Newsletter

search results

results of search on CRYSTALLOGRAPHY JOURNALS ONLINE

9 citations found for Batuk, D.

Search for Batuk, D. in the World Directory of Crystallographers

Select bibliographic records for downloading using the checkboxes or select all button

Results 1 to 9, sorted by name:


Download citation
Acta Cryst. (2011). A67, C191
Download citation


Download citation
Download citation

link to html
Using examples of anion-deficient perovskites modulated by periodic crystallographic shear planes, it is demonstrated what kind of local structural information can be obtained using various transmission electron microscopy techniques and how this information can be implemented in the crystal structure refinement against the powder diffraction data.

Download citation
Acta Cryst. (2011). A67, C759-C760
Download citation



Download citation
Acta Cryst. (2014). A70, C1805
Download citation

link to html
Anion deficiency in perovskite-based ferrites containing lone pair cations Pb2+ and Bi3+ can be accommodated by the formation of crystallographic shear (CS) planes. In this contribution, using (Pb1-zSrz)1-xFe1+xO3-y as a model system, we demonstrate that the lone pair cations are not only responsible for the formation of the CS planes, but also control their orientation. The isovalent substitution of Pb2+ by stereochemically inactive Sr2+ highlights the influence of the A-cation electronic structure owing to very close ionic radii of these cations. Employing a combination of transmission electron microscopy and X-ray and neutron powder diffraction, we have systematically investigated the structure evolution of the compounds with changing P/Sr ratio. Two compositional ranges with distinct orientations of the CS planes have been identified in the system: 0.05 [less-than or equal to] z [less-than or equal to] 0.2, where the CS planes orientation systematically varies but stays close to (203)p, and 0.3 [less-than or equal to] z [less-than or equal to] 0.45 with the (101)p CS planes. The incommensurate structure of Pb0.792Sr0.168Fe1.040O2.529, a representative compound of the first range, has been refined from the neutron powder diffraction data (S.G. X2/m([alpha]0[gamma]), X = [1/2,1/2,1/2,1/2], a = 3.9512(1)Å, b = 3.9483(1)Å, c = 3.9165(1)Å, [beta] = 93.268(2)0, q = 0.0879(1)a* + 0.1276(1)c*, RF = 0.023, RP = 0.029, T = 900K). Comparing the CS structures in both compositional ranges, we demonstrate that the orientation of the CS planes is primarily governed by a specific bonding configuration of the lone pair cations with the anions.

Download citation
Acta Cryst. (2014). A70, C227
Download citation

link to html
"It is known that lone pair cations, such as Bi3+ or Pb2+ have a flexible coordination environment that enables them to operate as ""chemical scissors"". Their flexibility reduces the strain that would otherwise be present at the interfaces separating structure modules. We have found that in complex oxides it allows many variants of interfaces, for example crystallographic shear planes or (non)conservative twin planes in structures, enabling the synthesis of new structural families. A common characteristic for all these new compounds is the presence of magnetical frustration. As a first example, this concept allowed to introduce crystallographic shear planes into the perovskite structure, a feat that was considered highly unlikely before. This allowed to generate a new anion deficient perovskite based homologous series AnBnO3n-2 (n = 4 - 6). There is magnetic frustration at the crystallographic shear plane separating the perovskite blocks, due to competing FM and AFM interactions. Also incommensurately modulated perovskites can be obtained, for example (Pb,Bi)1-xFe1+xO3-y. These arise by replacing Bi3+ with Pb2+, which introduces an oxygen deficiency, which is then accommodated by periodically spaced CS planes to reduce the coordination of the A-cations at the interface. The flexible coordination environment of Bi3+ and Pb2+ makes them ideally suited for these A cation positions. Other possibilities were encountered in BiMnFe2O6 and Bi4Fe5O13F. In BiMnFe2O6 the Bi3+ induces the existence of a non-conservative twin plane. The result is a new structure type with hcp structured modules. In Bi4Fe5O13F, the Bi3+-cations separate layers with magnetically frustrated Cairo lattices."

Download citation
Acta Cryst. (2014). A70, C1355
Download citation

link to html
The hematophanite Pb4Fe3O8Cl crystal structure is built of incomplete perovskite Pb4Fe3O8 blocks separated by layers of chlorine atoms [1,2]. Each perovskite block consists of a corner-sharing FeO6 octahedral layer sandwiched between the sheets of the FeO5 square pyramids. We have proven that the thickness of the perovskite block in the hematophanite structure can be extended to two and even three octahedral layers forming homologous series with the general formula An+1BnO3n-1Cl (where hematophanite is the n=3 member). The n=4 members with composition Pb4BiFe4O11Cl and Pb5Fe3TiO11Cl have been synthesized. We were also able to introduce Aurivillius-type PbBiO2 blocks between the hematophanite blocks forming another new homologous series [PbBiO2]An+1BnO3n-1Cl2. Two successive members with n=3 (Pb5BiFe3O10Cl2) and n=4 (Pb5Bi2Fe4O13Cl2 and isostructural Pb5BiFe3TiO13Cl2) have been obtained. The crystal and magnetic structure has been determined and refined in a wide temperature range (1.5 - 700 K) using a combination of neutron powder diffraction (NPD) and electron microscopy techniques (electron diffraction, high angle annular dark field scanning transmission electron microscopy (STEM), atomic resolution STEM-EDX). Using NPD and STEM-EDX data we demonstrated that Ti4+ cations occupy both octahedral and square-pyramidal sites. This makes these structural types rare examples of Ti4+ in five-fold oxygen coordination environment. Pb4BiFe4O11Cl and Pb5Fe3TiO11Cl are antiferromagnetically (AFM) ordered below 600(10) and 450(10) K, respectively. Pb5BiFe3O10Cl2, Pb5Bi2Fe4O13Cl2 and Pb5BiFe3TiO13Cl2 demonstrate signs of local magnetic ordering below ~600, ~600 and ~400 K, respectively. However, the long range magnetic ordering does not set in and the magnetic reflections appear enormously broadened merging into a halo. Presumably, AFM ordering establishes within the perovskite blocks but is disrupted along the c-axis, because of a high thickness of the non-magnetic modules.

Download citation
Acta Cryst A. (2013). A69, s224
Download citation



Follow IUCr Journals
Sign up for e-alerts
Follow IUCr on Twitter
Follow us on facebook
Sign up for RSS feeds