Search Results

You are looking at 111 - 120 of 878 items for :

  • "differential thermal analysis" x
  • All content x
Clear All

weight and enthalpy during reaction were obvious [ 10 – 15 ]. In this paper, the thermogravimetry–differential thermal analysis (TG–DTA) and Fourier transform infrared spectroscopy (FTIR) were used to real time monitor the reaction process of

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: E. Schnitzler, G. Bannach, O. Treu-Filho, C. T. Carvalho, and M. Ionashiro

means of thermogravimetry, derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA), X-ray powder diffractometry, and complexometry. Establishment of stoichiometry and the details of the thermal decomposition were the main purposes of

Restricted access

Abstract  

The effect of vibration grinding on the DTA curves of montmorillonite isolated from the most important locality of bentonite in the Slovak Republic (Jelšovy potok, Middle Slovakia) was studied in the temperature range 20–1500°C. Interpretation is offered for 6 endothermic and 3 exothermic peaks. vibration grinding modified the course of dehydration of the mineral, suppresses the “dehydroxylation’ peak at 700°C, enables the crystallization of high-temperature quartz, cristobalite and cordierite at lower temperatures in comparison with unground natural montmorillonite. Vibration griding slows down the crystallization of mullite which—unlike quartz, cristobalite and cordierite—does not belong to high-temperature phases of Cheto-montmorillonite. The order in which these high-temperature phases occur is not influenced by vibration grinding.

Restricted access

Abstract  

The phase diagram of the system Ag4SSe–As2Se3 is studied by means of X-ray diffraction, differential thermal analyses and measurements of the microhardness and the density of the materials. The unit-cell parameters of the intermediate phases 3Ag4SSeAs2Se3 (phase A) and Ag4SSe2As2Se3 (phase B) are determined as follows for phase A: a=4.495 , b=3.990 , c=4.042 , α=89.05, β=108.98, γ=92.93; for phase B: a=4.463 , b=4.136 , c=3.752 , α=118.60, β=104.46, γ=83.14. The phase 3Ag4SSeAs2Se3 and Ag4SSe2As2Se3 have a polymorphic transition α↔β consequently at 105 and 120C. The phase A melts incongruently at 390C and phase B congruently at the same temperature.

Restricted access

Abstract  

The phase diagram of the system Ag4SSe-SnTe is studied by means of X-ray diffraction, differential thermal and metallographic analyses and measurements of the microhardness and the density of the material. This diagram is divided into two eutectic-type subdiagrams by the composition Ag4SSe·2SnTe. The unit-cell parameters of the intermediate phases 3Ag4SSe·SnTe (phase A) and -Ag4SSe·2SnTe (phase B) are determined as follows: for phase A: a=0.7851 nm, b=0.7196 nm, c=0.6296 nm, =101.32°, =85.90°, =111.36°; for phase B: a=0.3662 nm, b=0.3303 nm, c=0.3343 nm, =90.74°, =108.94°, =91.91°. The phase Ag4SSe·2SnTe melts congruently at 615°C and a polymorphic transition of the phase takes place at T - =110°C.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: P. Byszewski, E. Kowalska, R. Diduszko, R. Aleksiyko, M. Berkowski, J. Fink-Finowicki, and J. Kapuśniak

Abstract  

The solid solution crystals, La1–xNdxGaO3 and La1–xPrxGaO3 have been studied by differential scanning calorimetry method; the crystals exhibit the first order phase transition, the temperature of the transition linearly increases with the concentration of Pr or Nd. The structure of the crystals has been determined by X-ray diffraction. The correlation between the phase transition temperature and crystalline structure at the temperature of the phase transition in both solid solution families is discussed.

Restricted access

Abstract  

Fly ash is the ash precipitated from the exhaust fumes of coal-fired power stations. It consists mainly of active silica and alumina, with large amounts of glass. The aim of this work was to study the pozzolanic activity of fly ash with lime by means of DTA as a function of the lime content and the curing time. The curves revealed that the rate of hydration, as indicated by the residual lime and hydrated compounds, increases with increasing lime content and curing time. It is concluded that fly ash can be used as a blending material in pozzolanic cement.

Restricted access

Abstract  

The decomposition behaviour of dolomite samples has been carried out by simultaneous DTA-TG experiments. Dolomite samples could be classified broadly into two categories as regular and iron-bearing dolomites based on DTA decomposition temperatures. The mass% FeO of all the dolomite samples was identified by DTA and the results are confirmed by atomic absorption spectrophotometer experiments.

Restricted access

Abstract  

The processes of nucleation of Li2O-Al2O3-SiO2 glasses with TiO2 and TiO2+ZrO2 as nucleating agents were discussed. The DTA peak temperature and DTA peak height shown a strong dependence on the nucleation temperature in the glass with TiO2, while in the glass with TiO2+ZrO2 this tendency was small. The optimum nucleation temperatures were 745 and 760°C for two glasses. It suggested that with TiO2+ZrO2 as nucleating agents, the crystallization had lower sensitivity for nucleation temperature, and the glass had higher nucleation efficiency than with TiO2.

Restricted access

an alumina crucible, followed by iced-water quenching and grinding to achieve particle size below 45 μm. Samples of glass frit (9 mg in an alumina pan) were submitted to heat treatments in an apparatus of differential thermal analysis

Restricted access