New heating/cooling stage available to users at P02.1J. Bednarcik, J. Gamcova, H.P. Liermann

Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany

High Resolution Powder Diffraction (HRPD) Beamline P02.1 is part of the “Hard X-ray DiffractionBeamline P02” at PETRA III (DESY Hamburg, Germany). P02.1 is operated at a fixed energyof 60 keV. Its design is optimized for high resolution powder diffraction as well as the analysisof nanocrystalline materials and real-time (time resolved) investigation of chemical and physicaltransformation in a variety of materials.In this contribution we describe a new heating/cooling stage (Linkam THMS 600 [1]) we makeavailable to users at beamline P02.1. Figure 1 shows detailed view of the Linkam THMS 600 heat-ing/cooling stage together with description of its main components. The temperature controllerT95, cooling pump LNP95 and 2 litre Dewar are part of the setup but are not shown here. The cool-ing/heating stage covers temperature range from -196 ◦C up to 600 ◦C and enables in-situ XRDexperiments in transmission geometry. Samples are usually put inside a quartz capillary with diam-eter of 1 mm and having length of only 20 mm. The reason to have shorter capillary is that it canstay completely enclosed inside a stage and thus possible oxidation from outside atmosphere canbe avoided. Capillary length is further determined by the heater geometry and its placement withinthe stage. Samples in the form of thin ribbons can be directly attached to the body of the heater byusing a Cu-based paste, which ensures good thermal conductivity. Figure 2 shows typical arrange-ment of the heating stage with respect to the incident monochromatic beam and two-dimensionaldetector (2D) PE1621 during in-situ XRD experiment performed in transmission geometry. Theimage is also indicating how to mount the sample. The upstream side of the heater has 1.6 mm holefor the incident beam. The downstream side of the heater has a conical opening with angle 2θ=30 ◦,

Figure 1: Detailed view on Linkam THMS 600 furnace from upstream direction. Hereis description of individual parts: gas inlet (1) and outlet (2), cooling water inlet (3) andoutlet (4), 22 mm diameter pure silver heating block (5), liquid N2 inlet (6) and outlet (7),four pin LEMO type connector (8) for heating current and PT100 temperature sensor.Black silhouette behind the Linkam furnace belongs to 2D detector PE1621.

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∆T =

Tsa

mple

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hea

ter

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Theater (°C)

10 °C/min

Figure 2: Schematic sketch showing geometry of theheater and its alignment with respect to the incidentbeam and 2D detector. Samples are usually loaded i)inside a quartz capillary or ii) they can be attached di-rectly onto heater body if they have a form of thin sheet.

Figure 3: The temperature error, i.e. ∆T = Tsample −Theater, as a function of the heater temperature Theater.

which is limiting the maximum momentum wave vector transfer to qmax = 4πsin(θ)/λ. If we con-sider that the energy at P02.1 beamline is fixed to 60 keV (λ=0.207 A) and θmax=15 ◦ then we haveqmax ≈ 15.7 A−1. Assuming that the image plate detector PE1621 is centered with respect to theincident beam then optimal sample-to-detector distance ensuring q = 15.7 A−1 would be 355 mm.It should be noted here that narrower q-range with higher angular resolution can be achieved byincreasing sample-to-detector distance [2].Further we investigated temperature accuracy of the Linkam THMS 600 during heating at a con-stant rate of 10 ◦/min. Instead of sample we placed inside the heater additional thermocouple whichmonitored the sample temperature Tsample. The heater temperature Theater is determined by built-intemperature sensor and is used by the temperature controller T95 to regulate output power for theheater. The difference between Tsample and Theater, i.e. ∆T = Tsample −Theater gives an error of tem-perature determination. As can be seen from Fig.3 the temperature error ∆T is within ± 1 ◦C rangeand is well reproducible after two independent runs. Temperature oscillations appearing above490 ◦C are due to some instabilities of the T95 temperature controller. However their amplitudetends to decrease with further temperature increase. At the end we can state that the heating stageLinkam THMS 600 is very reliable and the temperature error on temperature range 20–600 ◦C iswithin ± 1 ◦C range.

References[1] http://www.linkam.co.uk/thms600-features/[2] J. Bednarcik, A.C. Dippel and H.P. Liermann, Instrument resolution of 2D diffraction setup at P02.1, DESY,

Photon Science, Annual Report 2011.