in hydrogenchloride byproducts: CO2; Zr(CO3)2 dissolved in concd. HCl, refluxed for 1 h; cooled, filtered, washed with cold concd. HCl, recrystd. from aq. HCl, air dried;

N2 in neat (no solvent) at 400°C for 5 d;

in water T=20°C; pH=9; 6 h;

T=90°C; pH=8.6; 20 h;

ammonia pH=Ca. 9 - 10;

ammonium hydroxide in water pH 10.05; washing (H2O), drying (383 K, 24 h), calcination;

ammonium hydroxide in water prepd. by sol-gel method, Zr compd. dissolved in H2O, pH adjusted with aq. NH3 soln. to 9.0 (added dropwise), soln. kept at 60°C for 6 h; gel dried at 120°C overnight then calcined in air at 750°Cfor 4 h, cooled slowly to room temp., checked by XRD;

in water drying (100°C);