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Journal of Thermal Analysis and Calorimetry
Authors: N. Vega, R. Roque-Malherbe, and C. Gonzales
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Dielectric-differential thermal analysis

Part V: The role of cationic conduction

Journal of Thermal Analysis and Calorimetry
Authors: R. Roque-Malherbe, C. de las Pozas, and M. Carreras

A quantitative relation is given for the temperature function of the output voltage is thermodielectric analysis. Results obtained with zeolites show the validity of the equation.

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Dielectric differential thermal analysis

IX. The role of guest molecules

Journal of Thermal Analysis and Calorimetry
Authors: R. Roque-Malherbe, C. de las Pozas, and M. Carreras
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Journal of Thermal Analysis and Calorimetry
Authors: R. Gonzales-Santos and R. Roque-Malherbe

Dithionates (CaS2O6·4H2O, SrS2O6·4H2O, BaS2O6·2H2O, MnS2O6·4H2O, MgS2O6·6H2O, CoS2O6·6H2O, NiS2O6·6H2O, ZnS2O6·6H2O and CuS2O6·4H2O) were subjected to thermodielectric analysis. The thermoanalytical curves show low temperature effects from 60 to 350°. These are related with the dehydration and decomposition of the dithionates, which could be fully correlated with the knowledge of the thermal behavior of these compouds obtained with other thermal methods.

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Starting from some satisfactory preliminary studies, the possibility of identifying single cations in solution has been investigated, by means of ionic exchange with a highly acidic resin (Dowex 50W) and a subsequent study by differential thermal analysis of the same resin. A catalogue of DTA curves has been prepared with 19 ionic forms of the said resin, and it has been found that the DTA curves are sufficiently distinguishable and reproducible to suggest an eventual analytical use in more complex cases of solutions containing more than one cationic species.

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With the aims of accounting for the effects of the internal thermal resistance of the sample holder on the parameters of recorded DTA curves, and of estimating the difference between the instrument with a thermally insulated sample holder and the gradientless model, a novel two-point method of differential thermal analysis has been developed. Its essence is that two thermoanalytical curves are recorded simultaneously, with the differential thermocouple at central and side positions relative to the sample. The theory of the method has been elaborated, and formulae are derived which allow quantitative estimation of the thermal resistance of the sample holder, depending on the manner of packing and on the state of the sample in the holder, and which also indicate the optimum manner of packing. If the packing is not dense and not uniform, the thermal resistance of the holder increases and the accuracy of instrument calibration at the tail-end of the differential curve decreases by 10–20%. Through introduction of a correction term into the formula, this effect can be eliminated. A basic formula is given for DTA calculation in the general case of a sample holder with non-zero internal thermal résistance.

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High-pressure differential thermal analysis (HP-DTA)

II. Dehydroxylation reactions at elevated pressures in phyllosilicates

Journal of Thermal Analysis and Calorimetry
Authors: S. Guggenheim and A. van Groos
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The “Ignition” criteria taken from the theory of combustion are suggested for the determination of various kinetic characteristics with the thermophysical parameters depending upon the temperature.

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