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Master's Dissertation
DOI
10.11606/D.85.2018.tde-21082018-150358
Document
Author
Full name
Rafael Lima Denaldi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Baldochi, Sonia Licia (President)
Courrol, Lilia Coronato
Santo, Ana Maria do Espirito
Title in Portuguese
Investigação do crescimento de fibras monocristalinas de LiLa(WO4)2 codopadas com Yb3+ e Er3+ para estudos espectroscópicos
Keywords in Portuguese
micro pulling-down
fibras monocristalinas
tungstatos duplos
Abstract in Portuguese
Neste trabalho foi estudado o crescimento de fibras da matriz LiLa(WO4)2 (LLW) pura e co-dopada com íons Yb3+ e Er3+ via micro pulling-down. Foram crescidas fibras homogêneas e transparentes de LiLa(WO4)2:Yb3+:Er3+ com teor de dopante de 2, 5, 7, 10 e 15 mol% de Yb3+, todas co-dopadas com teor de 0,5 mol% de Er3+, com 1mm de diâmetro e até 22 mm de comprimento. Partindo-se da dopagem de 20 mol% não foi possível o crescimento de fibras com a mesma qualidade das demais, ocorrendo segregação e, possivelmente, formação de fase secundária. A temperatura de fusão dos compostos diminui com a adição de Yb3+, indo de 1020°C para o LLW puro, para 991°C com dopagem de 20 mol%. Para a análise de espectroscopia de emissão, as fibras foram excitadas com laser na região do infravermelho em 972 nm, sendo observada a emissão dos íons Er3+ via conversão ascendente. Foram observadas emissões referentes às transições 4S3/24I15/2 (centroide em 550 nm), 2H11/24I15/2 (527 nm) e 4F9/24I15/2 (653 nm); sendo a primeira a mais intensa. A eficiência de emissão aumentou de ~7% para a fibra pura, para 36% na fibra com 15 mol% de Yb3+. Foi encontrado que, para a maior intensidade de emissão, a quantidade ideal de Yb3+ deve ser de 11,5 mol%.
Title in English
Growth study of Yb3+ and Er3+-doped LiLa(WO4)2 single crystal fibers for spectroscopic characterization
Keywords in English
micro pulling-down
double tungstes
single crystal fibers
Abstract in English
In the current work, was studied the growth of pure and Yb3+ and Er3+-doped LiLa(WO4)2 (LLW) by micro pulling-down technique. Were grown homogeneous and transparent fibers of Yb3+:Er3+:LiLa(WO4)2 with a dopant content of 2, 5, 7, 10 and 15 mol% of Yb3+, all co-doped with 0.5 mol% Er3+, 1 mm diameter and up to 22 mm length. It was not possible grow fibers with 20 mol% of Yb3+ due segregation and, possibly, formation of secondary phases. Noticed the melting temperature of the doped compounds decreases with the addition of Yb3+, from 1020 °C (pure LLW) to 991 °C (20 mol% Yb-doped). For emission studies, the fibers were excited in the infrared region at 972 nm and up conversion emission of Er3+ ions was registered. Emissions referring to transitions 4S3/24I15/2 (centroid at 550 nm), 2H11/24I15/2 (527 nm) and 4F9/24I15/2 (653 nm) were observed; the first one being the most intense. Emission efficiency increased from ~ 7% in pure fiber to 36% in doped fiber with 15 mol% of Yb3+. It was found that, for the highest emission intensity, the ideal amount of Yb3+ should be 11.5 mol%.
 
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Publishing Date
2018-09-19
 
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