Título: | ADDITION OF DIVALENT CATIONS (ZN(2+), NI(2+)) TO ZRMGMO(3)O(12) AND THEIR EFFECTS ON PHYSICAL PROPERTIES | ||||||||||||
Autor: |
ALISON TATIANA MADRID SANI |
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Colaborador(es): |
BOJAN MARINKOVIC - Orientador |
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Catalogação: | 13/ABR/2020 | Língua(s): | ENGLISH - UNITED STATES |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=47415&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=47415&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.47415 | ||||||||||||
Resumo: | |||||||||||||
Although the vast majority of materials dilates when heated and contract
when cooled, there is a class of materials that contracts or does not change their
dimensions when heated, presenting a negative thermal expansion coefficient
(NTE) or close to zero (ZTE), respectively. The possibility of reducing the
coefficient of thermal expansion while increasing its physical properties has been
the main driving force in the search for crystalline phases within the A(2)M(3)O(12)
family and its subfamilies. In the present study, we propose to synthesize two new
systems, ZrMg(1-x)Zn(x)Mo(3)O(12) (x = 0.1, 0.3, 0.35, 0.4) and ZrMg(1-x)Ni(x)Mo(3)O(12) (x =
0.05; 0.1, 0.15, 0.2), to try to reduce the coefficient of thermal expansion of the
ZrMgMo(3)O(12) phase. The solubility limit of Zn(2+) and Ni(2+)
in the ZrMgMo(3)O(12)
system is in the range of 0.35
less than or equal to x
less than or equal to 0.4 and 0.1
less than or equal to x
less than or equal to 0.2, respectively. The lowest
coefficient of thermal expansion (alfa l=2.82x10(-7)K
(-1)) was obtained for the
composition x = 0.1 in the ZrMg(1-x)Zn(x)Mo(3)O(12)system in the temperature range of
213 K to 298 K. In this system, the phase transition from monoclinic to
orthorhombic was observed, occurring below the room temperature for all
compositions from x = 0.1 to x = 0.4. This transition temperature increases as the
Zn(2+) composition increases. Analyzes of thermogravimetry indicated that the
phases of the two systems are not hygroscopic. Applying the Kubelka-Munk
equation, and considering an indirect transition to ZrMg(1-x)Zn(x)Mo(3)O(12), it was
concluded that there are no significant differences in the band gap energy of the
analyzed phases. However, for an indirect transition to ZrMg1-xNixMo3O12 there is
a decrease in energy of the band energy, as Ni2+ content increases in composition,
in addition to the appearance of absorption in the visible spectrum due to d-d
transition. Finally, the results of this study showed that it is possible to obtain a
ceramic material, within the systems studied, that presents a thermal expansion
behavior close to zero.
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