“…(VWR International GmbH, Darmstadt, Germany, q: 0.79 g cm -3 ) in PE bottles. The stabilizing effect of this dispersing agent has already been published in the past [6,31]; the amount of dispersing agent was set to 3 wt% with respect to the solid content. Yttrium-stabilized milling balls (YTZ Grinding Media, Nikkato Corporation, Tokyo, Japan) of 0.5, 1, 3, and 10 mm diameter were added and the mixture was dispersed for 24 h in a tumbling mixer (Turbula, Willy A. Bachofen AG, Basel, Swiss).…”