Abstract: This invention relates a non-sintered green sheet or tape comprising a corrugated surface having alternating crests and troughs arranged along both a first direction of the surface and a second direction of the surface, the second direction forming an angle of between 60° to 120° to the first direction, wherein the corrugation periods and/or corrugation amplitudes in the first direction differ from those in the second direction. The invention enables preparation of a reliable, large-sized ceramic sheet material, e.g. as a ceramic electrolyte layer for use in solid oxide cells, as a ceramic sheet for filter or membrane applications, or as sintering substrate or setter. In addition, sintered ceramic sheets and electrolytes, methods of preparation, and solid oxide cells (SOCs) making use of the non-sintered green sheet or tape are described.