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Strontium substituted lanthanum manganites La1–xSrxMnO3 (x=0, 0.1, 0.16, 0.2 and 0.3) have been prepared by a solution combustion process using lanthanum nitrate, strontium nitrate and manganese nitrate as oxidizers and oxalyl dihydrazide as fuel at 300 °C in a pre-heated muffle furnace. As-formed lanthanum manganites are X-ray crystalline showing cubic symmetry. The cubic LaMnO3 with 36% Mn4+ changes to a rhombohedral phase (Mn4+=28%) on calcination at 1000 °C. The surface area and average agglomerated particle size of the as-formed manganites are in the range 12–19 m2 g–1 and 5.4–8.0 µm, respectively. Sintering, thermal expansion and dc electrical conductivity measurements of La(Sr)MnO3 have been carried out. Strontium substituted lanthanum manganites achieve >80% theoretical density after sintering at 1350 °C for 4 h and the percentage theoretical density decreases with increasing strontium content. The thermal expansion coefficient of La(Sr)MnO3 increases with increasing Sr2+ content and La0.84Sr0.16MnO3 shows a highest conductivity value of 202 S cm–1 at 900 °C in air.

Amorphous silver nanoparticles of ca. 20 nm size have been prepared by the sonochemical reduction of an aqueous silver nitrate solution in an atmosphere of argon-hydrogen. The silver nanoparticles have been characterized by TEM, X-ray diffraction, absorption spectroscopy, differential scanning calorimetry and EPR spectroscopy. The mechanism of the sonochemical reduction has been discussed, and occurs through the generation of hydrogen radicals during the sonication process.