Mass spectrometric study of the vaporization of sodium borosilicate glasses

A mass spectrometric Knudsen effusion method has been used to study the vaporization behaviors of three sodium borosilicate glasses with the compositions of 1Na₂O-1B₂O₃-3SiO₂(Glass-1), 1Na₂O-1.5B₂O₃-3SiO₂(Glass-2) and 1.5Na₂O-1B₂O₃-3SiO₂(Glass-3) in the temperature range 915–1172 K. Vapor species of NaBO₂(g) and Na₂(BO₂)₂(g) have been identified over Glass-1 and Glass-2, in which the mole ratio of Na₂O to B₂O₃ is equal to and less than unity, respectively. Over Glass-3, in which the ratio is larger than unity, vapor species of Na(g) has been observed in addition to NaBO₂(g) and Na₂(BO₂)₂(g), and the total vapor pressure over Glass-3 is much higher as compared with those over Glass-1 and Glass-2. From the measured partial pressures of Na(g), NaBO₂(g) and Na₂(BO₂)₂(g), the activity coefficient of NaBO₂ in Glass-1, enthalpies of vaporization, enthalpies of formation and dissociation energies for the vapors have been determined.     

Thermochemical study of vaporization of LiTiO by a mass spectrometric Knudsen effusion method

The vaporization of Li₄TiO₄ has been studied by a mass spectrometric Knudsen effusion method in the temperature range 1082–1582 K. Identified vapors are Li(g), LiO(g), Li₂O(g) and Li₃O(g). When the vaporization proceeds, the content of Li₂O in the Li₄TiO₄ sample decreases and the condensed phase of the sample changes to β-Li₄TiO₄ plus l-Li₂TiO₃ below 1323 K, to β-Li₄TiO₄ plus h-Li₂TiO₃ in the range 1323–1473 K and to h-Li₂TiO₃ plus liquid above 1473 K. On the basis of the partial pressure data, the enthalpies of formation for β-Li₄TiO₄ from elements and from constituent oxides have been determined to be ΔH_f,298^°(β-Li₄TiO₄,s) = −2247.8 ± 14.3 kJ mol⁻¹ and Δ_fox,298^°(β-Li₄TiO₄, s) = −107.3 ± 14.3 kJ mol⁻¹, respectively.     

Mass spectrometric investigation of the vaporization of li2tio3(s)

The vaporization of Li₂TiO₃(s) has been investigated by the mass spectrometric Knudsen effusion method. Partial pressures of Li(g), LiO(g), Li₂O(g), Li₃O(g) and O₂(g) over Li₂TiO₃(s) have been obtained in the temperature range 1180–1628 K. When the vaporization of Li₂TiO₃(s) proceeds, the content of Li₂O in the Li₂TiO₃(s) sample decreases. The phase of the sample is a disordered Li₂TiO₃ solid solution above 1486 K. The enthalpies of formation and the atomization energies for LiO(g) and Li₃O(g) have been evaluated from the partial pressures to be ΔH^o_f0(LiO, g) = 65.4 ± 17.4 kJ/mol, ΔH^o_f0(Li₃O, g) = − 207.5 ± 56.6 kJ/mol, D^o₀(LiO) = 340.5 ± 17.4 kJ/mol and D^o₀(Li₃O) = 931.6 ± 56.6 kJ/mol, respectively.     

The vaporization and thermal stability of lithium molybdates

Two lithium molybdates, δ-Li₄MoO₅ and Li₂MoO₄, were evaporated and measured by high temperature mass spectometry. Various lithium and molybdenum oxide ions were observed, and their partial pressures were obtained. From the thermochemical calculation of evaporation, the heats of formation of the molybdates were obtained for the following reactions, $\text{Li}{}_2\text{O(c) +}\text{1}\text{2}\text{MoO}{}_3\text{(c) =}\text{1}\text{2}\text{δ-Li}{}_4\text{Mo0}{}_5\text{(c), ΔH}{}_{\mathrm{r.298}}{}^{\mathrm{o}}\text{= ? 120.4 kj.mol}{}^{\mathrm{?1}}$, and $\text{Li}{}_2\text{O(c) + MoO}{}_3\text{(c) = Li}{}_2\text{MoO}{}_4\text{(c), ΔH}{}_{\mathrm{r.298}}{}^{\mathrm{o}}\text{= ? 154.7 kj.mol}{}^{\mathrm{?1}}$. Thermochemically, $\text{Li}{}_2\text{MoO}{}_4$ is less stable than $\text{δ-Li}{}_4\text{MoO}{}_5$.     

Mass spectrometric study of collision interactions of fast charged particles with water and NaCl solutions

A new experimental technique has been developed for the investigation of secondary particle emission from liquid targets resulting from collision interactions with fast charged particles. Secondary ion mass spectra are presented for the first time for liquid water and 0.1 M, 1 M and 5 M NaCl aqueous solutions bombarded by 2.0 MeV He⁺ ions. The mass spectra exhibit a series of negative cluster ions of the form of X_mY_nR⁻, where X and Y stand for neutral molecules such as H₂O, NaCl and NaOH and R⁻ stands for a negative charged ion such as O⁻, OH⁻ and Cl⁻. Intensities of negative ions are found to change significantly as a function of the concentration. The results imply evidently that the cluster structure in liquid targets changes drastically depending on the abundance of NaCl in solutions.     

Mass spectrometric study of the evaporation of Li5FeO4 as a corrosion product in the compatibility experiment of Li2O pellets with Fe-Ni-Cr alloys

The measurement of the vapor species and pressures over Li₅FeO₄ as a corrosion product in the compatibility experiment of Li₂O pellets with Fe-Ni-Cr alloys has been done in the temperature range 1200–1500 K by means of the Knudsen effusion mass spectrometric technique. The evaporation process of liquid Li₅FeO₄ was established and expressed by the reaction Li₅FeO₄(1) = LiFeO₂(s) + 4 Li(g) + O₂(g). The enthalpy of formation of Li₅FeO₄ at 298 K was derived to be 1950 kJ/mol from the third-law treatment. Although a congruent process was suggested for the sublimation, it could not be confirmed in detail.     

Mass spectrometric studies of alloys proposed for high-temperature reactor systems: I. Alloy IN-643

In connection with the application for advanced gas-cooled high temperature reactors and the frequent use of nickel base alloys in thermonuclear fusion devices the vaporization of the alloy IN-643 was studied by high temperature mass spectrometry. In order to check the device the heat of vaporization of pure cobalt was redetermined. The following partial pressures could be obtained over the alloy: logp_Ni (atm) = −2.158 × 10⁴/T + 6.754, logp_Cr (atm) = −1.846 × 10⁴/T + 5.590, logp_Fe (atm) = −2.000 × 10⁴/T+ 5.309, (1350–1510 K), and logp_Co (atm) = −2.116 × 10⁴/T + 6.007, (1215–1505 K). Chemical activities, partial free energies and excess partial free energies of mixing of the alloy components were computed from the partial pressures. The results are discussed with respect to the thermodynamic properties of the alloy.     

Thermogravimetric study of the kinetics of lithium titanate reduction by hydrogen

The lithium titanate powder was synthesized by gel-combustion route. The mechanism and the kinetics of hydrogen interaction with lithium titanate powder were studied using non-isothermal thermogravimetric technique. Lithium titanate underwent reduction in hydrogen atmosphere which led to the formation of oxygen deficient non-stoichiometric compound in lithium titanate. One-dimensional diffusion appeared to be the most probable reaction mechanism. The activation energy for reduction of lithium titanate under hydrogen atmosphere was found to be 27.4 kJ/mol/K. Structural changes after hydrogen reduction in lithium titanate were observed in X-ray diffraction analysis.     

Mass spectrometric study of the evaporation of LiCrO2 as a corrosion product in the compatibility experiment of Li2O pellets with Fe-Ni-Cr alloys

A mass spectrometric Knudsen effusion study of the vaporization of LiCrO₂ in the temperature range of 1673–1873 K has shown the following: (1) The major vapor species over solid LiCrO₂ are Li(g), Cr(g), CrO(g), CrO₂(g) and LiCrO₂(g). (2) The vaporization process involves a sublimation reaction, LiCrO₂(s) = LiCrO₂(g), and a dissociation reaction, $\text{LiCrO}{}_2\text{(s) =}\text{1}\text{2}\text{Cr}{}_2\text{O}{}_3\text{(s) + Li(g) +}\text{1}\text{4}\text{O}{}_2\text{(g)}$. (3) The standard enthalpy of solid LiCrO₂ at 298 K is derived to be (?935 ± 21) and (?966 ± 18) kJ/mol from the 2nd and 3rd law treatments, respectively.     

Thermodynamics of liquid uranium vaporization

The vaporization of liquid uranium contained in single crystal cups of tantalum and tungsten was studied up to 3000 K using Knudsen effusion assembly. The flux of U(g) vapours effusing through the K-cell orifice was corrected for the solubility of Ta (or W) in liquid uranium and the equilibrium vapour pressure of liquid uranium was determined as: $\text{Log (P°}{}_{\mathrm{u}}\text{/aim) = (6.295 ± 0.164) - (2.642 ± 0.041) × 10}{}^4\text{/T}$ The sublimation enthalpy of uranium at 298.15 K was evaluated to be 126.3 ± 0.3 kcal/mol.     

On the separation of lithium isotopes by the method of molecular distillation of liquid lithium

This study determines the value of the separation factor of lithium isotopes in the evaporation of liquid metallic lithium in a single-stage still. At a temperature of 500 °C the value of the separation factor is 1.08 ± 0.02. We carried out studies of the separation of lithium isotopes by the method of molecular distillation in an 8 -stage cascade-type metal still. It was shown that when the cells of the still are filled with metallic packing and the condensation temperature of the lithium is raised to 350 °C, the efficiency of one stage of the still is 0.4–0.5.     

Development of a high energy pulsed plasma simulator for the study of liquid lithium trenches

To simulate detrimental events in a tokamak and provide a test-stand for a liquid-lithium infused trench (LiMIT) device [1], a pulsed plasma source utilizing a theta pinch in conjunction with a coaxial plasma accelerator has been developed. The plasma is characterized using a triple Langmuir probe, optical methods, and a calorimeter. Clear advantages have been observed with the application of a coaxial plasma accelerator as a pre-ionization source. The experimental results of the plasma gun in conjunction with the existing theta pinch show a significant improvement from the previous energy deposition by a factor of 14 or higher, resulting in a maximum energy and heat flux of 0.065 ± 0.002 MJ/m² and 0.43 ± 0.01 GW/m². A few ways to further increase the plasma heat flux for LiMIT experiments are discussed.     

Metrological support for the ASKRO spectrometric channel

The application of statistical algorithms in the problem of early detection of technogenic, nuclear power plant emissions in the atmosphere near the ground by means of the spectrometric channel of ARMS (Automatic Radiation Monitoring System) is examined. It is noted that the changes in the radon progeny content which are associated with the diurnal behavior of the intensity of turbulent mixing influence the variance of the readings in the ¹³¹I and ¹³⁷Cs detection ranges. As a result, when a stationary Poisson model is used in the algorithm the number of false alarms increases and the algorithm becomes ineffective. Regional corrections lowering the probability of false alarms to ≤10^–3 with correct detection probability ≥0.7 were introduced into the detection and classification algorithm on the basis of the results of monitoring performed over the course of a year for intervals with stationary γ background.     

Mssbauer 谱仪数据接口的改进

对Ｍｏｓｂａｕｅｒ谱仪数据接口进行了改进。通过简化电路，以软件实现硬件的功能。在测量中省却了单道分析器，使测量系统更为简单、可靠和高效。