Bernier, J.C.

Bonnenfant, A.

Friedt, J.M.

Laville, H.

J.M. Friedt

A. Bonnenfant

H. Laville

J.C. Bernier

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57Fe HYPERFINE INTERACTION MEASUREMENTS IN AN IRON CONCENTRATED OXIDE GLASS Fe203(30)BaO(45)B2O3(25)

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57Fe HYPERFINE INTERACTIONMEASUREMENTS IN AN IRON CONCENTRATEDOXIDE GLASS Fe203(30)BaO(45)B2O3(25)J.M. Friedt, A. Bonnenfant, H. Laville, J.C. BernierTo cite this version:J.M. Friedt, A. Bonnenfant, H. Laville, J.C. Bernier. 57Fe HYPERFINE IN-TERACTION MEASUREMENTS IN AN IRON CONCENTRATED OXIDE GLASSFe203(30)BaO(45)B2O3(25). International Conference on Mossbauer Spectroscopy, 1979, Por-torez, 41 (C1), pp.C1-273-C1-274, 1980, <10.1051/jphyscol:1980195>. <jpa-00219788>HAL Id: jpa-00219788https://hal.archives-ouvertes.fr/jpa-00219788Submitted on 1 Jan 1980HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.L’archive ouverte pluridisciplinaire HAL, estdestine´e au de´poˆt et a` la diffusion de documentsscientifiques de niveau recherche, publie´s ou non,e´manant des e´tablissements d’enseignement et derecherche franc¸ais ou e´trangers, des laboratoirespublics ou prive´s.JOURNAL DE PHYSIQUE Colloquq C1, suppl6ment au n O 1 ,  Tome 41, janvier 1980, page C1-273 57~e HYPERFINE INTERACTION MEASUREMENTS IN AN IRON CON$ENTRATED OXIDE GLASS ~ e ~ 0 ~  (30)~a0(45) ~0~(25) b.M, Friedt, A.Bonnenfant, H. Laville and J.C. Bernier Labomtoire de Chide  Nucllaire, Centre de Recharches ~uele'aires,  STRASBOURG e t  D6partement de Sciences des Mat6riaux, BNSCS, SSTRASBOURG (Francs). We have investigated the p,reparative, struc- tural, electronic and magnetic properties of an iron concentrated oxide glass Fe 0 (30) 2 3 BaO(45) B203(25) and.of its recrystallisation pro- duct$. The present report concentrates on the mea- surement of the " ~ e  hyperfine interaction parame- ters in the amorphous phase (between 1.5 and a- bout 680 K) and on their interpretation in terms of distributions of these parameters.. The glass is prepared by a splat cooling technique. Baryum borate and Fe203 are heated in nominal proportions at I050 K for 6 hours, melted in a special crucible and quenched between steel rollers /I/. Thin ribbons are thus obtained. Their amorphous nature is characterized from X-ray dif- fraction and electron microscopy. Crystallisation involving the formation of successive phase is observed from DTA, X-ray diffraction and ~6ssbauer spectroscopy above - 700 K. In the temperature range from 39 to 680 K, the M6ssbauer spectra present a symmetric quadru- pole doublet, with resonance widths (FWHM) estima- ted from a sum of two Lorentzians fit of 0.78 and 0.53 mm/s at these respective temperatures. The doublet develops into a pure magnetic hyperfine spectrum between 40 and 30 K ; in this temperature range one observes unresolved spectra, comporting apparently a superposition of the high temperature doublet and of a magnetic component with increa- sing relative intensity. The magnetic hyperfine spectra are fully symmetric around their center of gravity below 29 K, in apparent contradiction with the high temperature quadrupole interaction. However, the linewidths of the spectral components are unequal ; sum of torentzian fits provides FWHM of 1.50, 1.08 and 0.75 m / s  for the outer, middle and inner components respectively at 4.2 K. The relative intensities of these components, extrapo- lated to zero thickness absorbers, differ from the theoretical ratio of 3 : 2 : 1 whereas the relatiye component areas fit satisfactorily with these va- lues. Several models have been applied to analyze these results in terms of distributions of hyper- fine interactions. A RHSP model predicts a disrri- bution of quadrupole splitting 2 2 (A = 1/2 e qQ(1 + 9 /3)1/2) given by /2/ : 4 2 P(A) = A exp - (a2/2a ) This model has been tested to fit the qua- drupole data. However, better fits are obtained with a pure Gaussian distribution of A around an average value A and a FWHM for the distribution WG as sumarized in Table 1 (fig. 1). Of course, the respective distributions of VZZ and 9 cannot be separated out. There is no indication for any correlation between isomer shift and the distri- bution in A. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1980195c1-$74 JOURNAL D~ PHYSIQUE Table 1 Fig; 1 : '"~e Msssbauer spectra at 300 and 4.2 K .  The quadrupole spectrum is fitted with a gaussian distribution of A. The solid line in the 4.2 K spectrum is a simula- tion based on the approximations discus- sed in the text and with spectral compo- nent intensities constrained to relative values of 3 : 2 : 1 .  The symmetry of the low temperature magnetic spectra point out that the distribution of A is symmetric about zero and is around both 4 A and - Ao. The primary features of the magnetic spectra ate reproduced by the following model calculation (fig. 1): a) The electric field gradient is as- sumed of axial symmetry (17 = o) , b) The disttibu- tidd of VZZ is constrained to the Gaussian distri- bution determined for A at 42 K around positive and negative Ao, C) A spherical orientation bet- ween V Z Z  and hyperfine field axis and d) An addiA tional Gaussian distribution of hyperfine field ' 45 1.05 1.00 0.363 Temperature (K); 673 ! 300 50 kOe. This suggests exchange interactions of random character and dominating the anisotropy ibtetactions, which is a reasonable conclusion for an S state ion itl an amorphous oxide. Thick- ness and orientational effects have been shown experimentally to be negligible in the magnetic A. (mm/s) WG (m/s) ijIS(mmI~) vs Fe - 300K spectra. The deviation between calculated and experimental data in Fig.1 is thought to arise from the debatable assumptions of zero asymmetry parameter and spherical distribution of 0.  The nature of ordered structure, of magne- tic transition and of recrystallisation behavior will be discussed elsewhere. Structural model calculations interpreting the quadrupole interac- tion distribution are known to be difficult in a random network model appropriate for such oxide glasses, where every information indicates that iron participates in the structure as a network former. It will be worthwhile to check for the validity of the observed distribution in other comparable systems. 0.884 1 1 . 0 0  1 References 0.79 -0.015 / I /  Laville, H. and Bernier, J.C., J. Material Science, to be published. 0.94 0.262 / 2 /  Czjzek, G., private communication. around an average value of 433 kOe and a FWHM of 

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57Fe HYPERFINE INTERACTION MEASUREMENTS IN AN IRON CONCENTRATED OXIDE GLASS Fe203(30)BaO(45)B2O3(25)

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