Dynamies of KIO3 phase transitions in the temperature range 4.2 to 370 K investigated by the nuclear quadrupole resonance method

1975 ◽  
Vol 27 (1) ◽  
pp. 315-320 ◽  
Author(s):  
D. F. Baisa ◽  
A. I. Barabash ◽  
A. K. Moskalev ◽  
G. K. Semin
Keyword(s):  
Phase Transitions ◽  
Nuclear Quadrupole Resonance ◽  
Resonance Method ◽  
Temperature Range ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

scholarly journals 79Br and 127І Nuclear Quadrupole Resonance Investigations of Ortho-Substituted Anilinium Halides, 2-RC6H4NH3⊕ X⊖ with X = Br, I and R = CI, CN, C2H5, NH2, and NH3⊕ X⊖

1991 ◽  
Vol 46 (4) ◽  
pp. 367-375 ◽  
Author(s):  
Jutta Hartmann ◽  
Alarich Weiss
Keyword(s):  
Phase Transitions ◽  
Nuclear Quadrupole Resonance ◽  
Temperature Range ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract The 79Br and 127I nuclear quadrupole resonance, NQR, spectra of ortho-substituted anilinium bromides and iodides 2-RC6H4NH3⊕ X⊖ with X = Br, I and R = CI, CN, C2H5, NH2, and NH3⊕ X⊖ have been investigated in the temperature range 77 < T/K <420. Phase transitions occur in 2-(C2H5)C6H4NH3⊕ Br⊖ ½H2O at Tc= 164 K. in 2-(C2H5)C6H4NH3⊕ I⊖ at Tc = 214 K, in [1,2-C6H4(N(H,D)3)-]2⊕[Br⊖]2 at Tc = 209 K, and in [1,2-C6H4(NH3)2]2⊕[I⊖]2 at Tc = 173 K. The NQR data are discussed and compared with NQR spectra of para-substituted anilinium halides

Chlorine nuclear quadrupole resonance lineshape in the cubic antifluorite K2OsCl6

1985 ◽  
Vol 63 (3) ◽  
pp. 350-353 ◽  
Author(s):  
Maximo E. Ramia ◽  
Robin L. Armstrong
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Point Defects ◽  
Temperature Dependent ◽  
Local Strains ◽  
Temperature Range ◽  
Quadrupole Resonance ◽  
Symmetric Line ◽  
Nuclear Quadrupole

Chlorine nuclear quadrupole resonance lineshapes are reported for the cubic antifluorite K2OsCl6 in the temperature range 70–300 K. For temperatures above 172 K the spectrum consists of a single symmetric line; for temperatures below 172 K an asymmetric line is observed which can be represented as a sum of two symmetric lines. The symmetric lines are temperature dependent mixtures of Lorentzian and Gaussian profiles. The explanation is that the nuclear quadrupole resonance lines observed in K2OSCl6 are inhomogeneously broadened by temperature dependent local strains caused by point defects and dislocations.

Nuclear Quadrupole Resonance Study of 35Cl in Chloral Hydrate, CCl3CH(OH)2, and Chloral Deuterate, CCl3CH(OD)2

1967 ◽  
Vol 22 (7) ◽  
pp. 1124-1126 ◽  
Author(s):  
Dieter Biedenkapp ◽  
Alarich Weiss
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Crystal Field ◽  
Room Temperature ◽  
Chloral Hydrate ◽  
Temperature Range ◽  
Field Effects ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The nuclear quadrupole resonance (NQR) spectra of 35Cl in chloral hydrate and chloral deuterate were investigated in the temperature range between 77°K and 323 °K. Two modifications have been found for each substance. One of the modifications is unstable at room temperature and changes within a few weeks into the stable modification. The NQR spectrum can be explained in terms of crystal field effects.

Neutron-diffraction study of the structural phase transitions in the antifluorite K2PtBr6

1985 ◽  
Vol 63 (7) ◽  
pp. 988-996 ◽  
Author(s):  
Robin L. Armstrong ◽  
Rose M. Morra ◽  
Brian M. Powell
Keyword(s):  
Phase Transitions ◽  
Nuclear Quadrupole Resonance ◽  
Goodness Of Fit ◽  
Structural Phase ◽  
Spectral Characteristics ◽  
Neutron Diffraction Study ◽  
Structural Phase Transitions ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Neutron-powder-diffraction profiles are reported for the antifluorite K2PtBr6 at temperatures of 296, 160, 141, and 120 K. Bromine nuclear-quadrupole-resonance measurements have shown that each of these temperatures corresponds to a different crystal structure and have provided information on the most probable structures. A variety of structural models with symmetries obtained from a group theoretical classification of structural phase transitions are fitted to the diffraction data. A comparison of goodness-of-fit parameters for the models considered at each temperature allows the space group of each phase to be identified. The results provide (i) a definitive test of the validity of a classification scheme proposed for nuclear-quadrupole-resonance spectral characteristics, and (ii) support for the proposition that the allowable, continuous distortions of a crystal are given by the nondisruptive criterion rather than the more restrictive group–subgroup criterion.

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