Seeded growth from flux and neutron study of La1-xBaxMnO3 (0.2 < x < 0.5) single crystals

The flux technique for growing large crystals of La1-xBax MnO3(0.2 < x < 0.5) with a seed is discussed. Based on up to 40 wt% solubility of the solute, good rheological properties of corresponding flux melts, and desirable Ba substitution, the 25-40 mol% B2O3/45-60 mol% BaO/15-30 mol% BaF2 range of solvents has been selected to grow crystals up to 1.5 cm(3) in volume. The best crystals have been grown under constant or a very slow increase of temperature in the interval 950-1250 degrees C. Crystals with rocking curves of similar to 0.3 degrees FWHM have been obtained. Layer-by-layer X-ray fluorescent analysis has confirmed a high homogeneity of Ba distribution in volume. Neutron triple-axis measurements have been done to study the spin dynamics of the La0.68Ba0.32MnO3 crystal. Resistivity and AC-susceptibility results show that the peak occurs at a temperature T-p well above T-c (= 336 K). The data support the assumption that charge ordering exists to pin carriers. (C) 2000 Elsevier Science B.V. All rights reserved.