Energy and economic analysis of evaporative vacuum easy desalination system with brine tank

Journal of Thermal Analysis and Calorimetry - Nowadays, the freshwater is one of the most critical issues for humans. In this regard, desalination systems can be beneficial. In this research, at...     

A Raman and NMR study of KSbF6

The ¹⁹F spin-lattice relaxation results in the laboratory frame show that upon cooling from the tetragonal phase, KSbF₆(I), the transition to the cubic phase, KSbF₆(II), occurs over a wide temperature range (~38 K) in which the two phases co-exist. The Raman results using powdered samples agree with this observation but co-existence of phases has of course not been observed in single crystal Raman measurements. Upon rapid cooling of the powdered samples in the Raman studies the tetragonal phase could be super-cooled. Upon heating from the cubic phase, the transition was observed at 302 ± 2 K in all the measurements. The Raman spectra of KSbF₆(I) give no evidence of a non-centrosymmetric structure but it is shown that this is so because the Sb-atoms are only very slightly displaced from centro-symmetrical positions. ¹⁹F second moment results are in agreement with a model in which the SbF^?₆-octahedra are stationary below 180 K and reorient isotropically above 260 K. The importance of scalar spin-spin coupling between fluorine and antimony nuclei is reflected by the T_1p results in the vicinity of the T₁ minimum. The Raman spectra of the cubic phase at higher and lower temperatures are different and the polarized spectra of single crystals are used to assign the bands in terms of a C₃-site group symmetry for the SbF^?₆-groups and a T unit cell group symmetry.     

Determination of the dissociation constants of oxalic acid and the ultraviolet spectra of the oxalate species in 3M perchlorate medium

The dissociation constants for oxalic acid in 3.0M sodium perchlorate medium at 25.0 degrees have been determined by potentiometric and spectrophotometric titrations. The values for the concentration constants are K(a1) = (5.32 +/- 0.15) x 10(-2) and K(a2) = (1.53 +/- 0.02) x 10(-4). The absorption spectra for the individual oxalate species are reported.     

Complexation between molybdenum(VI) and oxalate: Crystal and molecular structure of [(−)Co(en)3][MoO3(C2O4)OH2]I·2 H2O

The crystal structure of the product of the reaction between [(–)Co(en)₃]I₃ and a mixture of Na₂MoO₄ and NaHC₂O₄ in aqueous solution is reported: [(–)Co(en)₃][MoO₃(C₂O₄)OH₂]I·2H₂O, space groupP2₁2₁2₁,a=8.131(2),b=14.590(4),c=17.509(4) Å;Z=4. FinalR=0.048,R _w=0.050,w=( ² F)^–1 for 1899 reflections. The configuration of the Mo(VI) oxalate complex differs notably from that proposed previously on the basis of chemical analysis and equilibrium studies.     

Thermostability of amorphous zirconium aluminate high-k layers

One challenge in the development of high-k dielectric films is to preserve their amorphous nature during the processing of CMOS. In this work, the feasibility of using ZrO₂-Al₂O₃ binary alloys to obtain a stable homogeneous amorphous structure in a high-k layer is investigated. In situ high temperature X-ray diffraction tests show that the onset crystallisation temperature of the binary alloy with 42 and 61 mol% Al₂O₃ is 900, 400 °C higher than that of the pure ZrO₂. After rapid thermal process anneals up to 900 °C, the ZrAl_xO_y film remains amorphous. At 1000 °C, tetragonal ZrO₂ forms in the ZrAl_xO_y film. In addition, it is demonstrated that there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 900 °C in the ZrO₂-Al₂O₃ system.     

An infrared,Raman, and single-crystal x-ray study of cesium hexafluorophosphate

CsPF₆:M,=277.87, cubic,Fm3m-O _h ⁵, witha 8.228(5) Å,V 557(1) ų,Z=4,D _x =3.31 Mg m^–3, X(MoK)=0.7107 Å,(MoK)=6.85 mm^–1 F(000)=496,R=0.0327 for 114 reflections. The PF₆ ion exhibits orientational disorder; infrared and Raman spectra show that its point symmetry is lower thanm3m-O _h , in agreement with the equilibrium atomic positions found in the X-ray study. The rule of mutual exclusion is not obeyed in the spectra of CsPF₆; this can be explained if the disorder also involves a small shift of the P atom away fromm3m-O _h site symmetry. Such an effect could not be modelled in the X-ray study. The deviation from octahedral symmetry of PF₆ is small and, from a consideration of the vibrational spectra of the MPF₆ series, it is concluded that both the reorientational and other motions such as librational and torsional oscillations contribute toward the breadth of some vibrational modes.     

Study of interfacial reactions and phase stabilization of mixed Sc, Dy, Hf high-k oxides by attenuated total reflectance infrared spectroscopy

Grazing angle attenuated total reflectance Fourier transform infrared spectroscopy is applied to study ultrathin film Hf⁴⁺, Sc³⁺ and Dy³⁺oxides, due to its high surface sensitivity. The (multi)metal oxides studied, are of interest as high-k dielectrics. Important properties affecting the permittivity, such as the amorphous or crystalline phase and interfacial reactions, are characterized.Dy₂O₃ is prone to silicate formation on SiO₂/Si substrates, which is expressed in DyScO₃ as well, but suppressed in HfDyO_x. Sc₂O₃, HfScO_x and HfO₂ were found to be stable in contact with SiO₂/Si. Deposition of HfO₂ in between Dy₂O₃ or DyScO₃ and SiO₂, prevents silicate formation, showing a buffer-like behavior for the HfO₂.Doping of HfO₂ with Dy or Sc prevents monoclinic phase crystallization. Instead, a cubic phase is obtained, which allows a higher permittivity of the films. The phase remains stable after anneal at high temperature.