scholarly journals Высокотемпературная теплоемкость германатов Pr-=SUB=-2-=/SUB=-Ge-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- и Nd-=SUB=-2-=/SUB=-Ge-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- в области 350-1000 K

2018 ◽  
Vol 60 (3) ◽  
pp. 618
Author(s):  
Л.Т. Денисова ◽  
Л.А. Иртюго ◽  
В.В. Белецкий ◽  
Н.В. Белоусова ◽  
В.М. Денисов

AbstractPr2Ge2O7 and Nd2Ge2O7 were obtained via solid-phase synthesis from Pr2O3 ( Nd2O3 ) and GeO2 with multistage firing in air within 1273–1473 K. A temperature effect on molar heat capacity of the oxide compounds was measured with a differential scanning calorimetry. Their thermodynamic properties were calculated from the C _ P = f ( T ) dependences.

2020 ◽  
Vol 62 (2) ◽  
pp. 332
Author(s):  
Л.Т. Денисова ◽  
М.С. Молокеев ◽  
Л.А. Иртюго ◽  
В.В. Белецкий ◽  
Н.В. Белоусова ◽  
...  

SmGaGe2O7 has been prepared by solid-phase synthesis in air at temperatures from 1273 to 1473 K using the Sm2O3, Ga2O3, and GeO2 oxides as starting materials. The structure of the studied germanate was determined by X-ray diffraction (space group P2_1 / c; a = 7.18610(9) Angstrem, b = 6.57935(8) Angstrem, c = 12.7932(2) Angstrem). Its high-temperature heat capacity has been measured by differential scanning calorimetry. The obtained experimental dependence C_p = f (T) has been used to evaluate the thermodynamic properties of the compound.


2020 ◽  
Vol 62 (4) ◽  
pp. 640
Author(s):  
Л.Т. Денисова ◽  
Е.О. Голубева ◽  
Л.Г. Чумилина ◽  
В.М. Денисов

Abstract The Y_0.4Bi_0.6VO_4 and Y_0.6Bi_0.4VO_4 solid solutions two-phase at x _Bi = 0.95, 0.90, and 0.80 have been formed by the solid-phase synthesis from the initial Y_2O_3, Bi_2O_3, and V_2O_5 oxides burned in air at a temperature of 1173 K for 200 h and their high-temperature heat capacity has been measured in the range of 350–1000 K by differential scanning calorimetry. The thermodynamic properties of the solution solutions have been calculated using the data obtained.


2020 ◽  
Vol 62 (11) ◽  
pp. 1828
Author(s):  
Л.Т. Денисова ◽  
М.С. Молокеев ◽  
В.М. Денисов ◽  
Е.О. Голубева ◽  
Н.А. Галиахметова

The compounds Pb10 ‒ xBix(GeO4)2+x(VO4)4-x (x = 0-3) with an aatite structure were first synthesized from the initial oxides of PbO, Bi2O3, GeO2 and V2O5 by solid ‒ phase synthesis with annealing in air in the temperature range of 773-1073 K. Their structure was determined using x-ray diffraction analysis. The influence of temperature on the heat capacity of synthesized compounds was studied using differential scanning calorimetry. Using the experimental data on Cp = f(T), the thermodynamic properties of the compound have been calculated.


2015 ◽  
Vol 59 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Sławomir Bakier ◽  
Kamila Goderska ◽  
Krzysztof Mansfeld

Abstract Thermodynamic properties of selected honeys: glass transition temperature (Tg), the change in specifi c heat capacity (ΔCp), and enthalpy (ΔH) were analysed using differential scanning calorimetry (DSC) in relation to the composition i.e. water and sugar content. Glass transition temperatures (Tg) of various types of honey differed significantly (p<0.05) and ranged from -49.7°C (polyfloral) to -34.8°C (sunflower). There was a strong correlation between the Tg values and the moisture content in honey (r = -0.94). The degree of crystallisation of the honey also influenced the Tg values. It has been shown that the presence or absence of sugar crystals influenced the glass transition temperature. For the decrystallised honeys, the Tg values were 6 to 11°C lower than for the crystallised honeys. The more crystallised a honey was, the greater the temperature difference was between the decrystallised and crystallized honey. In conclusion, to obtain reliable DSC results, it is crucial to measure the glass transition after the complete liquefaction of honey.


2004 ◽  
Vol 59 (11) ◽  
pp. 825-828
Author(s):  
L. Rycerz ◽  
E. Ingier-Stocka ◽  
B. Ziolek ◽  
S. Gadzuric ◽  
M. Gaune-Escard

The heat capacity of solid and liquid LaBr3 was measured by Differential Scanning Calorimetry (DSC) in the temperature range 300 - 1100 K. The obtained results were fitted by a polynomial temperature dependence. The enthalpy of fusion of LaBr3 was also measured. By combination of these results with the literature data on the entropy, S0m (LaBr3, s, 298.15 K) and the standard molar enthalpy of formation, ΔformH0m (LaBr3, s, 298.15 K), the thermodynamic functions of lanthanum tribromide were calculated up to 1300 K


2019 ◽  
Vol 486 (2) ◽  
pp. 193-196
Author(s):  
L. T. Denisova ◽  
A. D. Izotov ◽  
Yu. F. Kargin ◽  
L. A. Irtugo ◽  
V. V. Beletskiy ◽  
...  

SmFeGe2O7 germanate was obtained by solid-state reactions from stoichiometric mixtures of starting oxides with multistage firing within 1273-1473 K. The effect of temperature on the heat capacity of the compound was studied using differential scanning calorimetry. Based on the dependence Cp = f(T), its thermodynamic properties are calculated.


2019 ◽  
Vol 487 (6) ◽  
pp. 640-643
Author(s):  
L. T. Denisova ◽  
A. D. Izotov ◽  
Y. F. Kargin ◽  
L. A. Irtugo ◽  
V. V. Beletskiy ◽  
...  

SmFeGe2O7 germanate was obtained by solid-state reactions from stoichiometric mixtures of starting oxides with multistage firing within 1273-1473 K. The effect of temperature on the heat capacity of the compound was studied using differential scanning calorimetry. Based on the dependence Cp = f(T), its thermodynamic properties are calculated.


2001 ◽  
Vol 56 (9-10) ◽  
pp. 647-652 ◽  
Author(s):  
F. Da Silva ◽  
L. Rycerz ◽  
M. Gaune-Escard

Abstract The temperature and enthalpy of the phase transition and fusion of EuCl2 were determined and found to be 1014 K, 11.5 kJ mol-1and 1125 K, 18.7 kJ mol-1 , respectively. Addition­ ally, the heat capacity of solid EuCl2 was measured by Differential Scanning Calorimetry in the temperature range 306 -1085 K. The results were fitted to the linear equation C0p,m = (68.27 + 0.0255 T/K) J mol -1 K-1 in the temperature range 306 -900 K. Due to discrepancies in the liter­ ature on the temperature of fusion of EuCl2, the determination of the NaCl-EuCl2 phase diagram was repeated. It consists of a simple eutectic equilibrium at Teut = 847 K with x(EuCl2) = 0.49.


2019 ◽  
Vol 61 (7) ◽  
pp. 1358
Author(s):  
С.Н. Каллаев ◽  
Н.М-Р. Алиханов ◽  
З.М. Омаров ◽  
С.А. Садыков ◽  
М.А. Сирота ◽  
...  

AbstractThe heat capacity and dielectric properties of microcrystalline and nanostructured SmFeO_3 ceramics obtained by solid phase synthesis are studied. The ceramics is synthesized by the treatment of the batch at room temperature in Bridgman anvils by forceful action combined with shear deformation followed by sintering. It is established that the mechanoactivation results in noticeable broadening antiferromagnetic–ferroelectric transition and shifting the temperature of phase transition in the low-temperature area. The phase transition having typical for relaxation oscillator frequency dependent character is found at 558 K. It is shown that the defect structure can take a dominant place in the formation of the physical properties of ceramics.


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