Síntese e caracterização das perovskitas CaTiO3 e Ca1-x-yErxYbyTiO3

• Autor(a) principal: SILVA, Ana Regina de Queiroz
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFMA
• Texto Completo: http://tedebc.ufma.br:8080/jspui/handle/tede/1342
• topic: Cerâmicas; Perovskita; CaTiO3; Terras raras; Ceramics; Perovskite; Rare Earth; Física da Matéria Condensada

In recent years, research has increased in order to develop new materials processing methods have more advantages over conventional methods currently used which are quicker and cheaper. It has become common to use ceramics to obtain electronic devices, dielectric or piezoelectric. The CaTiO3 ceramic material has been widely used in electronic devices. The objective of this study was to synthesize and characterize perovskite ceramic-based CaTiO3 (Titanate Calcium) replaced with rare earths. The synthesis and replacement of perovskite were made from the starting materials Ca(OH)2, TiO2, Er2O3 and Yb2O3 by mechanical milling in a ball mill for 30 min at 250 rpm to homogenization and then was taken calcination in a muffle furnace. The obtained material powder showed perovskite phase to the orthorhombic space group Pbnm 62. The unit cell of the crystal lattice parameters showed a = 5.378 Å, b = 5.441 Å and c = 7.640 Å for the CaTiO3, which has four per unit cell formula. The number and type of modes provided for each frame can be given by the factor groups having a total of 24 vibrational modes Raman for CaTiO3 with said structure. The morphological characteristics were observed for the samples CTO (calcium titanate) prepared by solid state reaction, demonstrating the formation of small, round grain vacancies, which may be caused by distortions in the crystal lattice. The CTO replaced with Er2O3 and Yb2O3 showed typical bands of green light at 525 and 547 nm corresponding to the transition 4H11/2 → 4I15/2. The two smaller emission bands in the red, correspond to transition 4F9/2 to the ground state 4I15/2. The results obtained for the ceramic systems were satisfactory as the method used for synthesis, who presented with lower cost compared to existing processes.