The structure and hyperfine interactions in the Bi9Ti3Fe5O27 Aurivillius compound were studied using
X-ray diffraction and Mössbauer spectroscopy. Samples were prepared by the conventional solid-state sintering
method at various temperatures. An X-ray diffraction analysis proved that the sintered compounds formed
single phases at temperature above 993 K. Mössbauer measurements have been carried out at room and liquid
nitrogen temperatures. Room-temperature Mössbauer spectrum of the Bi9Ti3Fe5O27 compound confirmed its
paramagnetic properties. However, low temperature measurements revealed the additional paramagnetic phase
besides the antiferromagnetic one

Czekaj, Dionizy

Jartych, E.

Lisińska-Czekaj, Agata

Mazurek, M.

Surowiec, Z.

Acta Physica Polonica A

English

Repozytorium Uniwersytetu Śląskiego RE-BUŚ

             Title: Structure and hyperfine interactions in Aurivillius Bi9Ti 3Fe5O27 conventionally sintered compound  Author: M. Mazurek, Agata Lisińska-Czekaj, Z. Surowiec, E. Jartych, Dionizy Czekaj  Citation style: Mazurek M., Lisińska-Czekaj Agata, Surowiec Z., Jartych E., Czekaj Dionizy. (2011). Structure and hyperfine interactions in Aurivillius Bi9Ti 3Fe5O27 conventionally sintered compound. "Acta Physica Polonica A" (Vol. 119, nr 1 (2011), s. 72-74).  Vol. 119 (2011) ACTA PHYSICA POLONICA A No. 1Proceedings of the All-Polish Seminar on Mössbauer Spectroscopy, Warsaw, Poland, June 18–21, 2010Structure and Hyperfine Interactions in AurivilliusBi9Ti3Fe5O27 Conventionally Sintered CompoundM. Mazureka,∗, A. Lisińska-Czekajb, Z. Surowiecc, E. Jartycha and D. CzekajbaDepartment of Experimental Physics, Institute of Physics, Technical University of LublinNadbystrzycka 38, 20-618 Lublin, PolandbDepartment of Materials Science, University of Silesia, Śnieżna 2, 41-200 Sosnowiec, PolandcInstitute of Physics, Maria Curie-Skłodowska University, pl. M.C. Skłodowskiej 1, 20-031 Lublin, PolandThe structure and hyperfine interactions in the Bi9Ti3Fe5O27 Aurivillius compound were studied usingX-ray diffraction and Mössbauer spectroscopy. Samples were prepared by the conventional solid-state sinteringmethod at various temperatures. An X-ray diffraction analysis proved that the sintered compounds formedsingle phases at temperature above 993 K. Mössbauer measurements have been carried out at room and liquidnitrogen temperatures. Room-temperature Mössbauer spectrum of the Bi9Ti3Fe5O27 compound confirmed itsparamagnetic properties. However, low temperature measurements revealed the additional paramagnetic phasebesides the antiferromagnetic one.PACS: 81.05.Je, 81.20.Ev, 31.30.Gs, 76.80.+y1. IntroductionRecently, an upsurge of scientific interest in multifer-roic materials may be observed. In multiferroics ferro-electric and ferro(antiferro-)magnetic (and/or ferroelas-tic) properties are simultaneously combined and theseare materials known from 1960s ([1] and Refs. therein).Until now, however, the microscopic mechanism of co-existence in one material the magnetic and ferroelectricordering is not well recognized, especially in systems withperovskite-like structure (BiFeO3, BiMnO3, YMnO3) orin Aurivillius compounds [1, 2].The Aurivillius compounds of the Bi4Ti3O12–BiFeO3 system are described with the general formulaBim+1Ti3Fem−3O3m+3 where m indicates the numberof perovskite-like layers {(Bim+1Fem−3Ti3O3m+1)2−}per slab between fluorite-like bismuth-oxygen layers{(Bi2O2)2+}. These compounds are ceramics whichcombine ferroelectric, semiconducting and antiferromag-netic properties making them very attractive materialsto applications in information processing and storage([3] and Refs. therein). In this work the investigatedBi9Ti3Fe5O27 compound has eight perovskite layers be-tween the Bi2O2 layers.The traditional solid-state sintering technology forpreparation of ceramic materials is widely used and wellestablished. While the structure of the Aurivillius com-pounds is described in the literature and databases quite∗ corresponding author; e-mail: mariusz.mazurek@pollub.plwell, the hyperfine interactions in these materials havenot yet been studied in sufficient detail. In our earlier pa-pers [4, 5] room-temperature Mössbauer measurementsperformed for Bim+1Ti3Fem−3O3m+3 with m = 4, 6, 7and 8 revealed that all compounds were in paramagneticstate, what is consistent with the literature data con-cerning the Néel temperature of these ceramics (TN issmaller than room temperature) [6]. Low temperatureMössbauer measurements for Bi9Ti3Fe5O27 compoundhave been carried out more than thirty years ago [7, 8],however, besides spectra not all values of hyperfine inter-action parameters were reported by the authors.The aim of this work was to determine the hyper-fine interaction parameters of Bi9Ti3Fe5O27 compoundboth at room and liquid nitrogen temperatures usingMössbauer spectroscopy (MS). Structure of the sin-tered Bi9Ti3Fe5O27 ceramic was investigated using X-raydiffraction (XRD).2. Experimental detailsTo prepare the Bi9Ti3Fe5O27 compound the appropri-ate amounts of precursors, viz. Fe2O3, Bi2O3, and TiO2(all 99.9% purity, Aldrich Chemical Co.) were weightedand mixed with an agate mortar and pestle to give the de-sired composition and thus provide conditions for the fol-lowing solid state reaction:6TiO2 + 9Bi2O3 + 5Fe2O3 → 2Bi9Ti3Fe5O27. (1)The mixture of powders was pressed under 300 MPa in20 mm diameter stainless-steel die. The obtained com-pacts were then placed in an alumina crucible and fired(72)Structure and Hyperfine Interactions in Aurivillius Bi9Ti3Fe5O27 Conventionally Sintered Compound 73in air at temperature 993 K for 2 hours. As EDS (EnergyDispersive Spectroscopy) measurements performed aftercalcination proved, the chemical composition of the com-pound was conserved with the relative accuracy of ±3%.After calcination the compacts were re-milled, pressedinto discs of 10 mm in diameter under 600 MPa, and thensintered at temperatures 1123 K and 1223 K, for 2 h ina sealed alumina crucible (free sintering method), withheating and cooling rates of 5 K min−1. All the sampleswere then furnace-cooled to room temperature.XRD measurements were performed using the PhilipsPW3710 diffractometer with CoKα radiation. The anal-ysis of X-ray patterns was performed with an X’PertHighScore Plus computer programme equipped withthe newest ICSD data base and Rietveld method ofthe crystalline structure refinement.MS studies were carried out at room and liquid ni-trogen temperatures in standard transmission geometryusing a source of 57Co in a rhodium or a chromium ma-trix.3. Results and discussionAs reported in our earlier work [5], X-ray diffractionand Mössbauer studies revealed that the Bi9Ti3Fe5O27compound synthesized at 993 K contained residualhematite. Sintering at 1123 K and 1223 K resulted inthe formation of the single-phased compound. A detailedanalysis of XRD measurements allowed to determinethe lattice parameters for the Bi9Ti3Fe5O27 compoundwhich are as follows: a = 5.602(4) Å, b = 5.536(5) Å,c = 75.16(5) Å, α = β = γ = 90◦ and agree well with thedata reported in [3].Figure 1 presents room-temperature Mössbauer spec-trum obtained for the Bi9Ti3Fe5O27 compound sinteredat 1123 K. In order to reveal some details of the Möss-bauer spectrum it was registered at smaller velocityrange. For the sample sintered at 1223 K both XRDand MS studies gave the similar results.Fig. 1. Room-temperature Mössbauer spectrumof Bi9Ti3Fe5O27 compound sintered at 1123 K.In the numerical fitting procedure the spectrum was fit-ted using one doublet what reflects one 57Fe-position, i.e.in the center of the oxygen octahedron, where iron maysubstitute Ti atoms. The hyperfine interaction parame-ters are listed in Table and they are typical for the highspin trivalent iron.It is known that the Aurivillius compounds are an-tiferromagnetics and with increasing the number ofperovskite-like layers, the antiferromagnetic Néel tem-perature increases ([6] and Refs. therein) being smallerthan room temperature for m = 4–7. In the case ofthe Bi9Ti3Fe5O27 compound there are some discrepan-cies in the reported data. The value of TN is estimatedas greater than 300 K by the authors of [9]. Our re-sults agree well with the data reported in [7], wherethe authors have observed the quadrupole doublets at270 K and 300 K. Moreover, they have suggested that inthe Bi9Ti3Fe5O27 compound the Néel temperature hadno precisely determined value but the transition fromantiferromagnetic to paramagnetic state may occur atvarious temperatures from a relatively broad range, i.e.between 80 K and 270 K.In Fig. 2 Mössbauer spectrum measured forthe Bi9Ti3Fe5O27 compound at liquid nitrogen temper-ature (80 K) is shown. It may be seen, that besidesthe six-line pattern the doublet line exists in the spec-trum. This means that some second phase, invisible inXRD pattern as well as in room temperature MS spectra,exists in the sample. Qualitatively, our spectrum issimilar to that reported in [7, 8] where the authors haveobserved the spectra consisted of doublet and sextetsat temperature range of 80–270 K. However, at 80 Kthey have registered broadened six-line pattern withouta doublet [7].Fig. 2. Liquid nitrogen temperature Mössbauer spec-trum of Bi9Ti3Fe5O27compound.The numerical fitting of the spectrum was performedusing one doublet and three sextets with no fixed param-eters. The hyperfine interaction parameters of the com-ponents are listed in Table.74 M. Mazurek, A. Lisińska-Czekaj, Z. Surowiec, E. Jartych, D. CzekajTABLEHyperfine interaction parameters obtained from the numerical fitting of the Mössbauerspectra for Bi9Ti3Fe5O27 compound measured in room temperature (RT) and liquid ni-trogen temperature (LN): δ — isomer shift relative to α-iron, QS — quadrupole splittingof the doublet, ∆ — quadrupole shift of the magnetically split spectrum, Bhf — hyper-fine magnetic field, Γ — half width at half maximum of spectral lines, C1 : C2 : C3 —ratio of line amplitudes in sextets; uncertainty of the parameters are given in parenthesesfor the last significant numbers.δ [mm/s] QS [mm/s] ∆ [mm/s] Bhf [T] Γ [mm/s] C1 : C2 : C3 χ2 RemarksRT 0.35(1) 0.28(1) — — 0.23(1) — 1.01 doubletLN0.32(1) 0.29(1) — — 0.25(2) —0.98doublet0.37(3) — −0.03(2) 40.38(28)0.35(5) 2.5 : 2 :1sextet 10.42(1) — −0.02(1) 45.49(19) sextet 20.46(1) — 0.02(1) 49.18(10) sextet 34. ConclusionsOn the basis of the performed X-ray diffractionstudies it may be stated that Aurivillius compoundBi9Ti3Fe5O27 prepared by sintering is a single-phasedmaterial. However, Mössbauer spectroscopy revealedthe existing of the second phase and distribution of hy-perfine magnetic field.The second phase, which has practically the same hy-perfine interaction parameters as the major one, mayoriginate from the isolated iron-oxygen octahedra ofthe almost the same symmetry as the main Bi9Ti3Fe5O27compound. Three sextets, giving some kind of distri-bution, may be caused by some non-collinear magneticstructure.The main result of this work is the determination ofthe value of hyperfine magnetic field induction which wasdone firstly, in accordance with the knowledge of the au-thors.AcknowledgementInvestigations were partially financed by Polish Min-istry of Education and Science from the funds for sciencein 2008–2011 as a research project N N507 446934.References[1] D.I. Khomskii, J. Magn. Magn. Mater. 306, 1 (2006).[2] C. Ederer, N.A. Spaldin, Nat. Mater. 3, 849 (2004).[3] N.A. Lomanova, M.I. Morozov, V.L. Ugolkov,V.V. Gusarov, Inorg. Mater. 42, 189 (2006).[4] E. Jartych, M. Mazurek, A. Lisińska-Czekaj,D. Czekaj. J. Magn. Magn. Mater. 322, 51 (2010).[5] M. Mazurek, E. Jartych, A. Lisińska-Czekaj,D. Czekaj, D. Oleszak, J. Non-Cryst. Solids 356, 1994(2010).[6] A. Srinivas, S.V. Suryanarayana, G.S. Kumar,M.M. Kumar, J. Phys. Condens. Matter 11, 3335(1999).[7] S.A. Kizhaev, G.D. Sultanov, F.A. Mirishli, Fiz.Tverd. Tela 15, 297 (1973), in Russian; Sov. Phys.Solid State 15, 214 (1973), English Translation.[8] G.D. Sultanov, R.M. Mirzababayev, N.G. Guseinov,R.A. Mamedov, Fiz. Tverd. Tela 20, 1888 (1978), inRussian; Sov. Phys. Solid State 20, 1091 (1978), En-glish Translation.[9] A. Srinivas, D.-W. Kim, K.S. Hong, S.V. Surya-narayana, Mater. Res. Bull. 39, 55 (2004).

Structure and hyperfine interactions in Aurivillius Bi9Ti 3Fe5O27 conventionally sintered compound

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Structure and hyperfine interactions in Aurivillius Bi9Ti 3Fe5O27 conventionally sintered compound

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