Changtai Xia

Fabrication of textured thermoelectric layered cobaltites with various rock salt-type layers by using β-Co(OH)2 platelets as reactive templates

Textured bulk ceramics have been prepared of various cobaltites including the common CdI2-type CoO2 layer (i.e., [Ca2(Co0.65Cu0.35)2O4]0.624[CoO2]: CCO-4-layer, [Bi2M2−xO4]p[CoO2] (M2 = Sr2: BSCO, M2 = Ca1Sr1: B(SC)CO, M2 = Ca2: BCCO)) by using β-Co(OH)2 (CdI2-type) platelets as reactive templates, and their thermoelectric (TE) properties have been examined. All the specimens were found to be highly c-axis aligned ceramics. Especially for CCO-4-layer, B(SC)CO and BCCO, the present study is the first report on the fabrication of textured ceramics. Our textured ceramic specimens exhibited larger values of electrical conductivity (σ) than the ceramics prepared by a conventional solid-state reaction (SSR specimens): e.g., σab = 0.46 × 104 S m−1 for the textured specimen and σSSR = ∼0.26 × 104 S m−1 at 1060 K for the SSR specimen for BCCO. This study indicated that our preparation method using β-Co(OH)2 templates is a versatile and effective technique to fabricate cobaltites, including CoO2 layers, with a high degree of orientation and improved TE properties.

Hidden magnetic transitions in the thermoelectric layered cobaltite [Ca2CoO3]0.62[CoO2]

A positive muon spin rotation and relaxation

Topotactic synthesis of highly-textured thermoelectric cobaltites

({\ensuremath{\mu}}^{+}\mathrm{SR})

A common behaviour of thermoelectric layered cobaltites : Incommensurate spin density wave states in [Ca2Co4/3Cu2/3O4]0.62[CoO2] and [Ca2CoO3]0.62[CoO2]

experiment on

Synthesis of textured thermoelectric layered cobaltites by reactive templated grain growth

[{\mathrm{Ca}}_{2}{\mathrm{CoO}}_{3}{]}_{0.62}[{\mathrm{CoO}}_{2}]

A common behavior of thermoelectric layered cobaltites: an incommensurate spin density wave state

(i.e.,

Electronic structure of misfit-layered calcium cobaltite

{\mathrm{Ca}}_{3}{\mathrm{Co}}_{4}{\mathrm{O}}_{9},

Anisotropic magnetic properties of Ca 3 Co 4 O 9 : Evidence for a spin-density-wave transition at 27 K

a layered thermoelectric cobaltite) indicates the existence of two magnetic transitions at

Platelet crystals of thermoelectric layered cobaltites; pure and Sr-doped [Ca2CoO3]0.62[CoO2]

\ensuremath{\sim}100\mathrm{K}

Growth of In2O3(ZnO)5 platelet micro-crystals by flux methods

and 400--600 K; the former is a transition from a paramagnetic state to an incommensurate (IC) spin-density wave (SDW) state. The anisotropic behavior of zero-field