Thermoelectric Properties of Arc-Melted Ba8Al16Si30 Clathrate

2007 ◽  
Vol 539-543 ◽  
pp. 3309-3312 ◽  
Author(s):  
Jung Il Lee ◽  
Jong Bum Park ◽  
Sin Wook You ◽  
Joo Ho Lee ◽  
Young Ho Kim ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Density Measurement ◽  
Hardness Test ◽  
Homogenization Temperature ◽  
Vacuum Furnace ◽  
Type I ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Type Conduction

Ba8Al16Si30 type I clathrate was produced by arc melting and thermoelectric properties were investigated. The phase transformation behavior of arc-melted type I Ba8Al16Si30 was examined by thermogravimetric analysis, differential scanning calorimetry, hardness test, density measurement, X-ray diffraction and scanning electron microscope analyses. Homogenization was carried out to induce the transformation to a thermoelectric phase at 773K to 973K for 5 hours and 24 hours in the vacuum furnace. Thermoelectric properties in the temperature range between 300K and 600K were measured and evaluated. Electrical conductivity was decreased and Seebeck coefficient was increased with increasing homogenization temperature and time. The arc-melted and the homogenized specimens represented n-type conduction at temperatures examined, and they showed reliable thermoelectric behaviors with increasing homogenization temperature and time.

Effects of Annealing Treatment on Microstructure and Thermoelectric Properties of Ba8Al16Si30

2006 ◽  
Vol 118 ◽  
pp. 561-564 ◽  
Author(s):  
Jung Il Lee ◽  
Jong Bum Park ◽  
Sin Wook You ◽  
Joo Ho Lee ◽  
Il Ho Kim ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Isothermal Annealing ◽  
Annealing Treatment ◽  
Hardness Test ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Annealing Effects ◽  
Type Conduction

Clathrate Ba8Al16Si30 was produced by arc melting and annealing effects on the microstructure and thermoelectric properties were investigated. The phase transformation behavior of arc-melted Ba8Al16Si30 was examined by thermogravimetric analysis, differential scanning calorimetry, hardness test, X-ray diffraction and scanning electron microscope analyses. Isothermal annealing was carried out to induce the transformation to a thermoelectric phase at 500°C to 700°C for 5 hrs. Thermoelectric properties in the temperature range between 300K and 600K were measured and evaluated. Electrical conductivity was decreased and Seebeck coefficient was increased with increasing isothermal annealing temperature. The arc-melted and the isothermal annealed specimens represented n-type conduction at temperatures examined, and they showed reliable thermoelectric behaviors.

Microstructure Evolution and Properties of 7A56 Aluminum Alloy by Homogenization

2017 ◽  
Vol 898 ◽  
pp. 153-158 ◽  
Author(s):  
Da Xu ◽  
Zhi Hui Li ◽  
Guo Jun Wang ◽  
Long Bing Jin ◽  
Hong Wei Yan ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Microstructure Evolution ◽  
Equilibrium Phase ◽  
Hardness Test ◽  
Homogenization Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Second Phases ◽  
Al Matrix

The microstructure evolution and properties of Al-matrix in homogenized 7A56 alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), electrical conductivity and hardness test. The second phases in as-cast 7A56 alloy consisted of AlZnMgCu, Al2Cu and Al7Cu2Fe. With the homogenization temperature increasing, more non-equilibrium phase AlZnMgCu was dissolved into Al-matrix. The diffusion of alloying elements from AlZnMgCu phase into Al-matrix leads to a decrease of electrical conductivity and an increase of hardness. The lattice constant of α-Al has an increases of 0.0019 Å, 0.0032 Å and 0.0053 Å after 380°C/24h,430°C/24h,and 470°C/24 h treatment,respectively.

Effects of Homogenization Treatment on Thermoelectric Properties of Ba8Al16Si30

2007 ◽  
Vol 544-545 ◽  
pp. 275-278 ◽  
Author(s):  
Joo Ho Lee ◽  
Jung Il Lee ◽  
Young Ho Kim ◽  
Il Ho Kim ◽  
Kyung Wook Jang ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Transformations ◽  
Thermoelectric Properties ◽  
Treatment Time ◽  
Type I ◽  
X Ray Diffraction ◽  
Homogenization Treatment ◽  
X Ray ◽  
Arc Melting ◽  
Melting Technique

The Arc melting technique was employed to synthesize the type I clathrate of Ba8Al16Si30 compound. Phase transformations during synthesis and homogenization treatment were investigated using X-ray diffraction (XRD) and thermal analysis (TG/DSC). Thermoelectric properties as functions of temperature and homogenization treatment time were evaluated in this study. Maximum ZT was 0.14 at 590K for homogenized at 1173 K for 168hrs specimen and it is strongly expected to show higher value above 600K.

Effects of Cooling Rate and Sn Addition on the Microstructure of Ti-Nb-Sn Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 190-195 ◽  
Author(s):  
Giorgia T. Aleixo ◽  
Eder S.N. Lopes ◽  
Rodrigo Contieri ◽  
Alessandra Cremasco ◽  
Conrado Ramos Moreira Afonso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Melting Furnace ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Arc Melting ◽  
Ti Alloys ◽  
Ω Phase

Ti-based alloys present unique properties and hence, are employed in several industrial segments. Among Ti alloys, β type alloys form one of the most versatile classes of materials in relation to processing, microstructure and mechanical properties. It is well known that heat treatment of Ti alloys plays an important role in determining their microstructure and mechanical behavior. The aim of this work is to analyze microstructure and phases formed during cooling of β Ti-Nb-Sn alloy through different cooling rates. Initially, samples of Ti-Nb-Sn system were prepared through arc melting furnace. After, they were subjected to continuous cooling experiments to evaluate conditions for obtaining metastable phases. Microstructure analysis, differential scanning calorimetry and X-ray diffraction were performed in order to evaluate phase transformations. Depending on the cooling rate and composition, α” martensite, ω phase and β phase were obtained. Elastic modulus has been found to decrease as the amount of Sn was increased.

Crystallization of Amorphous Cu49.7Ti31.8Zr11.3Ni7.2 Alloy

2016 ◽  
Vol 869 ◽  
pp. 464-469 ◽  
Author(s):  
Carlos Triveño Rios ◽  
R. Contieri
Keyword(s):  
Low Cost ◽  
Centrifugal Casting ◽  
Amorphous State ◽  
Bulk Sample ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
High Fracture ◽  
Crystalline Materials ◽  
Thermal Crystallization ◽  
Arc Melting

Bulk metallic glasses are attractive materials for structural and functional applications when compared to crystalline materials. The Cu-based glasses exhibit particular interest due primarily to their relatively low cost and high fracture resistance. In this work the Cu49.7Ti31.8Zr11.3Ni7.2 alloy was prepared from the mixture of pure metals by arc melting and following the ingot was re-melted by centrifugal casting in wedge-section copper mould. The structure of wedge bulk sample was evaluated by a combination of X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The results show that the amorphous state is formed in the thinner region and it is maintained up to thickness of 3.5 mm in the wedge bulk-sample. The crystallization temperature was observed above 400 °C coinciding with the studies of thermal crystallization by XRD and DSC. Dynamical heating of the amorphous phase from room temperature up to 750°C showed the formation of CuTi, Cu10Zr7 e Cu2TiZr crystalline phases.

Annealing Effect on the Thermoelectric Properties of Undoped CoSb3

2006 ◽  
Vol 118 ◽  
pp. 565-570 ◽  
Author(s):  
Il Ho Kim ◽  
Jung Il Lee ◽  
Soon Chul Ur ◽  
Kyung Wook Jang ◽  
Good Sun Choi ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Annealing Effect ◽  
Metallic Behavior ◽  
Arc Melting ◽  
P Type ◽  
Type Conduction

Binary skutterudite CoSb3 compounds were prepared by the arc melting and hot pressing processes and their thermoelectric properties were investigated at 300K-600K. Annealing effect was examined and it was correlated to phase transformation and homogenization. Thermoelectric properties of the arc-melted and hot-pressed CoSb3 were discussed and compared. Undoped CoSb3 prepared by the arc melting showed p-type conduction and metallic behavior at all temperatures examined. However, hot pressed specimens showed n-type conduction, possibly due to Sb evaporation. Thermoelectric properties were remarkably improved by annealing in vacuum and they were closely related to phase transitions.

scholarly journals Structural Phase Transition and Related Thermoelectric Properties in Sn Doped AgBiSe2

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1016
Author(s):  
Xiao-Cun Liu ◽  
Ming-Yan Pan
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Thermoelectric Material ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Complex Structural

AgBiSe2, which exhibits complex structural phase transition behavior, has recently been considered as a potential thermoelectric material due to its intrinsically low thermal conductivity. In this work, we investigate the crystal structure of Sn-doped AgBiSe2 through powder X-ray diffraction and differential scanning calorimetry measurements. A stable cubic Ag1−x/2Bi1−x/2SnxSe2 phase can be obtained at room temperature when the value of x is larger than 0.2. In addition, the thermoelectric properties of Ag1−x/2Bi1−x/2SnxSe2 (x = 0.2, 0.25, 0.3, 0.35) are investigated, revealing that Ag1−x/2Bi1−x/2SnxSe2 compounds are intrinsic semiconductors with a low lattice thermal conductivity. This work provides new insights into the crystal structure adjustment of AgBiSe2 and shows that Ag1−x/2Bi1−x/2SnxSe2 is a potentially lead-free thermoelectric material candidate.

scholarly journals IMPROVEMENT OF DISSOLUTION RATE OF VALSARTAN BY SOLID DISPERSION SYSTEM USING D(−) MANNITOL

2017 ◽  
Vol 10 (3) ◽  
pp. 288 ◽  
Author(s):  
Erizal Zaini ◽  
Salman Umar ◽  
Nurhidayah Nurhidayah
Keyword(s):  
Dissolution Rate ◽  
Solid Dispersion ◽  
In Vitro Dissolution ◽  
Type I ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dispersion System ◽  
Grinding Technique

ABSTRACTObjective: To improve dissolution rate of valsartan from solid dispersion system of valsartan and D(−) mannitol using co-grinding approach.Methods: Valsartan solid dispersion with different ratio of D(−) mannitol (1:1; 1:3 and 1: 5) were prepared by co-grinding method. Solid statecharacterization of the solid dispersion system was evaluated in term of crystallographic properties (powder X-ray diffraction), thermal behavior(differential scanning calorimetry [DSC]) and morphology (scanning electron microscope). The profile of dissolution rate was examined using USPdissolution apparatus type I at a temperature of 37±0.5°C.Results: Based on thermal analysis DSC and powder X-ray diffraction analysis, valsartan was transformed from semicrystalline phase to amorphousstate as indicated by the disappearance of its melting endothermic peaks and the characteristic diffraction peaks. The in vitro dissolution rate studyrevealed that all solid dispersion system showed significant increase in dissolution rate compared with the intact valsartan.Conclusion: Solid dispersion of valsartan with D(−) mannitol prepared by co-grinding technique has successfully improved the dissolution ratecompared with intact valsartan.Keywords: Valsartan, D(−) mannitol, Solid dispersion, Co-grinding, Dissolution rate.

Phase Purity and Thermoelectric Properties of Type-I Clathrates Ba8CuxSiyGe46-x-y (4 ≤ x ≤ 6.5, y = 0 and 5.15 ≤ x ≤ 6.425, 2.05≤ y ≤ 36.9)

2017 ◽  
Vol 1142 ◽  
pp. 37-44
Author(s):  
Yue Dong ◽  
Xin Lin Yan ◽  
Zhao Hui Tang ◽  
Xue Yong Ding ◽  
Xu Dong Sun ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Ball Milling ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Type I ◽  
Phase Purity ◽  
Arc Melting ◽  
Elemental Substitution ◽  
Plasma Sintering ◽  
Spark Plasma

Type-I clathrates have been considered as very promising thermoelectric (TE) materials thus attracting attention widely. Here we report new clathrates Ba8CuxSiyGe46-x-y (4≤ x ≤ 6.5, y = 0 and 5.15 ≤ x ≤ 6.425, 2.05≤ y ≤ 36.9), focusing on their phase purity and TE properties. Our results show that samples prepared by arc melting followed by annealing are multi-phases alloys. The composition of the clathrate phase is also inhomogeneous. This indicates that the kinetic factor dominates the reaction of forming the clathrate phase during element-melting and sample-annealing. We select three compositions in these two series of samples, which have less impurity and better composition homogeneity for the clathrate phase, and the annealed alloys are furthered processed by ball milling (BM) and powder-solidification (either by hot pressing (HP) or by spark plasma sintering (SPS)) for TE properties investigations. The BM and HP/SPS processes can improve the phase purity and homogeneity. The TE measurements show that the Si-substituted samples have better performance than the Ge-based sample, mainly by decreasing the electrical resistivity. This indicates that the elemental substitution may be still an effective way to improve the TE performance of clathrates.

scholarly journals Influence of Annealing on Strength of Ultrafine Grained Low Carbon Steels by ECAP

2010 ◽  
Vol 638-642 ◽  
pp. 1899-1904 ◽  
Author(s):  
T. Akita ◽  
Masahide Gotoh ◽  
Sergey V. Dobatkin ◽  
Kazuo Kitagawa ◽  
Yukio Hirose
Keyword(s):  
Low Carbon Steel ◽  
Hardness Test ◽  
Carbon Steels ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermal Reactions ◽  
Fine Grained ◽  
Angular Pressing ◽  
Ultrafine Grained

In the present study, ultra fine-grained low carbon steel samples were processed by equal channel angular pressing (ECAP). Mechanical properties of the specimens annealed statically at several temperatures were evaluated by tensile and hardness test. In addition, grain sizes of the specimens were measured by SEM-electron back scattering pattern (SEM-EBSP) and X-ray diffraction analysis. Differential scanning calorimetry (DSC) measurement also evaluated thermal reactions in anneal process of the specimen. As a result, the grain size was changed at the temperature between 550oC and 600oC drastically and the tensile strength also became lower at the same temperature. The relation between yield stress and averaged grain diameter of specimens obeyed the Hall-Petch relation except the normalized specimen. Behavior of grain growth and recovery in structural observation by EBSP corresponded to reaction signal of the DSC curve.

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