Low Temperature X-Ray Diffractometer with Closed Cycle Refrigeration System

1978 ◽  
Vol 22 ◽  
pp. 89-99
Author(s):  
U. Benedict ◽  
Y. Cornay ◽  
C. Dufour
Keyword(s):  
Phase Transformation ◽  
Low Temperature ◽  
Thermal Gradient ◽  
Quartz Crystal ◽  
Powdered Sample ◽  
Closed Cycle ◽  
Refrigeration System ◽  
Lattice Contraction ◽  
X Ray ◽  
Metallic Foils

An assembly consisting of an X-ray tube, a quartz crystal monochromator, and a vertical X-ray goniometer with proportional counter was mounted in a glove box for work with actinide metals and compounds. An evacuated camera containing the expander tube of a closed-cycle cryogenic system was fitted onto the goniometer. A thin layer of the powdered sample was fixed on the end-plate of the expander tube. Beryllium windows were provided in the camera wall for the incident and for the diffracted beam.The cooling camera is suitable for use with thin powder layers or metallic foils. Thicker layers can be studied, but a strong thermal gradient perpendicular to the specimen surface is expected. The camera has been applied to the study of lattice contraction and phase transformation at low temperature In actinide metals and compounds .

Displacive Phase Transformation in Vanadium - Substituted Lanthanum Niobate

1983 ◽  
Vol 24 ◽  
Author(s):  
A. T. Aldred ◽  
S.-K. Chan ◽  
M. H. Grimsditch ◽  
M. V. Nevitt
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Raman Scattering ◽  
Transformation Temperature ◽  
Complex Oxides ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order

ABSTRACTThe displacive transformations in complex oxides of the type LaNb1-xVxO4 has been studied by x-ray diffraction and Raman scattering for 0 < x < 0.3. X-ray diffraction results indicate that the transformation from the tetragonal high temperature structure (C4h6) to the monoclinic low-temperature structure (C2h6) is higher than first order and that the transformation temperature Tc is depressed significantly by V substitution. Raman scattering results show that the force constant between the nearest (Nb, V)O4 tetrahedral units behave uniquely compared to others. It softens at Tc as a function of composition and it also softens as a function of temperature as Tc is approached from above.

Charles S. Barrett: X-Ray Metallurgist — An Informal Portrait

1987 ◽  
Vol 2 (3) ◽  
pp. 163-175
Author(s):  
R. N. Rose
Keyword(s):  
Physical Chemistry ◽  
Phase Transformation ◽  
Low Temperature ◽  
First Principles ◽  
Atomic Level ◽  
X Ray Diffraction ◽  
Wide Audience ◽  
X Ray

Charles Barrett's work in phase transformation at the atomic level helped redefine the underpinnings of the science and practice of metallurgy. His work in low temperature physical chemistry has extended its range. And, perhaps more than anyone else, as a teacher and author, he has helped introduce the technique of X-ray diffraction to the present generations of practicing metallurgists.The relevance of his contributions is demonstrated by the continuing utility of his widely translated metallurgical text, Structure of Metals, which, when it first appeared, made the understanding of metallurgy at the atomic level accessible to a wide audience. Today this book has become a compendium of first principles.

A novel low-temperature X-ray goniometer with closed-cycle cooling to about 18 K

1980 ◽  
Vol 13 (5) ◽  
pp. 425-432 ◽  
Author(s):  
S. Samson ◽  
E. Goldish ◽  
C. J. Dick
Keyword(s):  
Low Temperature ◽  
Closed Cycle ◽  
X Ray

Ultra-low-temperature X-ray data collection with a newly developed 0.1 mm Kapton-film cylinder for a closed-cycle helium cryostat

2003 ◽  
Vol 36 (6) ◽  
pp. 1452-1454 ◽  
Author(s):  
Marc Meserschmidt ◽  
Mathias Meyer ◽  
Peter Luger
Keyword(s):  
Low Temperature ◽  
Data Collection ◽  
Vacuum Chamber ◽  
Closed Cycle ◽  
X Ray ◽  
Helium Cryostat ◽  
Fine Pitch ◽  
Low Costs ◽  
Data Collections ◽  
Ccd Detectors

A 0.1 mm Kapton-film vacuum chamber was constructed to be mounted on the cold head of a closed-cycle helium cryostat. The use of Kapton instead of beryllium results in a low and practically non-structured background, which is thus tolerable on the area-detection frames of modern CCD detectors. The Kapton chamber is only fixed at the upper and lower holders of the cryostat and its counterweight, and is stabilized by spanning with fine pitch threads, holding constant the necessary vacuum of 10−6 mbar for at least several days. Low costs and non-toxicity are further advantages of this material; moreover, the sample remains visible even after cooling. Data collections on strychnine single crystals at 15 K showed improvedI/σ ratios of high-order reflections compared with 100 K data, most favourably when synchrotron primary radiation was used.

New high- and low-temperature apparatus for synchrotron polycrystalline X-ray diffraction

1998 ◽  
Vol 5 (3) ◽  
pp. 929-931 ◽  
Author(s):  
C. C. Tang ◽  
G. Bushnell-Wye ◽  
R. J. Cernik
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Closed Cycle ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Furnace ◽  
Wide Range ◽  
Powder Samples ◽  
Heater Coil ◽  
Temperature Furnace

A high-temperature furnace with an induction heater coil and a cryogenic system based on closed-cycle refrigeration have been assembled to enhance the non-ambient powder diffraction facilities at the Synchrotron Radiation Source, Daresbury Laboratory. The commissioning of the high- and low-temperature devices on the high-resolution powder diffractometer of Station 2.3 is described. The combined temperature range provided by the furnace/cryostat is 10–1500 K. Results from Fe and NH4Br powder samples are presented to demonstrate the operation of the apparatus. The developments presented in this paper are applicable to a wide range of other experiments and diffraction geometries.

NANO-VANADIUM DOPING-DRIVEN LOW TEMPERATURE STRUCTURAL PHASE TRANSFORMATION IN TITANIA

2009 ◽  
Vol 23 (29) ◽  
pp. 3543-3549
Author(s):  
ANUJ KUMAR ◽  
BHASKER GAHTORI ◽  
NEERAJ KUMAR ◽  
V. P. S. AWANA ◽  
A. K. SRIVASTAVA ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Low Temperature ◽  
Structural Phase ◽  
Rutile Phase ◽  
Vanadium Content ◽  
Scanning Electron Micrographs ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Vanadium Doping

Synthesis, X-ray diffraction (XRD), morphological, and magnetization studies of nano-vanadium doped TiO 2 are reported here. Commercially available anatase nano- TiO 2 and nano-vanadium powders were mixed and heat-treated in air at 600°C. X-ray diffraction revealed a complete anatase to rutile phase transformation at low vanadium content of 5%. Samples annealed under different environments such as Ar and O 2 also exhibited the same trend. Such a phase transformation at relatively low temperature (600°C) has been explained based on enhanced reactivity between vanadium and TiO 2 powders. Scanning electron micrographs elucidated the tunable microstructures from irregular-shaped, in the pristine TiO 2 (x=0.0), to well-faceted polyhedra V-doped (x=0.05 to 0.15) samples. Room temperature magnetization results revealed that upto 10% vanadium doping the samples are diamagnetic in nature and exhibit a paramagnetic transition for higher V content which presumably can be attributed to the presence of vanadium pentaoxide observed in the XRD.

A low-temperature X-ray Weissenberg goniometer with closed-cycle cooling to about 28 K

1982 ◽  
Vol 15 (2) ◽  
pp. 241-244 ◽  
Author(s):  
W. Adlhart ◽  
H. Huber
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Single Crystal ◽  
Scattered Radiation ◽  
Angular Range ◽  
Closed Cycle ◽  
Cold Finger ◽  
X Ray ◽  
Crystal Rotation

A low-temperature camera for single-crystal X-ray investigation between 28 and 350 K has been developed for a modified Weissenberg goniometer. Cooling is provided by a double-stage cryorefrigerator which is firmly attached to the low-temperature camera. Stranded copper cables ensure a flexible heat transfer between crystal and cold finger allowing a crystal rotation of 180°. Compared to the usual Weissenberg technique almost no further limitation is given on the accessible angular range of the scattered radiation.

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