Structure cristallinea`295 K de la phase ferroelectrique Li 0,02Na 0,98NbO 3

Abstract

The structural determination of the Li 0.02Na 0.98NbO 3 phase has been carried out by single crystal diffraction analysis. The space group of the orthorhombic cell is Pc2 1b ; the cell parameters are a = 5.494, b = 15.461, c = 5.551A˚. The structure derives from the perovskite type; it differs from that of NaNbO 3 only by the sequence of the NbO 6 octahedra tilting and by small atomic displacements allowed by the less symmetric space group. The material is antiferroelectric along the c axis and ferroelectric along b. The direction of the polar axis fits well with previous physical measurements.