Authors:A. Ianculescu, A. Braileanu, M. Zaharescu, I. Pasuk, E. Chirtop, C. Popescu, and E. Segal
It is well known that the manganites-based solid solutions are interesting for their electric and magnetic properties. LaMnO3 exhibits a distorted perovskite structure due to Mn3+ ion, which determines the presence of the Jahn–Teller effect. Replacing La3+ host ions by cations of lower valence leads to the disappearance of this effect and changes the characteristics of these
Although the formation of manganites-based solid solutions has been intensively studied, there are some unelucidated aspects
concerning their formation mechanism, depending both on the precursors used and on the thermal treatment applied in order
to obtain suitable properties.
In this work the formation mechanism of La0.7M0.3MnO3 (M=Ca, Sr, Ca+Sr in equimolecular mixture) solid solutions, in isothermal and non-isothermal conditions, was studied. For this
purpose XRD, DTA/TG and spectral techniques were used. The solid solutions formation was found to be more dependent on the
Mn-precursors type than the thermal treatment conditions.
DTA, TG, XRD and IR methods were used to study the formation of solid solutions in the selected subsolidus range of the PbZrO3-K0.5Bi0.5TiO3 system by heating mixtures prepared using oxide substrates, i.e. PbO, Bi2O3, ZrO2, TiO2 and K2CO3. It was found that solid solutions are formed in the reaction of PbO and ZrO2 with intermediate compound, i.e. K0.5Bi0.5TiO3. PbZrO3 was not found to be formed as an intermediate phase.
Authors:F. El-Kabbany, F. M. Mansey, H. Naguib, and A. Al-Huwari
The effect of partial replacement of K+ by Ag+ in the mixed system of KNO3 and AgNO3 during a set of DSC heating cycles was studied by means of a modern computerized DSC system. Thermal analysis was performed in the vicinity of the phase transition II → I for pure KNO3. The results revealed a large change in enthalpy and the phase transition temperature close to the morphotropic boundary x=0.5–0.6. At this boundary, the transformation enthalpy reached the maximum value of ∼101 J g−1. On the basis of the data obtained from this accurate thermal analysis work, a model is suggested for the energy barrier of rotation of the nitrate ion in the mixed nitrate system.
Authors:A. Blonska-Tabero, E. Filipek, and P. Tabero
Physicochemical properties of solidsolutions are possible to modify, which is very important for designing of new functional materials. The knowledge on the influence of the change of composition of the solid
Authors:N. Z. Lyakhov, T. F. Grigoryeva, and A. P. Barinova
The heats of ordering for mechanochemically synthesized nano-sized supersaturated solid solutions were demonstrated for Ni-In,
Ni-Sn, Ni-Al, Cu-Sn, Cu-Hg systems. It is shown that increasing concentration of doping element leads to decreasing of decomposition
temperature and to increasing of decomposition enthalpy. The concentration heterogeneity of doping elements in mechanochemically
synthesized supersaturated solid solutions was found. The reactivity of alloys Cu 20 mass % Sn for commercial powder and MA
powder was investigated.
The preparation of rutile type solid solutions in (TiO2)x -(RuO2)1−x system in the 0≤x ≤0.7 concentration range is described. The single phase solid solutions are formed by controlled nanocrystallization of amorphous
gels prepared by the sol-gel method. The kinetics of this crystallization process has been analyzed. It was found that the
crystallization does not correspond to the Johnson-Mehl-Avrami model and it can be described by the two-parameter Šestk-Berggren
X-ray phase analysis (XRD), differential thermal analysis (DTA) and IR spectroscopy have shown that continuous substitution
solid solutionsin are formed in the FeVMoO7–CrVMoO7 system. With increasing the degree of Cr3+ ion incorporation into the FeVMoO7 structure, a crystal lattice contraction of the Fe1–xCrxVMoO7 solid solution arise. Elevation of temperature of its incongruent melting and gradual shifting of the corresponding IR absorption
bands towards higher wavenumbers have been noticed, as well. The solid product of incongruent melting for x≤0.5 is the Fe4–yCryV2 Mo3 O20 solid solutions phase, whereas for x>0.5 Fe2–zCrz(MoO4)3 and Fe2–u Cru O3 solid solutions.
Authors:A. Porto, W. Magalhães, C. Carvalho, and J. Machado
Positron Lifetime Spectroscopy (LS) measurements were performed in a series of binary molecular solid solutions of the general formula M1–xGxL3, where L(ligand)=acetylacetone, dipivaloylmethane, or N-benzoyl-N-phenylhydroxylamine, M=Al(III), Ga(III) or In(III), as matrix, and G=Cr(III), Mn(III), Fe(III), Co(III), Ru(III), Rh(III) and Ir(III), as guest molecules, and the corresponding mechanical mixtures. For the solid solutions, the o-Ps yield values (I3) decrease very rapidly with the increase of the guest mole fraction, showing a high efficient Ps inhibition process, while for the corresponding mechanical mixtures, these values decrease linearly with the increase of the guest molecule concentration, indicating the presence of two distinct phases. These results confirm our previous proposal that the LS technique is able to characterize solid solutions formed by one matrix, in whichI3 values are high, and one guest, in which theI3 values are very low.