Fabrication and thermoelectric properties of highly textured NaCo2O4 ceramic

Cheng, Jinguang; Sui, Yu; Fu, Haijin; Lü, Zhe; Wei, Bo; Qian, Zhengnan; Miao, Jipeng; Liu, Zhiguo; Huang, Xiao; Zhu, Rong; Wang, Xianjie; Su, Wenhui

doi:10.1016/j.jallcom.2005.06.020

Cited by 16 publications

(6 citation statements)

References 16 publications

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“…[1][2][3][4] Since Terasaki et al found the high thermopower and conductivity of NaCo 2 O 4 single crystals at 300 K in 1997, 5 the sodium cobalt oxides Na x Co 2 O 4 have been widely studied for thermoelectric applications. [6][7][8][9][10][11] It was verified that the thermoelectric properties of a Na x Co 2 O 4 polycrystalline sintered body could be improved by obtaining high crystallographic orientation using special technology such as hot-pressing, 6 cold high-pressure, 7 spark plasma sintering, 8 and reactive templated grain growth method. 9 Biomacromolecules such as lipids, 12 proteins, 13 and polysaccharides 14 can exquisitely control the inorganic crystal type and hierarchical material self-assembly.…”

Section: Introductionmentioning

confidence: 96%

Preparation of Well-Tiled γ-Na x Co2O4 by a Novel and Simple Sodium Alginate Gel Method and Its Electrical Properties

Zhang

Tang

Gao

2009

Journal of Elec Materi

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In this paper, a novel and simple sodium alginate (SA) gel method was developed to prepare c-Na x Co 2 O 4 . This method involved the chemical gelling of SA in the presence of Co 2+ ions by cross-linking. After calcining at 700°C to 800°C, single-phase c-Na x Co 2 O 4 crystals were obtained. The arrangement of about 1 lm to 4 lm flaky particles exhibited a well-tiled structure along the plane direction of the flaky particles. SA not only acted as the control agent for crystal growth, but also provided a Na source for the c-Na x Co 2 O 4 crystals. The electrical properties of c-Na x Co 2 O 4 ceramics prepared via ordinary sintering after cold isostatic pressing were investigated. The Seebeck coefficient and power factor of the bulk material were 177 lV K À1 and 4.3 9 10 À4 W m À1 K À2 at 850 K, respectively.

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Section: Introductionmentioning

confidence: 96%

Preparation of Well-Tiled γ-Na x Co2O4 by a Novel and Simple Sodium Alginate Gel Method and Its Electrical Properties

Zhang

Tang

Gao

2009

Journal of Elec Materi

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“…3-10 NaCo 2 O 4 , as a representative metal oxide thermoelectric material, has been studied with promising results in recent years due to its excellent thermal and chemical stability at high temperatures in air. 11,12 The performance of thermoelectric materials is generally characterized by the dimensionless figure of merit ZT, defined as ZT = a 2 rT/j, where T, a, r, j, and a 2 r are the thermodynamic temperature, Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor, respectively. A higher ZT value indicates better performance of the material.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of (Na1−y M y )1.4Co2O4 (M = Sr, Li)

Liu

Jiang

et al. 2011

Journal of Elec Materi

136

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Oxide thermoelectric materials (Na 1Ày M y ) 1.4 Co 2 O 4 (M = Sr, Li; y = 0 to 0.4) were prepared by a sol-gel method. The influence of doping on the thermoelectric properties was investigated, and the phase composition was characterized by x-ray diffraction. Experimental results showed that the main crystalline phase of the undoped and Sr/Li-doped samples was c-Na 1.4 Co 2 O 4 . The thermoelectric properties of Na 1.4 Co 2 O 4 can be improved slightly by doping with Sr. Doping with Li improves the thermoelectric properties of Na 1.4 Co 2 O 4 . For a doping fraction of y = 0.1, the electrical conductivity of (Na 1Ày Li y ) 1.4 Co 2 O 4 at 288 K achieves its maximum value of 301.19 (X mm) À1 . The Seebeck coefficient and power factor of (Na 1Ày Li y ) 1.4 Co 2 O 4 at 288 K achieve their maximum values of 172.28 lV K À1 and 7.44 mW m À1 K À2 at a doping fraction of y = 0.4.

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“…Phase transformations within crystals or the development of biased domains or twins have recognized contributions to anisotropy in noncubic ceramics. These efforts have resulted in an ever increasing range of anisotropic properties including elasticity, strength, fracture toughness, optical properties, conductivity, thermoelectricity, 14–16 superconductivity, 17 magnetic properties, 18 shape‐memory properties, 19 and piezoelectricity 12,20 . In this last category, our recent research has shown that the behavior of domains inherent to most ceramic piezoelectrics couples with crystallographic texture and concurrent changes in other property tensors.…”

Section: Introductionmentioning

confidence: 99%

Texture and Anisotropy of Polycrystalline Piezoelectrics

Jones

Iverson

Bowman

2007

Journal of the American Ceramic Society

101

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Piezoelectricity is manifested in ferroelectric ceramics by inducing a preferred volume fraction of one ferroelectric domain variant orientation at the expense of degenerate orientations. The piezoelectric effect is therefore largely controlled by the effectiveness of the electrical poling in producing a bias in ferroelectric (180°) and ferroelastic (non‐180°) domain orientations. Further enhancement of the piezoelectric effect in bulk ceramics can be accomplished by inducing preferred orientation through grain‐orientation processes such as hot forging or tape casting that precede the electrical‐poling process. Coupled crystal orientation and domain orientation processing yields ceramics with an even greater piezoelectric response. In this paper, preferred orientations of domains and grains in polycrystalline piezoelectric ceramics generated through both domain‐ and grain‐orientation processing are characterized through pole figures and orientation distribution functions obtained using data from a variety of diffraction techniques. The processing methods used to produce these materials and the methods used to evaluate preferred orientation and texture are described and discussed in the context of prior research. Different sample and crystal symmetries are explored across a range of commercial and laboratory‐prepared materials. Some of the variables presented in this work include the effects of in situ thermal depoling and the detailed processing parameters used in tape casting of materials with preferred crystallite orientations. Preferred orientation is also correlated with anisotropic properties, demonstrating a clear influence of both grain and domain orientations on piezoelectricity.

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Fabrication and thermoelectric properties of highly textured NaCo2O4 ceramic

Cited by 16 publications

References 16 publications

Preparation of Well-Tiled γ-Na x Co2O4 by a Novel and Simple Sodium Alginate Gel Method and Its Electrical Properties

Preparation of Well-Tiled γ-Na x Co2O4 by a Novel and Simple Sodium Alginate Gel Method and Its Electrical Properties

Thermoelectric Properties of (Na1−y M y )1.4Co2O4 (M = Sr, Li)

Texture and Anisotropy of Polycrystalline Piezoelectrics

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