Magnetic phase transitions in dibromo(4H-1,2,4-triazole)copper(II) and related copper(II) complexes as studied by nitrogen-14 nuclear quadrupole resonance and magnetic susceptibility measurements

1983 ◽  
Vol 22 (2) ◽  
pp. 202-206 ◽  
Author(s):  
Tetsuo Asaji ◽  
Hideki Sakai ◽  
Daiyu Nakamura
Keyword(s):  
Magnetic Susceptibility ◽  
Phase Transitions ◽  
Nuclear Quadrupole Resonance ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions ◽  
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

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.

scholarly journals Studies of 139La and 63/65Cu-NQR in La 2-xMxCuO4 (M = Ba, Sr)

1990 ◽  
Vol 45 (3-4) ◽  
pp. 433-438 ◽  
Author(s):  
K. Kumagai ◽  
Y. Nakamura ◽  
I. Watanabe ◽  
H. Nakajima
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Electronic State ◽  
Magnetic Phase ◽  
Hole Doping ◽  
Anomalous Change ◽  
Quadrupole Interactions ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

AbstractThe nuclear quadrupole resonance of 139La and 63/65Cu in La2-x CMxCuO4 (M = Ba, Sr) is investigated for x up to unity. The shift of the resonance frequency of 139La-NQR for 0.01 < x <0.05 indicates an anomalous change of the quadrupole interactions at T*c, where the frustrated magnetic phase appears. The Cu-NQR reveals clear changes of T1-1 and T2-1 and also of the profile of the Cu-NQR spectra with increasing x beyond x = 0.3~0.4, suggesting a suppression of antiferromagnetic fluctuations by hole-doping, and also a change of the electronic state of the La-system around x = 0.3 ~0.4.

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