Thermoelastic and structural properties of ionically conducting cerate perovskites: (II) SrCeO₃ between 1273 K and 1723 K

Abstract

The temperature dependence of the crystal structure and the thermoelastic properties of SrCeO 3 have been determined from Rietveld refinement of high resolution, neutron time-of-flight powder diffraction data collected in 5 K intervals between 1273 K and 1723 K. No evidence was found for critical behaviour in the amplitudes of the modes that soften in zone boundary phase transitions in perovskite-structured phases suggesting SrCeO 3 may remain orthorhombic, space group Pbnm from 1.2 K up to the 1 atm melting point of 2266 K. The temperature variation of the crystal structure has been determined from mode decomposition techniques and the structural evolution has been inferred from the temperature-dependences of the spontaneous shear strain and the order parameter associated with the anti-phase tilt. Thermoelastic properties have been derived from the temperature variation of the unit cell, isobaric heat capacity, and atomic displacement parameters and shows good agreement with earlier work carried out on the lightly doped system SrCe 0.95 Yb 0.05 O  ( ~ 3). Temperaturedependent corrections for the bond valence parameters for strontium and cerium are reported.

Characterization and Rietveld refinements of new dense ceramics Ba3−xSrxTb3−xCexO9 (x = 1 and 1.5) perovskites

“…For doped BaTiO 3 ceramics, oxygen vacancies (V O ) can be detected in the low-temperature rhombohedral phase of T ≤ −100 °C (Lu et al ., 2016c). It is reported that SrCeO 3 may remain orthorhombic, the space group Pbnm from 1.2 K up to the 1 atm melting point of 2266 K. (Knight et al ., 2015). Our experiments confirm that no additional V O -related EPR signal was observed for BSTC1 and BSTC3/2 (not presented here) because no phase transition was observed in these two ceramics.…”

“…Perovskite-type oxides, such as BaCeO 3 and SrCeO 3 , are state-of-the-art high-temperature proton conductors as electrolytes in solid oxide fuel cells (SOFC) because of its high protonic conductivity when exposed to a humidified hydrogen-containing atmosphere at temperatures higher than 300 °C (Uchida et al ., 1983; Scherban et al ., 1988; Iwahara et al ., 2004; Tolchard and Grande, 2007; Fu and Weng, 2014; Knight et al ., 2015). In order to improve proton conductivity, several kinds of rare-earth-doped BaCeO 3 and SrCeO 3 ceramics have been developed: (1) BaCe 1− x RE x O 3− δ , via the B-site replacement of Ce 4+ by acceptor-type trivalent rare-earth ions (RE 3+ ) such as RE 3+ = Y 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Eu 3+ , Tb 3+ , and Yb 3+ (Matsumoto et al ., 1999; Wang et al ., 2004; Wu et al ., 2004; Sharova et al ., 2005; Malavasi et al ., 2008); (2) Ba(Ce 0.8− y Pr y Gd 0.2 )O 2.9 , via the B-site co-doping with double rare-earth ions Pr 3+ and Gd 3+ (Mukundan et al ., 2001); and (3) BaCe 0.2 Zr 0.7 RE 0.1 O 3− δ , via the B-site co-doping with Zr 4+ and RE 3+ (=Y 3+ , Sm 3+ ) (Barison et al ., 2008; Ricote et al ., 2012; Kannan et al ., 2013; Choi et al ., 2014).…”

Eutectoid decompositions in Ce‐containing ABO3 perovskites: Part I, the case of cooperative growth in CeAlO3

“…The decomposition of functional oxides composed of redox‐active ions has been well documented in systems such as multiferroic BiFeO 3 17 and oxygen‐ion conducting pseudocubic perovskites 18 . ABO 3 perovskites containing Ce 3+ ions, rather than the commonly found Ce 4+ ions substituting the perovskite B ‐site, 19,20 are particularly interesting because both displacive and reconstructive phase transformations have been documented in the same system, for example, CeAlO 3 21 . Under moderately oxidizing conditions there is a driving force for the Ce 3+ cations to oxidize to Ce 4+ and this driving force results in decomposition of the perovskite.…”

First‐Principles Calculations of Pressure Effects on the Structural, Electronic, Elastic, and Thermodynamic Properties of Rb2MF6 (M = Si, Ni, Pd) Crystals

“…Since the number of chemical elements in double perovskites’ formula is increased, the number of possibilities for making solid solutions with partial or complete cation substitution or introducing various dopant ions is also increased tremendously. Currently specific materials are used in many technologies such as magnetoelectronic, [ 7,8 ] thermoelastic, [ 9 ] photodetecting, [ 10 ] optoelectronic, [ 11 ] and scintillating, [ 12 ] to name a few. The environmentally friendly lead‐free double perovskites are attractive materials for photovoltaics.…”