An EPR study of some SrTiO3 samples and of their properties Cesare Oliva(*), Serena Cappelli, Laura Fabbrini, Ilenia Rossetti, Alexander Kryukov($) and Lucio Forni Dipartimento di Chimica Fisica ed Elettrochimica, Università degli Studi di Milano, via Golgi, 19, I-20133 Milano, Italy (*) E-mail: cesare.oliva@unimi.it ($)D.I.Mendeleev University of Chemical Technology of Russia, Miusskaya sq. 9, Moscow, Russia. _______________________________________________________________________ Three SrTiO3 catalysts have been compared. One of them (T3) was prepared by the traditional sol–gel procedure, the other two through the flame hydrolysis (FH) technique, in the presence of either 1.5 mol excess of citric acid (sample T2) or 3 mol excess of tartaric acid (sample T1) as complexing agent in the precursor solution. All the catalysts possessed the perovskite-like structure, with some SrCO3 as impurity. T1 was more crystalline than the other two samples and showed the most active as catalyst for the flameless combustion of methane. Isolated T3+ ions were found in T3 by EPR analysis, while a different EPR feature was noticed with T2 and attributed to Ti4+/O2-. A high concentration of isolated Ti3+ ions was observed with T1, accompanied by Ti4+/O2- species, but with O2- in a different position with respect to sample T2. The energy gap () for the electron transfer between Ti3+ and O2, to form O2-, was calculated for these two samples from the gzz value of the A and A’ spectra.  was about twice as high with T2 than with T1. This difference, likely connected with the different temperature attained during the FH process with the two different complexing agents, can explain the higher oxidising activity of the T1 sample, occurring through the reaction O2- + Ti4+  Ti3+ + O2.

An EPR study of some SrTiO(3+d) samples and their properties / C. Oliva, S. Cappelli, L. Fabbrini, I. Rossetti, A. Kryukov, L. Forni. ((Intervento presentato al convegno 37th Annual Intern. Meeting ESR of RSC tenutosi a Warwick (U.K.) nel 2004.

An EPR study of some SrTiO(3+d) samples and their properties

C. Oliva
Primo
;
S. Cappelli
Secondo
;
L. Fabbrini;I. Rossetti;L. Forni
Ultimo
2004

Abstract

An EPR study of some SrTiO3 samples and of their properties Cesare Oliva(*), Serena Cappelli, Laura Fabbrini, Ilenia Rossetti, Alexander Kryukov($) and Lucio Forni Dipartimento di Chimica Fisica ed Elettrochimica, Università degli Studi di Milano, via Golgi, 19, I-20133 Milano, Italy (*) E-mail: cesare.oliva@unimi.it ($)D.I.Mendeleev University of Chemical Technology of Russia, Miusskaya sq. 9, Moscow, Russia. _______________________________________________________________________ Three SrTiO3 catalysts have been compared. One of them (T3) was prepared by the traditional sol–gel procedure, the other two through the flame hydrolysis (FH) technique, in the presence of either 1.5 mol excess of citric acid (sample T2) or 3 mol excess of tartaric acid (sample T1) as complexing agent in the precursor solution. All the catalysts possessed the perovskite-like structure, with some SrCO3 as impurity. T1 was more crystalline than the other two samples and showed the most active as catalyst for the flameless combustion of methane. Isolated T3+ ions were found in T3 by EPR analysis, while a different EPR feature was noticed with T2 and attributed to Ti4+/O2-. A high concentration of isolated Ti3+ ions was observed with T1, accompanied by Ti4+/O2- species, but with O2- in a different position with respect to sample T2. The energy gap () for the electron transfer between Ti3+ and O2, to form O2-, was calculated for these two samples from the gzz value of the A and A’ spectra.  was about twice as high with T2 than with T1. This difference, likely connected with the different temperature attained during the FH process with the two different complexing agents, can explain the higher oxidising activity of the T1 sample, occurring through the reaction O2- + Ti4+  Ti3+ + O2.
Settore CHIM/02 - Chimica Fisica
An EPR study of some SrTiO(3+d) samples and their properties / C. Oliva, S. Cappelli, L. Fabbrini, I. Rossetti, A. Kryukov, L. Forni. ((Intervento presentato al convegno 37th Annual Intern. Meeting ESR of RSC tenutosi a Warwick (U.K.) nel 2004.
Conference Object
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/199316
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact