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The development of new environmentally friendly binder from calcium carbide residue and fly ash wastes were investigated in this study. The key point of this work is difference to several previous investigations in that the optimized mixture proportion of the raw materials were calculated based on their chemical composition and their reaction. The compressive strength development over the curing age was also compared with reference mortar created with OPC binder. Mortar cubes were cast from the mix containing the calcium carbide residue and fly ash, at the optimized ratio. The compressive strength of the mortar was then monitored over an extended period: at 56 days it was 10.66 MPa, which is approximately 47% of the reference mortar. The morphologies and chemical compositions of the developed mortar showed the presence of spherically shaped of unreacted fly ash powder particles embedded in a cement C–S–H gel resulting from the pozzolanic reaction of raw materials.

The effect of the firing conditions on the phase formation, microstructure, and electrical properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 (KNNT) ceramics synthesized by the solid-state combustion technique using glycine as fuel has been investigated. All samples were calcined at 600°C to 800°C for 2 h and sintered at 1150°C to 1190°C for 2 h to 5 h. Pure KNNT powders were produced after calcination at 600°C for 2 h. The average particle size increased when the calcination temperature was increased. The KNNT powder calcined at 600°C for 2 h showed rather square morphology with average particle size of ∼ 160 nm. The x-ray diffraction (XRD) analysis results for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. When sintering at 1150°C for 4 h, the O:T ratio was 50:50, as verified by the Rietveld refinement technique. The average grain size, density values, and dielectric properties tended to increase when the dwell time was increased from 2 h to 4 h, but then degraded. The KNNT ceramic produced at the optimum firing condition (1150°C for 4 h) showed good crystalline morphology, the highest density (ρ = 5.28 g/cm3), the highest dielectric constant (eC = 5002), and good ferroelectric behavior (Pr = 18.50 μC/cm2 and Ec = 9.04 kV/cm).

Lead-free 0.94Bi0.50Na0.50TiO3–0.06Ba0.85Ca0.15Ti0.90Zr0.10O3–xmol%Bi2FeCrO6 ceramics, with x = 0–0.021 (BNT–BCTZ–xBFCO), were calcined at 650 °C for 2 h and sintered at 1150 °C for 2 h using the solid-state combustion technique. The effect of BFCO content (x) on the phase formation, microstructure, electrical and magnetic properties was studied. The sintered pellets exhibited a pure perovskite phase with the coexistence of rhombohedral (R3c) and tetragonal (P4bm) phases in all the studied compositions. The percentage of R3c increased as x increased from 0 to 0.013, before decreasing, as obtained from the Rietveld refinement analysis (Fullprof). A morphotropic phase boundary of BNT–BCTZ–xBFCO ceramics was observed at x = 0.013, and the ratio between the rhombohedral and tetragonal phases of this composition was 51.0:49.0. The scanning electron microscopy analysis showed polyhedral-shaped grains whose average size increased with increase in the BFCO content (x). The appropriate amount of BFCO doped into BNT–BCTZ ceramics enhanced the electrical, ferroelectric and piezoelectric properties. At optimum doping (x = 0.013), the sample exhibited the highest relative density (98.2%), a high dielectric constant (eR = 1572 and em = 5137), maximum remanent polarization (Pr = 42.41 µC/cm2), low coercive field (Ec = 33.57 kV/cm), maximum piezoelectric coefficient (d33 = 241 pC/N) and the highest normalized strain ($$ d_{33}^{*} $$ = Smax/Emax = 765 pm/V). These improvements to BNT–BCTZ make the ceramic a potential candidate for use in capacitors, sensors and actuators. The magnetic properties also changed with different BFCO content (x). The sample with x = 0 showed diamagnetic behavior, while the samples with 0.003 ≤ x ≤ 0.021 exhibited a paramagnetic behavior with higher magnetization at higher BFCO content.

In this paper, we studied the effect of Cr2O3 doping (0–0.8 wt%) on the phase formation, dielectric, ferroelectric and magnetic properties of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCTZ) ceramics prepared...

This article reports an investigation into ferrite and nanocrystalline materials for the medium-frequency transformer of a dual active bridge DC-DC converter, which plays a key role in the converter’s efficiency and power density. E65 MnZn ferrite cores and toroidal and cut nanocrystalline cores are selected for the construction of 20-kHz transformers. Transformer performance is evaluated with a 1.1-kW (42–54 V)/400 V dual active bridge DC-DC converter with single-phase shift and extended phase shift modulations. The experimental results indicate that the toroidal nanocrystalline transformer had the best performance with an efficiency range of 98.5–99.2% and power density of 12 W/cm3, whereas the cut-core nanocrystalline transformer had an efficiency range of 98.4–99.1% with a power density of 9 W/cm3, and the ferrite transformer had an efficiency range of 97.6–98.8% with a power density of 6 W/cm3. A small mismatch in the circuit parameters is found to cause saturation in the nanocrystalline toroidal core, due to its high permeability. The analytical and experimental results suggest that cut nanocrystalline cores are suitable for the dual active bridge DC-DC converter transformers with switching frequencies up to 100 kHz.

Three tin pigmented aluminium oxide (Sn-Al 2 O 3 )films were prepared with different tin content using an anodization process, which is applied as a selective solar absorber in a new prototype of evacuated tube collector (ETC). The morphology and distribution of elements on the coatings were characterized using a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray (EDX) analyzer. The spectrally selective properties, defined as the ratio of solar absorptance ( α sol ) to thermal emittance ( e therm ) were examined. In order to investigate the thermal performance of ETC using Sn-Al 2 O 3 on an Al fin as a solar receiver, thermal efficiency ( η ) of the ETC was collected under steady-state conditions, as prescribed by ISO 9806-1 standard. The results, of the Sn-Al 2 O 3 coatings reached a darker black colour with an increase in the colouring time. The samples were composed of different contents of Sn in the Al 2 O 3 layer. The solar selectivity ( α sol / e therm ) significantly increased with the increases in Sn content. The maximum thermal efficiency ( η max ) of the ETC under the nearly constant heat loss coefficient ( U L ), was obviously increased with the increasing Sn content. Therefore, the Sn-Al 2 O 3 with different Sn contents is a good candidate for selective solar absorbers in a new prototype of ETC.

The effect of Fe2O3 doping (0–1.0 wt%) on phase formation, microstructure, electric and magnetic properties of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 ceramics was investigated. The samples were fabricated ...

Polycrystalline samples of undoped and doped indium tellurosilicate: InSiTe3 were synthesized and their thermoelectric (TE) properties were investigated in the temperature range from 323 to 723 K. Phosphorus (P) was selected as an electron dopant, i.e., the starting compositions were set as InSi1-xPxTe3 (x = 0, 0.02, 0.04, 0.06, and 0.1), The P doping increases the carrier concentration, which leads to decrease in both the electrical resistivity (ρ) and the Seebeck coefficient (S), while has little effect on the thermal conductivity (κ). As the results, the figure of merit ZT = S2ρ−1κ−1T increases with increasing the P content. The maximum ZT value is 0.14 at 723 K, obtained for InSi0.9P0.1Te3. The present results suggest that InSiTe3 can be a good TE material.

Cobalt antimonide (CoSb) in the stoichiometric ratio of 1:1 was synthesized by the microwave induced plasma heating method at the power of 1000 watt for 5, 15 and 30 min. The evolution of phases and lattice parameters of the synthetized CoSb thermoelectric materials were investigated using X-ray diffractometer (XRD), and analyzed by the Rietveld method with the FullProf Suite software. A single phase of CoSb with the lattice parameters of a = b = 3.8747 A and c = 5.1717 A was obtained at the synthesized time of 30 min. The optical properties were also measured by the UV-VIS spectrophotometer which could be used to determine the direct and indirect energy gaps as 4.15 eV and 3.85 eV, respectively. The electrical properties of the consolidated CoSb were subsequently measured from the temperature range of 50–500°C by ZEM-3 device. The electrical resistivity and power factor showed the increasing tendency with increasing temperature, while the Seebeck coefficient showed the results in the opposite way.

In a commercial evacuated tube collector (ETC) with a double layer tube, a solar absorber coated on outer surface of the inner glass of a vacuum tube, and aluminium (Al) fin is used for transferring heat from the solar absorber to the heat pipe. In the present study, the Al fin inside the ETC was initiated to be a solar absorber and heat transfer medium together with using a clear double layer evacuated tube. Various thicknesses of Ni-pigmented alumina (Ni-Al2O3) layer over the Al fin were prepared using the anodic anodization process. The thickness and solar absorptance (α) of all samples were investigated. The collector thermal efficiency (η) of the ETC with different thicknesses of Ni-Al2O3 coating over Al fin as the solar absorber was evaluated, following standard ISO 9806-1. The thicknesses of Ni-Al2O3 coatings were 11, 12, and 16 µm. For each thickness, the α over the whole wavelength of the solar spectrum had an identical value (∼0.94). The maximum collector thermal efficiency, FR (τα), of the new prototype ETC at each thickness was 0.71, 0.72 and 0.81. The -FRUL term for each thickness was -15.66, -15.83 and -18.56 W/m2·°C.

Ni-Al coating has been considered a promising candidate as a solar absorber material in solar thermal applications operating at mid-to high-temperatures. In a previous study by the current authors, a Ni-Al composite layer was applied as a coating onto a stainless steel 316L pipe using the flame spray technique. The solar absorptance (αsol) achieved, however, was relatively low compared to other commercial solar absorber coatings. To enhance the αsol of the Ni-Al, the annealing process was performed on this coating. The results clearly revealed that the metal oxides on the surface of the Ni-Al coating were NiO and Al2O3. As the annealing temperature increased, the reflectance (R) slightly decreased, while the αsol significantly increased. This was caused by the layer of metal oxides covering the surface of the Ni-Al coating functioning as an antireflection (AR) layer. The αsol of the Ni-Al coating increased approximately 13% after annealing at 800°C, compared to the unannealed Ni-Al coating. It is therefore clear that the annealed Ni-Al coating enhances the αsol due to the antireflection effect between the metal oxide layer and the underlying Ni-Al composite coating.

The Sr1-xLaxTiO3 (SLTO) nanopowder with varied La contents was successfully synthesized by a new route sol-gel auto combustion technique. The results of the X-ray Diffraction (XRD) patterns of the undoped and La-doped SLTO samples showed a pure phase with cubic perovskite structure, together with the position of the (110) peak slightly shifted toward the lower 2θ angle with increasing amounts of La dopant. The La doping increases the lattice parameter and the unit cell density due to the substitution of the larger ionic radius of La3+ into the smaller ionic radius of the Sr2+. As well, the crystallite size and particle size of the SLTO samples decreased as the La doping content increased. Specific surface area and total pore volume increased with the increase of La doping content. The band gap (Eg) was determined for the samples to be 4.10–4.12 eV. The photoluminescence (PL) at room temperature showed violet, green, and blue emissions at an excitation of 327 nm. The photocatalytic activity of SLTO, resulting from degrading methylene blue (MB) under UV irradiation, increased with increasing La content and reached a maximum at x = 0.07. The effect of La doping on Eg, PL, and mechanism photocatalytic activity of SLTO nanopowders, resulting from the oxygen vacancy in the SLTO structure, was also proposed and discussed. The results emphasize the significance of sol-gel auto combustion technique, which preserves the nanostructure of SLTO and improving photocatalytic activity.

In commercial evacuated tube collector (ETC) with double layers evacuated tube, a solar absorber is coated on the outer surface of the inner glass vacuum tube. In order to reduce cost of production and maintenance, our previous research work has been successfully initiated to place an aluminum fin inside the ETC to be a solar receiver together with clear double layers evacuated tube. Therefore, the objective of this present research is focused on the effect of aluminum (Al) fin thickness coated with solar paint on the thermal performance of ETC. Commercial Al fins with three different thicknesses (11, 13, and 24 µm) were considered in this study. An available solar paint (Thurmolax 250 selective black solar collector coating) was coated on the Al fin solar absorber using an air spray deposition technique with three different coating thicknesses. Spectral reflectance and thickness of the coatings were characterized using Ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer at the wavelengths 300-2500 nm and a Mini Test 730 equipment respectively. The solar absorptance (α) was calculated based on the relationship of observed reflectivity (R), and the solar spectral irradiance of AM 1.5 in the whole wavelength range of the solar spectrum. The collector thermal efficiency (η) of ETC with different thicknesses of Al fin coated with solar paint as solar receiver was evaluated, following a standard ISO 9806-1. As a result, it is found that the α of all the thicknesses of solar paints considered was identical (α=0.94), indicating that the thickness of solar paint was an insignificant effect on the α. The η, heat removal factor ( FR), and overall heat loss coefficient (UL ) were calculated for different Al fin thicknesses with 1x solar paint coating thickness and were found to be increasing with decreased Al fin solar absorber thickness. The results revealed that the FR was predominant for the increase in the η with the reduction of Al fin solar absorber thickness. It can be concluded that the thinner Al fin (11µm) with single layer solar paint coating is suggested to be used in ETC due to its relatively higher η and FR, including light weight and low cost.

Nowadays, developing solar cooling technologies, especially ejector refrigeration system, has become preferable to scientific researchers. Exergy analysis is a technique in which the basis of evaluation of thermodynamic losses follows the second law rather than the first law of thermodynamics. An experimental exergy analysis of a solar-driven dual parallel-connected ejector (DPE) refrigeration system was conducted using water as working fluid. Saturated steam with 2 bar and 120oC was provided by heat–pipe evacuated tube solar collector with an assistant of an electric heater. The saturated stream was used as a motive flow for the ejectors. The exergy destruction and exergetic efficiency of the main components of the DPE refrigeration system were determined and compared with those when using a single ejector (SE) under same operating conditions. It was found that the most irreversibilities of both systems occurred at the solar collector, electric boiler and ejectors, respectively. Also, the total irreversibility (Exergy destruction) of the system when using DPE was lower than using a SE. In additions, the exergetic efficiency of the ejector, evaporator, and overall system when using DPE were increased by 21%, 10%, and 27%, respectively. The system thermal ratio (STR) and coefficient of performance (COP) of the system using DPE compared with SE were increased by 20% and 23%, respectively.

Antimony sulfide (Sb2S3) nanostructure was synthesized using a 600 W microwave irradiation technique. The precursors including Sb(CH3CO2)3 and Na2S2O3.5H2O were dissolved into 50 mL ethylene glycol (EG) solution with containing 0 and 1 g of hydroxyethyl cellulose (HEC). Phase, morphology and optical properties of the as-synthesized products were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and photoluminescence (PL). Energy band gap of Sb2S3 nanostructure exhibits the value of 1.90 and 2.06 eV for synthesizing condition with and without HEC containing, respectively.

This present study reports results of performance evaluation of a solar-driven dual parallel-connected ejector (DPE) cooling system using the concept of solar fraction (SF). The experiments were conducted in July and August, 2015 from 09:00 to 16:00 hours at School of Renewable Energy Technology (SERT), Naresuan University, Thailand, with a solar collector area of 2.4 m2, auxiliary heater of 3 kW, operating at boiler pressure of 2 bar and using water as working fluid. Temperature was measured for inlet and outlet of solar collector. The results showed that the solar collector supplied about 24% of energy required to operate the system. The solar collector performance was 11% and the monthly average SF was 23.9% for July and 23.5% for August.

In this research, a Ni-Al solar absorber was successfully prepared by the flame spray technique with Ni-5 wt.%Al particles as a starting material. The Ni-5 wt.%Al particles were melted and sprayed onto the outer surface of a stainless steel 316L tube in order to form a Ni-Al composite coating. The phase, morphology and reflectance (R) spectrum of the Ni-Al solar absorber were characterized by X-ray Diffraction (XRD), a Scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) analyzer and an Ultraviolet-visible-near infrared spectrophotometer at the wavelength 300-2500 nm. The results revealed that the surface of the Ni-Al solar absorber was rough, and its cross section was overlapped layer by layer. The Ni-Al solar absorber was composed of Nickel (Ni) and aluminum (Al) phases. NiO and Al2O3 phases were also found on the surface. The chemical composition of the Ni-Al solar absorber was Ni (72.94 wt.%), Al (11.76 wt.%) and O (15.29 wt.%). The solar absorptance (α)of this solar absorber was 0.77. This demonstrates that a Ni-Al composite coating can be applied as a solar absorber material for solar collector at high operating temperatures.

In present work, tin-pigmented alumina (Sn-Al2O3) solar absorber on the aluminium substrate was successfully prepared by anodic anodization and further characterized by different methods. The phase, morphology, reflectance (R) and thermal conductivity of the Sn-Al2O3 solar absorber were measured by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) equipped with energy dispersive X-ray (EDX) analyzer, and Ultraviolet-visible-near infrared spectrophotometer in the wavelength of 300-2500 nm. The solar absorptance (α) was calculated based on the relationship of the spectral reflectance, R(λ), and the solar spectral irradiance of AM 1.5, Is(λ), in the wavelength interval of 300-2500 nm. As the results, the surface color of the Sn-Al2O3 film was dark-black color. The XRD pattern of Sn-Al2O3 films was indexed as aluminium and tin phases. The chemical composition of the Sn-Al2O3 films composed of tin (Sn), aluminum (Al) and oxygen (O) elements. The average thickness of the produced films was 18.9 μm. It was found that Sn-Al2O3 films showed the low R (0.09) and high α (0.93) values for the whole wavelength 300-2500 nm, corresponding to theoretical properties of the solar absorber. Therefore, it can be concluded that the Sn-Al2O3 film on aluminium substrate can be applied to be the solar absorber in solar collector due to high α, which is similar to the commercial solar absorbers.

The use of delafossite CuAlO2 (CAO) powder as an additive in composite gel electrolyte (CGE) of the quasi-solid state dye-sensitized solar cell (DSSC) is first reported. In order to achieve an improvement of power conversion and long-term performance of the quasi-solid state DSSC, different contents of CAO powder containing in CGE, a mixture of polyethylene glycol (PEG), iodide/tri-iodide (I−/I3−) liquid electrolyte (LE) and 4-tertbutylpyridine (4-tBP), were used in the present study. The photocurrent density–voltage characteristic (J–V curve) and photovoltaic performance parameters of the cells, such as the short-circuit current density (Jsc), open-circuit voltage (Voc), power conversion efficiency (η) and fill factor (FF) were investigated. The CGE containing the dispersed CAO powder exhibited high ionic conductivity due to the charge diffusion through free channels. The power conversion efficiency of the quasi-solid state DSSC was significantly improved by adding CAO powder to the CGE. The optimum CAO powder content in the CGE was 0.05 wt%. In this research, the power conversion efficiency was 1.71 times of the LE and 2.85 times of the CGE with no CAO powder adding. The quasi-solid state DSSC based on the addition of CAO powder to CGE had long-term stability better than the normal DSSC based on the LE.

Rice kernel (RK)-like bismuth telluride (Bi2Te3) crystals were successfully synthesised by microwave-induced plasma heating of Bi and Te powders. Phase and morphology characterisation revealed the presence of the Bi2Te3 structure in the shape of RKs. The crystal orientation factor (f value) of RK Bi2Te3 powder was larger than that of the RK Bi2Te3 hot-pressed disk. A comparison of the f values of both samples suggested that the RK shape has significant influence in reducing the f value after hot processing. The Seebeck coefficient (S), electrical resistivity (ρ) and thermal conductivity (κ) of the RK Bi2Te3 disk were determined over the temperature ranging from 323 to 623 K. The S value was negative over the whole temperature range, indicating an n-type thermoelectric RK Bi2Te3 disk. The power factor (S 2 ρ −1) was the highest at about 1.07 × 10−3 W/m K2 at 323 K and decreased with increasing temperature. The maximum dimensionless figure of merit (ZT) of the RK Bi2Te3 disk was 0.26 at about 366 K.

A single phase of delafossite CuAlO 2 (CAO) was successfully synthesized by a 600 W microwave radiation for 20 min. The CAO sample was composed of quite distorted single-crystalline plates with 200–350 nm thick. Its atomic vibrations were detected at 760 and 550 cm −1 belonging to Al–O and Cu–O stretching, respectively. The direct and indirect energy gaps were respectively determined to be 3.9 and 2.9 eV. The photoluminescence (PL) at room temperature was at 585 nm (2.12 eV) corresponding to the indirect energy gap and at 760 nm (1.63 eV) corresponding to the p-type native defect. For its thermoelectric (TE) properties, the Seebeck coefficient ( S ) was positive value, with holes as the majority of charge carriers. By increasing of the test temperature, both the electrical resistivity and absolute value of Seebeck coefficient were decreased, but the power factor was in the opposite manner. The dimensionless figure of merit (ZT) of the crystalline CAO was evaluated to be the maximum of 9 × 10 −3 at 1073 K.

This study investigates tantalum oxide (Ta2O5) nanorods prepared by the dc magnetron sputtering with the glancing angle deposition (GLAD) technique. Silicon (100) wafer and glass slides were used as the substrates. The effect of the glancing angle varying from 73-87°, on the structural and optical properties were investigated by field-emission scanning electron microscopy (FE-SEM), atomic force microscope (AFM) and spectrophotometry. The results show that the deposition rate and diameter of Ta2O5 nanorod films were decreased with the increase in the glancing angle. At the highest glancing angle of 87°, the prepared Ta2O5 nanorod yielded the highest porosity from the vertically aligned columnar structure, and were must suitable for many functional applications.

Low rural electrification rate is a major problem, and continue posing huge challenges especially in remote areas. It was found that Farafenni town is present in a region with the high solar radiation values (4.5–7 kWh/m 2 /day) in all year round, making it a suitable town for PV power plant investments. 1 MW PV power plant was studied to evaluate the feasibility between crystalline Si (c-Si) and thin film (CdTe) modules by varying the feed in tariffs (FIT). The present FIT of 0.24 US$/kWh showed that CdTe modules present not only higher NPV (2,053,869 US$), IRR (7%), BCR (1.60), but also shorter PBP (9.48 years) values than those values of the c-Si modules with NPV (1,189,576 US$), IRR (4%), BCR (1.30) and longer PBP (11.68 years). Based on technical and economic assessments of the c-Si and CdTe PV power plants, the CdTe PV power plant presented the reasonable technology for rural electrification in The Gambia.

 Abstract—This paper presents the technical and economic analysis of PV battery charging stations in Kampot, Cambodia's situation. The solar radiation reflected by the air molecules, clouds and ground was obtained from the satellite data. The absorption of solar radiation due to water vapor was calculated from precipitable water derived from ambient relative humidity and temperature from Cambodian meteorological stations. The annual solar radiation from January to reach a peak in the summer months of March and April each year and the yearly map showed the features of a high solar radiation pattern in the southeast of Cambodia. The average value is 5.10kWh/m 2 /day can be observed in the southeast of the country. With the highest values of solar radiation, solar PV battery charging stations (PVBCS) will be installed in each village, which are not electrified by national grid or mini-grid projects by 2020, and where no battery charging station is currently operating in order to ensure that the Royal Government of Cambodia's political objective of 100% village having electricity supply by 2020 from different sources of energy. With capacity of 10kW PV battery charging station in Kampot was calculated to evaluate and compare the technical and economic evaluation of c-Si PV modules and diesel battery charging station under the Kampot climate. The present electricity price of rural areas is about 0.22US$/kWh showed that c-Si PV modules present not only high NPV (15,986US$), IRR (0.041%), BCR (1.52) but shorter payback period (8.82 years) than the diesel battery charging station of 0.22US$/kWh with the NPV (7,450US$), IRR (12%), BCR (1.70) and payback period (14.74 years) values. Based on the technical and economic evaluation of c-Si PV battery charging station, in fact, pointed the most suitable technology for people in rural areas in the kingdom of Cambodia.

Zn4Sb3 nanocrystals were synthesized by a 900 W microwave of 4.5:3 M ratio Zn:Sb with a total mass of 1 g for 5 min. Phase, internal texture, constituents, vibration mode and energy gap were detected using X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), Raman spectroscopy and UV–visible spectroscopy. In this research, Zn4Sb3 nanocrystals with a prominent vibration mode at 144 cm−1 and 1.22 eV optical band gap were detected, including Zn4Sb3–ZnSb composites were also synthesized using microwave plasma for 10 min.

ZnIn2Te4 and CdIn2Te4 have a defect-chalcopyrite tetragonal crystal structure with structural vacancies. In order to investigate the effects of vacancies on the lattice thermal conductivity (κlat), single phase samples of ZnIn2Te4 and CdIn2Te4 were synthesized and their κlat values were examined in the temperature range from room temperature to 850 K. The κlat data for ZnIn2Te4 and CdIn2Te4 were compared with those of Zn- and Cd-series chalcopyrite compounds with no vacancies. The results revealed that the presence of vacancies alone in the defect-chalcopyrite structure does not result in effective phonon scattering.

Ni 3 GaSb and Ni 3 InSb were successfully synthesized by the direct reaction of Ni and GaSb or InSb. The XRD patterns and the lattice parameters of these compounds were in good agreement with the literature data. The Seebeck coefficient ( S ), the electrical resistivity ( ρ ), and the thermal conductivity ( κ ) of Ni 3 GaSb and Ni 3 InSb were examined in the temperature range from room temperature to 1073 K. Both compounds indicated metal-like characteristics. The power factor ( S 2 ρ −1 ) values increased with temperature and reached maximum at 1073 K. The κ and the dimensionless figure of merit ZT of both samples increased with temperature. The maximum values of the ZT of Ni 3 GaSb and Ni 3 InSb were obtained at 1073 K to be 0.022 and 0.023, respectively.