Magnetic field enhanced structural instability in EuTiO_{3}

EuTiO_{3} undergoes a structural phase transition from cubic to tetragonal at T_S = 282 K which is not accompanied by any long range magnetic order. However, it is related to the oxygen ocathedra rotation driven by a zone boundary acoustic mode softening. Here we show that this displacive second order structural phase transition can be shifted to higher temperatures by the application of an external magnetic field (increased by 4 K for mu_{0}H = 9 T). This observed field dependence is in agreement with theoretical predictions based on a coupled spin-anharmonic-phonon interaction model.Comment: 4 pages, 4 figure

Crystallographic and optical study of PbHfO3 crystals

The symmetry of the intermediate high-temperature phase of PbHfO3 has been determined unambiguously to be orthorhombic using a combination of high-resolution X-ray diffraction and birefringence imaging microscopy measurements of crystal plates. While lattice parameter measurements as a function of temperature in the intermediate phase are consistent with either orthorhombic or tetragonal symmetry, domain orientations observed in birefringence imaging microscopy measurements utilizing the Metripol system are only consistent with orthorhombic symmetry with the unit cell in the rhombic orientation of the pseudocubic unit cell

The role of septal perforators and "myocardial bridging effect" in atherosclerotic plaque distribution in the coronary artery disease

The distribution of atherosclerotic plaque burden in the human coronary arteries is not uniform. Plaques are located mostly in the left anterior descending artery (LAD), then in the right coronary artery (RCA), circumflex branch (LCx) and the left main coronary artery (LM) in a decreasing order of frequency. In the LAD and LCx, plaques tend to cluster within the proximal segment, while in the RCA their distribution is more uniform. Several factors have been involved in this phenomenon, particularly flow patterns in the left and right coronary artery. Nevertheless, it does not explain the difference in lesion frequency between the LAD and the LCx as these are both parts of the left coronary artery. Branching points are considered to be the risk points of atherosclerosis. In the LCx, the number of side branches is lower than in the LAD or RCA and there are no septal perforators with intramuscular courses like in the proximal third of the LAD and the posterior descending artery (PDA). We hypothesized that septal branches generate disturbed flow in the LAD and PDA in a similar fashion to the myocardial bridge (myocardial bridging effect). This coronary architecture determines the non-uniform plaque distribution in coronary arteries and LAD predisposition to plaque formation

Synthesis and Characterization of a Novel Platinum Ligand Complex ((κ-N,C,N- 2,6-bis(diethylaminomethyl)phenyl)(4- tert-butylphenyl) platinum(II))

A novel platinum ligand complex (NCN)PtAr, ((κ-N,C,N- 2,6-bis (diethylaminomethyl)phenyl)(4- tert-butylphenyl) platinum(II)), was synthesized. A reaction of 1-Bromo-4-tert-butylbenzene Grignard with (NCN)PtCl, (where NCN = 2,6-bis(diethylaminomethyl)phenyl) yielded the (NCN)PtAr (where Ar = 4-tert­-butylphenyl). The product was then characterized with NMR spectra through 1H NMR, 13C NMR, COSY, HSQC, and HMBC to verify it structure

Tadeusz Sławek częściowo poznany

Cóż obywatel uczelni wyższej pochodzący z obszaru tzw. nauk ścisłych (nie lubię tej nazwy, jak nie wiem co) może napisać panegirycznie o Nim, profesorze Tadeuszu Sławku z Wydziału Filologicznego Uniwersytetu Śląskiego, który jubileuszy nie lubi i gdyby tylko mógł, nie uczestniczyłby w żadnym. Cóż facet, myślący w zasadzie matematyczno‑ fizycznie i skąpy w wypowiadaniu oryginalnych słów czy też barwnych sentencji, może napisać o Uczonym i Jego osiągnięciach z zakresu literatury pięknej, poezji, filozofii – i w ogóle z szeroko pojętego obszaru nauk humanistycznych? Tę, w jakimś sensie miłą powinność zawodową, pozostawiam fachowcom i znawcom tego wszystkiego, czym do tej pory profesor Tadeusz Sławek zachwycił, czego dokonał, na co skierował uwagę akademickich poszukiwaczy tematów oryginalnych, tego, co badał i analizował, kim potrafił zafascynować, które z wartości życia uniwersyteckiego potrafił trafnie nazwać i, między innymi, w tekst misji naszego uniwersytetu włożyć[…

Determination of elastic stiffness coefficients of lead zirconate single crystals in the cubic phase by Brillouin light scattering

The temperature dependence of the three independent elastic constants of antiferroelectric lead zirconate single crystals was determined in the cubic, paraelectric phase by Brillouin light scattering spectroscopy. Two longitudinal elastic moduli of C11 and (C11 + C12+2 C 44)/2 showed softening upon cooling toward the phase transition temperature, indicating the coupling of the acoustic waves to the polarization fluctuations of the precursor polar clusters. Among the two transverse acoustic modes, C44 was almost constant while (C11-C 12)/2 showed a noticeable softening in the paraelectric phase. This was attributed to the acoustic instability of lead zirconate toward the orthorhombic ground state

Phase transitions and local polarity above TC in a PbZr0.87Ti0.13O3 single crystal

Solid solutions of PbZr1_xTixO3 (PZT) are one of the most widely used piezoelectric materials with perovskite structure. Despite the decades of research, the phase diagram of PZT reported in 1971 has not been resolved yet. Recently, it turned out that single crystals of good quality of these solid solutions can be grown. By means of top-seeded solution growth (TSSG) technique, we succeeded to grow a single PbZr0.87Ti0.13O3 crystal. Hence, a partial verification of the diagram could be performed through investigations of the optical, dielectric, pyroelectric and elastic properties of this crystal, in a wide temperature range. The obtained results confirmed that the PbZr0.87Ti0.13O3 crystal undergoes a sequence of phase transitions, such as those observed in ceramics of similar chemical composition. However, additional anomalies of investigated physical properties were observed and discussed. Moreover, the influence of electric field on optical properties has been investigated for the first time and has proven the existence of local polar character of the phase above TC in a limited temperature range

Determination of elastic stiffness coefficients of lead zirconate single crystals in the cubic phase by Brillouin light scattering

The temperature dependence of the three independent elastic constants of antiferroelectric lead zirconate single crystals was determined in the cubic, paraelectric phase by Brillouin light scattering spectroscopy. Two longitudinal elastic moduli of C11 and (C11 + C12+2 C 44)/2 showed softening upon cooling toward the phase transition temperature, indicating the coupling of the acoustic waves to the polarization fluctuations of the precursor polar clusters. Among the two transverse acoustic modes, C44 was almost constant while (C11-C 12)/2 showed a noticeable softening in the paraelectric phase. This was attributed to the acoustic instability of lead zirconate toward the orthorhombic ground state