Monoclinic SmAl3(BO3)4: synthesis, structural and spectroscopic properties.

Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single-crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit-cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.1013 (4) Šand ß = 103.2240 (10)°. IR and Raman spectroscopic analyses confirmed the monoclinic structure of SmAl3(BO3)4. Under 532.1 nm excitation, luminescence spectra exhibit bands assignable to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2. The similarity of the luminescence spectra of the trigonal and monoclinic polymorphs is explained by the minor role of Sm-O bond distortion and the primary role of rotational distortion of SmO6 octahedra. The smaller covalency of the Sm-O bond in alumoborates is deduced in comparison with galloborates. Calorimetric measurements did not reveal high-temperature structural phase transitions up to a temperature of 720 K.

Thermal, mechanical and biodegradation studies of biofiller based poly-3-hydroxybutyrate biocomposites.

Biodegradable poly-3-hydroxybutyrate [P(3HB)] and natural fillers - clay, peat, and birch wood flour - were used to prepare powdered composites to form pellets and granules. Pellets were produced by cold pressing of polymer and filler powder whereas granules were produced from the powders wetted with ethanol. Characterization techniques like IR spectroscopy, differential scanning calorimetry, X-ray analysis, mechanical analysis and electron microscopy were employed to study the properties of the initial P(3HB) and fillers and the composites. Analysis of the IR spectra of the composites showed the absence of chemical bonds between the components, i.e. the composites were physical mixtures. Young's moduli of the pellets prepared from initial materials varied considerably, and the highest value was obtained for P(3HB) pellets (350 MPa). Studies of biodegradation of composite pellets and granules in the soil for 35 days showed that the residual mass of the pellets had decreased to 68% for P(3HB); 56.4% for P(3HB)/peat; 67% for P(3HB)/wood flour, and 64% for P(3HB)/clay; granules exhibited a similar mass loss, residual mass of the granules of P(3HB) was 68.4%, P(3HB)/peat 46.4%; P(3HB)/wood flour 77%, and P(3HB)/clay 74%. This shows the significance of the material as an eco-friendly composite without sacrificing its mechanical properties.