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Substitutions in vanadate garnets
Mat. Res. Bull. Vol. I0, pp. 51-56, 1975. in the United States.
P e r g a m o n P r e s s , Inc.
Printed
SUBSTITUTIONS IN VANADATE GARNETS R. R. Neurgaonkar and F. A. Hummel Material Sciences Department The Pennsylvania State University U n i v e r s i t y Park, Pennsylvania 16802 (Received July 3, 1974 and in final form November 6, 1974; Refereed) ABSTRACT Following the original s y n t h e s i s of Durif of NaCa2 Cu2V3012 and l a t e r synthesis by B a y e r of NaCa2M++V3012 and Ca3LLM++V3012 , where M was Mg, Co, Ni, Cu or Zn, forty-one variations were prepared as phase-pure garnets. The general formulae of the g a r n e t s attempted were [A2++B +] M2++V3012 (Type I) and AM3:+[B+M++]V3012 (Type II), where A ++ = Mg, Sr, Pb, Cd or Ba, = Mg, Co, NL, C u o r Z n a n d B + = LL, Ag, K o r R b . Introduction and L i t e r a t u r e Survey The f i r s t report of the complete substitution of V 5+ in the t e t r a h e d r a l position in garnet (NaCa2Cu2V3012) was by DurLf (1) in 1958. Geller and cow o r k e r s (2-5) made substitutions of V 5+ in the t e t r a h e d r a l position in connection with studies of f e r r i m a g n e t i c garnets. Bayer (6) reported a s e r i e s of garnets, based on D u r i f ' s original synthesis, of the type NaCa2M2V3012 and Ca3LiMV3012. He showed that M could be Mg ++, Co ++, NL++, Cu ++ and Zn ++ and that s y n t h e s i s was e a s i l y achieved at 700-725°C for 50 hours. Subsequently, Schwartz and Schmidt (7) made s i m i l a r a r s e n a t e analogues and other types such as Na3Cr2As3012 and Na3A12LL3F12. Ito (8) also synthesized a r s e n a t e garnets. Hrichova (9) made Mn3Cu2SiV2012 in air, and Mn3LiCuV3012 and Mn3LiCoV3012 in argon at 650-750°C. White and Keramidas (10) studied the Raman s p e c t r a of Y3Fe2Fe3012, Ca2NaZn2V3012 , and Ca2NaMg2V3012. Ronniger and Mill (11) made a substantial s e r i e s of r a r e earth vanadate garnets of the type (LnNa2)Mg2V2012. When Co ++, Ni ++, Zn ++, and Mn2+ were substituted for Mg ++, only BL~+ was successful in the eight fold coordinated position. Lipin and Nozik (12) made neutron diffraction studies of Ca2NaNi2V3012 and Ca2NaCu2V3012. Blanzat and Pannel (13) studied luminescence of Eu 3+ in (Ca2_2xNal+xEUx)Mg2V3012. Ronniger and Mill (14) studied g a r n e t s of the type 0.5(MM')4.5V3012, where M = Pb, Ca, and M' = Mg, Co, Ni, Zn, Mn 51
52
SUBSTITUTIONS IN VANADATE GARNETS
Vol. 10, No. 1
and Cd and found that vacancies developed mostly in the 6 -coordinated position, s o m e t i m e s in the 8-coordinated position, but not in the t e t r a h e d r a l position. Cd ++ was found to enter the t e t r a h e d r a l position in these garnets. Kasper (15) showed that Co ++ and Zn ++ would e n t e r the t e t r a h e d r a l position in Ca3Te2Zn3012, Ca3Te2Co2ZnO12, Cd3Te2Zn3012 and Cd2Te2CoZn2012. Ronniger and Mill (16) prepared twenty-nine garnets of the type (A+B22+)M22+V3012 where A + = Cu, Na, Ag, K, and Th B = Ca, Sr, Pb; and M = Ni, Co, Cu, Mg, Zn, Mn, and Cd. Geller (17) and Hrtchova (18) have made the most recent c o m p r e h e n s i v e reviews of the crystal c h e m i s t r y of the garnet structure. E x p e r i m e n t a l Procedure The compounds were synthesized by solid state reactions, using analytical grade chemicals. Well mixed batches were calcined at 600°C for about a day and after r e - m i x i n g they were reheated at 700-950°C for another 24 hours. Compositions containing lead were heated in sealed Pt capsules. X - r a y data were obtained with a Norelco d i f f r a c t o m e t e r with n i c k e l - f i l t e r e d CuK(~ radiation and a scanning speed of l ° 2 0 / m t n . Lattice p a r a m e t e r s were m e a sured accurately by scanning at 1/4°20/min. and calibrating with a silicon internal standard. Results and Discussion Substitution of Divalent ions for Ca ++ Table 1 s u m m a r i z e s the synthesis conditions, phase analyses and lattice p a r a m e t e r s of the garnets which were prepared, all of which had a pale c r e a m or yellow color. Complete r e p l a c e m e n t of Ca ++ by Sr ++ and Pb ++ was possible only in Ca2NaMg2V3012 (Type I). For the s e r i e s Cdl. 5Ca0. 5, Ca, St, Pb, the cell edge i n c r e a s e d linearly with i n c r e a s e in ionic radius. All other substitutions were partial. The solubility of Sr ++ and Pb ++ in Ca3LiMgV3012 (Type II) was only 0.5 mole. 1.5 moles of Cd ++ and 0.3 mole of Ba ++ could be substituted for Ca ++ in both compositions. The complete substitution of Cd ++ for Ca ++ is TABLE 1 well known in some Substitution of Mg ++, Sr ++, Pb ++, Cd ++, and Ba ++ silicate and many in Ca2NaMg2V3012 and Ca3LLMgV3012. g e r m a n a t e garnets, but Bayer (3) found Temp. Time Cell Edge that it was not posComposition °C hrs. ,~ sible in his vanadate garnets, nor was it 24 12.455 Ca2NaMg2V3012 750 pessLble in the p r e " 12.650 Sr2NaMg2V3012 950 sent study. 8 12. 755 Pb 2 NaMg2V 3012 800 SubstitutLon of Co ++. 24 12. 385 Cdl.5Ca0. 5NalVIg2V3O12 ,, 24 12.415 Ni ++, Cu ++ and Zn +~Ca3LLMgV 3 O12 750 f o r lVig++ " 12.381 Ca 2 MgLLMgV3012 ,, " 12. 432 Ca2.5Sr0.5 LLlVlgV3012 900 As shown in 8 12. 446 Ca2.5Pb0.5LiMgV3012 800 Table 2, one mole of 24 12. 353 Cal. 5Cdl. 5LLlVIgV3012 800 Mg++ can be replaced
Vol. 10, No. 1
SUBSTITUTIONS IN VANADATE GARNETS
53
TABLE 2 Substitution of Co ++, Ni ++, Cu ++ and Zn ++ f o r Mg ++ in Sr, lab and Cd G a r n e t s . Type I No.
Composition
Cell
Temp. °C
Time hrs.
Green Yellow Grey P a l e Yellow Dark Green D a r k Yellow Dark Grey laale Yellow Green Yellow Grey P a l e Yellow Dark Green ------Dark Green Yellow Grey Yellow Green Yellow Grey Yellow
1 2 3 4 5 6 7 8 9 10 11 12 13
Sr2 NaMgCoV3012 Sr2 NaMgNiV3 O12 Sr2 NaMgCuV3 O12 S r 2 NaMgZnV 3 O12 SrCaNaCo2V3 O12 S r C a N a N i 2 V~O1 2 S r C a N a C u 2V"3 "O12 SrCaNaZn2V3012 Pb2NaMgCoV 3 O12 Pb2 NaMgNiV3 O12 lab 2NaMgCuV 3 O12 Pb2NaMgZnV 3 O12 PbCaNaCo2V 3 O12
950 " " " 900 ",, " 800 " " " "
24 " " " " " " " 8 " " " "
14 15 16 17 18 19 20 21 22 23 24
labCaNaNi2V3 O12 labCaNaCu2V3 O12 labCaNaZn2V3012 Cdl. 5Ca0.5NaCo2V3012 C d l . 5Ca0.5NaNt2V3012 C d l . 5Ca0.5NaCu2V3012 C d l . 5Ca0. 5NaZn2V3012 Cd I 5Cal 5LiCoV3012 Cdll 5Cali 5LiNiV3 O12 Cd I. 5Ca I. 5LiCuV3012 C d l . 5Cal. 5LiZnV3012
" " " 750 " " " " " " "
" " " 24 " " " " " " "
Color
Ea~eJ
12 648 12 589 12 623 12 655 12 549 12 493 12 526 12 561 12 734 12 691 12 716 12. 740 12.641 12 592 12 632 12 659 12 375 12 32 12 371 12 391 12 352 12 295 12 347 12 354
by Co ++, Ni ++, Cu ++, and Zn ++ in Sr2NaMg2V3012 o r lab2NaMg2V3012. Att e m p t s to r e p l a c e all of the Mg ++ by these ions r e s u l t e d in a m i x t u r e of g a r n e t and the c o r r e s p o n d i n g o r t h o v a n a d a t e . If half of the Sr ++ o r lab ++ was r e placed by Ca ++ ( c o m p o s i t i o n s 5-8 and 13-16), t h e n all the Mg ++ could be r e p l a c e d by Co, Ni, Cu, or Zn, r e s p e c t i v e l y . In the c a s e of the c o m p o u n d s C d l . 5Ca0.5NaMg2V3 O12 (Type I) and Cdl. 5 C a l . 5LiMgV3OI2 (Type If) all of the Mg ++ could be r e p l a c e d by the t r a n s i t i o n m e t a l ions ( c o m p o s i t i o n s 17-24). On the b a s i s of t h e s e data, it s e e m s that the a m o u n t of t r a n s i t i o n m e t a l which c a n be s u b s t i t u t e d in the o c t a h e d r a l s i t e is v e r y d e p e n d e n t on the p r e s e n c e of Ca (or Ca and Cd) in the d o d e c a h e d r a l s i t e s . L a r g e r ions (Sr ++ o r lab ++) d e c r e a s e the solubility of Co ++, Ni ++, Cu ++, and Zn ++ in the o c t a h e d r a l sites. S u b s t i t u t i o n of Monovalent Ions f o r Na The r e s u l t s a r e shown in T a b l e 3.
In the c o m p o s i t i o n Ca2LiMg2V3012 ,
54
SUBSTITUTIONS IN VANADATE GARNETS
Vol. 10, No. 1
TABLE 3 Substitution of Li +, Ag +, K +, Rb + in Ca2NaMg2V3012. No. 1 2 3 4 5 6 7 8 9 10
Composition Ca2NaMg2V3012 Ca2 LiMg2V3012 Ca2AgMg2V3012 Ca2AgCo2V3012 Ca2AgNi2V3012 Ca2AgZn2V3012 Ca2 KMg2V3012 Ca2 KCo2V3012 Ca2 KNi2V3012 Ca2 KZn2V3012
T e°mCp .
Thirms .e
Phases
Color
750 " 800 " " " 750 " " "
24 " " " " " " " " "
Garnet " " " " " " " " "
Cream
Dark Green Yellow Cream Pale Yellow Dark Green Yellow Cream
Cell Edge
12 12 12 12 12 12 12 12 12 12
455 381 485 486 430 484 495 493 441 492
one cannot be s u r e that the l i t h i u m is in the 8 - c o o r d i n a t e d site. It is p o s s i b l e that the f o r m u l a should be w r i t t e n Ca2MgLiMgV3012 (see Table 1, line 6). If Co, N[, Cu, o r Zn was s u b s t i t u t e d for Mg in the f i r s t f o r m u l a , no g a r n e t was formed. A c o m p l e t e s e r i e s of s i l v e r and p o t a s s i u m g a r n e t s can be m a d e with the type f o r m u l a Ca2AgM2++V3012 o r Ca2KM2++V3012, w h e r e M is Mg, Co, NL, o r Zn. (Table 3, 3-6 and 7-10.) If Ca is r e p l a c e d by Sr, Pb, or C d l 5 C a 0 5 , a p h a s e - p u r e g a r n e t is not obtained (see c o m p o s i t i o n s 4-11, Apper~ciix), lq~bidium is not a c c e p t e d e v e n in a Ca 2 o r C d l . 5Ca0.5 g a r n e t ( c o m positions 10 and 11, Appendix). In Type II, Ca3LiMgV3012 , l i t h i u m cannot be r e p l a c e d by Na, Ag, K, o r Rb. Acknowledgment The a u t h o r s a r e g r a t e f u l f o r the f i n a n c i a l a s s i s t a n c e of the F e r r o C o r p o r a t i o n which m a d e this w o r k p o s s i b l e . References 1. A. Durif, Int. Conf. on P h y s i c s of the Solid State and Applications to E l e c t r o n i c s and T e l l e c o m m u n i c a t i o n s , 500-502. B r u s s e l s , B e l g i u m (1958). 2. S. G e l l e r , G. P. E s p i n o s a , H. J. W i l l i a m s , P,. C. S h e r w o o d and E. A. Nesbitt, Appl. Phys. Lett. 3, 60 (1963). 3. S. G e l l e r , G. P. E s p i n o s a , H. J. W i l l i a m s , R. C. Sherwood and E. A. Nesbitt, J. Appl. Phys. 355, 570 (1964). 4. G. P. E s p i n o s a and S. G e l l e r , J. Appl. P h y s . 3..~5, 2551 (1964). 5. S. G e l l e r , G. P. E s p i n o s a , R. C. S h e r w o o d and H. J. W i l l i a m s , J. A p p l P h y s . 3_66, 321 (1965). 6. G e r h a r d B a y e r , J. A m e r . C e r . Soc. 4.88, 600 (1965).
Vol. 10, No. 1
SUBSTITUTIONS IN VANADATE GARNETS
55
7. H. Schwarz and L. S. Schmidt, Inorg. Nucl. Chem. 3, 199 (1967). 8. Jun Ito, Amer. Min. 5_~3, 316 (1958). 9. Renata Hrtchova, J. Amer. Cer. Soc. 5__33, 112 (1970). 10. W. B. White and V. A. Keramidas, J. Amer. Cer. Soc. 54__, 472B (1971). 11. G. Ronninger and B. V. Mill, Kristallografiya 16___, 1035 (1971). 12. Y. V. Lipin and Y. Z. Nozik, Latv. PSR Zinat. Akad. Vestis, Fiz. Tech. Zinat. Ser. 122 (1971). 13. B. Blazat and C. Pannel, C. R. Acad. Sci. Set. B 276, 123 (1973). 14
G. Ronniger and B. V. Mill, Kristallografiya 1_88, 303 (1973).
15. M. Kasper, Mat. Res. Bull. 3, 765 (1968). 16 G. Ronniger and B. V. Mill, Kristallografiya 1._.88, 539 (1973). 17. S. Geller, Zeitschrift fur Krist. 125S, 1 (1967). 18. R. Hrichova, Silikaty 1_~6, 93 (1972).
TABLE 4 Auxiliary Compositions No. 1 2 3
4 5 6
7 8 9
10 11
Composition
Phases
MgCaNaMg 2 !Ba0 30Cal 70] I~Mg2V.~ 012
Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet
LBa130Ca2"
LLMgV3012
Sr2XgMg2~ ~ '-'12 Pb9 AgMg9 V~. call 5 ~O~v~g2V3 O12 Sr2 ~¢Ig2~3 ( ~12
Pb2KMg2V3')12
Cd I 5Ca 0 .~KMg2V3012 Ca2 ~R~bMg2~3 012 Cd~. 5 Cao~ 5 RbMg2V3 O12
U.P. = Unknown Phase
Color + U.P. + + + + + + + +
Ag20 Ag20 Ag~O U.P. U.P. U.P. RbgO Rb~ O
Cream Cream Cream Cream Yellow Yellow Cream Yellow Cream Cream Yellow
P e r g a m o n P r e s s , Inc.
Printed
SUBSTITUTIONS IN VANADATE GARNETS R. R. Neurgaonkar and F. A. Hummel Material Sciences Department The Pennsylvania State University U n i v e r s i t y Park, Pennsylvania 16802 (Received July 3, 1974 and in final form November 6, 1974; Refereed) ABSTRACT Following the original s y n t h e s i s of Durif of NaCa2 Cu2V3012 and l a t e r synthesis by B a y e r of NaCa2M++V3012 and Ca3LLM++V3012 , where M was Mg, Co, Ni, Cu or Zn, forty-one variations were prepared as phase-pure garnets. The general formulae of the g a r n e t s attempted were [A2++B +] M2++V3012 (Type I) and AM3:+[B+M++]V3012 (Type II), where A ++ = Mg, Sr, Pb, Cd or Ba, = Mg, Co, NL, C u o r Z n a n d B + = LL, Ag, K o r R b . Introduction and L i t e r a t u r e Survey The f i r s t report of the complete substitution of V 5+ in the t e t r a h e d r a l position in garnet (NaCa2Cu2V3012) was by DurLf (1) in 1958. Geller and cow o r k e r s (2-5) made substitutions of V 5+ in the t e t r a h e d r a l position in connection with studies of f e r r i m a g n e t i c garnets. Bayer (6) reported a s e r i e s of garnets, based on D u r i f ' s original synthesis, of the type NaCa2M2V3012 and Ca3LiMV3012. He showed that M could be Mg ++, Co ++, NL++, Cu ++ and Zn ++ and that s y n t h e s i s was e a s i l y achieved at 700-725°C for 50 hours. Subsequently, Schwartz and Schmidt (7) made s i m i l a r a r s e n a t e analogues and other types such as Na3Cr2As3012 and Na3A12LL3F12. Ito (8) also synthesized a r s e n a t e garnets. Hrichova (9) made Mn3Cu2SiV2012 in air, and Mn3LiCuV3012 and Mn3LiCoV3012 in argon at 650-750°C. White and Keramidas (10) studied the Raman s p e c t r a of Y3Fe2Fe3012, Ca2NaZn2V3012 , and Ca2NaMg2V3012. Ronniger and Mill (11) made a substantial s e r i e s of r a r e earth vanadate garnets of the type (LnNa2)Mg2V2012. When Co ++, Ni ++, Zn ++, and Mn2+ were substituted for Mg ++, only BL~+ was successful in the eight fold coordinated position. Lipin and Nozik (12) made neutron diffraction studies of Ca2NaNi2V3012 and Ca2NaCu2V3012. Blanzat and Pannel (13) studied luminescence of Eu 3+ in (Ca2_2xNal+xEUx)Mg2V3012. Ronniger and Mill (14) studied g a r n e t s of the type 0.5(MM')4.5V3012, where M = Pb, Ca, and M' = Mg, Co, Ni, Zn, Mn 51
52
SUBSTITUTIONS IN VANADATE GARNETS
Vol. 10, No. 1
and Cd and found that vacancies developed mostly in the 6 -coordinated position, s o m e t i m e s in the 8-coordinated position, but not in the t e t r a h e d r a l position. Cd ++ was found to enter the t e t r a h e d r a l position in these garnets. Kasper (15) showed that Co ++ and Zn ++ would e n t e r the t e t r a h e d r a l position in Ca3Te2Zn3012, Ca3Te2Co2ZnO12, Cd3Te2Zn3012 and Cd2Te2CoZn2012. Ronniger and Mill (16) prepared twenty-nine garnets of the type (A+B22+)M22+V3012 where A + = Cu, Na, Ag, K, and Th B = Ca, Sr, Pb; and M = Ni, Co, Cu, Mg, Zn, Mn, and Cd. Geller (17) and Hrtchova (18) have made the most recent c o m p r e h e n s i v e reviews of the crystal c h e m i s t r y of the garnet structure. E x p e r i m e n t a l Procedure The compounds were synthesized by solid state reactions, using analytical grade chemicals. Well mixed batches were calcined at 600°C for about a day and after r e - m i x i n g they were reheated at 700-950°C for another 24 hours. Compositions containing lead were heated in sealed Pt capsules. X - r a y data were obtained with a Norelco d i f f r a c t o m e t e r with n i c k e l - f i l t e r e d CuK(~ radiation and a scanning speed of l ° 2 0 / m t n . Lattice p a r a m e t e r s were m e a sured accurately by scanning at 1/4°20/min. and calibrating with a silicon internal standard. Results and Discussion Substitution of Divalent ions for Ca ++ Table 1 s u m m a r i z e s the synthesis conditions, phase analyses and lattice p a r a m e t e r s of the garnets which were prepared, all of which had a pale c r e a m or yellow color. Complete r e p l a c e m e n t of Ca ++ by Sr ++ and Pb ++ was possible only in Ca2NaMg2V3012 (Type I). For the s e r i e s Cdl. 5Ca0. 5, Ca, St, Pb, the cell edge i n c r e a s e d linearly with i n c r e a s e in ionic radius. All other substitutions were partial. The solubility of Sr ++ and Pb ++ in Ca3LiMgV3012 (Type II) was only 0.5 mole. 1.5 moles of Cd ++ and 0.3 mole of Ba ++ could be substituted for Ca ++ in both compositions. The complete substitution of Cd ++ for Ca ++ is TABLE 1 well known in some Substitution of Mg ++, Sr ++, Pb ++, Cd ++, and Ba ++ silicate and many in Ca2NaMg2V3012 and Ca3LLMgV3012. g e r m a n a t e garnets, but Bayer (3) found Temp. Time Cell Edge that it was not posComposition °C hrs. ,~ sible in his vanadate garnets, nor was it 24 12.455 Ca2NaMg2V3012 750 pessLble in the p r e " 12.650 Sr2NaMg2V3012 950 sent study. 8 12. 755 Pb 2 NaMg2V 3012 800 SubstitutLon of Co ++. 24 12. 385 Cdl.5Ca0. 5NalVIg2V3O12 ,, 24 12.415 Ni ++, Cu ++ and Zn +~Ca3LLMgV 3 O12 750 f o r lVig++ " 12.381 Ca 2 MgLLMgV3012 ,, " 12. 432 Ca2.5Sr0.5 LLlVlgV3012 900 As shown in 8 12. 446 Ca2.5Pb0.5LiMgV3012 800 Table 2, one mole of 24 12. 353 Cal. 5Cdl. 5LLlVIgV3012 800 Mg++ can be replaced
Vol. 10, No. 1
SUBSTITUTIONS IN VANADATE GARNETS
53
TABLE 2 Substitution of Co ++, Ni ++, Cu ++ and Zn ++ f o r Mg ++ in Sr, lab and Cd G a r n e t s . Type I No.
Composition
Cell
Temp. °C
Time hrs.
Green Yellow Grey P a l e Yellow Dark Green D a r k Yellow Dark Grey laale Yellow Green Yellow Grey P a l e Yellow Dark Green ------Dark Green Yellow Grey Yellow Green Yellow Grey Yellow
1 2 3 4 5 6 7 8 9 10 11 12 13
Sr2 NaMgCoV3012 Sr2 NaMgNiV3 O12 Sr2 NaMgCuV3 O12 S r 2 NaMgZnV 3 O12 SrCaNaCo2V3 O12 S r C a N a N i 2 V~O1 2 S r C a N a C u 2V"3 "O12 SrCaNaZn2V3012 Pb2NaMgCoV 3 O12 Pb2 NaMgNiV3 O12 lab 2NaMgCuV 3 O12 Pb2NaMgZnV 3 O12 PbCaNaCo2V 3 O12
950 " " " 900 ",, " 800 " " " "
24 " " " " " " " 8 " " " "
14 15 16 17 18 19 20 21 22 23 24
labCaNaNi2V3 O12 labCaNaCu2V3 O12 labCaNaZn2V3012 Cdl. 5Ca0.5NaCo2V3012 C d l . 5Ca0.5NaNt2V3012 C d l . 5Ca0.5NaCu2V3012 C d l . 5Ca0. 5NaZn2V3012 Cd I 5Cal 5LiCoV3012 Cdll 5Cali 5LiNiV3 O12 Cd I. 5Ca I. 5LiCuV3012 C d l . 5Cal. 5LiZnV3012
" " " 750 " " " " " " "
" " " 24 " " " " " " "
Color
Ea~eJ
12 648 12 589 12 623 12 655 12 549 12 493 12 526 12 561 12 734 12 691 12 716 12. 740 12.641 12 592 12 632 12 659 12 375 12 32 12 371 12 391 12 352 12 295 12 347 12 354
by Co ++, Ni ++, Cu ++, and Zn ++ in Sr2NaMg2V3012 o r lab2NaMg2V3012. Att e m p t s to r e p l a c e all of the Mg ++ by these ions r e s u l t e d in a m i x t u r e of g a r n e t and the c o r r e s p o n d i n g o r t h o v a n a d a t e . If half of the Sr ++ o r lab ++ was r e placed by Ca ++ ( c o m p o s i t i o n s 5-8 and 13-16), t h e n all the Mg ++ could be r e p l a c e d by Co, Ni, Cu, or Zn, r e s p e c t i v e l y . In the c a s e of the c o m p o u n d s C d l . 5Ca0.5NaMg2V3 O12 (Type I) and Cdl. 5 C a l . 5LiMgV3OI2 (Type If) all of the Mg ++ could be r e p l a c e d by the t r a n s i t i o n m e t a l ions ( c o m p o s i t i o n s 17-24). On the b a s i s of t h e s e data, it s e e m s that the a m o u n t of t r a n s i t i o n m e t a l which c a n be s u b s t i t u t e d in the o c t a h e d r a l s i t e is v e r y d e p e n d e n t on the p r e s e n c e of Ca (or Ca and Cd) in the d o d e c a h e d r a l s i t e s . L a r g e r ions (Sr ++ o r lab ++) d e c r e a s e the solubility of Co ++, Ni ++, Cu ++, and Zn ++ in the o c t a h e d r a l sites. S u b s t i t u t i o n of Monovalent Ions f o r Na The r e s u l t s a r e shown in T a b l e 3.
In the c o m p o s i t i o n Ca2LiMg2V3012 ,
54
SUBSTITUTIONS IN VANADATE GARNETS
Vol. 10, No. 1
TABLE 3 Substitution of Li +, Ag +, K +, Rb + in Ca2NaMg2V3012. No. 1 2 3 4 5 6 7 8 9 10
Composition Ca2NaMg2V3012 Ca2 LiMg2V3012 Ca2AgMg2V3012 Ca2AgCo2V3012 Ca2AgNi2V3012 Ca2AgZn2V3012 Ca2 KMg2V3012 Ca2 KCo2V3012 Ca2 KNi2V3012 Ca2 KZn2V3012
T e°mCp .
Thirms .e
Phases
Color
750 " 800 " " " 750 " " "
24 " " " " " " " " "
Garnet " " " " " " " " "
Cream
Dark Green Yellow Cream Pale Yellow Dark Green Yellow Cream
Cell Edge
12 12 12 12 12 12 12 12 12 12
455 381 485 486 430 484 495 493 441 492
one cannot be s u r e that the l i t h i u m is in the 8 - c o o r d i n a t e d site. It is p o s s i b l e that the f o r m u l a should be w r i t t e n Ca2MgLiMgV3012 (see Table 1, line 6). If Co, N[, Cu, o r Zn was s u b s t i t u t e d for Mg in the f i r s t f o r m u l a , no g a r n e t was formed. A c o m p l e t e s e r i e s of s i l v e r and p o t a s s i u m g a r n e t s can be m a d e with the type f o r m u l a Ca2AgM2++V3012 o r Ca2KM2++V3012, w h e r e M is Mg, Co, NL, o r Zn. (Table 3, 3-6 and 7-10.) If Ca is r e p l a c e d by Sr, Pb, or C d l 5 C a 0 5 , a p h a s e - p u r e g a r n e t is not obtained (see c o m p o s i t i o n s 4-11, Apper~ciix), lq~bidium is not a c c e p t e d e v e n in a Ca 2 o r C d l . 5Ca0.5 g a r n e t ( c o m positions 10 and 11, Appendix). In Type II, Ca3LiMgV3012 , l i t h i u m cannot be r e p l a c e d by Na, Ag, K, o r Rb. Acknowledgment The a u t h o r s a r e g r a t e f u l f o r the f i n a n c i a l a s s i s t a n c e of the F e r r o C o r p o r a t i o n which m a d e this w o r k p o s s i b l e . References 1. A. Durif, Int. Conf. on P h y s i c s of the Solid State and Applications to E l e c t r o n i c s and T e l l e c o m m u n i c a t i o n s , 500-502. B r u s s e l s , B e l g i u m (1958). 2. S. G e l l e r , G. P. E s p i n o s a , H. J. W i l l i a m s , P,. C. S h e r w o o d and E. A. Nesbitt, Appl. Phys. Lett. 3, 60 (1963). 3. S. G e l l e r , G. P. E s p i n o s a , H. J. W i l l i a m s , R. C. Sherwood and E. A. Nesbitt, J. Appl. Phys. 355, 570 (1964). 4. G. P. E s p i n o s a and S. G e l l e r , J. Appl. P h y s . 3..~5, 2551 (1964). 5. S. G e l l e r , G. P. E s p i n o s a , R. C. S h e r w o o d and H. J. W i l l i a m s , J. A p p l P h y s . 3_66, 321 (1965). 6. G e r h a r d B a y e r , J. A m e r . C e r . Soc. 4.88, 600 (1965).
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7. H. Schwarz and L. S. Schmidt, Inorg. Nucl. Chem. 3, 199 (1967). 8. Jun Ito, Amer. Min. 5_~3, 316 (1958). 9. Renata Hrtchova, J. Amer. Cer. Soc. 5__33, 112 (1970). 10. W. B. White and V. A. Keramidas, J. Amer. Cer. Soc. 54__, 472B (1971). 11. G. Ronninger and B. V. Mill, Kristallografiya 16___, 1035 (1971). 12. Y. V. Lipin and Y. Z. Nozik, Latv. PSR Zinat. Akad. Vestis, Fiz. Tech. Zinat. Ser. 122 (1971). 13. B. Blazat and C. Pannel, C. R. Acad. Sci. Set. B 276, 123 (1973). 14
G. Ronniger and B. V. Mill, Kristallografiya 1_88, 303 (1973).
15. M. Kasper, Mat. Res. Bull. 3, 765 (1968). 16 G. Ronniger and B. V. Mill, Kristallografiya 1._.88, 539 (1973). 17. S. Geller, Zeitschrift fur Krist. 125S, 1 (1967). 18. R. Hrichova, Silikaty 1_~6, 93 (1972).
TABLE 4 Auxiliary Compositions No. 1 2 3
4 5 6
7 8 9
10 11
Composition
Phases
MgCaNaMg 2 !Ba0 30Cal 70] I~Mg2V.~ 012
Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet Garnet
LBa130Ca2"
LLMgV3012
Sr2XgMg2~ ~ '-'12 Pb9 AgMg9 V~. call 5 ~O~v~g2V3 O12 Sr2 ~¢Ig2~3 ( ~12
Pb2KMg2V3')12
Cd I 5Ca 0 .~KMg2V3012 Ca2 ~R~bMg2~3 012 Cd~. 5 Cao~ 5 RbMg2V3 O12
U.P. = Unknown Phase
Color + U.P. + + + + + + + +
Ag20 Ag20 Ag~O U.P. U.P. U.P. RbgO Rb~ O
Cream Cream Cream Cream Yellow Yellow Cream Yellow Cream Cream Yellow