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Rietveld refinement of Sm0.55Sr0.45Mn0.4Fe0.6O3

Published online by Cambridge University Press:  27 March 2020

G. Murugesan Open the ORCID record for G. Murugesan [Opens in a new window] ,
R. Nithya  and
S. Kalainathan
G. Murugesan*
Affiliation:
Department of Physics, Vel Tech Rangarajan Dr. Sagunthala R & D Institute of Science and Technology, Avadi, Chennai600062, Tamil Nadu, India
R. Nithya
Affiliation:
Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu, India
S. Kalainathan
Affiliation:
Centre for Crystal Growth, School of Advanced Sciences, VIT, Vellore632014, Tamil Nadu, India
*
a)Author to whom correspondence should be addressed. Electronic mail: gmurux@gmail.com
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Abstract

Single crystals of Sm0.55Sr0.45Mn0.4Fe0.6O3 were grown by an optical floating zone technique in an oxygen atmosphere. The powder X-ray diffraction pattern for the grown crystal revealed single-crystalline nature. The lattice parameters and atomic structure were refined and indexed using a General Structure Analysis System (GSAS) to an orthorhombic structure with lattice parameters a = 5.4415 (32) Å, b = 7.6994 (27) Å, c = 5.43868 (28) Å, and space group Pnma.

Keywords

XRDmaterials characterizationin situ diffraction
Type
New Diffraction Data
Information
Powder Diffraction , Volume 35 , Issue 1 , March 2020 , pp. 31 - 33
Copyright
Copyright © International Centre for Diffraction Data 2020

I. INTRODUCTION

Oxide manganites with the perovskite structure have gained attention due to their extraordinary electrical and magnetic properties (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2018). Colossal magnetoresistance (CMR) behaviour is observed in these manganites due to hole doping of divalent ions like Sr, Ca, and Ba (Blanco et al., Reference Blanco, Insausti, De Muro, Lezama and Rojo2006). The sudden transition from an insulating state to metallic state and CMR behaviour in Sm1−xSrxMnO3 (x = 0.3–0.52) makes it a unique material for spintronic applications (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2018). Doping of other transition metals in Mn site results in the reduction of mobile electrons (Blanco et al., Reference Blanco, Insausti, De Muro, Lezama and Rojo2006). Several studies have been done for Fe-doped La0.7Sr0.3Mn1−xFexO3 (Huang, et al., Reference Huang, Li, Li and Ong2001) and Nd0.67Ba0.33Mn1−xFexO3 (Hcini et al., Reference Hcini, Boudard, Zemni and Oumezzine2014). The iron doping has not shown appreciable structural changes, but the metallic conduction and ferromagnetism were apparently reduced (Blanco et al., Reference Blanco, Insausti, De Muro, Lezama and Rojo2006). Spin glass behaviour is observed due to the doping of Fe in Mn site, which is due to the competition between the double exchange (Mn–O–Mn) and super exchange (Mn–O–Fe) interactions (Takeuchi et al., Reference Takeuchi, Hirahara, Dhakal, Miyoshi and Fujiwara2001). Single crystals of SSMFO were grown using an infrared image furnace by an optical floating zone method. The Griffiths phase has been observed in these crystals where ferromagnetic clusters are present in the paramagnetic region. Doping of Fe has suppressed the ferromagnetism by reducing the Mn3+/Mn4+ ratio (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2018). We have previously reported the powder X-ray diffraction (XRD) pattern of pristine compound Sm0.55Sr0.45MnO3 (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2016). Earlier an analogous compound Nd0.65Sr0.35Fe0.6Mn0.4O3 showed a transition from pure ferromagnetic ordering to weak ferromagnetic (non-collinear ordering) at higher temperatures (Abdel et al., Reference Abdel-Latif, Khramov, Trounov, Smirnov, Bashkirov, Parfenov, Tserkovnaya, Gumarov and Ibragimov2006), this initiated us to choose a similar composition in samarium manganite series and study its magnetic behaviour at higher temperatures, hereby we report the powder XRD pattern of Fe-doped Sm0.55Sr0.45Mn0.4Fe0.6O3 (SSMFO).

II. EXPERIMENTAL

A. Crystal growth

Single crystals of SSMFO were grown using an infrared furnace in an oxygen atmosphere. Detailed experimental conditions about the crystal growth have been already discussed in our previous reports (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2018).

B. Data collection

The powder XRD pattern for crushed single crystal powder was collected at room temperature using a Bruker D8 advance X-ray powder diffractometer operated in the Bragg–Brentano geometry with fixed slits using a LYNX-eye position sensitive detector (PSD). The powder was loaded in a Si single crystal, which gives zero background intensity in the angular range of the present study. The diffraction data were recorded using CuKα radiation (1.5406 Å), which was operated at 40 kV and 30 mA. For Rietveld refinement, diffraction data were collected in an angular range of 20°–90° in steps of around 0.02° with a count time of 1 s step−1.

III. RESULTS

The experimental XRD pattern for SSMFO single crystal is shown in Figure 1. Rietveld refinement for powder diffraction pattern of SSMFO crystal was performed using a General Structure Analysis System (GSAS) program (Larson and Von Dreele, Reference Larson and Von Dreele2000). The starting structure model used was that of the parent compound, Sm0.55Sr0.45MnO3 (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2016). The calculated powder pattern is shown as a solid blue colour line in Figure 1. The solid black line shown in Figure 1 is the difference between the calculated and experimental powder XRD patterns. The vertical lines below the black line in Figure 1 show expected Bragg diffraction peaks calculated as per space group Pnma.

Figure 1. Rietveld refinement of XRD data of SSMFO crystal and inset shows the crystal structure of SSMFO compound.

The crystal structure of SSMFO crystal has been drawn by using the Vesta software (Momma and Izumi, Reference Momma and Izumi2011) which is shown in Figure 1.

The fractional coordinates were refined from the starting parameters (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2016) and the refined coordinates; occupancy with the standard deviation is given in Table I. The refined lattice parameters are given in Table II. The metal–oxygen bond lengths are given in Table III. Due to similar ionic radii of Mn and Fe, only a slight variation in lattice parameters and bond lengths is observed. In comparison with the parent compound (Sm0.55Sr0.45MnO3), the lattice parameters and bond lengths have been varied due to the doping of Fe in Mn lattice (Murugesan et al., Reference Murugesan, Nithya and Kalainathan2016). The powder diffraction data of SSMFO is given in Table IV.

Table I. Refined fractional coordinates after the final cycle of the refinement.

Table II. Refined lattice parameters along with R-factors.

Table III. Metal–oxygen bond lengths.

Table IV. Powder diffraction data of SSMFO.

IV. CONCLUSIONS

The Rietveld refinement of SSMFO showed good agreement of the experimental data with the calculated pattern which crystallizes in an orthorhombic perovskite structure with lattice parameters a = 5.4415 (32) Å, b = 7.6994 (27) Å, c = 5.43868 (28) Å, and space group Pnma (#62). The crystal structure and powder diffraction data of SSMFO crystal was generated from its powder XRD pattern. Due to the similar ionic radii of Mn and Fe, slight variations of lattice parameters were only observed when compared with the pristine sample Sm0.55Sr0.45MnO3.

References

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Figure 0

Figure 1. Rietveld refinement of XRD data of SSMFO crystal and inset shows the crystal structure of SSMFO compound.

Figure 1

Table I. Refined fractional coordinates after the final cycle of the refinement.

Figure 2

Table II. Refined lattice parameters along with R-factors.

Figure 3

Table III. Metal–oxygen bond lengths.

Figure 4

Table IV. Powder diffraction data of SSMFO.