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Method of high active preparation and electrical properties of CuFeO2 delafossite-type
(2014-01-01)
Rudradawong, Chalermpol
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Wichainchai, Aree
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Sakulkalavek, Aparporn
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Hongaromkid, Yuttana
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Ruttanapun, Chesta
In this paper, the CuFeO<inf>2</inf> compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10. 68 S/cm, 244. 59 μV/K, 12. 86×1016 cm-3 and 494. 96 cm2/V. s, respectively. In addition, each CuFeO<inf>2</inf> compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossitetype (R3m) and a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO<inf>2</inf> from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0. 00052 and 0. 64×10-4 W/mK2, respectively. © (2014) Trans Tech Publications, Switzerland.
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Reinvestigation thermoelectric properties of CuAlO2
(2014-01-01)
Ruttanapun, Chesta
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Kosalwat, Wattana
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Rudradawong, Chalermpol
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Jindajitawat, Phumin
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Buranasiri, Prathan
Bulk CuAlO2 delafossite has been synthesized by solid state reaction to reinvestigate the thermoelectric properties. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured in a high temperature range of 300 to 960 K. The result of positive sign of Seebeck coefficient confirms p-type nature of CuAlO2 compund. The results of bulk sample for Seebeck coefficient, the electrical conductivity and thermal conductivity are range of 900 to 300 μV/K, of 0.01 to 2 S/cm, and of 3.5 W/mK to 1.5 W/mK. The maximum ZT value of bulk sample is 0.017 at a 960 K. These results can be concluded that the bulk CuAlO2 by solid state state displays thermoelelctric material.
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Designing apparatus for highly precise measurement of electrical conductivity and seebeck coefficient from 85 k to 1200 k
(2013-10-04)
Budngam, Sopon
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Wichainchai, Aree
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Pimmongkol, Saichol
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Tipparach, Udom
We describe the development of apparatus for measuring of electrical conductivity and Seebeck coefficient with high precision from 85 K to 1,200 K. Electrical resistance was measured by means of four-point probe method as a function of temperature. The temperature below 400 K was measured by using type T thermocouple in vacuum system was used and from 400 to 1,200 was measured by using Type S was applied for temperature between 400 and 1200 Kelvin in an inert gas system. With the dimensions of the specimen, the electrical resistivity (ρT) can be obtained in the unit of microohm-centimeter (μΩ - cm) and be written in polynomial, ρ<inf>T</inf> = -0.3191 + 6.8 × 10-3T - 6.0 × 10-7 T2 + 8.0 × 10-10T3. The electrical conductivity can be obtained by taking inversion of the electrical resistivity. Seebeck coefficient (α<inf>T</inf>) can be calculated in microvolt per Kelvin as follows: α<inf>T</inf> = 1.9653 - 1.49 × 10-2T + 9.0 × 10-5T2 - 2.0 × 10-7T3 + 2.0 × 10-10T4 - 1.0 × 10-13T5 + 3.0 × 10-17T6 when T is temperature in K. The Seebeck coefficient data was compared with X-ray diffraction (XRD) and X-ray fluorescence (XRF) of the specimen. The result showed that our developrd apparatus yields the same as standard method when copper with purity greater than 99 percent was employed. © (2013) Trans Tech Publications, Switzerland.
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Alcohol sensing of p-type CuFeO2 delafossite oxide
(2013-09-18)
Ruttanapun, Chesta
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Hongaromkid, Yuttana
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Thowladda, Warawoot
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Wichainchai, Aree
The sample of CuFeO2 delafossite was synthesized by solid state reaction for studying alcohol gas sensing properties. The Seebeck coefficient and electrical conductivity were measured in the high temperature ranging from 300 to 960 K. The CuFeO2 gas sensing displays high sensitive to ethyl alcohol gas in sensitivity ranging from 70 to 93 % and responding in 2 to 4 minute. The electronic characterization on the sample exhibits p-type conductor and displays electrical conductivity ranging from 3 to 13 S/cm with activation energy in 49 meV. This study suggests that CuFeO2 delafossite is a new one to be candidate in oxide material for alcohol gas sensing. © 2013 SPIE.
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Electrical and optical properties of p-type CuFe1-xSn xO2 (x = 0.03, 0.05) delafossite-oxide
(2013-01-14)
Ruttanapun, Chesta
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Boonchom, Banjong
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Thongkam, Montree
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Kongtaweelert, Samart
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Thanachayanont, Chanchana
The CuFe<inf>1-x</inf>Sn<inf>x</inf>O<inf>2</inf> (x = 0.03, 0.05) delafossite samples have been synthesized by a solid-state reaction to investigate electrical and optical properties of the transparent conducting oxide materials. Crystal structure was characterized by XRD. The electrical conductivity and Seebeck coefficient were measured in the high temperature range of 300 to 960 K, while the Hall coefficient, XPS, and UV-VIS-NIR spectra were analyzed at room temperature. The XRD peaks of the samples indicate the delafossite structure phase, and the XPS spectra reveal the stable Sn 2+-doping state. The Seebeck and Hall coefficient display a positive sign indicating the p-type conducting oxide. The optical allowed direct gap is 3.45 eV as a visible-transparent material. The activation energies for polaron hopping between Sn2+ sites and Fe3+ sites of 36 and 32 meV are obtained from the samples having x = 0.03 and 0.05, respectively. The CuFe<inf>1-x</inf>Sn<inf>x</inf>O<inf>2</inf> delafossite oxide compounds, of which the Fe3+ sites in the CuFeO<inf>2</inf> are substituted by the Sn2+ ions, are p-type transparent conducting oxide materials. The activation energy is found to decrease with an increased in Sn content. © 2013 American Institute of Physics.
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Optoelectronic properties of Cu1-xPtxFeO2 (0 ≤ x ≤ 0.05) delafossite for p-type transparent conducting oxide
(2012-01-01)
Ruttanapun, Chesta
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Prachamon, Wutthisak
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Wichainchai, Aree
The samples of Cu<inf>1-x</inf>Pt<inf>x</inf>FeO<inf>2</inf> (0 ≤ x ≤ 0.05) delafossite have been synthesized by solid-state reaction method to investigate their optical and electrical properties. The properties of electrical resistivity and Seebeck coefficient were measured in the high temperature ranging from 300 to 960 K, and the Hall effect and the optical properties were measured at room temperature. The obtained results of Seebeck showed the samples are p-type conductor. The optical properties at room temperature exhibited the samples are transparent visible light material with optical direct gap 3.45 eV. The low electrical resistivity, hole mobility and carrier density at room temperature displayed value ranging from 0.29 to 0.08 Ω cm, 1.8 to 8.6 cm2/V s and 1.56 × 1018 to 4.04 × 1019 cm-3, respectively. The temperature range for transparent visible light is below 820 K because the direct energy gap contains value above 3.1 eV. Consequently, the Cu<inf>1-x</inf>Pt <inf>x</inf>FeO<inf>2</inf> delafossite enhance performance for materials of p-type transparent conducting oxide (TCO) with low electrical resistivity. © 2011 Elsevier B.V. All rights reserved.
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Thermoelectric properties of Cu1-xPtxFeO2 (0.0 ≤ x ≤ 0.05) delafossite-type transition oxide
(2011-03-31)
Ruttanapun, Chesta
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Wichainchai, Aree
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Prachamon, Wutthisak
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Yangthaisong, Anucha
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Charoenphakdee, Anek
The samples of Cu<inf>1-x</inf>Pt<inf>x</inf>FeO<inf>2</inf> (0 ≤ x ≤ 0.05) delafossite were synthesized by solid state reaction method for studying thermoelectric properties. The properties of Seebeck coefficient, electrical conductivity and thermal conductivity were measured in the high temperature ranging from 300 to 960 K. The results of Seebeck coefficient, electrical conductivity and power factor were increased with increasing Pt substitution and temperature. The thermal conductivity was decreased from 5.8 to 3.5 W/mK with increasing the temperature from 300 to 960 K. An important results, the highest value of power factor and ZT is 2.0 × 10-4 W/mK2 and 0.05, respectively, for x = 0.05 at 960 K. © 2011 Elsevier B.V. All rights reserved.

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