Differences in partial thermodynamic functions of some sections of systems Tl−Ag−Te and Tl−Sb−Te

The EMF concentration cell method was applied to determine excess partial molar thermodynamic functions for some sections of the systems Tl?Ag?Te and Tl?Sb?Te. The presence of binary and ternary associates is assumed in Tl?Ag?Te solutions.     

Predicting of the thermodynamic properties for the ternary system Pb−Bi−Mg

R-function method for predicting the ternary thermodynamic properties from its binary ones was applied to the ternary system Pb−Bi−Mg. Activities, activity coefficients, partial and integral molar quantities for Pb, Bi and Mg for the quasibinary sections Pb-X (X=B, C, D, E, F) in the investigated ternary system Pb−Bi−Mg calculated by means ofR-function method are given in this paper. Also, it was determined that results obtained byR-function method reach a good agreement with the experimental results obtained by Oelsen calorimetry.     

Phase equilibria in the ternary system PbO−P2O5−PbCl2

Journal of Thermal Analysis and Calorimetry - In the ternary system PbO?P2O5?PbCl2, the partial ternary system Pb5Cl2O4?Pb3Cl2O2?Pb10(PO4)6Cl2 was examined by thermal,...     

A new phase in the Ag−O−S system

The investigations of reaction between Ag₂SO₄ and Ag₂S in air atmosphere have been carried. Results of DTA and X-ray phase powder diffraction of a reaction mixture have confirmed that in the Ag?O?S system exists a new phase. A formula of the phase is Ag₂SO₂.     

Thermal stability of the amorphous system Ge20As14(SexS1−x)52I14

Results of thermal investigations of the amorphous five-component chalcogenide system Ge₂₀As₁₄(Se_xS_1?x)₅₂I₁₄ are presented. Differential thermal analysis (DTA), derivative differential thermal analysis (DDTA), and dilatometry were employed to determine the temperatures of softening and partial crystallization of the samples. Thermal treatment of the samples at 1000°C and recording of the corresponding thermogravimetric (TG) and derivative thermogravimetric (DTG) curves allowed an elucidation of the full mechanism of their decomposition, which proceeds via seven characteristic phase transitions.     

Thermoanalytical study of the formation of compounds in the PbO−MO (M=Ca,Sr, Ca+Sr) system

In order to clarify the effect of PbO addition on the formation steps of the superconducting phases in the system Bi₂O₃?SrO?CaO?CuO, a study of solid-state reactions under non-isothermal conditions, in the PbO?MO (M=Ca, Sr, Ca+Sr) system has been carried out. Results suggest that the reactivity of the components in the system containing PbO and CaO is much higher than in the system containing SrO. The Ca₂PbO₄ compound is formed first even in the system whereM=Ca+Sr. It is confirmed that Ca₂PbO₄ systems containing PbO.     

Copper solubility and distribution in doped GaSb single crystals

For the GaSb single crystals doped with copper (grown using the Czochralski method without encapsulant in flowing atmosphere of hydrogen) the distribution coefficient of copper in GaSb,k _eff=0.0021±0.0006 was found and the copper solubility in GaSb was discussed. The region of copper solubility in GaSb was analyzed on the thermodynamic basis using chemical phase diagram in the Sb?Ga?Cu system. Due to a rather low solubility of copper, its excessive amount in GaSb caused probably an increase of the dislocation density at the end of the GaSb single crystals.     

Temperature calibration of thermo-balances with nickel-iron-nickel-bimetal

The behaviour of Ni?Fe?Ni sandwich material was investigated in air atmosphere up to 850°C with the NETZSCH microbalance TG 209. The aim was to determine if this substance is suitable for calibration. The results show that nickel-iron-nickel-bimetal makes it possible to calibrate thermobalances whilst expending a minimum of time and effort.     

Crystallization behaviour of Fe−(Nb,Cu)−Si−B metallic glasses

The crystallization behaviour and Curie temperatures of Fe?(Nb,Cu)?Si?B metallic glasses were studied by means of differential scanning calorimetry (DSC), thermomagnetic gravimetry (TMG) and X-ray diffraction. The agreement between the DSC and TMG results was complete. For all Fe?Si?B amorphous alloys, two-peak crystallization was observed with the primary crystallization of α-Fe(Si) followed by eutectic crystallisation. The effects of Cu and Nb additions on the crystallization behaviour and on the activation energies for each stage of the crystallization process of Fe?Si?B glass were investigated.     

Effect of in impurity on crystallization kinetics of (Se.7Te.3)100−xInx system

The effect of In impurity on the crystallization kinetics and the changes taking place in the structure of (Se₇Te₃) have been studied by DTA measurements at different heating rates (α=5 deg·min^?1, 10 deg·min^?1, 15 deg·min^?1 and 20 deg·min^?1). From the heating rate dependence of the values ofT _g,T _c andT _p, the glass transition activation energy (E _t) and the crystallization activation energy (E _c) have been obtained for different compositions of (Se₇Te₃)_100?xIn_x (0≤×≤20). The variation of viscosity as a function of temperature has been evaluated using Vogel-Tamman-Fulcher equation. The crystallization data are analysed using Kissinger's and Matusita's approach for nonisothermic crystallization. It has been found that for samples containing In=0, 10, 15, 20 at%, three dimensional nucleation is predominant whereas for samples containing In=5 at%, two dimensional nucleation is the dominant mechanism. The compositional dependence ofT _g and crystallization kinetics are discussed in terms of the modification of the structure of the Se?Te system.     

Comparative thermodynamic analysis of the binary system Bi−Sb

Results of the comparative thermodynamic analysis of the binary system Bi?Sb obtained by DTA measurements and predicting are presented in this paper. Activities, activity coefficients, partial and integral molar quantities for Bi and Sb at temperatures 973, 1073 and 1173 K in the investigated binary system Bi?Sb determined by DTA measurements and thermodynamic predicting are given. An excellent agreement between the experimental and predicted results is reached. Also, a phase diagram of the investigated system Bi?Sb obtained by DTA shows good agreement with literature and it can be concluded that DTA could be satisfactorily used for quantitative thermodynamic analysis of any binary system containing equilibrium between solid and liquid solutions. It was also determined that conclusion about linear dependence ofgKs constant for binary eutectic systems and systems with phase transformation is valid for binary system containing equilibrium between solid and liquid solutions too.     

Phase equilibria in the P2O5-rich part of the system Y2O3−Na2O−P2O5

In the ternary system Y₂O₃?Na₂O?P₂O₅, the partial system Y(PO₃)₃?NaPO₃?P₂O₅ was examined by means of differential thermal analysis and X-ray powder diffraction; its phase diagram is given.     

DSC analysis of the effect of processing technique on the dissolution/precipitation reactions in a hypereutectic Al−Si alloy

In the present study, the effect of primary processing route on the dissolution and precipitation reactions in a commercial Al?Si alloy (designated as A390) is investigated using differential scanning calorimetry (DSC). The Al?Si alloy selected for the present investigation was processed using conventional casting and spray atomization and deposition routes. The results of differential scanning calorimetry conducted on the as-processed samples indicated no significant dissolution reaction for the as-cast A390 alloy when compared to the similar results obtained for as-spray atomized and deposited samples. However, the thermal analysis conducted on the solutionized cast and spray deposited samples exhibited no significant difference in the kinetics of precipitation reactions. The results of the differential thermal analyses were finally rationalized in terms of observed microstructural features.     

Oxidation mechanism of Ni−P alloys

The powders of Ni?P alloys containing 13% of phosphorus were obtained by precipitation from the solution. The oxidation of Ni?P alloys in polythermal conditions was studied. It was found that oxidation of Ni?P alloys goes through stages and that intermediate products of the oxidation are: Ni₂P and Ni₂P₂O₇. The final products of oxidation process are NiO and Ni₃(PO₄)₂. The sequence of chemical reactions describing the oxidation of Ni?P alloys was proposed.     

Phenomenon of sinter network formation of ZnO in high-temperature environments

The process of sintering oxidation of zinc and lead sulfide concentrates is discussed. The process product is Zn?Pb sinter, the main metal-bearing ingredient for the ISP shaft furnace. Zn?Pb concentrates contain three principal metal sulfides: ZnS, PbS and FeS₂, of which ZnS plays the main role in forming the Zn?Pb sinter structure. It was decided to investigate the formation of ZnO crystallites. Zn?Pb sinters obtained on a D-L sinter belt (operating temperature 1250–1350°C) were subjected to SEM observations with simultaneous micro-X-ray analysis of sites chosen in the field under observation; ZnO crystallites formed as a result of the oxidation of ZnS have a typical dendrite structure leading to the formation of ‘sinter networks’; their structure is illustrated by SEM microphotographs.     

Synthesis and neel temperature determination of ferrites from the CuO−ZnO−Fe2O3 system

Conditions were established and individual and mixed ferrites with the general formula Cu_xZn_1?xFe₂O₄ (x=0; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 1.0) were synthesized from the CuO?ZnO?Fe₂O₃ system. X-ray phase analysis, Mössbauer spectroscopy and microscopic examinations revealed that the obtained ferrites are monophase samples. A magnetic device was attached to the Q-Derivatograph (MOM, Hungary) and successfully used for sample investigation in a magnetic field, and in particular for Curie (Neel) temperature determination. The ferrite composition and the thermal treatment conditions were shown to correlate with the Neel temperature of the synthesized ferrites.     

The system Y2O3−MgO−P2O5

The previously unknown ternary system Y₂O₃?MgO?P₂O₅ has been examined by thermal, X-ray and microscopic methods. Its phase diagram has been determined over the composition range: YPO₄?Mg₃(PO₄)₂?Mg(PO₃)₂?Y(PO₃)₃. In the system, the existence of two mixed phosphates: MgYP₃O₁₀ and MgY(PO₃)₅ has been found, and they occur, according to their composition, at the sections YPO₄?Mg(PO₃)₂ and Y(PO₃)₃?Mg(PO₃)₂, respectively.     

Thermal crystallization studies on Ga−Te glasses

Semiconducting Ga_xTe_100?x (17≤x≤25) glasses have been prepared by melt quenching method and thermal crystallization studies carried out using differential scanning calorimetry. On heating, virgin Ga_xTe_100?x glasses exhibit one glass transition and two crystallization reactions. The first crystallization reaction corresponds to the precipitation of hexagonal Te and the second one to the crystallization of the matrix into zinc blende Ga₂Te₃ phase. If Ga_xTe_100?x glasses are quenched to ambient temperature fromT _crl and reheated, they exhibit the phenomenon of double glass transition.     

Some aspects of the phase changes of the CuCl2−KCl system

The mixtures of CuCl₂ and KC1 with Cu to K molar ratios from 0.2 to 2.0 were analysed by thermogravimetry in air and argon atmosphere under different conditions. The samples differed in the temperature of their preparation. Conclusions were drawn concerning the phase changes and the constitution of the CuCl₂?KC1 system.     

Estimation of average heat capacities of condensed phase transformation products in the Y−Ba−Cu−O system

A method of calculation of average heat capacities of phase transformation products of complex oxides is suggested. The method takes into account the physical state of products and the increase in the heat capacities of products due to the change of entropy at a phase transformation. Average heat capacities of products formed in a congruous melting of compounds (YCuO₂ and Y₄Ba₃O₉), in an incongruous melting of compounds (Y₂Cu₂O₅, BaCuO₂, BaCu₂O₂, Y₂BaCuO₅, YBa₂Cu₃O₇, YBa₂Cu₃O₆) and in a decomposition in a crystalline state of compounds (Y₂BaO₄, Y₂Ba₂O₅, Y₂Ba₄O₇, Ba₂CuO₃, Ba₃Cu₅O₈, YBa₂Cu_3.5O_7.5, YBa₂Cu₄O₈, YBa₂Cu₅O₉) was estimated by using three methods.