III International Conference

PP-II-49SYNTHESIS AND CHARACTERISATION OF DOPED APATITE-TYPELANTHANUM SILICATES WITH A HIGH OXIDE ION CONDUCTIVITY ANDNICKEL/LANTHANUM SILICATES CERMET COMPOSITESKharlamova T.S., Pavlova S.N., Sadykov V.A., Lapina O.B., Khabibulin J.F.,Krieger T.A., Paukshtis E.A., Muzykantov V.S., Chaikina M.V. 1 , Uvarov N.F. 1Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia1 Institute of Solid State Chemistry SB RAS, Novosibirsk, RussiaE-mail: kharlamova@catalysis.ruApatite-type lanthanum silicates have been prepared with a variety of synthesis methodssuch as sol-gel, Pechini and mechanochemical activation followed by sintering. Thesemethods allow to obtain the apatite phase at 900-1200 °C that confirmed by XRD and IR.Synthesized samples have been studied by 29 Si NMR spectroscopy, oxygen isotope exchangemethod and electrical conductivity measurements. Ni/lanthanum silicate cermets have alsobeen prepared with different techniques and investigated as catalysts for methane steamreforming reaction.The scope of the more efficient and environmental friendly power generation ascompared to traditional thermal energy conversion has attracted considerable interest to fuelcells [1]. The development of solid oxide fuel cells (SOFCs) is a perspective direction in thisarea particularly due to the possibility of internal reforming of methane and other fuelsdirectly on the anode. The main problems limiting large scale practical application of SOFCbased on well-known electrolytes - yttria-stabilized zirconia (YSZ) are high operatingtemperatures (~1000 ºC) to ensure required ionic conductivity of YSZ and deactivation of theNi-based anodes as a result of carbon deposition during a direct hydrocarbon conversion[1, 2]. High operating temperatures cause serious problems concerning cell life, and itsreducing to 600–800 °C greatly improves cell reliability. In order to realize the intermediatetemperature SOFCs, ionic conductors which have a high conductivity at lower temperaturesare greatly desired.Recently, rare earth silicates with apatite-type structure have been found to exhibit a goodionic conductivity at intermediate temperatures [3, 4]. However, the conventional solid statemethod of apatite-type lanthanum silicate synthesis requires too high sintering temperatures(~1500 °C) which makes optimization of their synthesis methods highly important.In the present study doped lanthanum silicates with the general formulaLa 10-x A x Si 6-y B y O 26±y (A = Mg, Ca, Sr, Ba; B = Al) have been prepared using different252