Correlation Between Photoluminescence and Structural Defects in Ca1+xCu3−xTi4O12 Systems. Issue 1 (17th October 2012)

• Record Type: Journal Article
• Authors: Oliveira, Larissa H.; Paris, Elaine C.; Avansi, Waldir; Ramirez, Miguel A.; Mastelaro, Valmor R.; Longo, Elson; Varela, José A.; Chen, X. M.
• Is Part Of: Journal of the American Ceramic Society. Volume 96:Issue 1(2013)
• Page Start: 209
• Page End: 217
• Publication Date: 2012-10-17
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.12020
• Languages: English
• ISSNs: 0002-7820

Abstract

<abstract abstract-type="main" id="jace12020-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Ca<sub>1+<italic>x</italic></sub>Cu<sub>3<bold>−</bold><italic>x</italic></sub>Ti<sub>4</sub>O<sub>12</sub> powders were synthesized by a conventional solid‐state reaction. X‐ray diffraction (XRD) was performed to verify the formation of cubic CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> (CCTO) and orthorhombic CaTiO<sub>3</sub> (CTO) phases at long range. Rietveld refinements indicate that excess Ca atoms added to the Ca<sub>1<bold>−</bold><italic>x</italic></sub>Cu<sub>3<bold>−</bold><italic>x</italic></sub>Ti<sub>4</sub>O<sub>12</sub> (<italic>x </italic><bold>=</bold><italic> </italic>1.0) composition segregated in a CaTiO<sub>3</sub> secondary phase suggesting that solubility limit of Ca atoms in the CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> lattice was reached for this system. The FE‐SEM images show that the Ca<sub>1+<italic>x</italic></sub>Cu<sub>3<bold>−</bold><italic>x</italic></sub>Ti<sub>4</sub>O<sub>12</sub> (0 <bold><</bold> <italic>x </italic><bold><</bold><italic> </italic>3) powders are composed of several agglomerated particles with irregular morphology. X‐ray absorption near‐edge structure spectroscopy (XANES) spectra indicated [TiO<sub>5</sub>V<sub>o</sub><sup>z</sup>]‐[TiO<sub>6</sub>] complex clusters in the CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> structure which can be associated with oxygen vacancies (V<sub>o</sub><sup>z</sup> <bold>=</bold> V<sub>o</sub><sup><italic>x</italic></sup>, V<sub>o</sub><sup></sup>, and V<sub>o</sub><sup></sup>) whereas in the CaTiO<sub>3</sub> powder, this analysis indicated [TiO<sub>6</sub>]–[TiO<sub>6</sub>] complex clusters in the structure. Ultraviolet‐visible (UV–vis) spectra and photoluminescence (PL) measurements for the analyzed systems revealed structural defects such as oxygen vacancies, distortions, and/or strains in CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> and CaTiO<sub>3</sub> lattices, respectively.</p> </abstract>