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New ternary antimonides Ti5XSb2 with W5Si3 structure type
Intermetallics 11 (2003) 237–239 www.elsevier.com/locate/intermet
New ternary antimonides Ti5XSb2 with W5Si3 structure type A.Yu. Kozlov*, V.V. Pavlyuk Department of Inorganic Chemistry, Ivan Franko L’viv National University, Kyryla i Mefodiya str. 6, UA-79005 Lviv, Ukraine Received 21 August 2001; received in revised form 28 October 2002; accepted 28 October 2002
Abstract Three new ternary antimonides having W5Si3 structure type were found. These are Ti5AlSb2, Ti5GaSb2 and Ti5InSb2. The crystal structures of Ti5XSb2 (X=Al, Ga, In) were investigated by X-ray powder diffraction. # 2003 Elsevier Science Ltd. All rights reserved. Keywords: A. Intermetallics, miscellaneous; B. Crystal chemistry of intermetallics; B. Crystallography
1. Introduction During the investigation of the phase equilibria in the systems Ti–{Si, Ge}–Sb [1] new ternary compounds with the approximate compositions Ti5SiSb2 and Ti5GeSb2 were observed. The powder X-ray diffractions patterns were indexed on a body-centered tetragonal unit cell (W5Si3 structure type, I4/mcm space group) with the following lattice parameters a=1.0347(4), c=0.5180(6) nm for Ti5SiSb2 and a=1.0398(2), c=0.5231(1) nm for Ti5GeSb2. Other compounds with W5Si3 structure type based on antimony are also known. These are Zr5MxSb3-x (M=Fe, Co, Ni, x 0.5) [2], Hf10MxSb6-x (M=V, Cr, Mn, Fe, Co, Ni, Cu; 0.84 x 41.5 for M=Fe) [3], Ti5Mn0.45Sb2.55 [4], Ti5Cu0.45Sb2.5 [5], M5AlSn2 and M5AlPb2 (M=Ti, Zr, Hf, Nb), [6], Ti5Si1.2-1.6Sn1.8 1.4 [7], Nb5GaSn2 [8], V4SiSb2 [9]. In this study alloys were prepared by variation of the main group element X (=Al, Ga, In, Sn, Pb), yielding three new W5Si3 type ternary compounds: Ti5AlSb2, Ti5GaSb2 and Ti5InSb2.
2. Experimental The samples with the composition Ti:X:Sb=5:1:2 and a total mass of about 2 g were prepared by arc melting of pure metals (the purity of the ingredients was better than 99.99 at.%) in a high-purity argon atmosphere. All * Corresponding author. E-mail address: [email protected] (A.Y. Kozlov).
alloys were remelted twice to ensure homogeneity. The mass losses after the melting were less than 1 wt.%. After the melting the samples were sealed in evacuated quartz ampoules and annealed at 670 K during 720 h. After annealing the ampoules with the samples were quenched in cold water. X-ray powder diffraction patterns of the samples, which were used for phase analysis, were recorded using a DRON-2.0 powder diffractometer (FeKa radiation 20 424100 , Si or Ge as internal standard). The diffraction data for the crystal structure determination of the compounds were collected using a Siemens D5000 powder diffractometer (CuKa radiation, 10 424100 , step scan mode with a step size of 0.03 and counting time of 18 s per data point). For calculating the lattice parameters and for the crystal structure refinement the software packages LATCON and DBWS-9411 [10] have been used.
3. Results and discussion The existence of Ti5XSb2 (X=Al, Ga, In) compounds in the Ti–{Al, Ga, In}–Sb ternary systems at 670 K was found. The peaks of the X-ray powder patterns were indexed in a tetragonal unit cell with the lattice parameters listed in Table 1. Lattice parameters, intensities of the reflection and composition of the samples proved that these compounds are isostructural with the W5Si3 structure (space group I4/mcm). A further refinement of the Ti5AlSb2 structure was performed by the Rietveld method [11]. The atomic
0966-9795/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved. PII: S0966-9795(02)00232-7
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A.Y. Kozlov, V.V. Pavlyuk / Intermetallics 11 (2003) 237–239
Table 1 The lattice parameters of Ti5XSb2 (X=Si, Ge, Al, Ga, In) compounds Compound
a (nm)
c (nm)
V (nm3)
c/a
Reference
Ti5SiSb2 Ti5Si1.3Sb1.7 Ti5GeSb2 Ti5AlSb2 Ti5GaSb2 Ti5InSb2
1.0347(4) 1.0346(2) 1.0398(2) 1.0689(1) 1.0642(2) 1.0738(1)
0.5180(6) 0.5152(1) 0.5231(1) 0.5367(1) 0.5327(1) 0.5501(2)
0.555 0.552 0.566 0.613 0.603 0.634
0.501 0.498 0.503 0.502 0.501 0.512
[1] [12] [1] This work This work This work
Table 2 Atomic and isotropic thermal displacement parameters of the Ti5AlSb2 compound (see Fig. 2) Atom Site x
y
z
Biso10 nm2,
Ti1 Ti2 E1 E2
1/2 0.2184(3) 0 0.6683(2)
1/4 0 1/4 0
1.68 2.02 2.66 1.31
4b 16k 4a 8h
0 0.0771(4) 0 0.1683(3)
2
Occupancy 1 1 0.77Al+0.23Sb 0.91Sb+0.09Al
Table 3 Shortest interatomic distances in Ti5AlSb2 (see Fig. 2) Bond
d (nm)
Bond
d (nm)
Ti1–Ti1 Ti1–Ti2 Ti2–Ti2 Ti2–Ti2 Ti2–Ti2 Ti1–E2
0.2684 0.3397 0.3430 0.3091 0.3149 0.2876
Ti2–E1 Ti2–E2 Ti2–E2 Ti2–E2 E1–E1
0.2816 0.2774 0.3101 0.2889 0.2684
parameters, refined for 84 hkl reflections are listed in Table 2. The values of the agreement factors RBragg and RP are equal to 0.0553 and 0.0792, respectively. The final interatomic distances are listed in Table 3. The experimental X-ray diffraction pattern together with calculated and difference diffraction profiles for Ti5AlSb2 compound are shown in Fig. 1. Some ternary antimonides Zr5MxSb3-x (M=Fe, Co, Ni, x0.5) [2], Hf10MxSb6-x (M=V, Cr, Mn, Fe, Co, Ni, Cu; 0.84x41.5 for M=Fe) [3], Ti5Mn0.45Sb2.55 [4], Ti5Cu0.45Sb2.5 [5] are known to crystallize in ternary variants of the W5Si3 type. Therein, the linear E1 chain (Figs. 2 and 3) consists of different mixtures of M and Sb atoms; the M:Sb ratio may vary between 3:1 and 2:3, whereas in contrast to the situation in Ti5AlSb2 the second E site (E2) is exclusively occupied by Sb atoms. Probably the compounds most similar to Ti5XSb2 (X=Al, Ga, In) are isostructural to Ti5XSb2 (X=Si, Ge) [1,11], M5AlSn2 and M5AlPb2 (M=Ti, Zr, Hf, Nb), [6], Ti5Si1.2 1.6Sn1.8 1.4 [7], Nb5GaSn2 [8]. Another related compound is V4SiSb2, which forms a defect variant of the W5Si3 structure: the metal position on site 4b is unoccupied, and Si and Sb occupy without mixing 4a and 8h sites, respectively [9]. Thus, the Si atom in V4SiSb2 corresponds to the E1 site in Ti5AlSb2 and the Sb atom to the E2 site. The structure of Ti5AlSb2 compound (Fig. 2) can be described based on two (interconnected) different
Fig. 1. Experimental X-ray diffraction pattern, calculated and difference diffraction profiles for Ti5AlSb2 compound.
A.Y. Kozlov, V.V. Pavlyuk / Intermetallics 11 (2003) 237–239
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Fig. 4. The characteristic M10 polyhedra [atom in E2 (black circles) site surrounded by 10 Ti (gray circles)] in the A5n+6B3n+5-type structure.
Fig. 2. Projection of the structure of Ti5AlSb2 along c axis. Symbol: Ti (gray circles), E1 (white circles), E2 (black circles).
Acknowledgements The experimental part of this work was carried out at the Department of Inorganic Chemistry of Ivan Franko L’viv National University (L’viv, Ukraine) and MaxPlank-Institut fu¨r Metalforschung (Stuttgart, Germany). The author is grateful to Professor F. Aldinger for giving the opportunity to carry out this work.
References
Fig. 3. Columnar structure motifs of Ti5AlSb2; left: chain of Ti1, situated in Ti28E24 hexagonal antiprisms; right: chain of E1, situated in face-sharing Ti28 square antiprisms.
colums running parallel to the tetragonal c axis. These two columns are interconnected by numerous Ti–Sb and Ti–Ti bonds. One column consists of face-condensed E1-centered Ti28 square antiprisms. The other column consists of T1-centered Ti28E24 hexagonal antiprisms (Fig. 3). These central E1 and Ti1 atoms are connected to each other to form linear chains. In addition, all these compounds contain a metal M10 polyhedron (atom in E2 site surrounded by 10 Ti) that is observed in all members of the A5n+6B3n+5 family, shown in Fig. 4.
[1] Kozlov AYu, Pavlyuk VV. VIII International Conference on Crystal Chemistry of Intermetallic Compounds, Lviv, Ukrain, September 2002. p.68. [2] Kwon YU, Sevov SC, Corbett JD. Chem Mater 1990;2:550. [3] Kleinke H, Ruckert C, Felser C. Eur J Inorg Chem 2000. p. 315. [4] Tkachuk A, Gorelenko Yu, Stadnyk Yu, Padlyak B, Jankowska-Frydel A, Bodak O, Sechovsky V. J Alloys Comp 2001; 319:74. [5] Koblyuk NO, Romaka LP, Bodak OIJ. Alloys Comp 2000; 309:176. [6] Pietzka MA, Schuster JCJ. Alloys Comp 1995;230:L10. [7] Bulanova M, Meleshevich K, Samelyuk A, Tretyachenko L, Saltykov V, Kulak L, Firstov S, Miracle D. In: 6th International School-Conference ‘‘Phase Diagram in Materials Science’’, Kyiv, Ukrain, October 2001. p. 222. [8] Ukei K, Shishido T, Fukuda T. Acta Cryst 1989;C45:349. [9] Wollesen P, Jeitschko WJ. Alloys Comp 1996;243:67. [10] Young RA, Sakthivel A, Moss TS, Paria-Santos CO. Program DBWS-9411 for Rietveld analysis of X-ray and neutron powder diffraction patterns; Atlanta: Georgia Institute of Technology, 1995 [11] Rietveld HMJ. Appl Cryst 1969;2:65. [12] Kleinke H, Can J. Chem 2001;79:1338.
New ternary antimonides Ti5XSb2 with W5Si3 structure type A.Yu. Kozlov*, V.V. Pavlyuk Department of Inorganic Chemistry, Ivan Franko L’viv National University, Kyryla i Mefodiya str. 6, UA-79005 Lviv, Ukraine Received 21 August 2001; received in revised form 28 October 2002; accepted 28 October 2002
Abstract Three new ternary antimonides having W5Si3 structure type were found. These are Ti5AlSb2, Ti5GaSb2 and Ti5InSb2. The crystal structures of Ti5XSb2 (X=Al, Ga, In) were investigated by X-ray powder diffraction. # 2003 Elsevier Science Ltd. All rights reserved. Keywords: A. Intermetallics, miscellaneous; B. Crystal chemistry of intermetallics; B. Crystallography
1. Introduction During the investigation of the phase equilibria in the systems Ti–{Si, Ge}–Sb [1] new ternary compounds with the approximate compositions Ti5SiSb2 and Ti5GeSb2 were observed. The powder X-ray diffractions patterns were indexed on a body-centered tetragonal unit cell (W5Si3 structure type, I4/mcm space group) with the following lattice parameters a=1.0347(4), c=0.5180(6) nm for Ti5SiSb2 and a=1.0398(2), c=0.5231(1) nm for Ti5GeSb2. Other compounds with W5Si3 structure type based on antimony are also known. These are Zr5MxSb3-x (M=Fe, Co, Ni, x 0.5) [2], Hf10MxSb6-x (M=V, Cr, Mn, Fe, Co, Ni, Cu; 0.84 x 41.5 for M=Fe) [3], Ti5Mn0.45Sb2.55 [4], Ti5Cu0.45Sb2.5 [5], M5AlSn2 and M5AlPb2 (M=Ti, Zr, Hf, Nb), [6], Ti5Si1.2-1.6Sn1.8 1.4 [7], Nb5GaSn2 [8], V4SiSb2 [9]. In this study alloys were prepared by variation of the main group element X (=Al, Ga, In, Sn, Pb), yielding three new W5Si3 type ternary compounds: Ti5AlSb2, Ti5GaSb2 and Ti5InSb2.
2. Experimental The samples with the composition Ti:X:Sb=5:1:2 and a total mass of about 2 g were prepared by arc melting of pure metals (the purity of the ingredients was better than 99.99 at.%) in a high-purity argon atmosphere. All * Corresponding author. E-mail address: [email protected] (A.Y. Kozlov).
alloys were remelted twice to ensure homogeneity. The mass losses after the melting were less than 1 wt.%. After the melting the samples were sealed in evacuated quartz ampoules and annealed at 670 K during 720 h. After annealing the ampoules with the samples were quenched in cold water. X-ray powder diffraction patterns of the samples, which were used for phase analysis, were recorded using a DRON-2.0 powder diffractometer (FeKa radiation 20 424100 , Si or Ge as internal standard). The diffraction data for the crystal structure determination of the compounds were collected using a Siemens D5000 powder diffractometer (CuKa radiation, 10 424100 , step scan mode with a step size of 0.03 and counting time of 18 s per data point). For calculating the lattice parameters and for the crystal structure refinement the software packages LATCON and DBWS-9411 [10] have been used.
3. Results and discussion The existence of Ti5XSb2 (X=Al, Ga, In) compounds in the Ti–{Al, Ga, In}–Sb ternary systems at 670 K was found. The peaks of the X-ray powder patterns were indexed in a tetragonal unit cell with the lattice parameters listed in Table 1. Lattice parameters, intensities of the reflection and composition of the samples proved that these compounds are isostructural with the W5Si3 structure (space group I4/mcm). A further refinement of the Ti5AlSb2 structure was performed by the Rietveld method [11]. The atomic
0966-9795/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved. PII: S0966-9795(02)00232-7
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A.Y. Kozlov, V.V. Pavlyuk / Intermetallics 11 (2003) 237–239
Table 1 The lattice parameters of Ti5XSb2 (X=Si, Ge, Al, Ga, In) compounds Compound
a (nm)
c (nm)
V (nm3)
c/a
Reference
Ti5SiSb2 Ti5Si1.3Sb1.7 Ti5GeSb2 Ti5AlSb2 Ti5GaSb2 Ti5InSb2
1.0347(4) 1.0346(2) 1.0398(2) 1.0689(1) 1.0642(2) 1.0738(1)
0.5180(6) 0.5152(1) 0.5231(1) 0.5367(1) 0.5327(1) 0.5501(2)
0.555 0.552 0.566 0.613 0.603 0.634
0.501 0.498 0.503 0.502 0.501 0.512
[1] [12] [1] This work This work This work
Table 2 Atomic and isotropic thermal displacement parameters of the Ti5AlSb2 compound (see Fig. 2) Atom Site x
y
z
Biso10 nm2,
Ti1 Ti2 E1 E2
1/2 0.2184(3) 0 0.6683(2)
1/4 0 1/4 0
1.68 2.02 2.66 1.31
4b 16k 4a 8h
0 0.0771(4) 0 0.1683(3)
2
Occupancy 1 1 0.77Al+0.23Sb 0.91Sb+0.09Al
Table 3 Shortest interatomic distances in Ti5AlSb2 (see Fig. 2) Bond
d (nm)
Bond
d (nm)
Ti1–Ti1 Ti1–Ti2 Ti2–Ti2 Ti2–Ti2 Ti2–Ti2 Ti1–E2
0.2684 0.3397 0.3430 0.3091 0.3149 0.2876
Ti2–E1 Ti2–E2 Ti2–E2 Ti2–E2 E1–E1
0.2816 0.2774 0.3101 0.2889 0.2684
parameters, refined for 84 hkl reflections are listed in Table 2. The values of the agreement factors RBragg and RP are equal to 0.0553 and 0.0792, respectively. The final interatomic distances are listed in Table 3. The experimental X-ray diffraction pattern together with calculated and difference diffraction profiles for Ti5AlSb2 compound are shown in Fig. 1. Some ternary antimonides Zr5MxSb3-x (M=Fe, Co, Ni, x0.5) [2], Hf10MxSb6-x (M=V, Cr, Mn, Fe, Co, Ni, Cu; 0.84x41.5 for M=Fe) [3], Ti5Mn0.45Sb2.55 [4], Ti5Cu0.45Sb2.5 [5] are known to crystallize in ternary variants of the W5Si3 type. Therein, the linear E1 chain (Figs. 2 and 3) consists of different mixtures of M and Sb atoms; the M:Sb ratio may vary between 3:1 and 2:3, whereas in contrast to the situation in Ti5AlSb2 the second E site (E2) is exclusively occupied by Sb atoms. Probably the compounds most similar to Ti5XSb2 (X=Al, Ga, In) are isostructural to Ti5XSb2 (X=Si, Ge) [1,11], M5AlSn2 and M5AlPb2 (M=Ti, Zr, Hf, Nb), [6], Ti5Si1.2 1.6Sn1.8 1.4 [7], Nb5GaSn2 [8]. Another related compound is V4SiSb2, which forms a defect variant of the W5Si3 structure: the metal position on site 4b is unoccupied, and Si and Sb occupy without mixing 4a and 8h sites, respectively [9]. Thus, the Si atom in V4SiSb2 corresponds to the E1 site in Ti5AlSb2 and the Sb atom to the E2 site. The structure of Ti5AlSb2 compound (Fig. 2) can be described based on two (interconnected) different
Fig. 1. Experimental X-ray diffraction pattern, calculated and difference diffraction profiles for Ti5AlSb2 compound.
A.Y. Kozlov, V.V. Pavlyuk / Intermetallics 11 (2003) 237–239
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Fig. 4. The characteristic M10 polyhedra [atom in E2 (black circles) site surrounded by 10 Ti (gray circles)] in the A5n+6B3n+5-type structure.
Fig. 2. Projection of the structure of Ti5AlSb2 along c axis. Symbol: Ti (gray circles), E1 (white circles), E2 (black circles).
Acknowledgements The experimental part of this work was carried out at the Department of Inorganic Chemistry of Ivan Franko L’viv National University (L’viv, Ukraine) and MaxPlank-Institut fu¨r Metalforschung (Stuttgart, Germany). The author is grateful to Professor F. Aldinger for giving the opportunity to carry out this work.
References
Fig. 3. Columnar structure motifs of Ti5AlSb2; left: chain of Ti1, situated in Ti28E24 hexagonal antiprisms; right: chain of E1, situated in face-sharing Ti28 square antiprisms.
colums running parallel to the tetragonal c axis. These two columns are interconnected by numerous Ti–Sb and Ti–Ti bonds. One column consists of face-condensed E1-centered Ti28 square antiprisms. The other column consists of T1-centered Ti28E24 hexagonal antiprisms (Fig. 3). These central E1 and Ti1 atoms are connected to each other to form linear chains. In addition, all these compounds contain a metal M10 polyhedron (atom in E2 site surrounded by 10 Ti) that is observed in all members of the A5n+6B3n+5 family, shown in Fig. 4.
[1] Kozlov AYu, Pavlyuk VV. VIII International Conference on Crystal Chemistry of Intermetallic Compounds, Lviv, Ukrain, September 2002. p.68. [2] Kwon YU, Sevov SC, Corbett JD. Chem Mater 1990;2:550. [3] Kleinke H, Ruckert C, Felser C. Eur J Inorg Chem 2000. p. 315. [4] Tkachuk A, Gorelenko Yu, Stadnyk Yu, Padlyak B, Jankowska-Frydel A, Bodak O, Sechovsky V. J Alloys Comp 2001; 319:74. [5] Koblyuk NO, Romaka LP, Bodak OIJ. Alloys Comp 2000; 309:176. [6] Pietzka MA, Schuster JCJ. Alloys Comp 1995;230:L10. [7] Bulanova M, Meleshevich K, Samelyuk A, Tretyachenko L, Saltykov V, Kulak L, Firstov S, Miracle D. In: 6th International School-Conference ‘‘Phase Diagram in Materials Science’’, Kyiv, Ukrain, October 2001. p. 222. [8] Ukei K, Shishido T, Fukuda T. Acta Cryst 1989;C45:349. [9] Wollesen P, Jeitschko WJ. Alloys Comp 1996;243:67. [10] Young RA, Sakthivel A, Moss TS, Paria-Santos CO. Program DBWS-9411 for Rietveld analysis of X-ray and neutron powder diffraction patterns; Atlanta: Georgia Institute of Technology, 1995 [11] Rietveld HMJ. Appl Cryst 1969;2:65. [12] Kleinke H, Can J. Chem 2001;79:1338.