Synthesis and characterization of ß-BaB2O4 thin filmes from the BaO-B2O3-TiO2 system

Author(s)

Lauro June Queiroz Maia

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT)
• Defense date: 2003-03-26

Examining board members

Valmor Roberto Mastelaro; Sidney José Lima Ribeiro; Sergio Carlos Zilio

• Advisor: Valmor Roberto Mastelaro

Abstract

The main objective of this work was the synthesis and the characterization of the ß-BaB2O4 (ß-BBO) phase in a powder and thin film form from the BaO-B2O3-TiO2 ternary system. The powder and thin film samples were obtained using two different methods, the polymeric precursor method and the electron beam evaporation method. The study of the powder samples showed that the addition of titanium oxide to the BaO-B2O3 system accelerate the decomposition process, reduces the crystallization temperature and the ß-BBO melting point. The ß-BBO phase was obtained as the main phase for the sample containing 4% of titanium and heat-treated at 700°C for 2h. Structural, microstructural and optical properties of the thin films were also influenced by addition of TiO2. Thin films with 4% of TiO2 and crystallized at 650°C shown only ß-BBO phase with a higher degree of preferred orientation when coated on fused silica, silicon and quartz substrates. The microstructural and the optical properties of these thin films were affected by the type of the substrate and by crystallization temperature and by the heating rate. For the thin film deposited by electron beam evaporation the crystallization of ß-BBO phase \"in-situ\" was only possible when the substrates was heated at 650°C during the deposition. Thin films prepared by both methods presents the effect of Second Harmonic Generation (SHG). (AU)