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Indirect Exchange Interactions in Orthorhombic Lanthanide Aluminates

100%

Petrov D., Angelov B.

Acta Physica Polonica A

2012

vol. 122

issue 4

737-740

Magnetic exchange interactions in orthorhombic lanthanide monoaluminates LnAlO_3, Ln = Sm-Yb have been determined semiempirically within the Anderson model of exchange in insulators. The constants of magnetic exchange have been evaluated assuming indirect exchange between pairs of nearest Ln^{3+}-Ln^{3+} ions via 4f^{n} → 4f^{n-1}5d excitation and ionic polarization. The transfer integrals have been approximated by two-centre overlap integrals between four-term analytical 4f^{n} radial wave functions of Ln^{3+} ions. The results have been compared with the available experimental Néel temperatures in the same compounds. It has been found that in most cases the indirect exchange interactions present substantial contributions to the energy of the antiferromagnetically ordered state in LnAlO_3.

Microstructure of Zirconia-Based Sol-Gel Glasses Studied by SANS

42%

Ryukhtin V., Strunz P., Kopitsa G., Ezdakova K., Gubanova N., Ivanov V., Baranchikov A., Angelov B., Feoktistov A., Pipich V., Levinský P.

Acta Physica Polonica A

2015

vol. 128

issue 4

582-584

Zirconia-based bulk glasses were prepared for the first time by sol-gel method. Such materials are very promising for application as photochromic devices, catalytic systems, chemical sensors, lasers and other nonlinear optics devices. Obtained transparent and semi-transparent materials were studied by small and ultra-small angle neutron scattering (SANS and USANS) methods. As evidenced by SANS, morphology of zirconia glasses is very sensitive to parameters of sol-gel synthesis, e.g. temperature and concentration of reactants. SANS data correlates rather well with surface porosity data. Increasing water concentration in reaction mixtures containing zirconium propylate leads to a significant increase in fractal cluster size, while decrease of the temperature results in an increase of the fractal dimension. The obtained results indicate that parameters of the microstructure and consequently physical properties of zirconia glasses can be effectively controlled by parameters of synthesis.

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2 Acta Physica Polonica A

1 2015

1 2012

2 Angelov B.

1 Baranchikov A.

1 Ezdakova K.

1 Feoktistov A.

1 Gubanova N.

1 Ivanov V.

1 Kopitsa G.

1 Levinský P.

1 Petrov D.

1 Pipich V.

1 Ryukhtin V.

1 Strunz P.

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Indirect Exchange Interactions in Orthorhombic Lanthanide Aluminates

Microstructure of Zirconia-Based Sol-Gel Glasses Studied by SANS