ID-B Laser Heating Table
The Laser Heating table is equipped with a double-sided infrared laser heating system integrated with ID-B’s monochromatic micro X-ray diffraction capability for studying structure properties of polycrystalline, single crystal, and amorphous materials under simultaneous ultra high PT conditions. The laser heating system offers (1) tunable laser heating spot sizes ranging from 4 to > 60 microns in flat-top area of the laser intensity profile (FWHM 9 to > 120 microns) with two identical IPG YLR-100-1064-WC fiber lasers operating in continuous-wave mode or in modulation mode, and (2) simultaneous temperature measurements from a 4-micron area in the center of the heating spot on both sides of the heated sample with an Acton SpectroPro SP2560 imaging spectrograph equipped with two area detectors: a back-illuminated CCD detector (PIXIS 400BR, Princeton Instruments) and a em-ICCD detector (PI-MAX, Princeton Instruments). With a mirror-pinhole setup at the entrance of the spectrograph, experimenters can actually observed from where the temperature is measured relative to the total area of the heated spot for precise alignment of the temperature sampling area with the center of the heating spot and X-ray beam to ensure experiment data quality. Incident X-ray beam is typically focused to 6 X 5 micron in FWHM with a 320 X 320 mm KB or to 2 X 1 microns with a 200 X 100 mm KB, and is spatially filtered through a clean-up pinhole to remove tailing radiation intensity before reaching the sample position. The diffraction patterns are recorded with interchangeable MAR CCD, MAR imaging plate, or a Pilatus 1M detectors. Supporting equipment includes online ruby and Raman systems, membrane remote pressure control.
Recent additions (2017):
(1) X-ray focus 2 X 1 micron (FWHM) with 200 X 100 mm KB
(2) 2D XRD imaging
Meng et al. "New developments in laser-heated diamond anvil cell with in-situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team", Review of Scientific Instruments 86, 072201 (2015)
Sample preparation for high-pressure laser heating
In a laser-heated DAC, a sample is heated by absorbing the IR laser radiation (1064 nm). If a sample is completely transparent or opaque to this radiation, heating will not be achieved by directing the laser beam to the sample. Therefore, it’s critical that the sample absorbs the 1064 nm radiation, or the sample is mixed with a laser absorber material (Pt black or others) if you plan to use our system with 1064 nm lasers. Furthermore, since diamond is a superb thermal conductor, insulation layers between diamond culets and the sample are highly desired to achieve good quality heating. In some cases, for example when the sample is metallic, the thermal insulation layers are absolutely required. An ideal sample arrangement is as shown in the figure below. Commonly used thermal insulation materials are NaCl, KCl, Ar, MgO, Al2O3. When choosing an insulation material, one should consider (1) pressure and temperature range of the experiment, (2) XRD pattern of the insulation material, to minimize or eliminate overlaps with the sample, (3) potential chemical reactions between the insulation material and the sample. Polished single crystal plates of MgO and Al2O3 have proven to be more effective thermal insulation layers than the pressed polycrystalline plates. If MgO powder is to be used, freshly crushed MgO single crystal is recommended.