- Nano Express
- Open Access
Thermal Behaviour of Sm0.5 R 0.5FeO3 (R = Pr, Nd) Probed by High-Resolution X-ray Synchrotron Powder Diffraction
© Pavlovska et al. 2016
- Received: 2 December 2015
- Accepted: 22 February 2016
- Published: 27 February 2016
Mixed ferrites Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 with orthorhombic perovskite structure isotypic with GdFeO3 were synthesized by solid-state reaction technique in air at 1473 K. Structural parameters obtained at room temperature prove a formation of continuous solid solutions in the SmFeO3–PrFeO3 and SmFeO3–NdFeO3 pseudo-binary systems. Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 show strongly anisotropic nonlinear thermal expansion: thermal expansion in the b direction is twice lower than in the a and c directions. The average linear thermal expansion coefficients of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 in the temperature range of 298–1173 K are in the limits of (9.0–11.1) × 10−6 K−1, which is close to the values reported for the parent RFeO3 compounds. Subtle anomalies in the lattice expansion of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 detected at 650–750 K reflect magnetoelastic coupling at the magnetic ordering temperature T N.
- Mixed rare earth ferrites
- Crystal structure
- Thermal expansion
- Magnetoelastic coupling
Complex oxides with perovskite structure RFeO3, where R is the rare earth(RE), represent an important class of functional materials. The RFeO3-based materials are used as electrodes in solid oxide fuel cells, as catalysts, gas sensory materials and semiconductor ceramics [1–6]. Complementary, the interest in the rare earth ferrites is stimulated by their interesting fundamental physical properties, such as spin-reorientation transitions at 80–480 K and the para- to antiferromagnetic transitions at 620–750 K [7–10]. Just recently, the interest to RE ferrite perovskites was renewed due to reported multiferroic properties of NdFeO3, SmFeO3 and other RFeO3 compounds [11–13]. At room temperature (RT), all RE orthoferrites adopt orthorhombic perovskite structure isotypic with GdFeO3 [14, 15]. No structural phase transitions were reported in the literature for RFeO3 compounds, with an exception of LaFeO3, which undergoes a high-temperature (HT) transition to rhombohedral structure at 1220–1280 K [16, 17]. Orthorhombic RFeO3 perovskites show strongly anisotropic thermal expansion: the expansivity in the b direction in the Pbnm setting is ca. two times lower than in the a and c directions. Subtle anomalies in the lattice expansion of PrFeO3 and SmFeO3 are observed in the b direction at 600–800 K, which is indicative for magnetoelastic coupling at the magnetic ordering temperature T N [18, 19]. In ref. , it was shown that the spin-reorientation transition in NdFeO3 between 100 and 200 K is associated with changes of the b-lattice parameter, which has a broad local minimum in the spin-reorientation region near 160 K. However, no lattice anomalies in NdFeO3 were found around the Néel temperature of 687 K in .
The aim of the present work is the detail study of the thermal behaviour of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 in order to reveal the possible magnetoelastic coupling in these mixed perovskite ferrites.
Precursor oxides were ball-milled in ethanol for 5 h, dried, pressed into pellets and annealed in air at 1473 K for 20 h. The as-obtained product was repeatedly re-grinded and annealed at 1473 K for 20 h and, after that, slowly cooled to RT for 20 h.
X-ray phase and structural characterization of the samples was performed at room temperature by using imaging plate Guinier camera G670 (Cu Kα1 radiation, λ = 1.54056 Å). Thermal behaviour of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 structures has been studied in situ in the temperature range of 298–1173 K by means of high-resolution X-ray synchrotron powder diffraction technique. The corresponding experimental powder diffraction patterns were collected with the temperature steps of 30 K at beamline B2 of synchrotron laboratory HASYLAB/DESY (Hamburg, Germany). Structural parameters of the samples were derived from the experimental diffractograms by using full-profile Rietveld refinement technique applying WinCSD program package .
Lattice parameters, coordinates and displacement parameters of atoms in the Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 structures at RT, 753 and 1173 K
T = 298 K
T = 753 K
T = 1173 K
T = 298 K
T = 753 K
T = 1173 K
B iso, Å2
B iso, Å2
B iso, Å2
B iso, Å2
Temperature evolution of the lattice parameters of mixed Sm-Pr and Sm-Nd ferrites resemble for the most part the thermal behaviour of the parent compounds. In both cases, clear deviations from the “normal” trend are observed in the b direction at 650–750 K, whereas much less visible anomalies in the lattice expansion are observed in the a and c directions (Fig. 4a–c). It is evident that similar to SmFeO3 and PrFeO3, a kink in the b-lattice expansion of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 is associated with the para- to antiferromagnetic transitions that occurred in these specimens at the Néel temperatures. Earlier, nonlinear lattice expansion across the antiferromagnetic to paramagnetic transitions was also observed in LaFeO3 at T N = 735 K .
Subtle maxima at the TEC curves of Sm0.5Pr0.5FeO3 around 670 K (Fig. 5a) reflect the observed lattice anomalies at the Néel temperature. In spite of no obvious maxima observed on the TEC curves of Sm0.5Nd0.5FeO3, a change of the slope of the TEC(b) values occurs around 650–700 K (Fig. 5b). A similar step at the thermal expansion coefficient at 723 ± 50 K, corresponding with the Néel temperature, has been revealed in LaFeO3 by dilatometric measurements .
The lattice expansion of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 could be also affected by a possible change of the oxygen defect structure during the heating of the samples, as it was detected in PrFeO3 and SmFeO3 by thermogravimetric measurements . As it was shown, detectable weight loss due to the fast oxygen desorption begins in these ferrites above 573 K. As a consequence, thermal expansion behaviour of SmFeO3 shows a change of the slope at around 593 K close to the temperature of sharp weight loss detected by TGA .
Crystal structure parameters of the mixed samarium-praseodymium and samarium-neodymium ferrites Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 synthesized by solid-state reaction technique in air at 1473 K have been studied in a wide temperature range of 298–1173 K by means of high-resolution X-ray synchrotron powder diffraction technique. Close analysis of the temperature dependence of the unit-cell dimensions in comparison with the literature data for the parent RFeO3 compounds revealed strongly anisotropic lattice expansion and subtle anomalies associated with the para- to antiferromagnetic transitions at 650–750 K. The average linear thermal expansion coefficients of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 derived from the experimental values of the unit-cell dimensions in the temperature range of 298–1173 K are in the limits of (9.0–11.1) × 10−6 K−1, which is close to the corresponding values reported for the parent RFeO3 compounds.
The work was supported in part by the Ukrainian Ministry of Education and Sciences (Project “RZE” ) and ICDD Grant-in-Aid programme. The authors express especial gratitude to A. Berghäuser for his kind assistance in the maintenance of the equipment during the measurements at HASYLAB beamline B2 under the project I-20110214.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
- Sun C, Hui R, Roller J (2010) Cathode materials for solid oxide fuel cells: a review. J Solid State Electrochem 14:1125–1144View ArticleGoogle Scholar
- Bukhari S, Giorgi J (2012) Chemically stable and coke resistant Sm1−xCexFeO3−δ perovskites for low temperature solid oxide fuel cell anode applications. J Power Sources 198:51–58View ArticleGoogle Scholar
- Ciambelli P, Cimino S, De Rossi S, Lisi L, Minelli G, Porta P, Russo G (2001) AFeO3 (A = La, Nd, Sm) and LaFe1−xMgxO3 perovskites as methane combustion and CO oxidation catalysts: structural, redox and catalytic properties. Appl Catal B: Environmental 29:239–250View ArticleGoogle Scholar
- Ding J, Lü X, Shu H, Xie J, Zhang H (2010) Microwave-assisted synthesis of perovskite ReFeO3 (Re: La, Sm, Eu, Gd) photocatalyst. Mater Sci Eng B 171:31–34View ArticleGoogle Scholar
- Itagaki Y, Mori M, Hosoya Y, Aono H, Sadaoka Y (2007) O3 and NO2 sensing properties of SmFe1−xCoxO3 perovskite oxides. Sens Actuators B 122:315–320View ArticleGoogle Scholar
- Prasad B, Rao G, Chen J, Babu D (2011) Abnormal high dielectric constant in SmFeO3 semiconductor ceramics. Mater Res Bull 46:1670–1673View ArticleGoogle Scholar
- Gorodetsky G, Levinson L (1969) Spin reorientation in SmFeO3. Solid State Commun 7:67–70View ArticleGoogle Scholar
- Pinto H, Shaked H (1972) Long wavelength neutron diffraction study of the magnetic structures of PrFeO3 and NdFeO3. Solid State Comm 10:663–665View ArticleGoogle Scholar
- Sławiński W, Przeniosło R, Sosnowska I, Suard E (2005) Spin reorientation and structural changes in NdFeO3. J Phys Condens Matter 17:4605–4614View ArticleGoogle Scholar
- Sławinski W, Przeniosło R, Sosnowska I, Brunelli M, Bieringer M (2007) Anomalous thermal expansion in polycrystalline NdFeO3 studied by SR and X-ray diffraction. Nucl Instrum Methods Phys Res, Sect B 254:149–152View ArticleGoogle Scholar
- Tokunaga Y, Furukawa N, Sakai H, Taguchi Y, Arima T, Tokura Y (2009) Composite domain walls in a multiferroic perovskite ferrite. Nat Mater 8:558–562View ArticleGoogle Scholar
- Lee J-H, Jeong Y, Park J, Oak M-A, Jang H, Son J, Scott J (2011) Spin-canting-induced improper ferroelectricity and spontaneous magnetization reversal in SmFeO3. Phys Rev Letters 107:117201View ArticleGoogle Scholar
- Hu G, Umehara I, Shuang X, Yuan S, Cao S (2012) Pressure effect in multiferroic phase transition of perovskite ferrite crystals NdFeO3 and ErFeO3. JPCS 400:032023–032027Google Scholar
- Marezio M, Remeika J, Dernier P (1970) The crystal chemistry of the rare earth orthoferrites. Acta Cryst B 26:2008–2022View ArticleGoogle Scholar
- Berenov A, Angeles E, Rossiny J, Raj E, Kilner J, Atkinson A (2008) Structure and transport in rare-earth ferrates. Solid State Ionics 179:1090–1093View ArticleGoogle Scholar
- Fossdal A, Menon M, Wærnhus I, Wiik K, Einarsrud M-AN, Grande T (2004) Crystal structure and thermal expansion of La1-xSrxFeO3-δ materials. J Am Ceram Soc 87:1952–1958View ArticleGoogle Scholar
- Selbach S, Tolchard J, Fossdal A, Grande T (2012) Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO3 investigated by high temperature X-ray diffraction. J Solid State Chem 196:249–254View ArticleGoogle Scholar
- Kharko O, Vasylechko L (2013) Anomalous thermal expansion of new mixed praseodymium cobaltites-ferrites. Visnyk Lviv Polytechnic Natl University Electronics 764:61–66Google Scholar
- Kuo C-Y, Drees Y, Fernández-Díaz M, Zhao L, Vasylechko L, Sheptyakov D, et al (2014) k = 0 magnetic structure and absence of ferroelectricity in SmFeO3. Phys Rev Lett 113:217203–217208Google Scholar
- Akselrud L, Grin YU (2014) WinCSD: software package for crystallographic calculations (Version 4). J Appl Cryst 47:803–805View ArticleGoogle Scholar
- Leineweber A (2011) Understanding anisotropic microstrain broadening in Rietveld refinement. Z Kristallogr 226:905–923View ArticleGoogle Scholar
- Vasylechko L, Senyshyn A, Bismayer U (2009) Perovskite-type aluminates and gallates. In: Gschneidner KA Jr, Bünzli J-CG, Pecharsky VK (eds) Handbook on the physics and chemistry of rare earths, vol 39. North-Holland, Netherlands, pp 113–295Google Scholar
- Senyshyn A, Vasylechko L, Knapp M, Bismayer U, Berkowski M, Matkovskii A (2004) Thermal expansion of the NdGaO3 perovskite. J All Comp 382:84–91View ArticleGoogle Scholar
- Senyshyn A, Oganov AR, Vasylechko L, Ehrenberg H, Bismayer U, Berkowski M, Matkovskii A (2004) The crystal structure and thermal expansion of the perovskite-type Nd0.75Sm0.25GaO3: powder diffraction and lattice dynamical studies. J Phys Condens Matter 16:253–265View ArticleGoogle Scholar
- Vasylechko L, Pivak Y, Senyshyn A, Savytskii D, Berkowski M, Borrmann H et al (2005) Crystal structure and thermal expansion of PrGaO3 in the temperature range 12–1253 K. J Solid State Chem 178:270–278View ArticleGoogle Scholar
- Hung M-H, Rao M, Tsai D-S (2007) Microstructures and electrical properties of calcium substituted LaFeO3 as SOFC cathode. Mater Chem Phys 101:297–302View ArticleGoogle Scholar
- Köferstein R, Ebbinghaus S (2013) Synthesis and characterization of nano-LaFeO3 powders by a soft-chemistry method and corresponding ceramics. Solid State Ionics 231:43–48View ArticleGoogle Scholar