in the system for an equivalent electrical output. The result is that, despite the fact that the theoretical thermal storage capacity of NaMgH2F (1416 kJ kg-1) is substantially lower than the theoretical values for MgH2 (2814 kJ kg-1), Mg2FeH6 (2090 kJ kg-1) and NaMgH3 (1721 kJ kg-1), its higher enthalpy and operating temperature leads to the lowest installed cost of the systems considered. A further decrease in cost could be achieved by utilizing metal hydrides with yet higher enthalpies and operating temperatures or by finding a lower cost option for the LTMH.
    RSC Advances 01/2014; 4:26552 - 26562. · 3.71 Impact Factor
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    ABSTRACT: a Silicon nanoparticles have been synthesised using mechanochemical ball milling and an inert salt buffer to limit the growth and control the size of the Si particles produced. The solid–liquid metathesis reaction used silicon tetrachloride and lithium with LiCl as the buffer to generate Si nanoparticles. Once the LiCl was removed, X-ray amorphous Si was identified using electron energy loss spectra, at 99 eV and energy filtered transmission electron microscopy. The morphological analysis showed spherical like particles with an average size between 10–30 nm depending on the amount of salt buffer phase added to the reactants. This synthesis method can be used to produce very small Si particles in tuneable sizes for a wide range of applications.
    RSC Advances 01/2014; 42(4):21979-21983. · 3.71 Impact Factor
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    ABSTRACT: Some renewable energy power plants store solar energy as heat, which is used to generate electricity after sunset. But as with many clean energy technologies, economics influences how far energy storage can spread through the emerging market for commercial-scale solar power. A class of materials called metal hydrides could be the next generation of heat storage materials to help reduce the cost of thermal energy storage at solar power plants, and thus further the development of renewable energy worldwide.
    MRS Bulletin 12/2013; 38:1012 - 1013. · 5.07 Impact Factor
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    ABSTRACT: A series of monometallic borohydrides and borohydride eutectic mixtures have been investigated during thermal ramping by mass spectroscopy, differential scanning calorimetry, and photography. Mixtures of LiBH4-NaBH4, LiBH4-KBH4, LiBH4-Mg(BH4)2, LiBH4-Ca(BH4)2, LiBH4-Mn(BH4)2, NaBH4-KBH4, and LiBH4-NaBH4-KBH4 all displayed melting behaviour below that of the monometallic phases (up to 167 °C lower). Generally, each system behaves differently with respect to their physical behaviour upon melting. The molten phases can exhibit colour changes, bubbling and in some cases frothing, or even liquid-solid phase transitions during hydrogen release. Remarkably, the eutectic melt can also allow for hydrogen release at temperatures lower than that of the individual components. Some systems display decomposition of the borohydride in the solid-state before melting and certain hydrogen release events have also been linked to the adverse reaction of samples with impurities, usually within the starting reagents, and these may also be coupled with bubbling or frothing of the ionic melt.
    Physical Chemistry Chemical Physics 10/2013; · 4.20 Impact Factor
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    ABSTRACT: The thermal decomposition of anhydrous Pa3[combining macron] Li2B12H12 was studied in situ by high resolution synchrotron X-ray diffraction. A first-order phase transition can be observed at 355 °C where the unit cell volume expands by ca. 8.7%. The expanded β-Li2B12H12 polymorph simultaneously decomposes to a hydrogen poor γ-Li2B12H12-x phase. Expansion of the unit cell across the discontinuity is consistent with reorientational motion of B12H12(2-) anions, and the presence of a frustrated Li(+) lattice indicating Li ion conduction.
    Physical Chemistry Chemical Physics 08/2013; · 4.20 Impact Factor
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    ABSTRACT: Aluminium sulphide (Al2S3) is predicted to effectively destabilise sodium aluminium hydride (NaAlH4) in a single-step endothermic hydrogen release reaction. The experimental results show unexpectedly complex desorption processes and a range of new sulphur containing hydrogen storage materials have been observed. The NaAlH4–Al2S3 system releases a total of 4.9 wt% of H2 that begins below 100 oC without the need for a catalyst. Characterisation via temperature programmed desorption, in situ synchrotron powder X-ray diffraction, ex situ x-ray diffraction, ex situ Fourier transform infrared spectroscopy and hydrogen sorption measurements reveal complex decomposition processes that involve multiple new sulphur-containing hydride compounds. The system shows partial H2 reversibility, without the need for a catalyst, with a stable H2 capacity of ~1.6 wt% over 15 cycles in the temperature range of 200 oC to 300 oC. This absorption capacity is limited by the need for high H2 pressures (>280 bar) to drive the absorption process at the high temperatures required for reasonable absorption kinetics. The large number of new phases discovered in this system suggests that destabilisation of complex hydrides with metal sulphides is a novel but unexplored research avenue for hydrogen storage materials.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 06/2013; 1:12775 - 12781.
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    ABSTRACT: The purpose of this study is to compare the thermal and structural stability of single phase Li2B12H12 with the decomposition process of LiBH4. We have utilized differential thermal analysis/thermogravimetry (DTA/TGA) and temperature programmed desorption-mass spectroscopy (TPD-MS) in combination with X-ray diffraction (XRD) and Fourier Transform Infra-Red (FTIR) spectroscopy to study the decomposition products of both LiBH4 and Li2B12H12 up to 600°C, under both vacuum and hydrogen (H2) backpressure. We have synthesized highly pure single phase crystalline anhydrous Li2B12H12 (Pa-3 structure type), and studied its sensitivity to water and the process of deliquescence. Under either vacuum or H2 backpressure, after 250°C, anhydrous Li2B12H12 begins to decompose to a sub-stoichiometric Li2B12H12-x composition, which displays a very broad diffraction halo in the d-spacing range 5.85- 7.00 Å, dependent on the amount of H released. Ageing Pa-3 Li2B12H12 under 450°C/125 bar H2 pressure for 24 hours produces a previously unobserved well-crystallized beta-Li2B12H12 polymorph, and a nanocrystalline gamma-Li2B12H12 polymorph. The isothermal release of hydrogen pressure from LiBH4 along the plateau and above the melting point (Tm = 280°C) initially results in the formation of LiH and gamma-Li2B12H12. The gamma-Li2B12H12 polymorph then decomposes to a sub-stoichiometric Li2B12H12-x composition. The Pa-3 Li2B12H12 phase is not observed during LiBH4 decomposition. Decomposition of LiBH4 under vacuum to 600°C produces LiH and amorphous B with some Li dissolved within it. The lack of an obvious B-Li-B or B-H-B bridging band in the FTIR data for Li2B12H12-x suggests the H poor B12H12-x pseudo-icosahedra remain isolated and are not polymerized. Li2B12H12-x is persistent to at least 600°C under vacuum, with no LiH formation observable, and only a ca. d = 7.00 Å halo remaining. By 650°C, Li2B12H12-x is finally decomposed and amorphous B can be observed, with no LiH reflections. Further studies are required to clarify the structural symmetry of the beta and gamma-Li2B12H12 polymorphs, and sub-stoichiometric Li2B12H12-x.
    Journal of the American Chemical Society 04/2013; 135:6930. · 10.68 Impact Factor
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    ABSTRACT: The Mg–Si–H system is economically favorable as a hydrogen storage medium for renewable energy systems while moving toward sustainable energy production. Hydrogen desorption from MgH2 in the presence of Si is achievable, forming magnesium silicide (Mg2Si). However, absorbing hydrogen into Mg2Si remains problematic due to severe kinetic limitations. The objective of this study is to reduce these kinetic limitations by synthesizing Mg2Si nanoparticles to limit the migration distance for magnesium atoms from the Mg2Si matrix to produce MgH2 and Si, thus improving the reversibility of the Mg–Si–H system. Mg2Si nanoparticles were synthesized using a reduction reaction undertaken by solid–liquid mechanochemical ball milling. Particle size was controlled by adding a reaction buffer (lithium chloride) to the starting reagents to restrict particle growth during milling. The reaction buffer was removed from the nanoparticles using tetrahydrofuran and small-angle X-ray scattering revealed an average Mg2Si particle size of 10 nm, the smallest Mg2Si nanoparticles synthesized to date. High-pressure hydrogen measurements were undertaken above thermodynamic equilibrium at a range of temperatures to attempt hydrogen absorption into the Mg2Si nanoparticles. X-ray diffraction results indicate that partial hydrogen absorption took place. Under these absorption conditions bulk Mg2Si cannot absorb hydrogen, demonstrating the kinetic benefit of nanoscopic Mg2Si.
    The Journal of Physical Chemistry C. 01/2013; 118(2):1240-1247.
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    ABSTRACT: The hydrogen (H) cycled planetary milled (PM) NaAlH4 + 0.02TiCl3 system has been studied by high resolution synchrotron X-ray diffraction and transmission electron microscopy during the first 10 H cycles. After the first H absorption, we observe the formation of four nanoscopic crystalline (c-) Ti-containing phases embedded on the NaAlH4 surface, i.e. Al2Ti, Al3Ti, Al82Ti18 and Al89Ti11, with 100% of the originally added Ti atoms accounted for. Al2Ti and Al3Ti are observed morphologically as a mechanical couple on the NaAlH4 surface, with a moderately strained interface. Electron diffraction shows that the Al82Ti18 phase retains some ordering from the L12 structure type, with the observation of forbidden (100) ordering reflections in the fcc Al82Ti18 lattice. After 2 H cycles the NaAlH4 + 0.02TiCl3 system displays only two crystalline Ti-containing phases, Al3Ti and Al89Ti11. After 10 H cycles, the Al89Ti11 is completely converted to Al85Ti15. Al89Ti11, Al85Ti15 and Al3Ti do not display any ordering reflections, and they are modeled in the A1 structure type. Quantitative phase analysis indicates that the Al3Ti proportion continues to increase with further H cycles. The formation of Ti-poor Al1 − xTi x (x 2Ti/NaAlH4 interface present during the first absorption of hydrogen.
    Philosophical Magazine 01/2013; 93(9). · 1.60 Impact Factor
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    ABSTRACT: A simple mechanical milling and annealing process has been used to synthesize CaNi5- based hydrogen storage alloys. Heat treatment at 800 �C under vacuum results in the formation of a crystalline CaNi5 phase. Secondary phases, including Ca2Ni7 and MoeNi, are formed when substituting Mo for Ni. Replacement of Ni by Al or Mo leads to an increase in the unit cell volume of the CaNi5 phase. The hydrogen storage capacity of all substituted alloys is reduced and the plateau pressures are lower than those of pure CaNi5. Fairly flat plateau regions are retained for all compositions except the CaNi4.8Mo0.2 composition where a Ca2Ni7 phase is dominant. The incorporation of Mo also causes slow sorption kinetics for the CaNi4.9Mo0.1 alloy. CaNi4.9Al0.1 maintains its initial hydrogen absorption capacity for 20 cycles performed at 85 �C but the other substituted alloys lose their capacity rapidly, especially the CaNi4.8Mo0.2 composition.
    International Journal of Hydrogen Energy 01/2013; 38:2325. · 3.55 Impact Factor
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    ABSTRACT: The hydrogen cycled (H) planetary milled (PM) NaAlH4 + xM (x < 0.1) system (M = 30 nm Ag, 80 nm Al, 2–3 nm C, 30 nm Cr, 25 nm Fe, 30 nm Ni, 25 nm Pd, 65 nm Ti) has been studied by high resolution synchrotron powder X-ray diffraction. Isothermal absorption kinetic isotherms have been measured over the first two H cycles. The PM NaAlH4 + 0.1Ti system has also been studied by high resolution transmission electron microscopy (TEM). 80 nm Al and 2–3 nm C were inactive, and would not allow hydrogen (H) desorption from NaAlH4. 30 nm Cr, 25 nm Fe, 30 nm Ni, and 25 nm Pd showed activity, but with weak kinetics of only ca. 1 wt.% H/hour. The NaAlH4 + 0.1Ti system displays absorption kinetics of ca. 7 wt.% H/hour, comparable to TiCl3 enhanced NaAlH4 after five H cycles. After H cycling the PM NaAlH4 + 0.1Ti system, we observe a body centred tetragonal (bct) χ-TiH2 phase, which displays intense anisotropic peak broadening. The broadening is evident as a massive dislocation density of ca. 1.20 × 1017/m2 in high resolution TEM images of the χ-TiH2 phase. All originally added Ti can be accounted for in the bct χ-TiH2 phase by quantitative phase analysis (QPA) after five H cycles. The PM NaH + Al + 0.02 (Ti-nano-alloy) system shows absorption kinetic rates in the order TiO2 > TiN > TiC > Ti, with rapid hydrogenation kinetics of ca. 23 wt.% H/hour for TiO2 enhanced NaAlH4, equivalent to TiCl3 enhanced NaAlH4. The TiN and TiC are partially reduced by ca. 7 and 22% respectively, and the TiO2 is completely reduced. The location of the reduced Ti cannot be discerned by X-ray diffraction at these minor proportions.
    International Journal of Hydrogen Energy 10/2012; 37(20):15175–15186. · 3.55 Impact Factor
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    ABSTRACT: This study elucidates the role of transition metal (TM) additives in enhancing hydrogen (H) reversibility and hydrogenation kinetics for the NaAlH4 system. The isothermal hydrogen absorption kinetics of the planetary milled (PM) NaAlH4 + xTMCln (TM row 1 = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu; row 2 = Zn, Y, Zr, Nb, Mo, Ru, Rh Pd; row 3 = Pt; 2 < n < 5) and cryo-milled (CM) NaAlH4 + xTMCln (TM row 1 = Ti, V, Cr, Fe, Co, Ni, Cu; 2 < n < 3) systems have been measured at 140 °C and 150 bar system pressure. The variation in hydrogenation kinetics across the TM series for NaAlH4 + xTMCln is strongly dependent on the TM species and additive level, milling technique, and the type, structure, and morphological arrangement of nanoscopic Al1–xTMx phases that are embedded on the NaAlH4 surface. In the most interesting case, the surface-embedded Al1–xTix phases in the TiCl3-enhanced NaAlH4 system perform a dual catalytic function, where the outer Al1–xTix surface performs dissociation/recombination of molecular H2 and the inner Al1–xTix surface allows the distortion of a minor number of Al–H bonds from AlH4– tetrahedra in the vicinity of the subsurface Al1–xTix/NaAlH4 interface. The density of Ti atoms in the subsurface interface (which is Al:Ti composition- and H cycling temperature-dependent) shows the strongest effects on hydrogenation kinetics.
    The Journal of Physical Chemistry C. 06/2012; 116(27):14205–14217.
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    ABSTRACT: We have studied the complex decomposition mechanism of cubic γ-Mg(BH4)2 (Ia3̅d, a = 15.7858(1) Å) by in-situ synchrotron X-ray diffraction, temperature-programmed desorption, visual observation of the melt, and Fourier transform infrared (FTIR) spectroscopy. The decomposition and release of hydrogen proceeds through eight distinct steps, including two polymorphic transitions before melting, with a new ε-Mg(BH4)2 phase at ca. 150 °C. After melting, strong changes in sample color from yellow to brown to gray are consistent with the unknown Mg–B–H phase(s) (that diffract with high d-spacing halos) in the sample changing from an average composition of MgB2H5.3 at 325 °C, to MgB2.9H3.2 at 350 °C, and to MgB4.0H3.7 by 450 °C. From 350 to 450 °C, the crystalline Mg proportion increases. No combination of previously assigned anionic BnHm species (including MgB12H12 and Mg(B3H8)2) can account for the average composition of the unknown proportion of the sample. This is supported by FTIR spectra showing an absence of terminal B–H resonances in the 2500 cm–1 region that are present for B12H12 and B3H8 anionic species. Our combined analysis strongly indicates the presence of as yet unidentified Mg–B–H phase(s) in postmelted decomposed Mg(BH4)2 samples.
    The Journal of Physical Chemistry C 06/2012; 116(29):15231. · 4.84 Impact Factor
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    ABSTRACT: Increased reliance on solar energy conversion technologies will necessarily constitute a major plank of any forward global energy supply strategy. It is possible that solar photovoltaic (PV) technology and concentrating solar thermal (CST) power technology will play roughly equal, but complementary roles by 2050. The ability to increase reliance on CST power technology during this period, however, will be constrained by a number of factors: the large plant sizes dictated by economies of scale, the high associated transmission infrastructure investment cost, and the limitations of current thermal energy storage technologies. Thus, solar technology's main midterm role is seen to be as hybrid solar thermal power plant. The development of low-cost, high-temperature, high-energy density thermal energy storage systems is needed to enable CST plants to be dispatchable and accelerate the deployment of this technology. Thermochemical storage has the best potential to achieve these energy storage requirements and a brief overview of thermochemical energy storage options for CST plants points to high-temperature metal-hydride thermochemical heat energy storage systems. Hydrogen storage systems offer the highest energy storage capacity per volume and are therefore the most likely candidates for achieving the goal of fully dispatchable CST plants. A number of high-temperature metal-hydride thermochemical solar energy storage systems have been proposed and a small number of these systems are currently being investigated and developed. A key component of this work is matching the thermochemical metal-hydride system with a suitable “low-temperature” hydrogen storage material to produce systems that are self-regulating. A summary of the development status of these systems suggests that, despite the technical challenges associated with high-temperature thermochemical energy storage systems, their potential advantages are now seeing development occurring. Although in- the early stages, their commercialisation could be fast tracked.
    Proceedings of the IEEE 03/2012; · 6.91 Impact Factor
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    ABSTRACT: CaNi5ebased alloys have been synthesized by mechanical alloying followed by isothermal annealing. The formation of the CaNi5 structure occurred when the milled powders were heated at 800 �C under vacuum for 3 h. The abundance of CaNi5 phase in the alloys ranges from 60 to 70 wt.%. Replacement of Zr into the Ca site reduces the unit cell volume of CaNi5 whilst replacement of Cr into the Ni site slightly increases the unit cell volume. The hydrogen storage capacity of all substituted alloys is decreased and the hydrogen sorption plateau regions are narrowed compared to those of pure CaNi5. Substitution of Zr into the Ca site extinguishes the flat plateau region unlike replacement of Cr into the Ni site where a flat plateau is maintained. The reaction enthalpy DH for both absorption and desorption are directly proportional to the unit cell volume of the alloys. The hydrogen storage capacity of all alloys rapidly decays for the first 50 cycles at 85 �C followed by a more gradual decline after 50 further cycles. The hydrogen storage capacity of the alloys after 200 cycles is in the range of 65-75% of the initial capacity.
    International Journal of Hydrogen Energy 02/2012; 37:7586. · 3.55 Impact Factor
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    ABSTRACT: The MgH2 þ 0.02Ti-additive system (additives ¼ 35 nm Ti, 50 nm TiB2, 40 nm TiC, <5 nm TiN, 10 � 40 nm TiO2) has been studied by high-resolution synchrotron X-ray diffraction, after planetary milling and hydrogen (H) cycling. TiB2 and TiN nanoparticles were synthesised mechanochemically whilst other additives were commercially available. The absorption kinetics and temperature programmed desorption (TPD) profiles have been determined, and compared to the benchmark system MgH2 + 0.01Nb2O5 (20 nm). TiC and TiN retain their structures after milling and H cycling. The TiB2 reflections appear compressed in d-spacing, suggesting Mg/Ti exchange has occurred in the TiB2 structure. TiO2 is reduced, commensurate with the formation of MgO, however, the Ti is not evident anywhere in the diffraction pattern. The 35 nm Ti initially forms an fcc Mg47.5Ti52.5 phase during milling, which then phase separates and hydrides to TiH2 and MgH2. At 300 �C, the MgH2 + 0.02 (Ti, TiB2, TiC, TiN, TiO2) samples display equivalent absorption kinetics, which are slightly faster than the MgH2 + 0.01Nb2O5 (20 nm) benchmark. All samples are contaminated with MgO from the use of a ZrO2 vial, and display rapid absorption to ca. 90% of capacity within 20 s at 300 �C. TPD profiles of all samples show peak decreases compared to the pure MgH2 milled sample, with many peak profiles displaying bi-modal splitting. TPD measurements on two separate instruments demonstrate that on a 30 min milling time scale, all samples are highly inhomogenous, and samplings from the exact same batch of milled MgH2 + 0.02Ti-additive can display differences in TPD profiles of up to 30 �C in peak maxima. The most efficient Ti based additive cannot be discerned on this basis, and milling times [ 30 min are necessary to obtain homogenous samples, which may lead to artefactual benefits, such as reduction in diffusion distances by powder grinding or formation of dense microstructure. For the hydrogen cycled MgH2 + 0.01Nb2O5 system, we observe a face centred cubic Mg/Nb exchanged Mg0.165Nb0.835O phase, which accounts for ca. 60% of the originally added Nb atoms.
    International Journal of Hydrogen Energy 11/2011; 37:4227. · 3.55 Impact Factor
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    ABSTRACT: Isotopic Mg11B2 has been deuterated at 400 °C and 800 bar, with the production of β-Mg(11BD4)2 observed by in situ neutron diffraction. A natural MgB2 sample has been deuterated under similar conditions and studied ex situ by high resolution X-ray synchrotron diffraction. In both cases, quantitative phase analysis (QPA) indicates a ca. 43% yield of the high temperature (β) phase, with the rest of the sample composed of unreacted MgB2 and Mg or MgD2. A joint refinement of the neutron and X-ray synchrotron data has been performed, yielding a final β-Mg(11BD4)2 structure in space group Fddd, with new D positions. Anisotropically broadened (odd, odd, odd) reflections are attributed to microstructural features, rather than antiphase boundaries. QPA of the isotopic sample indicates ca. 10% of B atoms are in a noncrystalline state. A broad feature is evident in the ex situ X-ray synchrotron data, covering a wide d-spacing range from ca. 3.80–5.45 Å, consistent with the formation of amorphous Mg(BD4)2 and amorphous B. For both samples, macroscopic fusing occurs, forming an extremely hard phase with a glassy black appearance, which is hydrogen impermeable and inhibits further formation of β-Mg(BH4)2. The fused surface regions of the sample have been studied by transmission (TEM) and scanning (SEM) electron microscopy. TEM studies show amorphous regions on the surface, consistent with amorphous B, and a Mg–B–O–H phase.
    The Journal of Physical Chemistry C. 10/2011; 115(45).
  • Drew A. Sheppard, Mark Paskevicius, Craig E. Buckley
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    ABSTRACT: NaMgH3 is synthesized by cryomilling (77 K) of NaH and MgH2 followed by annealing at 300 °C under 50 bar H2.
    Chemistry of Materials 09/2011; 23:4298. · 8.24 Impact Factor