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Doctoral Thesis
DOI
10.11606/T.54.1984.tde-11022015-160324
Document
Author
Full name
Aldo Tancredo
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1984
Supervisor
Committee
Carmo, Luiz Carlos Scavarda do
Evora, Cesar Augusto Por Deus
Gonzalez, Jose Pedro Donoso
Nascimento, Otaciro Rangel
Oliveira, Aderbal Carlos de
Title in Portuguese
Estudo e identificação de centros paramagnéticos por RPE no cristal de K3Cu(CN)4 irradiado por raios-x
Keywords in Portuguese
Não disponível
Abstract in Portuguese
Neste trabalho, estudamos e identificamos centros paramagnéticos criados em cristais de K3Cu(CN)4 irradiados (raios x), usando a técnica de Ressonância Paramagnética de Elétrons (RPE). Os cristais foram irradiados nas seguintes condições: a) temperatura próxima de N2-líquido (77K) e b) temperatura ambiente. Os centros paramagnéticos em cristais irradiados a temperatura próxima de N2-líquido são: a) Cu++ (g// = 2,0129 e g = 2,1615; A// = 74,5 gauss e A = 88,9 gauss) e b) Ko > (g// = 2,0090 e g = 2,0035; A// = 95,3 gauss e A = 26,1 gauss). Propomos modelos de campo cristalino para os centros paramagnéticos que determinaram as seguintes simetrias locais para satisfazerem os resultados experimentais: a) Cu++ em simetrias C3v e b) Ko em simetria octaédrica distorcida. Também estudamos o decaimento desses centros e observamos que o íon Cu++ é bastante instável e desaparece a T=148K. O átomo de Ko permanece até T ≅ 300K. Os centros paramagnéticos em cristais irradiados à temperatura ambiente são de Ko (gzz = 2,0101, gyy = 2,0083 e gxx = 2,0037; A1 = 100,1 gauss, A2 = 35,0 gauss e A3 = 36,8 gauss).O modelo proposto de campo cristalino é octaédrico distorcido que está em acordo com os resultados experimentais dos parâmetros de RPE
Title in English
Not available
Keywords in English
Not available
Abstract in English
In this present work, we study and identify paramagnetic centers created in K3Cu(CN)4 crystals by x-ray irradiation, using Electron Paramagnetic Resonance (EPR) technique. The crystals are irradiated in following conditions: a) liquid Nitrogen temperatures, b) room temperatures. The paramagnetic centers is irradiated crystals near liquid nitrogen temperature are: a) Cu++ (g// = 2,0129 and g = 2,1615; A// = 74,5 gauss and A = 88,9 gauss) and b) Ko > (g// = 2,0090 and g = 2,0035; A// = 95,3 gauss and A = 26,1 gauss). We also theoretically propose crystal field models of the paramagnetic centers which determine the following local symmetric in order to satisfy experimental results: a) Cu++ in C3v symmetry and b) Ko in distorted octahedral symmetry. We also study the decay of these centers and observe that Cu++ íons are very much unstable and disappear at T=148K. The Ko atom remain up to T ≅ 300K. The paramagnetic centers in crystals irradied at room temperature are of Ko (gzz = 2,0101, gyy = 2,0083 and gxx = 2,0037; A1 = 100,1 gauss, A2 = 35,0 gauss and A3 = 36,8 gauss). The proposed crystal Field model of these paramagnetic centers gives distorted octahedral symetry in order to satisfy experimental results
 
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Publishing Date
2015-02-12
 
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