Authors:D. Banerjee, R. Guin, S. Das, and S. Thakare
A new method for the possible incorporation of nuclear wastes has been attempted here by using ceramic matrix of TiO2 as a host precursor for confinement. Hafnium is used as a simulant for actinide high-level waste. After incorporating 181Hf tracer into TiO2 matrix, the leaching property of the resulting matrix was studied in water, sodium chloride and humic acid solutions. The
leaching was measured in each of the case by following the radioactivity of 181Hf. TiO2 matrix has also been exposed to γ-radiation in order to simulate the radiation field for nuclear waste. It has been investigated
with a nuclear technique called time differential perturbed Angular Correlation (TDPAC) that the lattice structure of titania
remains undisturbed even under a strong radiation field. The leaching of 181Hf has also been studied after irradiating the TiO2 matrix with γ-radiation and the leaching behavior was observed not to change from that before irradiation.
Sulphur substitution of oxygen in LiMn2O4
spinel destroyed the ideal symmetry of MnO6 octahedrons.
In consequence, the phase change at about room temperature is strongly retarded,
manifested by lowering heat of the transition and hysteresis of the temperature
dependence of electrical conductivity. The optimal conditions for preparation
of sulphur substituted spinel LiMn2O4–ySy
have been determined.
Authors:Y. Kuroiwa, S. Aoyagi, A. Sawada, H. Ikawa, I. Yamashita, N. Inoue, and T. Atake
The crystal structures of BaTiO3 and PbTiO3 fine particles have been investigated by powder diffraction using synchrotron radiation high energy X-rays. It is revealed
that a BaTiO3 fine particle essentially consists of tetragonal and cubic structure components at 300 K, whereas a PbTiO3 fine particle consists of a tetragonal structure. Adopting a structure model for the BaTiO3 particle that a cubic shell covers a tetragonal core, the thickness of cubic BaTiO3 shell is estimated at almost constant irrespective of particle sizes. Successive phase transitions are detected in 100 nm
particles of BaTiO3 near the phase-transition temperatures of a bulk crystal. The changes in diffraction profiles are small, but they are apparent
for a most up-to-date powder diffractometry.
The complexes of α-alanine-salicylal Schiff base of magnesium (α-ASSM), β-alanine-salicylal Schiff base of magnesium (β-ASSM)
and taurine-salicylal Schiff base of magnesium (TSSM) were synthesized. The formulae of the complexes are Mg[OC6H4CHNCH(CH3)COO]·2H2O, Mg[OC6H4CHNCH2CH2COO]·2H2O and Mg[OC6H4CHNCH2CH2SO3]·2H2O. The crystal structure belongs to orthorhombic system with the lattice parameters: a=1.6954 nm, b=2.0873 nm and c=2.3037 nm for the β-ASSM, to orthorhombic system with the lattice parameters: a=1.5586 nm, b=1.8510 nm and c=2.6240 nm for the β-ASSM, to monoclinic system with the lattice parameters: a=1.3232 nm, b=1.4960 nm, c=2.1543 nm and β=98.04° for the TSSM, respectively. The results of the thermal decomposition processes and infrared spectra
of the complexes show that the complexes may possess different coordination structures.
Authors:J. Song, R. Hu, B. Kang, Y. Lei, F. Li, and K. Yu
[Cd(NTO)4Cd(H2O)6]4H2O was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one and cadmium carbonate in excess. The single crystal
structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, space group C2/c with crystal parameters
of a=2.1229(3) nm, b=0.6261(8) nm, c=2.1165(3) nm, β=90.602(7), V=2.977(6) nm3, Z=4, Dc=2.055 gcm−3, μ=15.45 cm−1, F(000)=1824, λ(MoKα)=0.071073 nm. The final R is 0.0282. Based on the results of thermal analysis, the thermal decomposition mechanism of [Cd(NTO)4Cd(H2O)6]4H2O was derived. From measurements of the enthalpy of solution of [Cd(NTO)4Cd(H2O)6]4H2O in water at 298.15 K, the standard enthalpy of formation, lattice energy, lattice enthalpy and standard enthalpy of dehydration
have been determined as -(1747.84.8), -2394, -2414 and 313.6 kJ mol−1 respectively.
Authors:M. Döring, J. Wuckelt, W. Ludwig, and H. Görls
Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole
(HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates
or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine
the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible
for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa.
Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification
of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im).
In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is
characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole
heterocycles in copper chelate compounds.
Authors:M. Aksu, S. Durmuş, M. Sari, K. Emregül, I. Svoboda, H. Fuess, and O. Atakol
N,N′-bis(salicylidene)-1,3-propanediamine (LH2), N,N′-bis(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH2), N,N′-bis(salicylidene)-2-hydroxy-1,3-propanediamine (LOH3), N,N′-bis(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH2) and N,N′-bis(2-hydroxyacetophenone)-2,2′-dimethyl-1,3-propanediamine (LACDMH2) were synthesized and reduced to their phenol-amine form in alcoholic media using NaBH4 (LHH2, LDMHH2, LOHHH2, LACHH2 and LACDMHH2). Heterodinuclear complexes were synthesized using Ni(II), Zn(II) and Cd(II) salts, according to the template method in DMF
The complex structures were analyzed using elemental analysis, IR spectroscopy, and thermogravimetry. Suitable crystals of
only one complex were obtained and its structure determined using X-ray diffraction, NiLACH�CdBr2�DMF2, space group orthorhombic, Pbca, a=20.249, b=14.881, c=20.565 � and Z=8. The heterodinuclear complexes were seen to be of [Ni�ligand�MX2�DMF2] structure (ligand=LH2−, LDMH2−, LOHH2−, LACH2−, LACDMH2−, M=ZnII, CdII, X=Br−, I−). Thermogravimetric analysis showed irreversible bond breakage of the coordinatively bonded DMF molecules followed by decomposition
at this temperature.
Authors:Katalin Mészáros Szécsényi, V. Leovac, R. Petković, Ž. Jaćimović, and G. Pokol
The deaquation of two isostructural compounds of general formula [M(HL)2(H2O)2](NO3)2 (M=Co, Ni, HL=3,5-dimethyl-1H-pyrazole-1-carboxamidine) is discussed in the view of their crystal and molecular structure. The compounds contain the same
number and type of hydrogen bonds of the adjacent nitrate ions, only in the opposite orientation. On the basis of their deaquation
pattern such a small difference may be detected, i.e., methods of thermal analysis are sensitive enough to show very small
Authors:M. Caira, A. Foppoli, M. Sangalli, L. Zema, and F. Giordano
The thermal and structural characteristics of two crystal forms of ambroxol, (trans-((amino-2-dibromo-3,5-benzyl)amino)-4-cyclohexanol), a drug with remarkable mucolytic and expectorant properties marketed
in several drug products, were investigated. Form II (m.p. 92.4C) is obtained by spontaneous cooling from a hot water/ethanol solution while Form I (m.p. 99.5C) slowly separates from the mother liquor. The two forms can be identified by PXRD and DSC analyses. On the basis
of both thermal and structural data the thermodynamic relationship of enantiotropy was deduced. No metastable (Form I)?stable
(Form II) conversion was observed upon storage at ambient conditions. Form I crystallizes in the space group P21/n (alternative setting of P21/c) with Z=8. Form II crystallizes in the space group P21/c with Z=4 and a significantly different crystal packing arrangement from that in Form I. A third crystalline modification, Form III
(space group P21/c with Z=16) was detected on cooling a single crystal of Form I down to -70C. On warming to ambient temperature Form III was found
to revert to Form I. This reversible single crystal to single crystal transition was structurally characterised and found
to involve subtle changes in the types and extent of molecular disorder as well as the hydrogen bonding arrangement.
Authors:B. Stojanović, Z. Marinković, G. Branković, and E. Fidančevska
The formation of TiO2 prepared by hydrolysis method was presented. Thermodynamics and kinetics of anatase crystallization reaction were investigated.
Differential method of kinetic data evaluation in non-isothermal conditions according toKissinger, Ozawa and Kazeev-Yerofeev
was applied. Starting, crystallized and thermally treated powders were determined using X-ray powder diffraction analysis.
The characteristic parameters (the activation energy, constant rate and formal kinetic order of reaction) of TiO2 formation were calculated using DSC data.