Search Results
Abstract
The phase diagram of the binary system NaF-SnF2 was determined by using the thermal analysis method. In addition to the crystallisation fields of pure components the formation of three other crystallisation fields was observed and these were attributed to the compounds: NaF·2SnF2, NaF·SnF2 and 2NaF·SnF2. The coordinates of the four eutectic points are: e 1: 70 mol% NaF, 30 mol% SnF2 and 255°C e 2: 58 mol% NaF, 42 mol% SnF2 and 238°C e 3: 44 mol% NaF, 56 mol% SnF2 and 246°C e 4: 18 mol% NaF, 82 mol% SnF2 and 191°C The model independent on the real structure of the melt was applied for the calculation of phase diagram comprising the calculation of excess molar Gibbs energy of mixing. The probable inaccuracy in the calculated phase diagram is σ=2.0°C. XRD analysis of solidified mixtures was performed in order to confirm the formation of expected compounds.
Abstract
A mixture of equal quantities of powdered LiF and NaF was doped with 0.2% each of Ti, Mg and Mn and heated to obtain a LiF+NaF phosphor. After grinding and sieving, the thermoluminescent phosphor was used to obtain the thermoluminescence characteristics such as the glow curve; the dose-response curve, sensitivity, reproducibility and linearity were all established. The main goal was to introduce two new methods for the calculation of trap energy: the single-peak-differential and single-peak-integration methods, both modifications of the basic method of Randall-Wilkins. The plots used to calculate the trap energy were In[(dα/dT)1/(1-α)]vs. 1/T and ln[ln(1-α)/(T o-T)]vs. 1/T, respectively. These linear plots with slopes of (E/k) gave trap energies ofE=0.547 eV andE=0.551 eV, respectively.
Abstract
DTA runs and flux growth experiments have shown that the crystallization temperatures of WO3 from NaF flux are in the range of 1020–1090°C. Addition of Pb2+ influences the crystal growth and the crystallization temperatures are altered (within this range). A thermal effect giving rise to an exothermal DTA peak was observed above the crystallization temperature. This peak occurs at a higher temperature when lead ions are present. We propose an explanation based on pre-crystallization clustering and on the number of nucleation sites on the surface of the platinum crucible.
Abstract
FTIR thermal analysis was used for a hybrid xerogel, anilinepropylsilica, obtained from three different organic precursor amounts, using HF and NaF as catalysts in the sol–gelprocess. The aniline ring vibrational mode at 1500 cm−1 of attached aniline groups was used to obtain the relative aniline content in the xerogel materials after being submitted to thermal treatment in the temperature range from 100 to 400C. This technique allowed to evaluate the thermal stability of organic phase. The organic coverage on the surface and the fraction of trapped organic groups in closed pores can also be evaluated.
Interesting effects of fluoride additives, LiF, NaF and CaF2, on the solid-state reactions in the MgO - Cr2O3 and ZnO - Cr2O3 systems under an atmosphere of nitrogen were observed by means of DTA. For the MgO Cr2O3 - MF (M=Li, Na) systems, it was concluded that the melting of the fluoride additives plays an important role in accelerating the second reaction step at around 1000°. On the other hand, for the ZnO- Cr2O3 - MF (M=Li, Na) systems, a great acceleration by the additives was observed in the first reaction step at around 700°, a much lower temperature than the melting points of the fluorides. The effect of CaF2 was not clear in either system.
], the influence of mixtures of fluorides (NaF, KF) and/or copper or tin (IV) oxides on the burnability of the raw mix was studied. Both fluorides and oxides additions decrease the temperature at which starts the dissociation process of calcium carbonate
The highly crosslinked dimethacrylic/divinylbenzene copolymers
Characterization and thermal studies
-forming diluents (toluene/decan-1-ol) were presented. The new monomers were generated by treatment of epoxides derived from various diphenols: naphthalene-2,7-diol (NAF-2,7) naphthalene-2,3-diol (NAF-2,3), bis(4-hydroxyphenyl)methanone (BEP) or 4,4′-thiodiphenol
Abstract
The solubilities of lanthanum oxide in LiF, NaF, KF and eutectic melt LiF-NaF-KF (46.5 mole% LiF; 11.5 mole% NaF and 42.0 mole% KF) were measured in order to find the suitable electrolyte for electrodeposition of lanthanum. Solidus-liquidus lines were obtained by the method of thermal analysis. The solubility of lanthanum oxide in alkali fluorides is rather low and decreases in the order LiF>NaF>KF. It was found that lanthanum oxide reacts with the components of the melt. LaOF and alkali metal oxide are formed during dissolution of La2O3 in the melt.
Abstract
The Hamming weight of the non-adjacent form is studied in relation to the Hamming weight of the standard binary expansion. In particular, we investigate the expected Hamming weight of the NAF of an n-digit binary expansion with k ones where k is either fixed or proportional to n. The expected Hamming weight of NAFs of binary expansions with large (≥ n/2) Hamming weight is studied. Finally, the covariance of the Hamming weights of the binary expansion and the NAF is computed. Asymptotically, these Hamming weights become independent and normally distributed.
