Optička i električna svojstva neozračenog i rendgenskim zračenjem ozračenog PMABB

Studies of the optical and electrical (ferroelectric, electrical conductivity) properties of non- and X-ray-irradiated pentakis undecabromodibismuthate (PMABB) orthorhombic crystals were made. The crystal is anisotropic, weakly positively birefringent and optically biaxial with the optical angle 2V = 72◦ 150. The temperature dependence of linear birefringence ∆(∆nc) in the temperature range from 295 K to 320 K shows an anomaly at the phase-transition temperature Tc = 312 K, in agreement with the published result. The spontaneous polarization Ps seems slightly large in comparison with those of other ferroelectrics, owing to the strengthened packing along the polar axis. The results show that the microscopic mechanism driving the phase transition has the same influence on the spontaneous birefringence δs(∆nc) and on Ps in the compound. Effects of irradiation on the refractive indices and their dispersions as well as on the optical anisotropy and optical birefingence are studied. The coercive field Ec and the bias field Eb build up during the irradiation, while Ps shows no change with the enhanced doses until the threshold irradiation (D0 = 4 × 104 rad) is reached, then it begins to decay in a fairly rapid manner. The results are discussed in terms of the conventional double-minimum potential energy used for the description of the ferroelectric mechanism. Measurements of the electrical conductivity σ in the same temperature range show an anomaly at Tc due to the generation of protonic carriers as a result of rotational motion of cations. The maximum σ-value at the threshold irradiation D0 is observed and the variation of σ in the vicinity of D0 was studied.Proučavala su se optička i električna svojstva ortorombnih kristala pentakis undecabromodibismuthata (PMABB) prije ozračivanja i ozračenih s nekoliko doza rendgenskog zračenja. Kristali PMABB su anizotropni, malo pozitivno dvolomni i optički dvoosni s optičkim kutom 2V = 72◦ 150 . Spontana polarizacija Ps je relativno velika zbog snažnijeg slaganja vodikovim vezanjem duž polarne c-osi. Mikroskopski mehanizmi koji uzrokuju fazni prijelaz jednako utječu na Ps i na spontani dvolom δs(∆nc). Ps se ne mijenja za doze ispod kritične, DD0 smanjuje se naglo. Ishodi mjerenja se raspravljaju na osnovi dvostrukog minimuma potencijala koji se rabi za opis feroelektričnog mehanizma. Koercitivno polje Ec i polarizacijsko polje Eb rastu s ozračivanjem zbog promjena unutarnjih polja. Električna vodljivost σ pokazuje anomaliju na kritičnoj temperaturi Tc zbog stvaranja protonskih nositelja koji su posljedica zakretanja kationa. Pri DD0 smanjuje zbog djelovanja klopki

Work-Nonwork Factors as Explanatory Variables of Industrial Attitudes and Behaviour in a Developing Country: The Case of the Sudanese Blue-Collar Worker

The subject matter of this research project has been the attitudes and behaviour of the Sudanese industrial worker. The objective is to test the thesis that, given the novelty of the industrialization process in most of the developing countries, nonwork factors i.e. , workers' experience in the wider society, are more important in shaping attitudes to work than the immediate experience of it. This hypothesis was tested via exploring (i) the priorities, goals and preferences which the Sudanese industrial worker pursues in his employment, (ii) the importance of working in his life (his central life interests), his commitment to wage-employment and the ways in which these are related to his experience on the job, (iii) the similarities and differences workers may exhibit vis-a-vis their orientations and commitment to work along their skill levels and (vi) the ways in which workers' orientations and commitment to work are constrained by their social experience outside the work domain

Optička i električna svojstva neozračenog i rendgenskim zračenjem ozračenog PMABB

Studies of the optical and electrical (ferroelectric, electrical conductivity) properties of non- and X-ray-irradiated pentakis undecabromodibismuthate (PMABB) orthorhombic crystals were made. The crystal is anisotropic, weakly positively birefringent and optically biaxial with the optical angle 2V = 72◦ 150. The temperature dependence of linear birefringence ∆(∆nc) in the temperature range from 295 K to 320 K shows an anomaly at the phase-transition temperature Tc = 312 K, in agreement with the published result. The spontaneous polarization Ps seems slightly large in comparison with those of other ferroelectrics, owing to the strengthened packing along the polar axis. The results show that the microscopic mechanism driving the phase transition has the same influence on the spontaneous birefringence δs(∆nc) and on Ps in the compound. Effects of irradiation on the refractive indices and their dispersions as well as on the optical anisotropy and optical birefingence are studied. The coercive field Ec and the bias field Eb build up during the irradiation, while Ps shows no change with the enhanced doses until the threshold irradiation (D0 = 4 × 104 rad) is reached, then it begins to decay in a fairly rapid manner. The results are discussed in terms of the conventional double-minimum potential energy used for the description of the ferroelectric mechanism. Measurements of the electrical conductivity σ in the same temperature range show an anomaly at Tc due to the generation of protonic carriers as a result of rotational motion of cations. The maximum σ-value at the threshold irradiation D0 is observed and the variation of σ in the vicinity of D0 was studied.Proučavala su se optička i električna svojstva ortorombnih kristala pentakis undecabromodibismuthata (PMABB) prije ozračivanja i ozračenih s nekoliko doza rendgenskog zračenja. Kristali PMABB su anizotropni, malo pozitivno dvolomni i optički dvoosni s optičkim kutom 2V = 72◦ 150 . Spontana polarizacija Ps je relativno velika zbog snažnijeg slaganja vodikovim vezanjem duž polarne c-osi. Mikroskopski mehanizmi koji uzrokuju fazni prijelaz jednako utječu na Ps i na spontani dvolom δs(∆nc). Ps se ne mijenja za doze ispod kritične, DD0 smanjuje se naglo. Ishodi mjerenja se raspravljaju na osnovi dvostrukog minimuma potencijala koji se rabi za opis feroelektričnog mehanizma. Koercitivno polje Ec i polarizacijsko polje Eb rastu s ozračivanjem zbog promjena unutarnjih polja. Električna vodljivost σ pokazuje anomaliju na kritičnoj temperaturi Tc zbog stvaranja protonskih nositelja koji su posljedica zakretanja kationa. Pri DD0 smanjuje zbog djelovanja klopki

Shapiro and parametric resonances in coupled Josephson junctions

The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We compare the current-voltage characteristics for a stack of coupled Josephson junctions under external irradiation calculated in the framework of CCJJ and CCJJ+DC models.Comment: 4 pages, Manuscript for Dubna-Nano 2012, submitted for Journal of Physics:Conference Serie