The phase diagram for the AgNO3−KNO3 system has been determined using differential scanning calorimetry (DSC). Eutectic point has been found at 391 K andXAg=0.580 mole fraction AgNO3. The DSC curves indicate the existence of an intermermediate compound (AgNO3·KNO3) in the KNO3-rich region of the phase diagram. This compound was identified in the solid phase by X-ray diffraction. The melting and the
crystallization processes were followed with the aid of a hot stage microscope, too.
Authors:K. Szécsényi, M. Arnold, K. Tomor, and F. Gaál
The thermal behavior of different fly ashes from the electrical precipitators of various pulverized carbon fuel-fired boilers
was investigated by means of simultaneous TG, DTG, DTA and EGA analysis. The carbon and sulfur contents of the samples were
determined by gastitrimetry. The compositions of the samples were examined by X-ray diffraction. The quantitative oxide analysis
of the ashes was carried out by means of a classical method.
Authors:J. KŐmives, K. Tomor, J. Sztatisz, L. Lassu, and S. Gál
Changes in the water content of aluminium sulphate hydrate were investigated gravimetrically at room temperature in air with different relative humidities. The samples conditioned in this way were characterized by thermoanalytical (TG, DTG, DSC) and X-ray diffraction measurements. Industrial aluminium sulphate hydrate obtained by freezing the melt has a partly crystalline structure. After grinding, this material crystallizes during storage. This process requires a humid atmosphere; increasing relative humidity brings about more intensive crystallization.
Authors:J. Kőmives, S. Gál, K. Tomor, and Gy. Kovács
Thermogravimetry was applied in studies of aluminium foils for electrolytic capacitors. Scanning electron microscopy, X-ray diffraction and surface area determination were also used in the interpretation of the results.
Authors:C. Novák, G. Pokol, K. Tomor, J. Kőmíves, and S. Gál
The gibbsite →χ-alumina decomposition (in air) and theχ-alumina → boehmite transformation (under hydrothermal conditions) were investigated isothermally. Reaction products were characterized by TG and X-ray diffraction.
Authors:D. Kozma, J. Sztatisz, K. Tomor, G. Pokol, and E. Fogassy
The optical resolution of racemic mandelic acid (I) by S-2-benzylamino-butanol (II) was performed in water, ethyl acetate,
and water saturated ethyl acetate. It was found that the efficiency of the resolution is three times higher in water saturated
ethyl acetate than in either water or ethyl acetate. The salt mixtures produced during the resolutions and the pure diastereoisomeric
salts were analyzed by TG, DSC and X-ray powder diffraction measurements. The R-(-)-IS-(+)-II salt has the higher melting
point and heat of fusion value which indicates that this is the more stable salt. Though the general assumption is that diastereoisomeric
salt pairs of successful optical resolutions form eutectic systems, the R-mandelic acid-S-2-benzylamino-butanol and the S-mandelic
acid-S-2-benzylamino-butanol system was found to behave in a different way. Melting did not start at or near the estimated
eutectic temperature. The difference can be explained either by miscibility in the solid phase (solid solution) or by a blocked
interaction between the crystals of the two solid salts. This unusual behaviour of the salt pair should be responsible for
the unusual difference in the efficiency of the resolutions performed in different solvents
Authors:K. Marthi, M. Ács, G. Pokol, K. Tomor, and K. Eröss-Kiss
A complex system including thermoanalytical methods, infrared spectroscopy and X-ray powder diffraction for studying physico-chemical behaviour of binary mixtures is described. This system has been tested by investigating binary mixtures of amphetamine hydrochloride salts.
Authors:V. Leovac, E. Ivegeš, K. Szécsényi, K. Tomor, G. Pokol, and S. Gal
Solvate complexes of UO22+ andN(1), N(4)-bis(salicylidene)-S-methylisothiosemicarbazone, (H2Me-L1), of general formula [UO2(Me-L1)S] (S= H2O, MeOH, EtOH, Py, DMF and DMSO) were synthesized. The methanolic UO22+” adducts of N(1)-benzoylisopropylidene-N(4)-salicylidene-S-alkylisothiosemicarbazone, (H2R-L2,R=Me, Prn) of general formula [UO2(R-L2)· MeOH], were also prepared. Thermal decomposition of the complexes was investigated in air and argon. The complexes decompose
to α-U3O8 in air, while in argon the decomposition is not completed up to 1000 K. The temperature and the mechanism of decomposition
of the complexes are a function of the solvent belonging to the inner coordination sphere.
Authors:S. Békássy, T. Cseri, G. Kenessey, G. Pokol, K. Tomor, and G. Liptay
Montmorillonite-supported iron(III) nitrate and copper(II) nitrate reagents, and other supported metal nitrates prepared in
the same way, were investigated by thermal and X-ray powder diffraction methods. The metal nitrates are present on the support
in the form of crystalline hydrate and not as acetone solvate as supposed earlier. Thermal decomposition of metal nitrates
that are active in model reactions proceeds in a different way from that of the practically inactive nitrates. In the former
case, water release and nitrate decomposition itself are simultaneous process. These and other results contributed to determination
of suitable reaction conditions for the montmorillonite-supported reagents.