materials is mixed in equimolar quantities with approximately 30 strength nitric acid is heated until it is gently boiling and is reacted to form nitrates the following reaction equation applies 0 210 mol caco 3 0 105 mol srco 3 0 630 mol mgo 0 0275 mol eu 2 o 3 1 100 mol ga 2 o 3 8 6 mol hno 3 u2192 0 210 mol ca 2 0 105 mol sr 2 0 630 mol mg 2 0 055 mol eu 3 2 200 mol ga 3 8 6 mol no 3 4 3 mol h 2 o 0 315 mol co 2 u2191 a white suspension of precipitated nitrates is formed this suspension is evaporated until it reaches a highly viscous state the nitrate suspension obtained is transferred into a quartz boat and is dried in a stream of nitrogen at 300 u00b0 c the dried nitrate mixture is milled in a mortar mill for 20 minutes and is then pyrolyzed at 600 u00b0 c for four hours under nitrogen in accordance with the following reaction equation 0 210 mol ca no 3 2 0 105 mol sr no 3 2 0 630 mol mg no 3 2 0 055 mol eu no 3 3 2 200 mol ga no 3 3 u2192 1 mol 0 210 cao u00b7 0 105 sro u00b7 0 630 mgo u00b7 0 055 eu 2 o 3 u00b7 1 100ga 2 o 3 8 6mol no 2 2 15 mol o 2 the oxide mixture which is produced is introduced into a quartz boat and is heated to 900 u00b0 c in a tubular furnace under inert gas argon after the reaction temperature has.