New ternary compounds with CeFeSi-type structure (LuTiSi, LuTiGe) and CeScSi-type structure (ZrVGe and HfVGe)

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Journal of Alloys and Compounds 289 (1999) L10–L11

Letter

New ternary compounds with CeFeSi-type structure (LuTiSi, LuTiGe) and CeScSi-type structure (ZrVGe and HfVGe) A.V. Morozkin Department of Chemistry, Moscow Lomonosov State University, Leninskie Gory, Moscow, GSP-3, 119899, Russia Received 18 March 1999

Abstract Investigations made by powder X-ray diffraction on four new ternary LuTiSi, LuTiGe, ZrVGe and HfVGe compounds are reported. The compounds LuTiSi (a50.3974(1) nm, c50.7379(1) nm) and LuTiGe (a50.3992(1) nm, c50.7446(1) nm) crystallize in the tetragonal CeFeSi-type structure (space group P4 / nmm). The compounds ZrVGe (a50.3754(1) nm, c51.4488(1) nm) and HfVGe (a50.3725(1) nm, c51.4346(2) nm) crystallize in the tetragonal CeScSi-type structure (space group I4 / mmm).  1999 Published by Elsevier Science S.A. All rights reserved. Keywords: Ternary intermetallic compounds; Ternary silicides; Ternary germanides; Crystal structure

In the present investigation the compounds were made in an electric arc furnace under an argon atmosphere using a non-consumable tungsten electrode and a water-cooled copper tray. Silicon, germanium, titanium, vanadium, lutetium, zirconium and hafnium (purity of each component $99.99%) were used as the starting components. Titanium was used as a getter during melting. The melted alloys were subjected to an anneal in an evacuated quartz ampoule containing titanium chips as getter; the ampoule was placed in a resistance furnace. The samples were annealed at 1230 K for 300 h in argon atmosphere and were quenched in ice-cold water. X-ray powder diffraction analyses were obtained on an DRON-3.0 (Cu Ka -radiation, 2u 520–708, step 0.058, 1002 points). The obtained diffractograms were identified and

intensity calculatious were made in the isotropic approximation using the Rietan-programs [1]. Analysis of the powder X-ray diffractograms show that the new ternary LuTiSi and LuTiGe compounds crystallize in the tetragonal CeFeSi-type structure (P4 / nmm). In the CeFeSi-type structure the lutetium and silicon (germanium) atoms occupy the 2(c) site (1 / 4, 1 / 4, z) and the Ti atoms occupy the special position 2(a) (3 / 4, 1 / 4, 0) [2]. Analysis of the powder X-ray diffractograms show that the new ternary ZrVGe and HfVGe compounds crystallize in the tetragonal CeScSi-type structure (I4 / mmm). In the CeScSi-type structure the zirconium (hafnium) and germanium atoms occupy 4(e) site (0, 0, z) and the V atom occupies the special position 4(c) (0, 1 / 2, 0) [2]. The lattice parameters of the compounds, refined at room

Table 1 Lattice parameters a, c (nm), c /a, unit cell volume V (nm 3 ) and atomic position parameters of LuTiSi, LuTiGe, ZrVGe and HfVGe compounds (R5Lu, Zr, Hf; X5Si, Ge). The reliability factors R F are given in % Compound

Type structure

a

c

c /a

V

ZR

ZX

RF

LuTiSi LuTiGe ZrVGe HfVGe

CeFeSi CeFeSi CeScSi CeScSi

0.3974(1) 0.3992(1) 0.3754(1) 0.3725(1)

0.7379(1) 0.7446(1) 1.4488(1) 1.4346(2)

1.8568 1.8652 3.8593 3.8513

0.11653 0.11866 0.20417 0.19906

0.656(3) 0.653(3) 0.324(2) 0.324(2)

0.264(10) 0.267(7) 0.131(2) 0.137(5)

7.0 6.0 4.8 6.6

E-mail address: [email protected] (A.V. Morozkin) 0925-8388 / 99 / $ – see front matter  1999 Published by Elsevier Science S.A. All rights reserved. PII: S0925-8388( 99 )00179-6

A.V. Morozkin / Journal of Alloys and Compounds 289 (1999) L10 –L11

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Table 2 Interatomic distances in LuTiSi, LuTiGe, ZrVGe and HfVGe compounds D62?10 23 nm LuTiSi

LuTiGe

ZrVGe

HfVGe

Atom

D

Atom

D

Atom

D

Atom

D

Lu–4Si –1Si –4Ti –4Lu Ti–4Si –4Ti –4Lu Si–4Ti –4Lu –1Lu

0.287 0.289 0.322 0.363 0.278 0.2810 0.322 0.278 0.287 0.289

Lu–1Ge –4Ge –4Ti –4Lu Ti–4Ge –4Ti –4Lu Ge–4Ti –1Lu –4Lu

0.287 0.289 0.327 0.363 0.282 0.2823 0.327 0.282 0.287 0.289

Zr–4Ge –1Ge –4V –4Zr V–4V –4Ge –4Zr Ge–4V –4Zr –1Zr

0.273 0.280 0.317 0.341 0.2654 0.267 0.317 0.267 0.273 0.280

Hf–1Ge –4Ge –4V –4Hf V–4V –4Ge –4Hf Ge–1Hf –4Hf –4V

0.268 0.269 0.314 0.338 0.2634 0.271 0.314 0.268 0.269 0.271

temperature, the atomic position parameters of the compounds and the reliability factors R F resulting from the refinments are given in Table 1. Interatomic distances in LuTiSi, LuTiGe, ZrVGe and HfVGe compounds are given in Table 2.

References [1] F. Izumi, Rigaku J. 6 (1) (1989) 10–19. [2] E.I. Gladyshevsky, O.I. Bodak, in: Kristallohimia Intermetallicheskih Soedinenii Redkozemel’nyh Metallov, LSU, L’viv, 1982, p. 173, (in Russian).