Authors:D. Hellali, H. Zamali, A. Sebaoun, and M. Jemal
The phase diagram of the binary AgNO3–CsNO3 system was constructed using differential thermal analysis (DTA) technique in the range 300–700 K. The apparatus is described briefly. The results exhibit a congruently melting compound CsNO3·AgNO3 (m.p.=453 K) characterized by two allotropic varieties and , an incongruently melting compound AgNO3·CsNO3 (m.p.=450 K) with three forms
, two eutectics (16 mol% CsNO3, 442 K and 32.5 mol% CsNO3, 445 K) and a peritectic (38mol% CsNO3, 450 K). The occurrence of the transitions of intermediates was confirmed by X-ray diffraction at variable temperatures. The phase diagram exhibits also two plateaus at 429 K and 435 K corresponding to the phase transitions of CsNO3 and AgNO3, respectively.
Authors:M. Hichri, C. Favotto, H. Zamali, Y. Feutelais, B. Legendre, A. Sebaoun, and M. Jemal
Phase diagram of the binary system AgNO3—RbNO3 was studied using thermal analysis technique, differential scanning calorimetry and X-ray diffraction. This binary exhibits a congruently melting compound Ag0.5Rb0.5NO3 (m. p.=138°C), an incongruently melting one Ag0.33Rb0.66NO3 with two polymorphic varieties, two eutectics at (36 mol% RbNO3, 128°C) and at (60 mol% RbNO3, near 134°C) respectively and a peritectic at (60.5 mol% RbNO3, 141°C). This system contains also three invariant reactions at 164, 222 and 282°C due to the phase transitions of RbNO3 and another one at
164°C due to the phase transition of AgNO3.
Authors:E. Radomińska, T. Znamierowska, and W. Szuszkiewicz
previously unknown phase equilibria in the Rb 3 PO 4 –Ba 3 (PO 4 ) 2 system were investigated in the entire composition range up to a temperature of 1800 °C. BaRbPO 4 appeared as an intermediatecompound in the system. Due to the synthesis conditions of the
Authors:Alexandre Berche, Pierre Benigni, Jacques Rogez, and Marie-Christine Record
–Mg phase diagram suggested by Massalski [ 14 ] is presented in Fig. 1 . It corresponds to the assessment of the La–Mg phase diagram performed in 1988 by Nayeb-Hashemi and Clark [ 15 ]. This phase diagram contains five intermediatecompounds: LaMg, LaMg 2
Authors:B. A. Howell, H. Dangalle, and M. Al-Omari
A difunctional imide monomer may be produced from 4-nitrophthalic anhydride and m-phenylenediamine. The requisite anhydride may be generated by nitration of phthalimide followed by hydrolysis to the corresponding acid and dehydration. All intermediate compounds have been fully characterized using spectroscopic and thermal methods.
Potassium tetratitanate K2Ti4O9 was synthesized from the anatase-K2CO3 starting materials by the heating calcination. DTA, TG, DTG and XRD methods were used to study the formation of intermediate
compounds and the final product. The characterization of the K2Ti4O9 crystals was carried out by means of scanning electron microscope (SEM).
Authors:C. Marhag, Dalila Hassen-Chehimi, and H. Said
Thermodynamic exploration of solid-liquid equilibria of the MIPO3-Cu(PO3)2 (with MI=Li, Na, K, Rb, Cs, Ag, Tl) systems is carried out with a semi-empirical equation of the liquidus curves. The enthalpies
of fusion of pure polyphosphates and some intermediate compounds were determined from DTA curves. The temperature, enthalpy
and entropy of fusion are calculated for each solid phase with the exception of silver polyphosphate and the intermediate
compound Cs4Cu(PO3)6 which have very limited crystallization fields. The calculated values of the melting enthalpies are approximately equal to
the measured ones. The melting enthalpy of Cu(PO3)2 calculated from different binary systems shows a wide variation in the obtained values, 35-54 kJ mol-1. The experimental value is 33.65 kJ mol-1. The calculated temperatures and compositions in most binary systems are in good agreement with experimental determinations.
Synthesis of potassium bismuth titanate ferroelectric by heating of mixtures prepared using oxide precursors, i.e. Bi2O3, TiO2 and K2CO3 was investigated. DTA, TG, XRD and SEM methods were used to study the formation of intermediate compounds and the final product.
Usage of associated homogenization and grinding of precursors mixture permits to decrease the temperature of formation of
Authors:A. Karelin, N. Krot, R. Kozlova, O. Lobas, and V. Matukha
Thermal decomposition of Pu(C2O4)2·6H2O, Pu2(C2O4)3·10H2O and Np(C2O4)2 ·6H2O has been studied by using combination of gas chromatography, infrared spectroscopy, spectrophotometry and complex thermal analysis. We also investigated the decomposition of Pu oxalate under its -radiation. The reduction of Pu(IV) to Pu(III) has been confirmed. We found Np(V), which is formed from Np(IV), on the basis of infrared and absorption spectra of the intermediate compounds.
The dehydration of LiCl·H2O was studied under inert helium atmosphere by DTA/TG for different heating rates. The dehydration of LiCl·H2O proceeds through a two step reaction between 99–110 and 160–186°C, respectively. It leads to the formation of LiCl·0.5H2O as intermediate compound. The proposed mechanism is:
Based on the temperature peak of the DTA signals the activation energies of the two reactions were determined to be 240 kJ
mol−1 (step 1) and 137 kJ mol−1 (step 2), respectively.