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Evgeniy V Ivanov - One of the best experts on this subject based on the ideXlab platform.
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d2o h2o solvent isotope effects on the enthalpy of 1 1 3 3 tetramethyl 2 thiourea hydration at temperatures from 278 15 to 313 15 k and ambient Pressure
Thermochimica Acta, 2014Co-Authors: Evgeniy V Ivanov, Dmitriy V Batov, V K AbrosimovAbstract:Abstract The enthalpies of solution of 1,1,3,3-tetramethyl-2-thiourea (TMTU) in ordinary (H2O) and heavy (D2O) water were measured at (278.15, 283.15, 288.15, 298.15, and 313.15) K and atmospheric Pressure. Standard molar enthalpies and heat capacities of solution and hydration, together with D2O–H2O solvent isotope effects (IEs) on these quantities, were calculated. It was established that, unlike the process of forming aqueous 1,1,3,3-tetramethyl-2-urea (TMU), the dissolution of TMTU in both H2O and D2O is an endothermic effect over the whole temperature range studied, and the Standard enthalpy-isotopic effect undergoes a negative-to-positive sign inversion nearby of T = 304 K. Going from TMTU to TMU, the Standard heat capacity of solution (hydration) and corresponding IE become less positive.
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d2o h2o solvent isotope effects on the enthalpy of 1 3 dimethylpropyleneurea hydration at temperatures from 278 15 to 313 15 k and atmospheric Pressure
Thermochimica Acta, 2011Co-Authors: Dmitriy V Batov, Evgeniy V IvanovAbstract:Abstract The enthalpies of solution of 1,3-dimethylpropyleneurea in ordinary (H 2 O) and heavy (D 2 O) water were measured at (278.15, 283.15, 288.15, 298.15, and 313.15) K and atmospheric Pressure. Standard enthalpies and heat capacities of solution (hydration), along with D 2 O–H 2 O solvent isotope effects on the quantities studied, were computed. The enthalpies of solution as well as corresponding solvent isotope effects were found to be negative and decreasing in magnitude with increasing temperature. It was established that the hydration (mainly of a hydrophobic type) is enhanced in D 2 O and on going from 1,3-dimethylethyleneurea (1,1,3,3-tetramethylurea) to 1,3-dimethylpropyleneurea, whereas the enthalpy-isotope effects become less appreciable in the latter case.
Dmitriy V Batov - One of the best experts on this subject based on the ideXlab platform.
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d2o h2o solvent isotope effects on the enthalpy of 1 1 3 3 tetramethyl 2 thiourea hydration at temperatures from 278 15 to 313 15 k and ambient Pressure
Thermochimica Acta, 2014Co-Authors: Evgeniy V Ivanov, Dmitriy V Batov, V K AbrosimovAbstract:Abstract The enthalpies of solution of 1,1,3,3-tetramethyl-2-thiourea (TMTU) in ordinary (H2O) and heavy (D2O) water were measured at (278.15, 283.15, 288.15, 298.15, and 313.15) K and atmospheric Pressure. Standard molar enthalpies and heat capacities of solution and hydration, together with D2O–H2O solvent isotope effects (IEs) on these quantities, were calculated. It was established that, unlike the process of forming aqueous 1,1,3,3-tetramethyl-2-urea (TMU), the dissolution of TMTU in both H2O and D2O is an endothermic effect over the whole temperature range studied, and the Standard enthalpy-isotopic effect undergoes a negative-to-positive sign inversion nearby of T = 304 K. Going from TMTU to TMU, the Standard heat capacity of solution (hydration) and corresponding IE become less positive.
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d2o h2o solvent isotope effects on the enthalpy of 1 3 dimethylpropyleneurea hydration at temperatures from 278 15 to 313 15 k and atmospheric Pressure
Thermochimica Acta, 2011Co-Authors: Dmitriy V Batov, Evgeniy V IvanovAbstract:Abstract The enthalpies of solution of 1,3-dimethylpropyleneurea in ordinary (H 2 O) and heavy (D 2 O) water were measured at (278.15, 283.15, 288.15, 298.15, and 313.15) K and atmospheric Pressure. Standard enthalpies and heat capacities of solution (hydration), along with D 2 O–H 2 O solvent isotope effects on the quantities studied, were computed. The enthalpies of solution as well as corresponding solvent isotope effects were found to be negative and decreasing in magnitude with increasing temperature. It was established that the hydration (mainly of a hydrophobic type) is enhanced in D 2 O and on going from 1,3-dimethylethyleneurea (1,1,3,3-tetramethylurea) to 1,3-dimethylpropyleneurea, whereas the enthalpy-isotope effects become less appreciable in the latter case.
Thomas S. Duffy - One of the best experts on this subject based on the ideXlab platform.
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single crystal elasticity of diaspore alooh to 12 gpa by brillouin scattering
Physics of the Earth and Planetary Interiors, 2008Co-Authors: F Jiang, Juraj Majzlan, Sergio Speziale, Thomas S. DuffyAbstract:The high-Pressure elasticity of diaspore (AlOOH) has been determined by Brillouin spectroscopy to 12 GPa in diamond anvil cells. Experiments were carried out using a 16:3:1 methanol–ethanol–water mixture as Pressure medium, and ruby as Pressure Standard. Acoustic velocities were measured in three roughly orthogonal planes at ambient and eight elevated Pressures. The nine individual elastic stiffness constants of the orthorhombic crystal were obtained by fitting the velocity data to Christoffel’s equation. Aggregate elastic moduli and Pressure derivatives were calculated from the Cijs by fits to Eulerian finite strain equations, yielding: KS0 = 152(1) GPa, G0 = 117.2(5) GPa, (∂KS/∂P)T0 = 3.7(1), (∂G/∂P)0 = 1.5(1) for the Voigt–Reuss–Hill average. All individual Cijs increase with Pressure but C23 and C55 exhibit anomalously low Pressure derivatives. From calculated linear compressibilities, the a-axis is the most compressible. The b-axis becomes the least compressible axis at high Pressures. Over the examined Pressure range, the azimuthal P-wave anisotropy decreased from 22% to 16%, while the azimuthal S-wave anisotropy increased from 15% to 21%. Both volume and axial compression curves calculated using our Brillouin results are in good agreement with the results from static compression studies. High-Pressure sound velocities in diaspore exceed those of other hydrous minerals as well as many anhydrous phases relevant to Earth’s upper mantle.
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single crystal elasticity of brucite mg oh 2 to 15 gpa by brillouin scattering
American Mineralogist, 2006Co-Authors: F Jiang, Sergio Speziale, Thomas S. DuffyAbstract:The second-order elastic constants of brucite were determined by Brillouin scattering to 15 GPa in a diamond anvil cell. The experiments were carried out using a 4:1 methanol-ethanol mixture as Pressure medium, and ruby as a Pressure Standard. Two planes, one perpendicular to the c axis (basal plane) and the other containing the c axis (meridian plane), were measured at room Pressure and 10 elevated Pressures. Individual elastic stiffnesses, aggregate moduli, and their Pressure derivatives were obtained by Þ tting the data to Eulerian Þ nite strain equations. The inversion yields individual elastic constants of C11 = 154.0(14) GPa, C33 = 49.7(7) GPa, C12 = 42.1(17) GPa, C13 = 7.8(25) GPa, C14 = 1.3(10) GPa, C44 = 21.3(4) GPa, and their Pressure derivatives of (∂C11/∂P)0 = 9.0(2), (∂C33/∂P)0 = 14.0(5), (∂C12/∂P)0 = 3.2(2), (∂C13/∂P)0 = 5.0(1), (∂C14/∂P)0 = 0.9(1), (∂C44/∂P)0 = 3.9(1). Aggregate moduli and their Pressure derivatives are KS0 = 36.4(9) GPa, G0 = 31.3(2) GPa, (∂KS/∂P)T0 = 8.9(4), (∂G/∂P)0 = 4.3(1) for the Reuss bound, and KS0 = 43.8(8) GPa, G0 = 35.2(3) GPa, (∂KS/∂P)T0 = 6.8(2), (∂G/P)0 = 3.4(1) for the Voigt-Reuss-Hill average. The ratio of the linear compressibility along the c and a axes decreased from 4.7 to 1.3 over the examined Pressure range. The shear anisotropy (C66/ C44) decreased from 2.6(1) at ambient condition to 1.3(1) with increase of Pressure to 12 GPa. Axial compressibilities and a compression curve constructed from our Brillouin data are in good agreement with previous X-ray diffraction data. The increased interlayer interactions and hydrogen repulsion that occurs as brucite is compressed produce a continuous variation of elastic properties rather than any abrupt discontinuities.
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strength elasticity and equation of state of the nanocrystalline cubic silicon nitride γ si 3 n 4 to 68 gpa
Physical Review B, 2005Co-Authors: Boris Kiefer, Thomas S. Duffy, Sean R Shieh, Toshimori SekineAbstract:Lattice strains in nanocrystalline cubic silicon nitride were measured using an energy-dispersive x-ray diffraction technique under nonhydrostatic stress conditions up to a confining Pressure of $68\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. The high-Pressure elastic properties of $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ were also investigated theoretically using density-functional theory. The differential stress $t$ between 30 and $68\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ increases from $7\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}23\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and can be described beyond $40\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ as $t=7(4)+0.24(7)P$ where $P$ is the Pressure in GPa. The differential stress supported by $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ increases with Pressure from 3.5% of the shear modulus at $21\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ to 7.6% at $68\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ is one of the strongest materials yet studied under extreme compression conditions. The elastic anisotropy of $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ is large and only weakly Pressure dependent. The elastic anisotropy increases from $A=1.4$ to $A=1.9$ as the parameter $\ensuremath{\alpha}$ that characterizes stress-strain continuity across grain boundaries is decreased from 1 to 0.5. The high elastic anisotropy compares well with our first-principles calculations that lead to $A=1.92--1.93$ at ambient Pressure and $A=1.94--1.95$ at $70\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. Using molybdenum as an internal Pressure Standard, the equation of state depends strongly on $\ensuremath{\psi}$, the direction between the diamond cell axis and the normal of the scattering plane. The bulk modulus increases from $224(3)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}460(13)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ as $\ensuremath{\psi}$ varies from 0\ifmmode^\circ\else\textdegree\fi{} to 90\ifmmode^\circ\else\textdegree\fi{}. This large variation highlights the need to account properly for deviatoric stresses in nonhydrostatic x-ray diffraction experiments carried out at angles other than the particular angle of $\ensuremath{\psi}=54.7\ifmmode^\circ\else\textdegree\fi{}$, where deviatoric stress effects on the lattice vanish. At this angle we find a bulk modulus of $339(7)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ (${K}_{0}^{\ensuremath{'}}=4$, fixed). This result is in general agreement with our local density approximation calculations, ${K}_{0}=321\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, ${K}_{0}^{\ensuremath{'}}=4.0$, and previous shockwave and x-ray diffraction studies. However, our results are significantly lower than the recently reported bulk modulus of ${K}_{0}=685(45)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ for nanocrystalline $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ below $40\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$.
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Elasticity, shear strength, and equation of state of molybdenum and gold from x-ray diffraction under nonhydrostatic compression to 24 GPa
Journal of Applied Physics, 1999Co-Authors: Thomas S. Duffy, Guoyin Shen, Jinfu Shu, Ho-kwang Mao, Russell J. Hemley, Anil Kumar SinghAbstract:Lattice strains were measured as a function of the angle ψ between the diffracting plane normal and the stress axis of a diamond anvil cell in a layered sample of molybdenum and gold. The sample was compressed over the range 5–24 GPa and the lattice strains were measured using energy-dispersive x-ray diffraction. As ψ is varied from 0° to 90°, the mean lattice parameter of molybdenum increases by up to 1.2% and that of gold increases by up to 0.7%. A linear relationship between Q(hkl), which is related to the slope of the measured d spacing versus 1−3 cos2 ψ relation, and 3Γ(hkl), a function of the Miller indices of the diffracting plane, is observed for both materials as predicted by theory. The Pressure dependence of the uniaxial stress t for gold from this and other recent studies is given by t=0.06+0.015P, where P is the Pressure in GPa. The uniaxial stress in molybdenum can be described by t=0.46+0.13P. Using gold as an internal Pressure Standard, the equation of state of molybdenum depends strongly ...
V K Abrosimov - One of the best experts on this subject based on the ideXlab platform.
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d2o h2o solvent isotope effects on the enthalpy of 1 1 3 3 tetramethyl 2 thiourea hydration at temperatures from 278 15 to 313 15 k and ambient Pressure
Thermochimica Acta, 2014Co-Authors: Evgeniy V Ivanov, Dmitriy V Batov, V K AbrosimovAbstract:Abstract The enthalpies of solution of 1,1,3,3-tetramethyl-2-thiourea (TMTU) in ordinary (H2O) and heavy (D2O) water were measured at (278.15, 283.15, 288.15, 298.15, and 313.15) K and atmospheric Pressure. Standard molar enthalpies and heat capacities of solution and hydration, together with D2O–H2O solvent isotope effects (IEs) on these quantities, were calculated. It was established that, unlike the process of forming aqueous 1,1,3,3-tetramethyl-2-urea (TMU), the dissolution of TMTU in both H2O and D2O is an endothermic effect over the whole temperature range studied, and the Standard enthalpy-isotopic effect undergoes a negative-to-positive sign inversion nearby of T = 304 K. Going from TMTU to TMU, the Standard heat capacity of solution (hydration) and corresponding IE become less positive.
Kenichi Funakoshi - One of the best experts on this subject based on the ideXlab platform.
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simultaneous sound velocity and density measurements of nacl at high temperatures and Pressures application as a primary Pressure Standard
American Mineralogist, 2012Co-Authors: Masanori Matsui, Yuji Higo, Yoshihiro Okamoto, Tetsuo Irifune, Kenichi FunakoshiAbstract:The elastic compressional (P) and shear (S) wave velocities in NaCl were measured up to 12 GPa at 300 K, and up to 8 GPa at 473 and 673 K, by combining ultrasonic interferometry, in situ synchrotron X-ray diffraction, and X-ray radiographic techniques in a large-volume Kawai-type multi-anvil apparatus. The simultaneously measured sound velocity and density data at 300 K and high Pressures up to 12 GPa were corrected to transform the adiabatic values to isothermal values and then used to estimate the 300 K equation of state (EOS) by a least-squares fit to the fourth-order Birch-Murnaghan finite strain equation, without Pressure data. For a fixed isothermal bulk modulus K T0 of 23.7 GPa at 0 GPa and 300 K, we obtained the first and the second Pressure derivatives of K T0, K ′T0 = 5.14 ± 0.05 and K ″T0 = −0.392 ± 0.021 GPa−1, respectively. A high-temperature and high-Pressure EOS of NaCl was then developed using the Mie-Gruneisen relation and the Debye thermal model. To accomplish this, the simultaneously measured sound velocities and densities up to 8 GPa at both 473 and 673 K, as well as previously reported volume thermal expansion data of NaCl at 0 GPa were included in the fit. This resulted in a q parameter of 0.96, while holding the Gruneisen parameter and the Debye temperature, both at 0 GPa and 300 K, fixed at 1.56 and 279 K, respectively. Our EOS model accurately modeled not only the present measured K T data at Pressures up to 12 GPa and temperatures between 300 and 673 K, but also the previously reported volume thermal expansion and the temperature dependence of K T, both at 0 GPa. The new temperature-Pressure-volume EOS for NaCl, presented here, provides a Pressure-independent primary Pressure Standard at high temperatures and high Pressures.
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stability of phase a in antigorite serpentine composition determined by in situ x ray Pressure observations
Physics of the Earth and Planetary Interiors, 2005Co-Authors: Tetsuya Komabayashi, Kei Hirose, Kenichi Funakoshi, Naoto TakafujiAbstract:Abstract Here, we precisely determined the low-Pressure stability limit of phase A in the Mg-end-member antigorite bulk composition defined as the reaction forsterite + water = phase A + enstatite (“water-line” or “water-storage line”) in a multi-anvil apparatus. Pressures were determined by in situ synchrotron X-ray diffraction measurements using NaCl as an internal Pressure Standard. Results demonstrate that the water-line is located at 800 °C and 8.5 GPa and at 550 °C and 5.1 GPa with a Clapeyron slope of 13.6 MPa/°C. We also examined the conditions for the formation of phase A by the decomposition of antigorite on the basis of the phase relations in the systems MgO–SiO 2 –H 2 O (MSH) and MgO–Al 2 O 3 –SiO 2 –H 2 O (MASH). A descending slab peridotite retains water in phase A beyond the stability of antigorite only when temperature in the slab is lower than 550 or 660 °C at 5.1 GPa (corresponding to 160 km depth), in the system MSH or MASH, respectively. The double seismic planes observed within the slabs may be caused by the dehydration reaction of antigorite or chlorite. Their merging depths, which could represent the high-Pressure stability limit of antigorite or chlorite, are 160 km or deeper beneath northeast Japan, Aleutian, Kamchatka and Kuril. Water included in hydrous slab peridotite is transported into the transition zone and deeper mantle in these areas but recycled to the surface in other subduction zones.