Banca de DEFESA: ALINE ALENCAR EMERENCIANO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ALINE ALENCAR EMERENCIANO
DATA : 27/02/2019
HORA: 10:00
LOCAL: A definir pelo PPGCEM
TÍTULO:

SYNTHESIS AND CHARACTERIZATION OF Ca₃Co₄O₉ AS A THERMOELECTRIC MATERIAL

PALAVRAS-CHAVES:

Ca₃Co₄O₉; Amorphous Citrate Method; Proteic Sol Gel; Solid State Reaction, Seebeck Coefficient, Power Factor.

PÁGINAS: 90
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Faced with the requirement for cleaner and higher energy efficiency technologies, we have noticed a significant focus on the research of thermoelectric materials, capable of converting thermal energy into electric energy. The Ca3Co4O9 metal oxide is a great alternative, since its specific properties added to the improvement of its microstructure allow the production of a compound with considerable thermoelectric characteristics in relation to others reported in the literature. The stable phase Ca 3 Co 4 O 9, present in a very restricted range in the CaO-CoO phase diagram, can be obtained by controlling the composition and the temperature. In order to improve the production of calcium cobalt (C349) three different synthesis techniques were implemented in this project followed by thermal treatment (precalcination at 350 ° C / 2h, calcination at 900 ° C / 2h and sintering at 900 / 24h). The synthesis by the amorphous citrate method without the use of dispersant, the synthesis by the Sol gel protein method and the synthesis by Solid State Reaction with mechanical activation by high energy grinding - CaCO3 being one of its precursors, coming from shellfish, which further reinforces the environmental motivation in this work. In all samples there was the formation of subsystem [Ca2CoO3-δ] q [CoO2], identified by X-ray diffraction with Rietveld's refinement; the secondary Ca3Co2O6 phase was present in samples from the Citrate method. Their microstructures were analyzed by Electron Transmission Electron Microscopy (STEM) and X-ray Spectroscopy by Energy Dispersion (EDS) and the determination of the electrical properties of the compound was analyzed by obtaining the Seebeck Coefficient, electrical conductivity, electric resistivity and Power Factor. The processes presented grains in micro and nano scale, and in all of them there was the formation of the subsystem [Ca2CoO3-δ] q [CoO2]. In the three different methods, with relative densities around 66%, the highest value of the Power Factor at ~ 700 ° C was obtained in the pellets from the synthesis of C349 by the Sol-gel Proteico method (0.21 mW / mK2).

MEMBROS DA BANCA:
Presidente - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Interna - 2042234 - ANA PAULA CYSNE BARBOSA
Interno - 1300987 - CARLOS ALBERTO PASKOCIMAS
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFPB