Structural phase transitions in sodium-potassium niobate solid solutions by neutron powder diffraction

The structures of (Na,K)NbO₃ solid solutions have been determined by using the neutron powder-profile refinement technique: phases K and L at room temperature, and G and F at higher temperatures. In each case approximate values have been found for position parameters and temperature factors. The structural models proposed by Ahtee & Glazer [Acta Cryst. (1976), A32, 434-446] based on the lattice parameters and intensities of difference reflexions have been found to be substantially correct. Indications of vibrational modes have been found in the sequential phase transitions of Na_0.90K_0.10NbO₃.