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Abstract  

Powder X-ray diffraction measurements of La1-xYxAlO3 suggested that the space groups of x=0.3 and 0.9 samples are Pnma at room temperature and that a structural phase transition occurs from R-3c to Pnma above 200 K in x=0.1 sample. The unit cell volumes of x=0.1, 0.3, and 0.9 samples at 20 K are larger than the average one estimated from the volumes of LaAlO3 and YAlO3. The heat capacities of x=0.1 and 0.3 samples are larger than those of LaAlO3 in the range 3-20 K. On the other hand, the volumes of Y1-xLuxAlO3 (x=0.1, 0.3, and 0.5) at 20 K are close to the average one and the heat capacity increased as x is increased in the range 3-20 K.

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Journal of Thermal Analysis and Calorimetry
Authors: B. Legendre, G. Baziard-Mouysset, M. Anastassiadou, J. Leger, and M. Payard

Abstract  

The compound 2-(2-benzofuryl) Δ-2 imidazoline, has been studied by DSC, TG, X-ray diffraction and thermomicroscopy. We shall see that in the case of a study by DSC this compound presents a strange behaviour, which apparently is in contradiction with the thermodynamic rules. In a case of monotropy, if we have the α-phase (stable) and the γ-phase (metastable), after melting and cooling only theα-phase could crystallise. But this compound can give, according to the rate of cooling, theγ-phase metastable. The rate of cooling is of fundamental importance and the monotropic behaviour of this compound will be explained using the Gibbs function G=f(T) for P=1 atm.

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Two Mn(II) chloride complexes containing guest molecules

Solvothermal syntheses, crystal structures and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: Q. Yang, S. Chen, and S. Gao

Abstract  

Two phenanthroline-manganese inclusion complexes with [MnCl(H2O)(phen)2]+ core have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, thermogravimetric analyses. Uncoordinated 2-mercaptothiazole (tzdtH) and 2-mercaptobenzothiazole (bztzH) as guest molecules are included in the complexes with formulas [MnCl(H2O)(phen)2]Cl·tzdtH (1) and {[MnCl(H2O)(phen)2]Cl}2·bztzH (2). X-ray structural analyses for complexes revealed that the complex 1 is triclinic, space group P1 with a=9.724(1) Å, b=11.858(1) Å, c=12.644(2) Å; β=89.056(2)°; Z=2, D c=1.513 Mg m−3, F(000)=638 and the complex 2 is triclinic, space group P1 with a=9.861(1) Å, b=11.476(1) Å; c=12.908(3) Å; β=84.991(2)°; Z=1, D c=1.511 Mg m−3, F(000)=600. Two complexes exhibit high stability up to 650°C. The molar specific heat capacities for the two complexes 1 and 2 can be estimated as being 96.175±0.332 and 72.505±0.364 J mol−1 K−1 at 298.15 K by RD496-III microcalorimeter, respectively.

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Abstract  

The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)2(H2O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P21/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, =90.38(2)°, V=1.0806(2) nm3, Z=4, D c=2.97 g cm–3, µ=157.83cm–1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)2 H2O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6pz and 6py AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)2 H2O] is heated, ligand water is dissociated first and NO2 group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)2 H2O] has been derived. The lattice enthalpy and its lattice energy were also estimated.

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Nickel(II) complexes prepared from NNN type ligands and pseudohalogens

Synthesis, structure and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: F. Nazli Dınçer Kaya, Ingrid Svoboda, Orhan Atakol, Ümıt Ergun, Adnan Kenar, Musa Sari, and Kaan Emregül

Abstract  

Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N3)2]·MeOH (I) and thiocyanate [Nidmpp(SCN)2·MeOH] (VI) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen to be dinuclear as stated in literature, space group P21/n, monoclinic, a=10.503, b=10.681, c=13.291 Å, β=106.56° and Z=2 whereas complex VI was found to be mononuclear, space group P21/n, monoclinic, a=8.646, b=12.614, c=20.697 Å, β=97.18° and Z=2. The Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing complexes, followed by irregular degradation above 300°C.

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Some transition metal nitrate complexes with hexamethylenetetramine

Part LV. Preparation, X-ray crystallography and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: G. Singh, B. Baranwal, I. Kapoor, D. Kumar, C. Singh, and R. Fröhlich

Abstract  

Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H2O)4(H2O-HMTA)2](NO3)·4H2O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition of rapid heating.

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has an orthorhombic crystal structure and does not form a hydride: it reacts reversibly with hydrogen to produce Cu 2 Mg and MgH 2 [ 3 ]. However, CuLi x Mg 2− x ( x = 0.08) has a hexagonal crystal structure [ 4 ] (ICSD database [ 5 ]), just like

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shell [ 5 , 6 ]. The crystal structure, functional as well as vibrational studies of diglycine cadmium chloride (DGCC) was reported earlier [ 7 , 8 ]. However, to the best of our knowledge there is no report available on growth, powder X

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