Polymorphism of bismuth sesquioxide. II. Effect of oxide additions on the polymorphism of Bi2O3

Th e effect of sm all oxid e a dd itions on t he p olym orp hism of Bi,03 was studied by m eans of high-temperat ure x-ray diffrn,ctom etr y.Soli d us a nd occasiona l li q uidus temperatu res were approximated, so t hat te ntat ive partial phase diagra ms for 33 ox ide a dd ilions were con stru cted.Only t he m on ocli ni c a nd t he cubic f orms of B i, 0 3 were f ound to be stab le.Oth er phases, frequ en tly reported by p revious in vestigators, s uch as tetrago na l a nd bod ycentered cubic (b .c.c.), were shown to f orm m etastably fr om cooled liquid or eu bie.Au impure b. c.c. ph ase of distin ct but varia~~e e om pos i ~i o n apI;eared in systems of ZnO,.Pb O, 1320 3, AI,03, Ga203, Fe, 0 3, S10 " GeO" 110 " a nd 1 , 0 5, lhe Im p ure b.c.c.p hase 111 t he s ~' stem s with SiO" GeO" and Ti O, m elted congruently abo ut 100 ° C above the m .p. of 13 i,0 3' Th e im p ure b.c.c.p hase was f orm ed m etastably in s. vstems w it h R.b20, N iO, MnO, C d O, V, 0 5, an d Nb, 0 5; t he cond itions of fo rmation we re dependent on COHlposit ion, preparation, and heatin g sc hed ules.The impure b.c.c.p hases, bolh stabl e and metastable, had sm a ll er uni t cell dim ensions l han thal of pure Bi,0 3'