Nuclear quadrupole alignment ofLum176andLu177in a lutetium single crystal at low temperatures and systematics of electric field gradients in pure hexagonal transition metals

1979 ◽  
Vol 19 (9) ◽  
pp. 4460-4469 ◽  
Author(s):  
H. Ernst ◽  
E. Hagn ◽  
E. Zech ◽  
G. Eska
Keyword(s):  
Transition Metals ◽  
Electric Field ◽  
Single Crystal ◽  
Low Temperatures ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Nuclear Quadrupole ◽  
Quadrupole Alignment

Electric field gradients at Os nuclei in the hexagonal transition metals Os and Re

1979 ◽  
Vol 70 (3) ◽  
pp. 246-248 ◽  
Author(s):  
H. Ernst ◽  
W. Koch ◽  
F.E. Wagner ◽  
E. Bucher
Keyword(s):  
Transition Metals ◽  
Electric Field ◽  
Electric Field Gradients ◽  
Field Gradients

scholarly journals Investigation of the Negative Thermal Expansion of ZrW2O8

2000 ◽  
Vol 55 (1-2) ◽  
pp. 301-310 ◽  
Author(s):  
N. Ulbrich ◽  
W. Tröger ◽  
T. Butz ◽  
P. Blaha
Keyword(s):  
Thermal Expansion ◽  
Electric Field ◽  
Negative Thermal Expansion ◽  
Temperature Structure ◽  
Full Potential ◽  
Electric Field Gradients ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Field Gradients ◽  
Nuclear Quadrupole

The negative thermal expansion in ZrW2O8 was investigated on a microscopic scale by temperature dependent measurements of the electric field gradients at the nuclear probe 187W(β-) 187Re using time differential perturbed angular correlation spectroscopy. Two distinct nuclear quadrupole interactions I VzzRe1 l= 18.92(4) • 10 21 V/m2 , ηRe1 = 0.0 and I VzzRe1 l = 4.55(2) • 1021 V/m2 , ηRe1 = 0.053(3) were observed at 295 K, which are assigned to the two crystallographically distinct W0 4 tetrahedra of the room temperature structure. Ab initio calculations of electron densities and electric field gradients with 1:7 Re-impurities using the full potential linearized augmented plane wave package WIEN97 yield the electric field gradients VzzRe1 = 12.63 • 10 21 V/m2 , ηRe1 = 0.0 and VzzRe2 =4.90 • 10 21 V/m2 , ηRe2 =0.0. The observed temperature dependence of the nuclear quadrupole interactions agrees well with the structural phase transition at 428 K observed by neutron and x-ray diffraction. Our experiments corroborate the suggested mechanism of coupled librations of rigid ZrO6 octahedra and WO4 tetrahedra, which is an alternative description of transverse vibrations of oxygen atoms in Zr-O-W bonds, for the negative thermal expansion in ZrW2 O8

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