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Single phase MgAl2O4 was made from a one-to-one molar ratio of MgO and Al2O3 powders mixed using ball-milling. Mixtures of MgO and Al2O3 were subsequently treated in planetary ball mill for 30, 60, 90 and 120 minutes in air. The aim of this study was to examine phase composition, microstructure, and densification behavior of sintered specimens. After sintering in dilatometer at 1500°C, the powder was converted to single phase MgAl2O4. The results show that mechanical activation improved the densification behavior of MgAl2O4 sintered specimens, and it reduced the onset temperature for sintering by approx. 100°C. Based on dilatometer data, powders were subsequently densified at 1450°C by hot pressing. Almost аll specimens exhibited full density, while sample activated for 30 minutes showed the fastest densification rate. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172057, and Grant no. III 45007]

The crystal structure of new lanthanum strontium borate glass-ceramics was refined by the Rietveld method. The results showed that La2SrB10O19 has the monoclinic crystal structure, space group C2 (No. 5) with a = 11.1170(6), b = 6.5667(3), c = 9.2363(3) Å, β = 91.481°, V = 674.04(7) Å3, two formula units per unit-cell, and density 3.830 g cm−3. The main building units of the crystal structure are BO4 tetrahedra and BO3 triangles. Clusters composed of [B5O12] form an infinite double layer running perpendicular to the c-axis. Lanthanum atoms, situated in [B5O12]n layers, are coordinated with 10 oxygen atom in a form of LaO10 polyhedra, while Sr atoms, located between [B5O12]n layers, are coordinated with 8 oxygen atoms in a form of SrO8 polyhedra. Microstructural measurements contain both crystallite domain sizes and microstrain calculations obtained by the Warren-Averbach and the simplified integral-breadth methods. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI172004 and Grant no. TR34001]