Calorimetric Studies of High Temperature Oxide Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
Yasutoshi Saito ◽  
Tetsurõ Nakamura ◽  
Tooru Atake
Keyword(s):  
Heat Capacity ◽  
Adiabatic Calorimeter ◽  
Order Type ◽  
Heat Capacities ◽  
Oxide Superconductors ◽  
Heat Capacity Jump ◽  
Two Samples ◽  
Schottky Type ◽  
High Temperature Oxide ◽  
Calorimetric Studies

ABSTRACTThe heat capacities of single phase samples of Ba2DyCu3O7 and Ba2ErCu3O7 which were prepared by the method of powder-calcination have been measured over the temperature range 13–300 K by using a laboratory-made adiabatic calorimeter. A typical second-order type of anomaly was observed due to the superconducting phase transition at 92.5 K in Ba2DyCu3O7 and at 91.2 K in Ba2ErCu3O7. From the heat capacity jump at the transition temperature, the electronic heat capacity coefficient was estimated as 30 mJ·K-2.mol1 for Ba2ErCu3O7 and 32 mJ·K-2. mol-1 for Ba2ErCu3O7. Large differences were found in the low temperature heat capacities between the two samples, which were analyzed on the basis of Schottky-type of anomalies owing to the magnetic ions of Dy and Er.

Low-Temperature Heat Capacities and Thermodynamic Properties of a New Complex [Na(H2O)2]6[MoCo6O12(H2O)12]•4.3H2O(s)

2014 ◽  
Vol 525 ◽  
pp. 141-145
Author(s):  
Qing Fen Meng ◽  
Xiao San Xia
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Adiabatic Calorimeter ◽  
Heat Capacities ◽  
Dehydration Process ◽  
X Ray ◽  
X Ray Crystallography ◽  
Temperature Heat ◽  
Enthalpy And Entropy ◽  
Heat Capacity Measurements

A new complex [Na (H2O)2]6[MoCo6O12(H2O)12]·4.3H2O(s) was synthesized and determined by X-ray crystallography. Low-temperature heat capacities of the compound was measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. An obvious dehydration process was found in the heat capacity curve of the title compound. The temperature, enthalpy and entropy of the dehydration process were determined to be (370.266±0.292) K, (187.455±0.354) kJ·mol-1, (50.627±0.078) J·K-1·mol-1 by three series of repeated heat capacity measurements in the region of thermal decomposition.

SPECIFIC HEATS AND LATENT HEAT OF FUSION OF ICE

1930 ◽  
Vol 3 (3) ◽  
pp. 205-213 ◽  
Author(s):  
W. H. Barnes ◽  
O. Maass
Keyword(s):  
Heat Capacity ◽  
Latent Heat ◽  
Adiabatic Calorimeter ◽  
Heat Capacities ◽  
Heat Of Fusion ◽  
Final Temperature ◽  
Latent Heat Of Fusion ◽  
Temperature Range ◽  
Specific Heats

Values for the heat capacities of ice and resulting water from initial temperatures of between 0 °C. and − 78.5 °C. to a final temperature of + 25.00 °C. are measured to ± 0.05% or better with an improved adiabatic calorimeter previously described. The specific heats of ice over the temperature range 0° C. to − 80 °C. are found and the latent heat of fusion of ice at 0 °C. is obtained from these heat capacity determinations.

HYDROGEN PEROXIDE: THE LOW TEMPERATURE HEAT CAPACITY OF THE SOLID AND THE THIRD LAW ENTROPY

1954 ◽  
Vol 32 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Paul A. Giguère ◽  
I. D. Liu ◽  
J. S. Dugdale ◽  
J. A. Morrison
Keyword(s):  
Hydrogen Peroxide ◽  
Heat Capacity ◽  
Low Temperature ◽  
Adiabatic Calorimeter ◽  
Ideal Gas ◽  
Heat Of Fusion ◽  
A Value ◽  
Two Samples ◽  
Thermal Measurements ◽  
Heat Capacity Measurements

The heat capacity of crystalline hydrogen peroxide between 12° K. and the melting point has been determined with a low temperature adiabatic calorimeter. The heat of fusion was also measured and found to be 2987 ± 3 cal./mole. The two samples of hydrogen peroxide used were 99.97 mole % pure as deduced from behavior on melting and from premelting heat capacities; the triple point was estimated to be 272.74 K.The only anomaly observed in the heat capacity measurements was the absorption of 1.3 cal./mole at 216.8 ± 0.15° K., the lower eutectic temperature of H2O-H2O2 solutions. Such an effect is to be expected if the only significant impurity is water. The entropy of hydrogen peroxide as an ideal gas at 1 atm. pressure and 25° C. computed from the thermal measurements is 55.76 ± 0.12 cal./mole deg. Comparison of this datum with the recalculated statistical entropy leads to a value of 3.5 kcal./mole for the height of a hypothetical single barrier hindering internal rotation in the molecule. From these results it is concluded that hydrogen peroxide does not consist of two tautomeric modifications.

THE HEAT CAPACITY OF SILVER AND NICKEL BETWEEN 100° AND 500 °C.

1936 ◽  
Vol 14a (10) ◽  
pp. 194-199 ◽  
Author(s):  
H. L. Bronson ◽  
E. W. Hewson ◽  
A. J. C. Wilson
Keyword(s):  
Heat Capacity ◽  
Adiabatic Calorimeter ◽  
Heat Capacities ◽  
The Mean

The mean heat capacities of silver and nickel between 0 °C. and various temperatures from 100° to 500 °C. have been determined by the method of mixtures, an all-copper adiabatic calorimeter being used.A brief discussion deals with the difficulty of obtaining accurate values of the true heat capacity, Cp, from mean heat capacity, [Formula: see text], measurements.The following table gives a brief summary of the results:100° 150° 200° 250° 300° 350° 400° 450° 500°C.Silver[Formula: see text] 0.2364 0.2376 0.2389 0.2401 0.2415 0.2427 0.2440 0.2452 0.2465Cp 0.2389 0.2413 0.2439 0.2463 0.2490 0.2514 0.2540 0.256 0.259Nickel[Formula: see text] 0.4536 0.4636 0.4741 0.4856 0.4972 0.5117 0.5162 0.5177 0.5188Cp 0.474 0.495 0.517 0.543 0.575 0.627 0.531 0.529 0.527The uncertainty in [Formula: see text] of both silver and nickel is about 0.2%, in Cp of silver from about 0.2% at 100 °C. to nearly 1% at 500 °C., in Cp of nickel from about 0.5% at 100 °C. to 2% at 350 °C. and above.

Heat capacities of liquid 2,3,6-trimethylpyridine, 2,4,6-trimethylpyridine and 3-methoxypropionitrile within the range of temperatures of 300 to 328 K

1991 ◽  
Vol 56 (12) ◽  
pp. 2786-2790 ◽  
Author(s):  
Václav Svoboda ◽  
Milan Zábranský
Keyword(s):  
Temperature Interval ◽  
Atmospheric Pressure ◽  
Liquid State ◽  
Adiabatic Calorimeter ◽  
Heat Capacities

Molar heat capacities of 2,3,6-trimethylpyridine, 2,4,6-trimethylpyridine and 3-methoxypropionitrile in the liquid state were measured at the constant atmospheric pressure in the temperature interval of 300.60 to 328.35 K. The static type of adiabatic calorimeter was used for the measurements.

Heat capacities and enthalpies of fusion and transformation for solvates of some salts with dimethyl sulfoxide and dimethylformamide

1988 ◽  
Vol 53 (12) ◽  
pp. 3072-3079
Author(s):  
Mojmír Skokánek ◽  
Ivo Sláma
Keyword(s):  
Heat Capacity ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Dimethyl Sulfoxide ◽  
Liquidus Temperature ◽  
Molar Heat Capacity ◽  
Solid Phase ◽  
Zinc Nitrate ◽  
Heat Capacities ◽  
Liquid Phases

Molar heat capacities and molar enthalpies of fusion of the solvates Zn(NO3)2 . 2·24 DMSO, Zn(NO3)2 . 8·11 DMSO, Zn(NO3)2 . 6 DMSO, NaNO3 . 2·85 DMSO, and AgNO3 . DMF, where DMSO is dimethyl sulfoxide and DMF is dimethylformamide, have been determined over the temperature range 240 to 400 K. Endothermic peaks found for the zinc nitrate solvates below the liquidus temperature have been ascribed to solid phase transformations. The molar enthalpies of the solid phase transformations are close to 5 kJ mol-1 for all zinc nitrate solvates investigated. The dependence of the molar heat capacity on the temperature outside the phase transformation region can be described by a linear equation for both the solid and liquid phases.

An automated adiabatic calorimeter for heat-capacity measurements between 20 and 90 K

1988 ◽  
Vol 123 ◽  
pp. 105-111 ◽  
Author(s):  
Tan Zhicheng ◽  
Yin Anxue ◽  
Chen Shuxia ◽  
Zhou Lixing ◽  
Li Fuxue ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Adiabatic Calorimeter ◽  
Heat Capacity Measurements

NEUTRON POWDER DIFFRACTION AND OXIDE SUPERCONDUCTORS

1993 ◽  
Vol 07 (16n17) ◽  
pp. 3077-3093 ◽  
Author(s):  
A.W. HEWAT
Keyword(s):  
Heavy Metals ◽  
High Temperature ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Oxide Superconductors ◽  
X Rays ◽  
New Materials ◽  
Oxidation Reduction ◽  
High Temperature Oxide ◽  
Temperature Oxide

Neutron powder diffraction has been essential for understanding the structures of the new high temperature oxide superconductors because of the difficulty in locating oxygen with X-rays in the presence of heavy metals, especially when single crystals are usually not available. This understanding lead to the discovery of new materials. In this paper we will show how it also sheds light on the crystal chemistry of oxide superconductors—the effects of oxidation/reduction, phase separation, pressure etc.

Sign in / Sign up

Export Citation Format

Share Document