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Master's Dissertation
DOI
10.11606/D.97.2010.tde-20082013-143254
Document
Author
Full name
Leandro Marcos Salgado Alves
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Lorena, 2010
Supervisor
Committee
Santos, Carlos Alberto Moreira dos (President)
Nunes, Cristina Bórmio
Silva, Robson Ricardo da
Title in Portuguese
Comportamento elétrico não convencional no KxMoO2-δ
Keywords in Portuguese
Condutores unidimensionais.
KxMoO2-δ
Resistividade anômala
Abstract in Portuguese
Molibdatos têm atraído grande atenção devido à existência de compostos com caráter elétrico unidimensional como conseqüência da presença de cadeias contendo ligações de Mo-O ou Mo-Mo em suas estruturas cristalinas. Com o objetivo de estudar molibdatos com esta característica, amostras policristalinas do sistema K-Mo-O foram preparadas pelo método de reação de difusão no estado sólido e caracterizadas por difratometria de raios x, propriedades elétricas e magnéticas. Estes resultados demonstram a existência de uma nova fase neste sistema com estequiometria KxMoO2-δ. Medidas da resistência elétrica em função da temperatura deste material mostram comportamento metálico anômalo que está relacionado a um ordenamento antiferromagnético. Foi observado ainda que a anomalia na resistência elétrica em baixas temperaturas (T < TM) comporta-se segundo uma lei de potência com expoente próximo de 0,5, o que sugere que o comportamento elétrico do KxMoO2-δ pode ser descrito por um mecanismo de condutividade unidimensional.
Title in English
Unconvetional Electrical Behavior in the KxMoO2-δ
Keywords in English
Anomalous resistivity
KxMoO2-δ
One-dimensional conductors
Abstract in English
Molybdates have attracted great attention due to the existence of compounds which show one-dimensional electrical behavior as consequence of the channel containing Mo-O or Mo-Mo bonds in their crystalline structure. In order to study molybdates exhibiting onedimensional conductivity, polycrystalline samples of the K-Mo-O system were prepared using the solid state diffusion reaction method and characterized by X-ray powder diffractometry, electrical and magnetic properties. These results demonstrate the existence of a new phase in this system with KxMoO2-δ stoichiometry. Electrical resistance as a function of temperature measurements for this compound have shown anomalous metallic behavior which is related to an antiferromagnetic ordering. It has been also observed that the anomaly in the electrical resistance at low temperatures (T < TM) is fitted by power law temperature dependence with an exponent near 0.5 which suggests that the electrical behavior of the KxMoO2-δ can be well described by the one-dimensional conducting mechanism.
 
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EMD10002.pdf (1.01 Mbytes)
Publishing Date
2013-08-20
 
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