Temperature Dependence of the Positron Lifetime in an Al-Li Alloy

Results of molecular motion studies carried out in two liquid crystal forming compounds n-p-cyano-p-hexyloxybiphenyl (M18) and n-p-ethoxybenzylidene-p-butylaniline (EBBA) using positron lifetime spectroscopy (PLS) are presented. Temperature dependent positron lifetime measurements have been performed in each compound during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. In both the compounds, behaviors of the quenched and slow cooled samples are found to be different. The material in the quenched sample, unlike the slow-cooled sample, exhibits strong temperature dependence before it undergoes a glass transition. In each case, the temperature dependence of o-Ps pick-off lifetime in the quenched sample shows broad peaks at various characteristic temperatures. These peaks have been attributed to various intra- and inter-molecular motions associated with these compounds. The characteristic frequencies of some of the modes observed in the present work agree well with the literature reported values obtained from FIR and Raman studies. The present study demonstrates the usefulness of PLS in the study of molecular motions.

Download Full-text

Temperature Dependence of Positron Lifetime in the Two-Mixed-Phase BiSrCaCuO Superconductor

phys stat sol (a) ◽

10.1002/pssa.2211360146 ◽

1993 ◽

Vol 136 (1) ◽

pp. K51-K54 ◽

Cited By ~ 1

Author(s):

D. M. Zhang ◽

C. Q. Tang ◽

T. Gen ◽

G. Y. Li

Keyword(s):

Temperature Dependence ◽

Positron Lifetime ◽

Mixed Phase

Download Full-text

Unusual temperature dependence of the positron lifetime in a polymer of intrinsic microporosity

physica status solidi (RRL) - Rapid Research Letters ◽

10.1002/pssr.200701116 ◽

2007 ◽

Vol 1 (5) ◽

pp. 190-192 ◽

Cited By ~ 25

Author(s):

Rodrigo Lima de Miranda ◽

Jan Kruse ◽

Klaus Rätzke ◽

Franz Faupel ◽

Detlev Fritsch ◽

...

Keyword(s):

Temperature Dependence ◽

Positron Lifetime ◽

Polymer Of Intrinsic Microporosity ◽

Intrinsic Microporosity

Download Full-text

Temperature dependence of positron lifetime in ordered porous silica (SBA-3)

Radiation Physics and Chemistry ◽

10.1016/j.radphyschem.2009.06.030 ◽

2009 ◽

Vol 78 (12) ◽

pp. 1088-1091 ◽

Cited By ~ 8

Author(s):

S. Kunishige ◽

M. Koshimizu ◽

K. Asai

Keyword(s):

Temperature Dependence ◽

Positron Lifetime ◽

Porous Silica ◽

Ordered Porous

Download Full-text

Electron Irradiation Induced Vacancy Defects Detected by Positron Annihilation in 6H-SiC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.483-485.473 ◽

2005 ◽

Vol 483-485 ◽

pp. 473-476 ◽

Cited By ~ 2

Author(s):

Marie France Barthe ◽

L. Henry ◽

S. Arpiainen ◽

G. Blondiaux

Keyword(s):

Temperature Dependence ◽

Positron Annihilation ◽

Electron Energy ◽

Electron Irradiation ◽

Positron Lifetime ◽

Resolution Function ◽

Vacancy Defects ◽

Nitrogen Doped

This paper presents positron lifetime results which give information on the nature of vacancy defects induced by electron irradiation in bulk nitrogen doped (nD-nA= 2.3x1017 cm-3) Cree 6H-SiC. The electron irradiations have been performed at different energies and with different fluences from 5􀂗1017 e-cm-2 to 3􀂗1018 e-cm-2. Positron lifetime have been measured with a 22NaCl source as a function of temperature between 15 and 300 K. The lifetime spectra were analyzed as sums of two exponential lifetime components 􀁗i weighted by the intensities Ii, convoluted with the resolution function. From the temperature dependence of the lifetime spectra we can infer that several vacancy defects exist in the electron irradiated n-type 6H-SiC. The nature of detected vacancy defects depends on the electron energy.

Download Full-text