Comparative study for mutual separation characteristics of binary mixed oxides Y2O3–Ln2O3 (Ln=Dy, Ho and Er) and Ho2O3–Er2O3 using stepwise chlorination–chemical vapor transport reaction mediated by vapor complexes KLnCl4

Comparative study of the mutual separation characteristics for binary mixed oxides Er2O3–Ln2O3 (Ln=Sc, Y, La, Nd, Sm, Gd and Ho) mediated by vapor complexes KLnCl4

“…The SC-CVT reaction was carried out in a cylindrical alumina reactor tube, 25 mm inner diameter and 1000 mm length, with a given temperature gradient as described in previous paper [10][11][12][15][16][17][18][19][20][21][22]. Let T denote the highest temperature in the tube reactor, where the raw materials were placed.…”

“…The raw material was chlorinated by dry Cl 2 gas with a flow rate of 20 cm 3 min −1 at T = 800 K for 2 h. The Cl 2 gas was replaced by a dry Ar-Cl 2 mixed gas with the flow rates of 30 and 10 cm 3 min −1 , respectively, within the temperature range of T = 800-1300 K. Then, the rare earth chlorides reacted with KCl to form the vapor complexes KLnCl 4 , which were transported chemically along the temperature gradient in the tube reactor at T = 1300 K for 6 h with the Ar-Cl 2 carrier gas. At the end of each run, the amounts of the rare earth chloride produced were determined from the peak intensity of the characteristic bands: 337.271 nm for Er 3+ [22], in the form of deposition profiles for the rare earth chlorides transported versus fraction numbers (FN) of the receptors, taking KCl as complex former and Argon gas as carried gas in the given temperature gradient for 6 h.…”

“…Mutual separation characteristics of rare earth elements by a dry process so called chemical vapor transport reaction have been investigated intensively from several aspects, such as different vapor complexes KLnCl 4 [2,3,10,13,14,[20][21][22] or LnAl n Cl 3n+3 [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], different raw materials like as rare earth chloride mixtures, oxide mixtures, concentrates of ore and the scraps containing of rare earth elements. Moreover, the temperature gradients [4,22] and reaction steps for separation has been investigated too, that is the conventional chemical vapor transport (CVT) reaction [1][2][3][4][5][6][7][8][9][10][12][13][14] or stepwise selective chlorination-chemical vapor transport (SC-CVT) reaction [11,[15][16][17][18][19]…”

“…Moreover, the temperature gradients [4,22] and reaction steps for separation has been investigated too, that is the conventional chemical vapor transport (CVT) reaction [1][2][3][4][5][6][7][8][9][10][12][13][14] or stepwise selective chlorination-chemical vapor transport (SC-CVT) reaction [11,[15][16][17][18][19][20][21][22]. More efficient separation has been observed for oxide mixtures than for chloride mixtures [10,[12][13][14] and using SC-CVT than using CVT reaction [11,15,17,18], and a further improved separation efficiency and total transport yields realized mediated by KCl or KCl-AlCl 3 as complex former instead of only by AlCl 3 as complex former.…”

“…More efficient separation has been observed for oxide mixtures than for chloride mixtures [10,[12][13][14] and using SC-CVT than using CVT reaction [11,15,17,18], and a further improved separation efficiency and total transport yields realized mediated by KCl or KCl-AlCl 3 as complex former instead of only by AlCl 3 as complex former. Furthermore, the characteristics of CVT or SC-CVT have been discussed from the nature of the rare earth elements such as the ionic structure, ionic radius and the electronic configuration by investigating the mixed oxides which the rare earth elements located in different period of the periodic table [13,14,18,[20][21][22].…”