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1

Oxygen Precipitation in Si:O Annealed under High Hydrostatic Pressure

100%

Misiuk A., Bąk-Misiuk J., Bryja L., Kątcki J., Ratajczak J., Jun J., Surma B.

Acta Physica Polonica A

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2002

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vol. 101

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issue 5

719-727

EN

Effect of hydrostatic pressure up to 1.2 GPa on oxygen-implanted silicon, Si:O (O^+ dose, D, within the 6×10^{17}-2×10^{18} cm^{-2} range), treated at 1230-1570 K, was investigated by X-ray, transmission electron microscopy and photoluminescence methods. The pressure treatment affects oxygen precipitation and defect creation, especially in low oxygen dose implanted Si:O (D=6×10^{17} cm^{-2}). Such investigation helps in understanding the stress related phenomena in Si wafers with buried insulating layer.

2

Defect Structure of Pressure Treated Czochralski Grown Silicon Investigated by X-Ray Topography and Diffractometry

100%

Misiuk A., Härtwig J., Prieur E., Ohler M., Bąk-Misiuk J., Domagała J., Surma B.

Acta Physica Polonica A

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1997

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vol. 91

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issue 5

987-991

EN

The defect structure of Czochralski grown silicon single crystals annealed at 870-1400 K under hydrostatic pressure up to 1 GPa was investigated by conventional and synchrotron radiation X-ray topography and by reciprocal space mapping. Hydrostatic pressure promotes oxygen precipitation from oversaturated Si-O solid solution and the creation of structural defects.

3

Characterizing the Effects of Hot Isostatic Pressing on IN713C Superalloy Blade Microstructure by Electron Backscatter Diffraction

100%

Chmiela B., Kościelniak B., Roskosz S.

Acta Physica Polonica A

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2016

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vol. 130

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issue 4

1097-1099

EN

The integrity of turbine blades is essential for the safe operation of jet engines. Thus, the mechanical properties, especially creep resistance and fatigue strength at high temperatures, must be thoroughly optimized. In particular, it has previously been observed that the mechanical properties of blades depend on the microstructure and porosity resulting from the casting process. To decrease the internal porosity generated by investment casting, hot isostatic pressing can be applied. This paper aims to evaluate the effects of hot isostatic pressing on the microstructure of IN713C alloy blades. Two variants of hot isostatic pressing treatment, differing in pressure, were carried out, and each resulted in lowered porosity. Microstructural investigations, performed using scanning electron microscopy and electron backscatter diffraction revealed significant changes of γ' particles and high strain intensity in the surface layer of the blades after hot isostatic pressing treatment.

4

Study of Niobium Thin Films under Pressure

100%

Pristáš G., Gabáni S., Orendáč M., Komanický V., Gažo E.

Acta Physica Polonica A

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2014

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vol. 126

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issue 1

346-347

EN

Niobium is widely used in many important superconducting applications. At ambient pressure, bulk Nb has the highest critical temperature, T_c ≈ 9.25 K among the superconducting elements. Thin films of Nb show several differences in behavior in comparison with bulk Nb, e.g. substantial increase in the upper critical field (H_{C2}). Critical temperature of superconducting transition is usually lower for thin films than in bulk sample and depends on thickness of the film, size of grains etc. We prepared 100 nm thick niobium thin films in the high vacuum DC magnetron sputtering system, with T_c=8.95 K at ambient pressure. In this study, we performed measurements of superconducting transition temperature by electrical resistivity measurements of Nb thin film under hydrostatic pressure of up to 30 kbar. We observed an increase of T_c with increasing value of pressure (dT_c/dp=7.3 mK/kbar). On the other side in the case of bulk sample of Nb we observed a decrease of T_c value (dT_c/dp=-2.5 mK/kbar) with increasing applied pressure. Difference in superconducting properties between niobium bulk and thin film under pressure is discussed.

5

Pressure Variation of the Strain State of MnAs Nanoclusters Embedded in GaAs

100%

Bak-Misiuk J., Dynowska E., Romanowski P., Misiuk A., Sadowski J., Caliebe W.

Acta Physica Polonica A

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2012

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vol. 121

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issue 4

903-905

EN

Granular GaAs:(Mn,Ga)As films were prepared by annealing at 500°C under ambient and enhanced hydrostatic pressure (1.1 GPa), of Ga_{1-x}Mn_xAs/GaAs layers (x = 0.025, 0.03, 0.04, 0.05 and 0.063) grown at 230°C by molecular beam epitaxy method. Distinct influence of enhanced hydrostatic pressure applied during sample annealing on strain state of inclusions was found. An increase of lattice distortion and of strain of inclusions for the samples treated under hydrostatic pressure is related to different bulk moduli of GaAs and of MnAs

6

Phonon Dispersion Analysis as an Indispensable Tool for Predictions of Solid State Polymorphism and Dynamic Metastability: Case of Compressed Silane

100%

Kurzydłowski D., Grochala W.

Acta Physica Polonica A

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2011

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vol. 119

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issue 6

895-900

EN

Diamond anvil cell experiments suggest that upon compression above 26.5 GPa silane (SiH_4) forms a polymeric phase VI, whose crystal structure has not yet been solved. Here we present DFT calculations showing how phonon-guided optimization leads to a polymeric Fdd2 structure which is the lowest-enthalpy polymorph of SiH_4 above 26.8 GPa, and which most probably can be identified as the experimentally observed polymeric phase. The new algorithm of predicting the lowest-energy structures enables simultaneous inspection of the potential energy surface of a given system, calculation of its vibrational properties, and assessment of chances for obtaining a metastable ambient-pressure structure via decompression. Our calculations indicate that at room temperature the differences in the vibrational and entropy terms contributing to the Gibbs free energy of different polymorphs of silane are negligible in comparison with corresponding differences in the zero-point energy corrections, in contrast to earlier suggestions. We also show that the Fdd2 polymorph should be metastable upon decompression up to 5 GPa, which suggests the possibility of obtaining a polymeric ambient-pressure form of SiH_4. Polymeric silane should exhibit facile thermal decomposition with evolution of molecular hydrogen and thus constitute an efficient (12.5 wt%) material for hydrogen storage.

7

High-Pressure Treatment up to 25~GPa of Czochralski Grown Si Samples Containing Different Admixtures and Defects

88%

Shchennikov V., Shchennikov V., Korobeynikov I., Morozova N.

Acta Physica Polonica A

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2013

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vol. 124

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issue 2

244-249

EN

The thermoelectric properties of a set of single crystalline Si wafers with different oxygen concentration grown by the Czochralski technique have been studied at ultrahigh pressures up to 25 GPa. The dependence of semiconductor-metal transition pressure at Czochralski grown Si on the concentration c_{O} of the interstitial oxygen was found to present a convex curve with the maximum near c_{O} ≈ 9 × 10^{17} cm^{-3}. The high pressure thermoelectric power method seems to be suitable for characterization of impurity-defect structure of Si wafers. For Si_{1 - x}Ge_{x} crystals (1% < x < 3%) the strong changes of both the value and the sign of thermoelectric power have been observed at pressures much less than ones of Si-I → Si-II transition. From nanoindentation data the phase transition Si-I → Si-II, corresponding to semiconductor-metal electronic transformation has been detected at the loading up to ≈ 10 mN. These findings suggest a way for creation of integrated circuits, in which zones with different types of conductivity and hence different p-n, p-n-p etc. structures may be "written" by applied stress at nanoscale level, and the control on the value of the above stresses now is possible by the proposed nanoindentation technique.

8

Pressure Influence on the Curie Temperature

88%

Rutkowski J., Wojtczak L., Zajac Š.

Acta Physica Polonica A

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2010

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vol. 118

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issue 5

745-746

EN

The pressure dependence of the ferromagnetic-paramagnetic phase transition temperature T_{C} (p) is of high interest due to its direct technological implications. The theoretical investigations of the Curie temperature T_{C} (p) considered in the ferromagnetic crystals have been studied employing various methods of calculations. The present paper is devoted to its description by means of the pseudoharmonic approximation approach.

Refine search results

Oxygen Precipitation in Si:O Annealed under High Hydrostatic Pressure

Defect Structure of Pressure Treated Czochralski Grown Silicon Investigated by X-Ray Topography and Diffractometry

Characterizing the Effects of Hot Isostatic Pressing on IN713C Superalloy Blade Microstructure by Electron Backscatter Diffraction

Study of Niobium Thin Films under Pressure

Pressure Variation of the Strain State of MnAs Nanoclusters Embedded in GaAs

Phonon Dispersion Analysis as an Indispensable Tool for Predictions of Solid State Polymorphism and Dynamic Metastability: Case of Compressed Silane

High-Pressure Treatment up to 25~GPa of Czochralski Grown Si Samples Containing Different Admixtures and Defects

Pressure Influence on the Curie Temperature