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Journal ArticleDOI

Fine temperature stabilizer for x-ray diffraction measurements

01 Jun 1997-Review of Scientific Instruments (American Institute of Physics)-Vol. 68, Iss: 6, pp 2301-2304
TL;DR: In this paper, a simple and versatile method of high-temperature stability is presented for x-ray diffraction measurements near room temperature, which is capable of being directly and easily mounted on the commercially available goniometer head.
Abstract: A simple and versatile method of high-temperature stability is presented for x-ray diffraction measurements near room temperature. The small sample cell for the measurements possesses coaxial multishells to guarantee the temperature homogeneity in the shells. It is capable of being directly and easily mounted on the commercially available goniometer head. A double-stage temperature control is adopted using both a heater and a thermoelectric module. The temperature is regulated by an optimized proportional integral derivative (PID) control. The base-line stability of the temperature at the sample stage in the cell is within ±0.5 mK. X-ray precession patterns of PbCsCl3 single crystal were taken at two temperatures separated by 30 mK across the phase transition point, showing the appearance and disappearance of a diffraction spot from the superstructure.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the use of thermoelectric modules as heat flux sensor and as a heat pump in a hand-made calorimeter enables the authors to measure thermal phenomena with high sensitivity and high thermal stability at very slow heating and cooling rates.
Abstract: We constructed an apparatus that enables us to simultaneously detect structural changes of molecules and the accompanying thermal phenomena by combining a commercially available Raman spectrometer and a hand-made calorimeter. The use of thermoelectric modules as a heat flux sensor and as a heat pump in our calorimeter enables us to measure thermal phenomena with high sensitivity and high thermal stability at very slow heating and cooling rates. Efficiency is important to treat a small amount of sample and also to make the experimental conditions nearly quasi-static by balancing the heating effect of laser beam irradiation. As a performance test, we measured a prototype ionic liquid (IL), 1-buthyl-3-methylimidazolium bromide ([bmim]Br), which has some characteristic thermal properties. It was confirmed that the melting links to the cooperative conformational change of the butyl group in the [bmim]+ ion.

29 citations

Journal ArticleDOI
TL;DR: In this paper, X-ray diffraction measurements using a precession camera have clarified that BaTiO3 single crystals have coherent hybrid structures with tetragonal and monoclinic lattices.

14 citations

Journal ArticleDOI
TL;DR: In this paper, a cold stage for Bragg-Brentano geometry X-ray powder diffraction is described for use in the temperature range from about 250 to 300 K. The stage is constructed in such a way that it may be removed from the diffractometer and pre-cooled to its base temperature before the sample is loaded.
Abstract: A cold stage for Bragg–Brentano geometry X-ray powder diffraction is described for use in the temperature range from about 250 to 300 K. The stage is constructed in such a way that it may be removed from the diffractometer and pre-cooled to its base temperature before the sample is loaded. After loading, thermoelectric cooling maintains the specimen at low temperature (ice free) whilst the body of the stage is allowed to return to room temperature prior to remounting on the diffractometer.

13 citations


Cites background from "Fine temperature stabilizer for x-r..."

  • ...…been described previously for single-crystal X-ray diffraction (e.g. Machin et al., 1984; Fraase Storm & Tuinstra, 1986; Arndt & Stubbings, 1987; Kojima et al., 1997), single-crystal neutron diffraction (e.g. Agron & Levy, 1972) and X-ray powder diffraction (e.g. Horne et al., 1959; Auby et…...

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Journal ArticleDOI
TL;DR: In this paper, thermal and X-ray diffraction measurements were carried out for the phase transition in CsPbCl 3 using ''mK-stabilized cells' with the temperature stability less than a few mK.

12 citations

Journal ArticleDOI
TL;DR: In this paper, a millikelvin (mK)-stabilized cell was developed for the detailed x-ray diffraction study of solid phase transitions, which is easily mounted on a commercially available goniometer head.
Abstract: Based on our technique of fine temperature control, we developed a new “millikelvin (mK)-stabilized cell” having a function of sensing thermal anomalies for the detailed x-ray diffraction study of solid phase transitions. It is easily mounted on a commercially available goniometer head. The performance was tested using CsPbCl3 single crystal, in which a phase transition is known to take place at 320 K (47°C) from tetragonal to cubic. An abrupt variation in the distance between some two reciprocal points in the precession pattern was clearly detected in a 0.1 K temperature range centered at 47°C along with two thermal anomalies observed. The “mK-stabilized cell” will be very useful to investigate a mechanism of phase transitions occurring in a narrow temperature range.

12 citations

References
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Journal ArticleDOI
TL;DR: In this article, the phase transitions and the crystal structures of a superionic conductor Ag 3 SI were investigated by specific heat measurements and by X-ray as well as neutron diffraction methods.
Abstract: The phase transitions and the crystal structures of a superionic conductor Ag 3 SI were investigated by specific heat measurements and by X-ray as well as neutron diffraction methods. The transition entropies were measured to be 1.44 cal/mol·deg for the γ- β transition at 157 K and 2.71 cal/mol·deg for the β- α transition at 519 K. The least squares refinements of atomic positions and isotropic temperature factors were carried out. β-Ag 3 SI is cubic with space group Pm3m in which Ag is distributed into four positions apart 0.5 A from the face centered position toward [100], while in γ-Ag 3 SI below 157 K, Ag is located at one of these four positions obeying the symmetry of the rhombohedral space group R3. From these experimental results, it was found that the nature of the successive phase transitions in Ag 3 SI was not only of the order-disorder type but also of a structural phase transition. A comparison was made with the phase transition of CsPbCl 3 .

60 citations

Journal ArticleDOI
TL;DR: In this article, a temperature controller utilizing a thermistor in a high impedance ac Wheatstone bridge was constructed to maintain the temperature of a 1.3 liter volume to within ±15 μ°C, over a 40h period.
Abstract: We have constructed a temperature controller utilizing a thermistor in a high impedance ac Wheatstone bridge. It maintains the temperature of a 1.3 liter volume constant to within ±15 μ°C, over a 40 h period. The controller employs a ratio transformer, a simple homemade preamplifier, a commercial lock‐in amplifier, a small bipolar power amplifier, and a thermoelectric device. Access to the controlled region can be obtained in a few seconds.

44 citations

Journal ArticleDOI
TL;DR: In this paper, an active proportional thermostat for geophysical accelerometers in boreholes is described, which is of small size and weight, is simple to operate, and requires less than 5 W of power.
Abstract: The general problem of designing active proportional thermostats is discussed, and a design philosophy is deduced. The application of this philosophy to the construction and operation of a precision proportional thermostat for geophysical accelerometers in boreholes is described in detail. The thermostat discussed is of small size and weight, is simple to operate, and requires less than 5 W of power. It maintains the temperature of an instrument and its vacuum enclosure of 1688 cm3 total volume and 7 kg mass constant within 10 μ°C over periods of days in the presence of fluctuations in the ambient temperature of several degrees. Various models of the thermostat, with several different configurations of thermal insulation, have been tested extensively in both laboratory and borehole environments. Stable proportional operation has been achieved with setpoint temperatures ranging from 15 to 35 °C and with the difference between the setpoint and mean ambient temperatures varying from 4 to 10 °C. The electronic circuitry is designed to provide a maximum heater power of 15 W, and the thermistor is calibrated over the range −40–150°C. With suggested modifications, the thermostat is applicable to a variety of instruments over a fairly wide temperature range.

42 citations

Journal ArticleDOI
TL;DR: In this article, three phase transitions were confirmed in perovskite-type crystal CsPbCl 3 by observing changes of conoscopic figures with temperature, and measurements of the temperature dependence of birefringence and specific heat were also performed.

38 citations