Faculty of Nuclear Sciences and Physical Engineering

Department of Solid State Engineering

V Holešovičkách 2, 180 00 Prague 8, Czech Republic

Structure and Texture Analysis by Neutron Diffraction

Staff: S.Vratislav, M.Dlouhá, J.Marek

PhD students: M.Horký, A.Kláriková, K.Černá

Neutron power and single-crystal neutron diffraction have been developed into an important crystallographic tool in both basic and applied research. Applications to condensed matter cover the range from location of light atoms and cation distributions to magnetic structures and phase transitions. We have investigated some promising materials, e.g. zeolites (types Na-Y,Na,H-Y, kaersutite), ionic conductors (Cs(H,D)SO₄, Rb₃H(SeO₄)₂), hexaferrites (BaFe₁₂O₁₉, BaTi₂Co₂Fe₈O₁₉) and high temperature superconductors (types: YBa₂Cu₃O₇, Bi₂(Sr,Ca)₃Cu₂O_8+g - modulated structure).

Our group cooperates with many laboratories of the Czech Academy of Sciences, and with the Laboratory of Neutron Physics of JINR, Dubna. Recently we began scientific contacts with ILL Grenoble , the Institute of Energy, Kjeller, Norway and with Dept. Inorganic Chemistry of University in Barcelona, Spain.

Experimental equipment: The difractometer KSN-2 is used for powder structure investigations and for the quantitative texture analysis. It is equipped with a single BF₃ detector, and installation of a one dimensional position sensitive detector ORDELA 1250N is planned. The usable 2Q range is 2⁰ ¸ 95⁰ with the d-resolution value of 7.5´ 10^-3 at the minimum. A choice of the wavelength between 0.9¸ 1.6A is achieved by three monochromators (Zn(002), Cu(200) and Cu(111)) and by the continuous change of the take-of-angles. Sample and detector positions are automatically controlled by the DN-505-PC unit. The closed cycle refrigerator system mod. CP-62-ST/1 makes it possible to control sample temperature from 8K to room temperature. The texture goniometer TG-1 is available.

Projects supported by grants:

Vratislav, S.:"The location of active sites, adsorbed molecules and their fragments in the structure of zeolitic catalysts using neutron diffraction, EXAFS and ¹³C MAS NMR methods",GA CR 202-97-0425

Vratislav, S.:"Center for Fundamental and Applied Neutron Research",GA CR 202-97-K038

List of Selected Publications and Conference Contributions:

Dlouhá, M., Vratislav, S., Jirak, Z.: Neutron Diffraction Analysis of BaCuO₂. In: Proceedings of the Fifteenth European Crystallographic Meeting, Dresden, 28 April - 2 May 1994, p.452.

Vratislav, S., Dlouhá, M.: Texture Analysis of Zircaloy-4 Tubes by Neutron Diffraction, Proc. of the Int. Conf. Mathematical Methods of Texture Analysis, Dubna, Russia, 21-24 March 1995, p. 48.

Vratislav, S., Dlouhá, M., Bosáček, V.: A neutron diffraction study of chemisorbed methyl groups in the structure of Y zeolite, Physica B, 241-243, 1998, pp. 400-402.

Dlouhá, M., Vratislav, S., Jirák, Z.: A neutron diffraction study of the Pr3+-xA+xMn3+1-2xMn4+2xO3 (A=K, Na) perovskites, Physica B, 241-243, 1998, pp. 424-426.

Dlouhá, M., Vratislav, S., Natkaniec, I. and Smirnov, L.S.: The Study of Structural Features of Phase Transitions in N(H/D)4SCN (the Monoclinic Phase) by Neutron Scattering, Crystallography Reports, Vol.43, No.2, 1998, pp. 202-210.

Morales, M., Mestres, L., Dlouhá, M., Vratislav, S., Martinez, M.: Crystal structure of the mixed conductors phases, Li La Ti M O(M=Mn,Cr) with x=0.133 and y=0.20, J. Mater. Chem., 1998, 8, pp.2691-2694.