Hybrid materials, such as metal organic nanotubes (MON), are of interest because of their chemical tunability and permanent porosity. While an increasing number of compounds is being reported, very ...little is known about their thermodynamic stability. Herein, the energetics of a MON, (C4H12N2)0.5(UO2)(Hida)(H2ida)·2H2O (UMON, C10H21N3UO12) (ida = iminodiacetate), that possesses unique water exchange and uptake has been investigated by acid solution calorimetry, thermal analysis, and water adsorption calorimetry. The enthalpy of formation of UMON, C10H21N3UO12 (ΔH f,rxn), from the dense components (uranium oxide (UO3), piperazine (C4H10N2), and iminodiacetic acid (C4H7NO4) was −55.3 ± 0.9 kJ/mol, which was similar to values for other metal organic framework materials. The dehydration enthalpy to form an anhydrous UMON and gaseous H2O at 37 °C from thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) experiments was 57.8 ± 1.9 kJ/mol of water. This value is somewhat higher than the vaporization enthalpy of water (44 kJ/mol) and suggests modest bonding interactions of H2O with the inner walls of the nanotubes. Water adsorption calorimetry of (C4H12N2)0.5(UO2)(Hida)(H2ida)·2H2O indicated that the water molecules are confined inside the UMON material in two thermally distinct positions. The ice-like arrangement of the confined water molecules inside the nanotube impacts the energetics of the material and adds to the stabilization of the structure.
This book presents the fundamentals of novel gate dielectrics that are being introduced into semiconductor manufacturing to ensure the continuous scaling of CMOS devices. As this is a rapidly ...evolving field of research we choose to focus on the materials that determine the performance of device applications. Most of these materials are transition metal oxides. Ironically, the d-orbitals responsible for the high dielectric constant cause severe integration difficulties, thus intrinsically limiting high-k dielectrics. Though new in the electronics industry many of these materials are well-known in the field of ceramics, and we describe this unique connection. The complexity of the structure-property relations in TM oxides requires the use of state-of-the-art first-principles calculations. Several chapters give a detailed description of the modern theory of polarization, and heterojunction band discontinuity within the framework of the density functional theory. Experimental methods include oxide melt solution calorimetry and differential scanning calorimetry, Raman scattering and other optical characterization techniques, transmission electron microscopy, and X-ray photoelectron spectroscopy.
Many of the problems encountered in the world of CMOS are also relevant for other semiconductors such as GaAs. A comprehensive review of recent developments in this field is thus also given. The book will be of interest to those actively engaged in gate dielectric research, and to graduate students in Materials Science, Materials Physics, Materials Chemistry, and Electrical Engineering.
In the present work, for the first time, the inorganic Si-based materials lacking preexisting mixed bonds (O–Si–C, silicon in tetrahedral coordination bonded to both carbon and oxygen) have been ...successfully used as starting materials in a laser evaporation/condensation system for making hydrogenated silicon oxycarbide (Si–O–C–H) nanoparticles containing mixed bonds. The obtained materials are characterized by spectroscopic, microscopic, and calorimetric measurements. Thermodynamically stable 5–10 nm amorphous Si–O–C–H particles with a complex structure containing a combination of pure and mixed Si-based tetrahedral units (SiO
i
C4−i
; i = 0–4), and a considerable amount of Si–OH and C–H bonds have been synthesized. The nanoparticles possess high surface areas (428–467 m2/g), suggesting potential use in functionalities requiring high surface to volume ratios. In addition, making thermodynamically stable Si–O–C–H ceramics using a pathway different from the polymer route raises the likelihood of formation of similar carbon containing compounds in the planetary accretion and the Earth's interior.
Nanocrystalline
Sn
x
Ti
1−x
O
2 rutile solid solutions are important materials for a variety of gas sensors and catalysts. Although thermodynamic data are available for nanocrystalline
SnO
2 and
TiO
...2 and for bulk (coarse‐grained)
Sn
x
Ti
1−x
O
2 solid solutions, there is a lack of experimental thermochemical data on the energetics of
Sn
x
Ti
1−x
O
2 nanoparticles. In this work,
Sn
0.586
Ti
0.414
O
2 rutile solid solution nanoparticles were synthesized. The surface energies of anhydrous and hydrated nanoparticles were measured by combining high‐temperature oxide melt solution calorimetry molten 2PbO·B2O3 at 800°C and water adsorption calorimetry. The surface energy of the anhydrous surface is 2.02 ± 0.03 J·m−2, and that of the hydrated surface is 1.68 ± 0.03 J·m−2. These values lie between the previously reported surface energies of rutile SnO2 and TiO2. The integral heat of water adsorption is −80 kJ·mol−1, with a chemisorbed maximum coverage of ~6 H2O·nm−2. These values are also between those for TiO2 and SnO2 (rutile) reported previously. The strongly positive (unfavorable) energetics of mixing in SnO2–TiO2 bulk solid solutions are predicted to change little at the nanoscale, and the extensive solid solution seen in the nanophase system prepared near room temperature reflects kinetic hindrance to exsolution of an initially homogeneous precipitate rather than thermodynamic stability.
Energetics of rare earth, yttrium, and scandium stabilized zirconia and hafnia have been systematically investigated by oxide melt solution calorimetry. The enthalpies of formation with respect to ...the oxide end members were simultaneously fit to a quadratic function to extract interaction parameters and enthalpies of transition of the oxide end members to the fluorite structure. ZrO2–SmO1.5 and HfO2–SmO1.5 show the most exothermic enthalpies of formation and interaction parameters, whereas ZrO2–ScO1.5 has the least exothermic enthalpy of formation and interaction parameter. This suggests that the ZrO2–ScO1.5 system shows the least short range order among all investigated systems, consistent with its high ionic conductivity. The extrapolated enthalpy of transition of the rare earth oxide end members to the cubic fluorite structure increase to more endothermic values with decreasing cation size. The γ‐cubic fluorite phase transition in ZrO2–ScO1.5 was investigated by differential scanning calorimetry (DSC). The phase transition is reversible, occurs at 1000°–1200°C and shows hysteresis (∼100°C). The enthalpy of transition is endothermic on heating and increases from 1.7±0.1 kJ/mol (22 mol% ScO1.5) to 2.9±0.2 kJ/mol (30 mol% ScO1.5).
•ΔfusH°Yb2O3=102 ± 9 kJ/mol & ΔfusH°Lu2O3=125 ± 11 kJ/mol from Drop‘n Catch calorimetry.•ΔfusH°Yb2O3=124 ± 2 kJ/mol & ΔfusH°Lu2O3=124 ± 3 kJ/mol from Ab initio computations.•Computations determined ...high temperature Cp° and ΔV on melting for Yb2O3 and Lu2O3.•Experimental results indicate substantial dissolution of oxygen in liquid Lu2O3.•Konings et al. (2014) assessment for ΔfusH° is in best agreement with these results.
The energetics of melting of Yb2O3 (Tfus 2707 ± 20 K) and Lu2O3 (Tfus 2762 ± 15 K) were studied experimentally by drop-and-catch (DnC) calorimetry and computationally by ab initio molecular dynamic (AI MD) techniques. Fusion enthalpies for Yb2O3 (102 ± 10) kJ∙mol−1 and Lu2O3 (125 ± 10) kJ∙mol−1 were derived from the steps in enthalpy increments from DnC experiments performed on liquid and solid samples laser heated in an argon flow. Fusion enthalpy values for Yb2O3 and Lu2O3 obtained from AI MD computations were 124 ± 2 kJ/mol and 124 ± 3 kJ/mol, respectively. High temperature heat capacity values for solid and liquid phases and volume change on melting were obtained from AI MD. Computed volume change on melting for both oxides is less than 1%, prompting an experimental investigation due to difference with prior experimental results. Experimental results indicate substantial dissolution of oxygen in liquid Lu2O3.
Melanophlogite is a naturally occurring clathrasil possessing a framework of linked silicate tetrahedra surrounding small, isolated cages, which can host small molecules. The energetics of a ...guest-free natural sample was determined by oxide-melt solution calorimetry. Melanophlogite is energetically metastable with respect to α-quartz by 9.5±0.5 kJ/mol, a value similar to that for amorphous silica and for synthetic small-pore zeolitic silicas (Petrovic et al. 1993, Piccione et al. 2001). Thus, its occurrence in nature, for example in environments/where it can occlude volcanic gases, is reasonable on energetic grounds. Molecular modeling of the internal pore volume of melanophlogite confirms that this enthalpy follows the trend previously established for a variety of silica zeolites, which defines an internal surface energy of 0.093±0.010 J/m2, similar to that of the external surface energy of amorphous silica. Thus melanophlogite, despite its unique topology and isolated cages, behaves energetically as predicted from the enthalpies of more-open zeolitic frameworks.
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