Fabrication and Thermoelectric Properties of Bi2Te3 Prepared by Combining Chemical Bath Method and Hot Pressing

2013 ◽  
Vol 743-744 ◽  
pp. 65-69 ◽  
Author(s):  
Feng Yuan Li ◽  
Yuan Yuan Wang ◽  
Song Chen ◽  
Zhen Qin ◽  
Ke Feng Cai
Keyword(s):  
Thermoelectric Properties ◽  
Electrical Transport ◽  
Hot Pressing ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Bulk Materials ◽  
X Ray ◽  
Synthesis Conditions ◽  
Sulfur Addition ◽  
Before And After

Bi2Te3 bulk materials were prepared by combining chemical bath method and hot pressing at 80 MPa and 375 °C for 1 h. The samples before and after hot pressing were examined by X-ray diffraction, and the fracture surface of the bulk materials was observed by field emission scanning electron microscopy (FESEM). The electrical transport properties of the bulk materials were measured from room temperature up to 250 °C under Ar. The results indicate that sulfur addition can prevent the oxidation of Bi2Te3 nanostructures; however, it is not good to the thermoelectric properties of Bi2Te3 under the present synthesis conditions.

Influence of Cu Diffusion on Electrical Transport Properties of Bi0.5Sb1.5Te3

2013 ◽  
Vol 743-744 ◽  
pp. 70-75 ◽  
Author(s):  
Song Chen ◽  
Xin Wang ◽  
Zhi Gang Zou ◽  
Ke Feng Cai
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Electrical Transport ◽  
Impurity Phase ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Bulk Materials ◽  
Measurement Temperature ◽  
X Ray ◽  
Before And After

Bi0.5Sb1.5Te3 nanoplates from gas induced reduction (GIR) strategy were hot-pressed into bulk materials for thermoelectric properties investigation. During the electrical conductivity and Seebeck coefficient measurements, we found that the Cu from Cu electrodes diffused into samples when the measurement temperature was above 600 K. The phase composition and fracture surface of the samples before and after Cu diffusion were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). We found that the Cu diffusion resulted in the composition deviation and formation of impurity phase, Cu1.8Te. When the electrical conductivity and Seebeck coefficient of the samples were measured again but below 600 K, the samples showed different electrical transport behavior and had enhanced power factors.

Thermoelectric properties of polycrystalline Bi2Se3−x by powder compaction sintering

2020 ◽  
Vol 34 (18) ◽  
pp. 2050206
Author(s):  
Ying Zhou ◽  
Zhenhua Ge ◽  
Jun Guo ◽  
Jing Feng
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Electrical Transport ◽  
Bulk Material ◽  
Powder Compaction ◽  
Electrical Transport Properties ◽  
X Ray

[Formula: see text] is a [Formula: see text] compound (where Pn = Bi and Sb, Ch = Te, Se, and S), which has attracted increasing attention as a candidate for use in thermoelectric applications. Previous studies demonstrated the advantage of [Formula: see text] thermoelectric materials, despite an inferior thermoelectric performance. Herein, a series of [Formula: see text] ([Formula: see text], 0.10, 0.15, 0.20, and 0.25) thermoelectric materials were prepared by powder compaction sintering. The effects of phase structures and microstructure of the [Formula: see text] bulk material were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were measured systematically. The results show that carrier concentration increased with decreasing Se content, which in turn affected the electrical transport properties. Low Se contents gave larger power factor (PF) values than the pristine [Formula: see text] sample, the maximum PF value being [Formula: see text] at 320 K for [Formula: see text]. The variation in PF was attributed to the variations in electrical conductivity [Formula: see text] and Seebeck coefficient [Formula: see text] upon optimizing Se content. The [Formula: see text] samples showed an enhanced thermoelectric figure of merit (ZT) with increasing measurement temperature, due to the increased [Formula: see text] value, [Formula: see text], and decreased [Formula: see text]. The [Formula: see text] sample exhibited the highest ZT (0.28) at 575 K, while [Formula: see text] exhibited the lowest ZT (0.14) at 325 K. This indicated that tuning Se content was an effective way to enhance carrier concentration.

Study of Structural and Electrical Transport Properties of Polycrystalline La1-XCaXMnO3 (x=0.33, 0.5 and 0.9) Prepared by a Co-Precipitation Method

2013 ◽  
Vol 652-654 ◽  
pp. 576-580 ◽  
Author(s):  
Mya Theingi ◽  
Ji Ma ◽  
Hui Zhang ◽  
Xiang Gao ◽  
Jian Hong Yi ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Perovskite Phase ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
X Ray ◽  
Manganite Perovskite ◽  
Polycrystalline Ceramics ◽  
Co Precipitation

Manganite perovskite La1-xCaxMnO3(x=0.33, 0.5 and 0.9) have been prepared by chemical co-precipitation method. Ammonium carbonate was used to coprecipitate lanthanum, calcium and manganese ions as carbonates under basic condition. This precursor on calcining at 900°C yields La-Ca-Mn-O perovskite phase. Follow by sintering at 1200°C after the powders were pressed into pellets gave La1-xCaxMnO3(LCMO) polycrystalline ceramics. The crystal phases of the resulting powders and ceramics were examined by X-ray diffraction (XRD) technique. The morphology of the powders was observed by scanning electron microscopy (SEM) and electrical transport properties of ceramics were measured by conventional four-point probe technique.

Equation of state and electrical transport properties of mixture of Li1.2Mn0.54Co0.13Ni0.13O2 and LiNi0.87Co0.09Mn0.03Al0.01O2 at high pressure

2021 ◽  
pp. 2150227
Author(s):  
Lun Xiong ◽  
Pu Tu ◽  
Yongqing Hu ◽  
Xiang Hou ◽  
Shiyun Wu ◽  
...  
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Electrical Transport ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
X Ray ◽  
Diamond Anvil

The equation of state (EOS) of mixture of Li[Formula: see text]Mn[Formula: see text]Co[Formula: see text]Ni[Formula: see text]O2 and LiNi[Formula: see text] Co[Formula: see text]Mn[Formula: see text]Al[Formula: see text]O2 was studied by synchrotron radiation X-ray diffraction (XRD) at room-temperature in a diamond anvil cell (DAC). The results showed that the hexagonal structure is maintained to the highest pressure of 23.1 GPa. The bulk modulus and its first derivative obtained from XRD data are [Formula: see text] GPa and [Formula: see text], respectively. In addition, we have investigated the high-pressure electrical conductivity of the mixture of Li[Formula: see text]Mn[Formula: see text]Co[Formula: see text]Ni[Formula: see text]O2 and LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]Al[Formula: see text]O2 to 22.9 GPa in a DAC. It is found that the resistance decreases with the increase of pressure and changes exponentially.

Structural, Magnetic, and Transport Properties of La0.62Sb0.38MnO3 Ceramic

2013 ◽  
Vol 800 ◽  
pp. 398-401 ◽  
Author(s):  
Qiang Wang ◽  
Ping Duan ◽  
Ji You Wang ◽  
Lei Chang ◽  
Jin Liang Zhao ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
State Transition ◽  
Ferromagnetic State ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Hexagonal Crystal ◽  
Electrical Transport Properties ◽  
Metal Insulator ◽  
X Ray

The polycrystalline La0.62Sb0.38MnO3 sample has been prepared by the solid-state reaction method. Structural, magnetic and electrical transport properties have been researched. X-ray diffraction analysis confirms the hexagonal crystal symmetry. Magnetization measurements indicate La0.62Sb0.38MnO3 experienced from paramagnetic to ferromagnetic state transition with decreasing temperature at about 225 K. Resistivity dependences on temperature exhibit metal-insulator transition (MIT), and the maximum magnetoresistance (MR) ratio is about 33 % at temperature of 189 K and magnetic field of 2 T.

Fabrication and Mechanical Properties of High-Pure Ti3SiC2 Bulk Materials Directly by Hot-Pressing its Powder

2007 ◽  
Vol 336-338 ◽  
pp. 958-960
Author(s):  
Yang Song ◽  
Chang An Wang ◽  
Chun Qing Peng ◽  
Yong Huang
Keyword(s):  
Mechanical Properties ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Argon Atmosphere ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
Soaking Time ◽  
X Ray ◽  
Microstructure Evaluation

High-pure bulk Ti3SiC2 samples were fabricated by directly hot-pressing (HP) high-pure Ti3SiC2 powder without any additives at 1200°C to 1500°C for 0.5–2 hours in flow argon atmosphere. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used for phase identification and microstructure evaluation. The fabricated Ti3SiC2 materials have relative high density with high purity, flexural strength of 500-700MPa and fracture toughness of 9-12MPa·m1/2. The influence of sintering temperature and soaking time on the mechanical properties of Ti3SiC2 materials was discussed. The sintering mechanism for Ti3SiC2 powder without any additives was considered to be related with the fragile-ductile transformation of Ti3SiC2 at 1100°C.

Correlation of Microstructures with Electrical Transport Properties in Mn Doped Co Nanoferrite Particles

2012 ◽  
Vol 510-511 ◽  
pp. 487-492
Author(s):  
M. Akram ◽  
M. Anis-ur-Rehman ◽  
S. Nasir ◽  
G. Asghar
Keyword(s):  
Electrical Resistivity ◽  
Transport Properties ◽  
Cation Distribution ◽  
Electrical Transport ◽  
Research Work ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Dc Electrical Resistivity ◽  
X Ray

Magnetic nanocomposites are offering a variety of novel features and tune able properties, mainly depending on particle size, cation distribution, morphology and porosity of the prepared materials. The aim of this research work is to understand the effects of Mn doping on the microstructures and hence consequences on the electrical transport properties with shift of cation distribution in CoFe2O4. Co1-xMnxFe2O4nanocrystallite particles with stoichiometric proportion (x) varying from 0.0 to 1.0 were prepared by co-precipitation method. X-ray diffraction patterns confirmed the FCC spinel structure of synthesized particles. The crystal structure is found to be inverse cubic spinel with a space group Fd3m and the lattice constants ranges from 8.36 Å to 8.46 Å The crystallite sizes were calculated from the most intense peak (311) using the Debye-Scherrer formula for all the samples those were synthesized at reaction temperature of 70°C. Then samples were sintered at 600°C for 3 hours, characterized by X-ray diffraction at room temperature and DC electrical resistivity measurements were done as a function of temperature by two-probe method from 370 K to 690 K. The measurements showed that DC electrical resistivity decreased with increase in temperature ensuring the semiconductor nature of the material in this temperature range. DC electrical resistivity results were discussed in terms of polaron hopping model under the effects of cation distribution. AC electrical properties were also analyzed. All the observed properties were correlated with observed microstructures.

Microstructures, Electrical and Magnetic Properties of Zn Doped Co Nanoferrites

2012 ◽  
Vol 510-511 ◽  
pp. 221-226 ◽  
Author(s):  
M. Akram ◽  
M. Anis-ur-Rehman ◽  
M. Mubeen ◽  
M. Ali
Keyword(s):  
Magnetic Properties ◽  
Electrical Transport ◽  
Room Temperature ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Crystallite Sizes ◽  
Co Precipitation

Non toxicity, bio compatibility and nanometer sizes regime which is comparable to the size of a cell, makes nanocrystalline Co ferrites particles very proficient. In the present research Zn doped cobalt ferrites were prepared by the chemical co-precipitation method and characterized by X-ray diffraction (XRD) at room temperature for structural analysis. X-ray diffraction patterns confirmed the FCC spinel structure of synthesized particles. Crystallite sizes were calculated from the most intense peak (311) using the Debye-Scherrer formula. The obtained crystallite sizes were in nanometer range for all the samples synthesized at reaction temperature of 70°C. Then samples were sintered at 550°C for 2 hours, characterized again by X-ray diffraction at room temperature. The crystallite sizes and lattice constants for all the samples were calculated again from the data obtained by XRD. DC electrical resistivity and AC electrical transport properties were analyzed. The magnetic properties such as coercivity (Hc) and remanence (Mr) of Co1-xZnxFe2O4for x = 0.0, 0.2, 0.4 were measured at room temperature by vibrating sample magnetometer. Coercivity and remanence were found maximum with minimum value of Zn in Co1-xZnxFe2O4.Observed structural and conduction properties of synthesized nanomaterials were correlated.

Effect of Sintering Temperature on Structural and Electrical Transport Properties of (La0.7Ca0.3MnO3)0.97/(ZnO)0.03 Composite

2013 ◽  
Vol 378 ◽  
pp. 202-208
Author(s):  
Ho Je Cho ◽  
Seung Rok Lee ◽  
M.S. Anwar ◽  
Hang Joo Ko ◽  
Bon Heun Koo
Keyword(s):  
Electrical Transport ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Electrical Transport Properties ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
New Phase

The composites of (La0.7Ca0.3MnO3)0.97/(ZnO)0.03were fabricated with having different sintering temperature by conventional solid state reaction methods, and their magnetoresistance (MR) properties and electrical transport were investigated. The result of scanning electronic microscopy (SEM) and X-ray diffraction (XRD) indicated that no new phase appeared in the composites except LCMO and ZnO phases. specially, SEM results show that with increment of sintering temperature, the grain size of La0.7Ca0.3MnO3also increases, which plays a key on electrical and magnetic properties of the (La0.7Ca0.3MnO3)0.97/(ZnO)0.03composites. The electrical transport and magnetic was measured over a temperature range of 90 320K. tables etc. (2012H1B8A2026212), (NIPA-2013-H0301-13-2009)

The anisotropic powder metallurgy of n-type Bi2Te2.85Se0.15 thermoelectric material

1990 ◽  
Vol 5 (5) ◽  
pp. 1052-1057 ◽  
Author(s):  
Hideo Wada ◽  
Tetuji Sato ◽  
Kazuaki Takahashi ◽  
Norio Nakastukasa
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Thermoelectric Properties ◽  
Thermoelectric Material ◽  
Hot Pressing ◽  
Doping Level ◽  
Orientation Factor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermoelectric Measurements

The anisotropic powder metallurgy of n-type Bi2Te2.85Se0.15 doped with bromines was studied by both x-ray diffraction and thermoelectric measurements. The statistical orientation of platelet-like grains in the samples was characterized using the orientation factor estimated by the Lotgering formula from (0,0,1) x-ray diffraction intensities. It is demonstrated that the orientation factor which is strongly influenced by the hot-pressing conditions and the particle size of the starting material has a strong effect on the thermoelectric properties of the samples in this system. This implies that the powder metallurgy has the additional freedom of controlling the thermoelectric properties in addition to the doping level in the grains.

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