E Gratz et al 1996 J. Phys.: Condens. Matter 8 8351 doi:10.1088/0953-8984/8/43/026
Temperature- and pressure-induced structural transitions in rare-earth-deficient 
(R = Y, Sm, Gd, Tb) Laves phases
E Gratz
, A Kottar, A Lindbaum, M Mantler
, M Latroche§, V Paul-Boncour§, M Acet||, Cl Barner||, W B Holzapfel¶, V Pacheco+ and K Yvon+
Electrical resistivity, thermal expansion, and temperature-dependent x-ray diffraction measurements on 
compounds give mutually consistent evidence for structural phase transitions at 740 K, 550 K, 600 K, and 450 K respectively for R = Y, Sm, Gd, Tb; 0 < x < 0.05. Arguments are given as to why most of the rare-earth - nickel compounds with the 1:2 ratio do not crystallize in the simple cubic Laves phase (C15 type) but show a superstructure of the cubic Laves phase at room temperature and at ambient pressure. This superstructure with the space group 
and a doubled cell parameter is characterized by ordered vacancies on the R sites. It is shown that the observed structural instabilities result in transitions to the cubic Laves phase (space group 
), however with disordered vacancies at high temperatures. High-pressure x-ray powder diffraction experiments show that the phase transition in 
shifts down to room temperature for a pressure of 27 GPa.
- PACS
-
64.70.K- Solid–solid transitions
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
65.40.De Thermal expansion; thermomechanical effects
61.72.J- Point defects and defect clusters
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
- Subjects
- Dates
-
Issue 43 (21 October 1996)
Received 21 June 1996, in final form 12 August 1996
-
Temperature- and pressure-induced structural transitions in rare-earth-deficient (R = Y, Sm, Gd, Tb) Laves phases
E Gratz et al 1996 J. Phys.: Condens. Matter 8 8351
-
Orbital angular momentum and massless particles
M A Lohe 1977 J. Phys. A: Math. Gen. 10 525
-
Bayesian estimate of the zero-density frequency of a Cs fountain
D Calonico et al 2009 Metrologia 46 629
-
Path integral for quantum operations
Vasily E Tarasov 2004 J. Phys. A: Math. Gen. 37 3241
-
Quasiharmonic lattice dynamics of Bravais lattices. III. Thermal expansion of a rhombohedral lattice
T H K Barron and T G Gibbons 1974 J. Phys. C: Solid State Phys. 7 3287
-
An automatic timer control unit for the Farmer dosemeter type 2502/3
P J Rudd 1980 Phys. Med. Biol. 25 741
-
Hadronic production of the doubly charmed baryon Ξcc with intrinsic charm
Chao-Hsi Chang et al 2007 J. Phys. G: Nucl. Part. Phys. 34 845
-
Centripetal acceleration: often forgotten or misinterpreted
Chandralekha Singh 2009 Phys. Educ. 44 464
-
Anomalous behaviour in the phase transition and crystal structure of urea adducts with n-eicosane
Koji Fukao 1996 J. Phys.: Condens. Matter 8 2105
-
Methods to determine water vapour sorption on mass standards
A Picard and H Fang 2004 Metrologia 41 333
Related review articles
What's this?- Photoinduced phase transitions
- Integrable structure of box–ball systems: crystal, Bethe ansatz, ultradiscretization and tropical geometry
- Processes involving clusters and small particles in a buffer gas
