scholarly journals Thermodynamic, Electromagnetic, and Lattice Properties of Antiperovskite Mn3SbN

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Ying Sun ◽  
Yan-Feng Guo ◽  
Yoshihiro Tsujimoto ◽  
Xia Wang ◽  
Jun Li ◽  
...  
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Electronic Transport ◽  
Room Temperature ◽  
Lattice Distortion ◽  
Entropy Change ◽  
Temperature Curve ◽  
Tetragonal Structure ◽  
Cubic Structure ◽  
Transition Entropy

The physical properties of polycrystalline Mn3SbN were investigated using measurements of the magnetic, calorimetric, and electronic transport properties. At room temperature, the phase crystallizes in a tetragonal structure withP4/mmmsymmetry. A remarkably sharp peak in the heat capacity versus temperature curve was found near 353 K. The peak reaches 723 J mol−1 K−1at its highest, which corresponds to a transition entropy of 10.2 J mol−1 K−1. The majority of the large entropy change appears to be due to lattice distortion from the high-temperature cubic structure to the room-temperature tetragonal structure and the accompanying Ferrimagnetic transition.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Refrigerant Capacity and Magnetocaloric Effect on LaFe11.1Co0.8Si1.1BX Alloys

2011 ◽  
Vol 84-85 ◽  
pp. 667-670
Author(s):  
Guo Qiu Xie
Keyword(s):  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Field Change ◽  
Refrigerant Capacity ◽  
Structure Phase ◽  
Magnetic Field Change ◽  
Cubic Structure

In this paper, we report on the structure, magnetic properties and magnetocaloric effect in NaZn13-type LaFe11.1Co0.8Si1.1Bxalloys close to room temperature. The stable NaZn13cubic structure phase (space group isFm-3c) can easily obtained by annealing at 1080 °C for 225 hours. The maximal values of magnetic entropy change for LaFe11.1Co0.8Si1.1Bx(x=0.2, 0.25) were found to be 5.3 and 5.9 J/kg K at Curie temperature for a magnetic field change in 0-1.5 T, respectively. The calculated refrigerant capacity for a field change in 0–1.5 T is about 147 and 107 J/kg K, for LaFe11.1Co0.8Si1.1B0.2and LaFe11.1Co0.8Si1.1B0.25respectively, which is as larger as those of Gd(99.3%) alloy

A Calorimetric Study of Ammonium, Rubidium, and Potassium Hexafluophosphate

1963 ◽  
Vol 18 (2) ◽  
pp. 148-154 ◽  
Author(s):  
L. A. K. Staveley ◽  
N. R. Grey ◽  
M. J. Layzell
Keyword(s):  
Heat Capacity ◽  
Low Temperatures ◽  
Potassium Salt ◽  
Room Temperature ◽  
Entropy Change ◽  
Ammonium Ion ◽  
Calorimetric Study ◽  
First Order ◽  
Rubidium Salt ◽  
First Order Transition

Measurements have been made of the heat capacities of ammonium, rubidium, and potassium hexafluophosphate from ∼ 20°K to ∼ 300°K. The heat capacity curve of the ammonium salt shows two anomalous regions, and an order-disorder change also occurs in the rubidium salt. The potassium salt, however, undergoes a first-order transition with a large entropy change. The heat capacity of the ammonium and rubidium salts in the neighbourhood of room temperature (but not that of the potassium salt) is altered by cooling to low temperatures. In certain ranges of temperature it was unusually difficult with the rubidium salt to obtain reproducible heat capacity values. The results show that the rotation of the ammonium ion is not completely free, but they are consistent with almost free rotation in one degree of freedom and partially restricted rotation in the other two. The possible significance of the entropy changes of the various transitions is briefly discussed.

Thermodynamic Performance Characteristics of a Regenerative Brayton Refrigeration Cycle Using Gd0.45Tb0.55 and Gd as the Working Substance

2013 ◽  
Vol 750-752 ◽  
pp. 1016-1019 ◽  
Author(s):  
Shan He Su ◽  
Zhi Chao Xu ◽  
Guo Xing Lin ◽  
Gildas Diguet ◽  
Jin Can Chen
Keyword(s):  
Heat Capacity ◽  
Numerical Calculation ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Performance Characteristics ◽  
Refrigeration Cycle ◽  
Magnetic Entropy ◽  
Thermodynamic Performance ◽  
Brayton Refrigeration Cycle

Based on experimental characteristics of the iso-field heat capacity of the working substances Gd0.45Tb0.55and Gd, the magnetic entropy change with temperature is calculated. The regenerative Brayton refrigeration cycles employing these materials as the working substances are established. By means of thermodynamic analysis and numerical calculation, the effects of the non-perfect regeneration on the performance characteristics of the refrigeration cycles are revealed. Furthermore, the cyclic performances employing Gd0.45Tb0.55and Gd as the working substances are evaluated and compared. The results obtained may provide some useful information for the optimal design of the room temperature magnetic refrigerators.

Magnetocaloric behavior of REE porphyrin-based paramagnets at room temperature

2019 ◽  
Vol 23 (10) ◽  
pp. 1110-1117 ◽  
Author(s):  
V. V. Korolev ◽  
T. N. Lomova ◽  
A. G. Ramazanova ◽  
O. V. Balmasova ◽  
E. G. Mozhzhukhina
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Magnetic Fields ◽  
Single Molecule ◽  
Room Temperature ◽  
Magnetic Behavior ◽  
Entropy Change ◽  
Scanning Calorimetry ◽  
Single Molecule Magnet ◽  
Microcalorimetric Method

REE complexes with cyclic aromatic ligands are ranked as the molecular materials with both electronic functionality and a single-molecule magnet behavior at temperatures lower 80 K. At the temperature close to room, they display a positive magnetocaloric effect (MCE) often comparable with one in ferromagnetics. We were determined MCE during the magnetization of both (5,10,15,20-tetra(4-tert-butylphenylporphinato))ytterbium(III)chloride, (Cl)YbT[Formula: see text]BuPP and (5,10,15,20-tetraphenylporphinato)ytterbium(III)chloride, (Cl)YbTPP in their aqueous suspensions over the temperature range of 278–320 K and in magnetic fields from zero to 1 T by the direct microcalorimetric method. Specific heat capacity in the solid of (Cl)YbT[Formula: see text]BuPP/(Cl)YbTPP has been directly determined in zero magnetic fields using differential scanning calorimetry. Thermodynamic parameters of ytterbium(III) complexes magnetization namely enthalpy/entropy change was determined. To improve understanding of the correlation between (Cl)YbT[Formula: see text]BuPP/(Cl)YbTPP magnetic properties and its electronic structure, we have compared magnetic behavior of paramagnets studied with those for (Cl)MTPP where M = Gd, Eu, Tm.

Iron Oxide-based Magnetic Nanoparticles for High Temperature Span Magnetocaloric Applications

2014 ◽  
Vol 1708 ◽  
Author(s):  
V. Chaudhary ◽  
R. V. Ramanujan
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Magnetic Nanoparticles ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Average Crystallite Size ◽  
Entropy Change ◽  
Superparamagnetic Nanoparticles ◽  
Cooling Power ◽  
Magnetic Entropy

ABSTRACTThe magnetocaloric effect of chemically synthesized Mn0.3Zn0.7Fe2O4 superparamagnetic nanoparticles with average crystallite size of 11 nm is reported. The magnitude of the magnetic entropy change (ΔSM), calculated from magnetization isotherms in the temperature range of 30 K to 400 K, increases from - 0.16 J-kg-1K-1 for a field of 1 T to - 0.88 J-kg-1K-1 for 5 T at room temperature. Our results indicate that ΔSM values are much higher than primarily reported values for this class of nanoparticles. ΔSM is not limited to the ferromagnetic-paramagnetic transition temperature; instead, it occurs over a broad range of temperatures, resulting in high relative cooling power.

scholarly journals Высокотемпературная теплоемкость апатитов Pb-=SUB=-10-x-=/SUB=-Nd-=SUB=-x-=/SUB=-(GeO-=SUB=-4-=/SUB=-)-=SUB=-2+x-=/SUB=-(VO)-=SUB=-4-x-=/SUB=- (x=0-3)

2019 ◽  
Vol 61 (7) ◽  
pp. 1397
Author(s):  
Л.Т. Денисова ◽  
Е.О. Голубева ◽  
H.В. Белоусова ◽  
В.М. Денисов ◽  
Н.А. Галиахметова
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
High Temperature ◽  
Solid State ◽  
Gibbs Energy ◽  
Entropy Change ◽  
Apatite Structure ◽  
Scanning Calorimetry ◽  
High Temperature Heat Capacity ◽  
Temperature Heat

The Pb10-xNdx(GeO4)2+x(VO4)4-x (x = 0 ‒ 3) compounds with the apatite structure have been synthesized from PbO, Nd2O3, GeO2 and V2O5 oxides by the solid-state synthesis with successive burning in air within 773-1073 K. The high-temperature heat capacity of the compounds obtained was determined by differential scanning calorimetry. The CP = f(T) data have been used to evaluate their thermodynamic properties (enthalpy increment, entropy change, and reduced Gibbs energy).

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

NICROFER 5923 HMo-ALLOY 59

Alloy Digest ◽  
1993 ◽  
Vol 42 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Heat Treating ◽  
Face Centered Cubic ◽  
Low Carbon ◽  
High Alloy ◽  
Temperature Performance ◽  
Cubic Structure ◽  
Face Centered

Abstract NICROFER 5923 hMo, often called Alloy 59, was developed with extra low carbon and silicon contents and with a high alloy level of molybdenum to optimize its corrosion resistance. Nicrofer 5923hMo has a face-centered cubic structure. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, and joining. Filing Code: Ni-430. Producer or source: VDM Technologies Corporation.

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

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