HTD2: a single-crystal X-ray diffractometer for combined high-pressure/low-temperature experiments at laboratory scale

Abstract

High-pressure (HP) X-ray diffraction experiments at low temperature (LT) require dedicated instruments as well as non-standard sample environments and measuring strategies. This is especially true when helium cryogenic temperatures below 80 K are targeted. Furthermore, only experiments on single-crystalline samples provide the prerequisites to study subtle structural changes in the p–T phase diagram under extreme LT and HP conditions in greater detail. Due to special hardware requirements, such measurements are usually in the realm of synchrotron beamlines. This contribution describes the design of an LT/HP diffractometer (HTD2) to perform single-crystal X-ray diffraction experiments using a laboratory source in the temperature range 400 > T > 2 K while applying pressures of up to 20 GPa.

Experimental X-ray Charge-Density Studies─A Suitable Probe for Superconductivity? A Case Study on MgB2

“…Two different setups were employed to collect the XRD data in this paper: an experiment at 100(2) K was performed on a BRUKER Smart-Apex diffractometer featuring a D8 goniometer, an APEX II CCD detector, an INCOATEC AgK α microfocus sealed-tube as an X-ray source (λ = 0.56087 Å), and a standard OXFORD open-flow N 2 cooler (diffractometer 1) . Experiments at temperatures from RT down to sub-nitrogen cryogenic temperatures relied on a HUBER four-circle Eulerian cradle goniometer equipped with a DECTRIS Pilatus3R CdTe 300K pixel detector, an INCOATEC AgK α microfocus sealed-tube X-ray source (λ = 0.56087 Å), and an ARS closed-cycle helium cryocooler with an outer and inner beryllium vacuum and radiation shield (diffractometer 2) . Data collection at different temperatures was performed in direct sequence without sample reorientation.…”

“…13 Experiments at temperatures from RT down to sub-nitrogen cryogenic temperatures relied on a HUBER four-circle Eulerian cradle goniometer equipped with a DECTRIS Pilatus3R CdTe 300K pixel detector, an INCOATEC AgK α microfocus sealed-tube X-ray source (λ = 0.56087 Å), and an ARS closed-cycle helium cryocooler with an outer and inner beryllium vacuum and radiation shield (diffractometer 2). 14 Data collection at different temperatures was performed in direct sequence without sample reorientation. Recorded Bragg intensities were evaluated using the APEX2 12 (diffractometer 1) or the EVAL14 integration programs 15,16 (diffractometer 2) and subjected to scaling and absorption corrections using the program SADABS.…”

Peierls-type structural phase transition in the low-dimensional superconductor Sc3CoC4

“…The presence of a Peierls-type structurally distorted low-temperature phase in the transition-metal carbide Sc 3 CoC 4 has been observed in several earlier investigations [46][47][48][49][50][51][52]. It could be shown that the structural changes between high-temperature (HT) phase (space group Immm, no.…”

“…Additional laboratory-scale XRD experiments in the temperature range between 10 K and 300 K were performed employing a Huber four-circle Eulerian cradle goniometer fitted with an Incoatec AgK α microfocus sealedtube x-ray source (λ = 0.56087 Å), a Dectris PILATUS3 R CdTe 300K hybrid-pixel detector and an Advanced Research Systems closed-cycle helium cryocooler with domed beryllium vacuum and radiation shields (subsequently referred to as "laboratory-scale instrumental setup 2"; see Ref. 52 for a detailed description). The collected XRD data sets were processed using the program eval14 [68][69][70] to determine unit cell parameters and reflection intensities corresponding to the orthorhombic and monoclinic unit cells of HT-phase and LT-phase structural models.…”

“…Intriguing hybrids between electronic and structural phase transitions are the charge-density waves forming in quasi-onedimensional [34][35][36][37] and quasi-two-dimensional superconductors [35,[38][39][40][41][42][43][44] as well as copper-oxide-based super- * georg.eickerling@uni-a.de conductors [17][18][19][20][21][22][23][24][25]35]. Also in the transition-metal carbide Sc 3 CoC 4 [45][46][47][48][49][50][51][52][53][54][55][56][57], a Peierls-type structural phase transition from an orthorhombic high-temperature (HT) phase (space group Immm, no. 71 [58]) to a monoclinic low-temperature (LT) phase (space group C2/m, no.…”