Calculating models of mass action concentrations for NaBr(aq), LiNO_3(aq), HNO_3(aq), and KF(aq) binary solutions

The calculating models of mass action concentrations for electrolyte aqueous solutions NaBr-H2O, LiNO3-H2O, HNO3-H2O, and KF-H2O have been developed at 298.15 K and their molalities ranging from 0.1 mol/kg to saturation according to the ion and molecule coexistence theory as well as mass action law. The calculated mass action concentration is based on pure species as the standard state and the mole fraction as the concentration unit, and the reported activities are usually based on infinite dilution as the standard state and molality as the concentration unit. Hence, the calculated mass action concentration must be transformed to the same standard state and concentration unit. The transformation coefficients between calculated mass action concentrations and reported activities of the same component fluctuate in a very narrow range. Thus, the transformed mass action concentrations not only agree well with reported activities, but also strictly obey mass action law. The calculated results show that the new developed models can embody the intrinsic structure of investigated four electrolyte aqueous solutions. The results also indicate that mass action law has its widespread applicability to electrolyte binary aqueous solutions.

Universal thermodynamic model of calculating the mass action concentrations of omponents in a ternary strong electrolyte aqueous solution and its application in the NaCl-KCl-H_2O system

A universal thermodynamic model of calculating the mass action concentrations of components in a ternary strong electrolyte aqueous solution has been developed based on the ion and molecule coexistence theory,and verified in the NaCl-KCl-H2O ternary system at 298.15 K. To compare the difference of the thermodynamic model in binary and ternary strong electrolyte aqueous solutions,the mass action concentrations of components in the NaCl-H2O binary strong electrolyte aqueous solution were also computed at 298.15K. A transformation coefficient was required to compare the calculated mass action concentration and reported activity because they were obtained at different standard states and concentration units. The results show that the transformation coefficients between calculated mass action concentrations and reported activities of the same components change in a very narrow range. The calculated mass action concentrations of components in the NaCl-H2O and NaCl-KCl-H2O systems are in good agreement with the reported activities. This indicates that the developed thermodynamic model can reflect the structural characteristics of solutions,and the mass action concentration also strictly follows the mass action law.

Evidence for charge and spin density waves in single crystals of La_(3)Ni_(2)O_(7) and La_(3)Ni_(2)O_(6)

Charge and spin orders are intimately related to superconductivity in copper oxide superconductors.Elucidation of the competing orders in various nickel oxide compounds is crucial,given the fact that superconductivity has been discovered in Nd_(0.8)Sr_(0.2)NiO_(2)films.Herein,we report structural,electronic transport,magnetic,and thermodynamic characterizations of single crystals of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6).La_(3)Ni_(2)O_(7)is metallic with mixed Ni^(2+)and Ni^(3+)valent states.Resistivity measurements yield two transition-like kinks at~110 and 153 K.The kink at 153 K is further revealed from magnetization and specific heat measurements,indicative of the formation of charge and spin density waves.La_(3)Ni_(2)O_(6)single crystals obtained from the topochemical reduction of La_(3)Ni_(2)O_(7)are insulating and show an anomaly at~176 K on magnetic susceptibility.The transition-like behaviors of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6)are analogous to those observed in La_(4)Ni_(3)O_(10) and La_(4)Ni_(3)O_(8),suggesting that charge and spin density waves are a common feature in the ternary La-Ni-O system with mixed-valent states of nickel.

La_(2)Rh_(3+δ)Sb_(4):a new ternary superconducting rhodium-antimonide

Rhodium-containing compounds offer a fertile playground to explore novel materials with superconductivity(SC)and other fantastic electronic correlation effects.A new ternary rhodium-antimonide La_(2)Rh_(3)+δSb_(4)(δ≈1/8)has been synthesized by a Bi-flux method.It crystallizes in the orthorhombic La_(2)Rh_(3+δ)Sb_(4)-like structure,with the space group Pnma(No.62).The crystalline structure appears as stacking the two-dimensional RhSb_(4)-and RhSb_(5)-polyhedra networks along b axis,and the La atoms embed in the cavities of these networks.Band structure calculations confirm it as a multi-band metal with a van-Hove singularity like feature at the Fermi level,whose density of states are mainly of Rh-4d and Sb-5p characters.The calculations also imply that the redundant Rh acts as charge dopant.SC is observed in this material with onset transition at Ton c≈0.8 K.Ultra-low temperature magnetic susceptibility and specific heat measurements suggest that it is an s-wave type-II superconductor.Our work may also imply that the broad Ln_(2)Tm_(3+δ)Sb_(4)(Ln=rare earth,Tm=Rh,Ir)family may host new material bases where new superconductors,quantum magnetism and other electronic correlation effects could be found.