Crystalline to amorphous phase transition of tin oxide nanocrystals induced by SHI at low temperature

2012 ◽  
Author(s):  
Vijay Kumar ◽  
Deepti Pratap ◽  
Anshul Jain ◽  
D. C. Agarwal ◽  
I. Sulania ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Tin Oxide

The influence of surface roughening and Si{111} facets on low temperature Si homoepitaxy

1996 ◽  
Vol 54 ◽  
pp. 950-951
Author(s):  
O.P Karpenko ◽  
S.M. Yalisove
Keyword(s):  
Phase Transition ◽  
Surface Roughness ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Amorphous Phase ◽  
Substrate Surface ◽  
Growth Surface ◽  
Surface Roughening ◽  
Arrhenius Relation ◽  
Amorphous Si

Recent research in the area of low temperature (T<450°C) epitaxial growth of semiconductors has revealed a number of interesting phenomena which are not yet fully understood. One suchphenomena is the crystalline to amorphous phase transition which occurs during low temperature Si homoepitaxy. For low temperature Si homoepitaxy, crystalline growdi is limited by a critical epitaxial thickness (hepi), beyond which Si grows as an amorphous phase. It has been established that hepi follows an Arrhenius relation with temperature, is preceded by an increase in surface roughness,and is affected by the presence of impurities and the substrate surface orientation. Although the formation of amorphous Si is not fully understood, several models have been proposed to explain this phenomenon. One of these models suggests that Si amorphization is associated with surface roughening andthe formation of Si{111} facets at the growth surface. According to this model, hepi shoulddecreaseasthe density of Si{111} microfacets on the starting increases.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

Reversible displacive phase transition in [Ni(en)3]2+(NO3−)2: a potential temperature calibrant for area-detector diffractometers

2003 ◽  
Vol 36 (1) ◽  
pp. 141-145 ◽  
Author(s):  
L. J. Farrugia ◽  
P. Macchi ◽  
A. Sironi
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Low Temperature ◽  
Potential Temperature ◽  
Rapid Decrease ◽  
Data Sets ◽  
Area Detector ◽  
Displacive Phase Transition ◽  
Orientation Matrix ◽  
Bruker Smart Apex

The coordination complex [Ni(en)3]2+(NO{}_{3}^{- })2(en = 1,2-diaminoethane) undergoes a sharp reversible displacive phase transition at ∼109 K, changing space group fromP6322 above the transition temperature toP6522 below. The phase change is accompanied by a tripling of thecaxis on cooling, resulting in an easy detection of the transition in images from area-detector diffractometers. The transition has been followed using a Nonius KappaCCD and a Bruker SMART APEX CCD. Data sets were collected over the temperature range 100–113 K and integrated using the low-temperature orientation matrix. Reflections withl≠ 3nshow a smooth and rapid decrease in intensity to zero on warming from 106.5 to 111 K. The results are reproducible to within ±2 K in two laboratories and suggest that this compound may be useful as a liquid-nitrogen cryo-calibrant for diffraction instruments equipped with area detectors.

Possible low-temperature phase transition of Langmuir–Blodgett films of a charge–transfer complex detected by ESR

1998 ◽  
Vol 327-329 ◽  
pp. 391-394
Author(s):  
Keiichi Ikegami ◽  
Shin-ichi Kuroda ◽  
Tomoyuki Akutagawa ◽  
Taro Konuma ◽  
Takayoshi Nakamura ◽  
...  
Keyword(s):  
Phase Transition ◽  
Charge Transfer ◽  
Low Temperature ◽  
Charge Transfer Complex ◽  
Temperature Phase ◽  
Langmuir Blodgett ◽  
Langmuir Blodgett Films ◽  
Temperature Phase Transition ◽  
A Charge ◽  
Low Temperature Phase

Low-Temperature Structure (T = 235 K) and Structural Phase Transition in [(C2H5)4N]2SnCl6

1987 ◽  
Vol 103 (1) ◽  
pp. 73-78 ◽  
Author(s):  
H. Ketata ◽  
M. H. Ben Ghozlen ◽  
A. Daoud ◽  
I. Pabst
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Temperature Structure
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