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Technique of studying possible structural transformations in liquid gallium, tin and indium using synchrotron radiation diffraction
644
Nuclear Instruments and Methods m Physics Research A282 (1989) 644-645 North-Holland, Amsterdam
TECHNIQUE OF STUDYING POSSIBLE STRUCTURAL TRANSFORMATIONS IN LIQUID GALLIUM, TIN AND INDIUM USING SYNCHROTRON RADIATION DIFFRACTION A.I . ANCHAROV and B.R. GELCHINSKII Institute of lnorgamcal and Physical Chemistry, Academy of Sciences of the Kirgiz SSR, Frunze, 720071, USSR
A technique of studying possible structural transformations m liquid metals is discussed . The scheme of the experiment and apparatus for the study of structural transformations using the synchrotron radiation diffraction method are described
The idea
of structural
transformations in
liquid
metals appeared as a result of analysis of temperature and concentration dependences, the so-called structur-
The experimental installation was mounted on SR channel 5 of the VEPP-3 storage ring . The SR beam from
resistance, etc.) . However, measurement of structurally
the storage ring running along the vacuum channel falls on the monochromator. A curved silicon crystal with asymmetrical cut was used as a monochromator to
tion of structural transformations as the magnitude of
Then the monochromatized SR beam flows through a
ally
sensitive properties (density, viscosity, electrical
sensitive properties does not yet mean direct observa-
structurally sensitive properties may be affected by a number of factors hard to register. Therefore, to obtain
direct
information on
structural
transformations in
liquid metals, a diffractional experiment is quite natural. As a parameter to fudge on structural transformation
the position of the structural
factor's principal maximum or intensity curve is chosen .
Refs . [1,2] relate the temperature dependences of the
positions of the first maxima of liquid rubidium and cesium structural factors with the use of neutron diffraction . It
was proved
that
m a narrow range of temperatures (20-40 K) the position of the principal maximum changes sharply (0 .05-0.09 .4 - ') . Using an
X-ray tube for a radiation source, good resolution (0.01 f1 -i ) to the wave vector space cannot be
obtained
without considerable reduction of the radiation inten-
sity and, hence, prolongation of the experiment . Thus
the use of synchrotron radiation (SR) with natural collimation and high intensity for the study of structural transformations in liquid metals is expedient. An experimental arrangement during which the radi-
ation beam falls on the free surface of the sample and scattered radiation is registered under various angles
was discarded for a number of factors - first, SR propagates m the horizontal plane while the liquid
metal surface is also horizontal ; second, a displacement of the sample surface from the goniometer axis contrib-
obtain a converging SR beam with high radiation flow . collimation system consisting of three sets of vertical and horizontal slits, forming the required beam dimen-
sions, and falls on the sample . The sample was installed
to the high-temperature chamber of the UVVD-2500 installation . The chamber was modified for registration
of scattering in the vertical plane and consists of a water-cooled casing with Be windows for beam entrance
and exit, a system of Mo heat screens and a tungsten foil strip heater. The sample holder is a tungsten support carrying two 2 mm stainless steel polished plates with a 3 mm central hole . Two plates clamp the sample, being a "sandwich" of two 10 pin mica plates, with a 10-30 win foil of the metal under investigation between them . Such a holder construction enables to cut off the
X-ray radiation scattered in the air and at the chamber
entrance window . The temperature was measured by a W-Re thermocouple placed in the sample holder support .
The temperature was controlled precisely, to better than 1 K. The high-temperature chamber was placed on
the axis of the "Philips PW 1060" vertical gonometer. A scintillation detector [4] was used for the registration of the scattered radiation. A 30% absorption ionization
chamber monitored the initial radiation . CAMAC units and "Odrenok" [5] crate controllers served as a basis for automation of the experiment .
utes greatly to the wave vector resolution . With a change
99 .9% purity samples of indium, gallium and tin were used for the experiments. The electron energy at
the sample, crucible, holder
length radiation. First. solid samples were studied to
of temperature the displacement may change uncontrollably due to a change of the meniscus shape caused by temperature expansion . Therefore, a "transmission" arrangement was used [3] .
0168-9002/89/$03 .50 U Elsevier Science Publishers B.V . (North-Holland Physics Publishing Division)
the storage ring was 2 GeV with a current of 100-200 mA . The monochromator was adjusted to 1.38 A wavecheck the correctness and stability of the experimental
A./. Ancharoo, B R. Gelchtnskii / Studying possible structural transformations to liquid Ga, Sn and In
equipment. Then the liquid samples were studied. The position of the principal maximum was precisely determined by scanning in a narrow range of angles with 0,01 f\ -1 steps. The usage of narrower slits (0 .1 mm) forming the vertical dimension of the beam enables to focus the position of the principal maximum with an accuracy of not less than 0.005 A-t . The position of the principal maximum at the melting point coincides with the published data . The above technique enables to study the temperature dependence of the structural factor's first maximum with the required angle and temperature resolutions . The insufficient number of measurements obtained so far prevented us from a statistical analysis of the experimental data to present the final results in a curve with the range of statistical errors . However, even pre-
645
limmary data obtained from melted gallium, indium and tin testify to the presence of considerable changes of the structural factor's first maximum for some temperatures in a rather wide range of measurements .
References [11 U I. Sharykin et al ., Dok. Akad . Nauk SSSR 244 (1979) 78 [2] A.U . Astapkovtch et al., Dok. Akad. Nauk SSSR 263 (1982) 73 [3] D.M . North and C.N . Wagner, J Appl . Crystallogr. 2 (1969) 149. [4] E.N . Dementyev, M.A . Sheromov and A S. Sokolov, Nucl Instr. and Meth A246 (1986) 549. [5] N.A Mezentsev and V.F. Pindyunn, INP-Prepnnt 87-107 .
V. MATERIALS SCIENCE
Nuclear Instruments and Methods m Physics Research A282 (1989) 644-645 North-Holland, Amsterdam
TECHNIQUE OF STUDYING POSSIBLE STRUCTURAL TRANSFORMATIONS IN LIQUID GALLIUM, TIN AND INDIUM USING SYNCHROTRON RADIATION DIFFRACTION A.I . ANCHAROV and B.R. GELCHINSKII Institute of lnorgamcal and Physical Chemistry, Academy of Sciences of the Kirgiz SSR, Frunze, 720071, USSR
A technique of studying possible structural transformations m liquid metals is discussed . The scheme of the experiment and apparatus for the study of structural transformations using the synchrotron radiation diffraction method are described
The idea
of structural
transformations in
liquid
metals appeared as a result of analysis of temperature and concentration dependences, the so-called structur-
The experimental installation was mounted on SR channel 5 of the VEPP-3 storage ring . The SR beam from
resistance, etc.) . However, measurement of structurally
the storage ring running along the vacuum channel falls on the monochromator. A curved silicon crystal with asymmetrical cut was used as a monochromator to
tion of structural transformations as the magnitude of
Then the monochromatized SR beam flows through a
ally
sensitive properties (density, viscosity, electrical
sensitive properties does not yet mean direct observa-
structurally sensitive properties may be affected by a number of factors hard to register. Therefore, to obtain
direct
information on
structural
transformations in
liquid metals, a diffractional experiment is quite natural. As a parameter to fudge on structural transformation
the position of the structural
factor's principal maximum or intensity curve is chosen .
Refs . [1,2] relate the temperature dependences of the
positions of the first maxima of liquid rubidium and cesium structural factors with the use of neutron diffraction . It
was proved
that
m a narrow range of temperatures (20-40 K) the position of the principal maximum changes sharply (0 .05-0.09 .4 - ') . Using an
X-ray tube for a radiation source, good resolution (0.01 f1 -i ) to the wave vector space cannot be
obtained
without considerable reduction of the radiation inten-
sity and, hence, prolongation of the experiment . Thus
the use of synchrotron radiation (SR) with natural collimation and high intensity for the study of structural transformations in liquid metals is expedient. An experimental arrangement during which the radi-
ation beam falls on the free surface of the sample and scattered radiation is registered under various angles
was discarded for a number of factors - first, SR propagates m the horizontal plane while the liquid
metal surface is also horizontal ; second, a displacement of the sample surface from the goniometer axis contrib-
obtain a converging SR beam with high radiation flow . collimation system consisting of three sets of vertical and horizontal slits, forming the required beam dimen-
sions, and falls on the sample . The sample was installed
to the high-temperature chamber of the UVVD-2500 installation . The chamber was modified for registration
of scattering in the vertical plane and consists of a water-cooled casing with Be windows for beam entrance
and exit, a system of Mo heat screens and a tungsten foil strip heater. The sample holder is a tungsten support carrying two 2 mm stainless steel polished plates with a 3 mm central hole . Two plates clamp the sample, being a "sandwich" of two 10 pin mica plates, with a 10-30 win foil of the metal under investigation between them . Such a holder construction enables to cut off the
X-ray radiation scattered in the air and at the chamber
entrance window . The temperature was measured by a W-Re thermocouple placed in the sample holder support .
The temperature was controlled precisely, to better than 1 K. The high-temperature chamber was placed on
the axis of the "Philips PW 1060" vertical gonometer. A scintillation detector [4] was used for the registration of the scattered radiation. A 30% absorption ionization
chamber monitored the initial radiation . CAMAC units and "Odrenok" [5] crate controllers served as a basis for automation of the experiment .
utes greatly to the wave vector resolution . With a change
99 .9% purity samples of indium, gallium and tin were used for the experiments. The electron energy at
the sample, crucible, holder
length radiation. First. solid samples were studied to
of temperature the displacement may change uncontrollably due to a change of the meniscus shape caused by temperature expansion . Therefore, a "transmission" arrangement was used [3] .
0168-9002/89/$03 .50 U Elsevier Science Publishers B.V . (North-Holland Physics Publishing Division)
the storage ring was 2 GeV with a current of 100-200 mA . The monochromator was adjusted to 1.38 A wavecheck the correctness and stability of the experimental
A./. Ancharoo, B R. Gelchtnskii / Studying possible structural transformations to liquid Ga, Sn and In
equipment. Then the liquid samples were studied. The position of the principal maximum was precisely determined by scanning in a narrow range of angles with 0,01 f\ -1 steps. The usage of narrower slits (0 .1 mm) forming the vertical dimension of the beam enables to focus the position of the principal maximum with an accuracy of not less than 0.005 A-t . The position of the principal maximum at the melting point coincides with the published data . The above technique enables to study the temperature dependence of the structural factor's first maximum with the required angle and temperature resolutions . The insufficient number of measurements obtained so far prevented us from a statistical analysis of the experimental data to present the final results in a curve with the range of statistical errors . However, even pre-
645
limmary data obtained from melted gallium, indium and tin testify to the presence of considerable changes of the structural factor's first maximum for some temperatures in a rather wide range of measurements .
References [11 U I. Sharykin et al ., Dok. Akad . Nauk SSSR 244 (1979) 78 [2] A.U . Astapkovtch et al., Dok. Akad. Nauk SSSR 263 (1982) 73 [3] D.M . North and C.N . Wagner, J Appl . Crystallogr. 2 (1969) 149. [4] E.N . Dementyev, M.A . Sheromov and A S. Sokolov, Nucl Instr. and Meth A246 (1986) 549. [5] N.A Mezentsev and V.F. Pindyunn, INP-Prepnnt 87-107 .
V. MATERIALS SCIENCE