7 was reached this was aged for 1 hr and then it was filtered and washed with a copious amount of water it was dried at 80 u00b0 c overnight and then calcined in air at 600 u00b0 c for 1 hr 12 2 g of lanthanum hydrate nitrate la no 3 3 xh 2 o in 20 ml of demineralised water acidified with nitric acid hno 3 were added to 10 1 g of niobium chloride nbcl 5 in 20 ml of demineralised water acidified with nitric acid hno 3 while stirring after that a solution of ammonium hydroxide was added until ph 7 was reached this was aged for 1 hr and then it was filtered and washed with a copious amount of water it was dried at 80 u00b0 c overnight and then calcined in air at 600 u00b0 c for 1 hr 5 g of aluminum chloride alcl 3 in 25 ml of demineralised water acidified with nitric acid hno 3 were added to 13 4 g of tantalum chloride tacl 5 in 25 ml of demineralised water acidified with nitric acid hno 3 to while stirring after that a solution of ammonium hydroxide was added until ph 7 was reached this was aged for 1 hr and then it was filtered and washed with a copious.