Quantitative texture analysis by Rietveld refinement

Abstract

A generalized spherical‐harmonic description of the texture for polycrystalline materials has been implemented in a multiple‐phase/multiple‐data‐set Rietveld refinement code. It has been tested using two sets of neutron time‐of‐flight data taken from a standard calcite sample previously used for a round‐robin study [Wenk (1991). J. Appl. Cryst.24, 920–927] and has been shown to give similar texture results as those obtained from individual pole figures. Simultaneous refinement of the calcite crystal structure including anisotropic thermal parameters gives results essentially identical to a recent single‐crystal X‐ray study.

Improper ferroelectricity in helicoidal antiferromagnet Cu3Nb2O8

“…The baseline of specific heat (below 22 K) of 0.97 J/mole-K 2 is associated with development of short range magnetic correlation that relate to collective contribution of lattice and spin [14]. In the inset of Figure 2b, heat capacity C P is plotted over a broader temperature range and we can observe deviation around 60 K as well, the reason for which is yet to be ascertained.…”

“…First sintering was done at 800°C for 36 hour and next was done at 950°C for 40 hour. Powder X-ray diffraction (XRD) pattern was performed using PANalytical X'Pert PRO at room temperature and Rietveld refinement was done with GSAS software [14]. Neutron diffraction (ND) was carried out on powder sample using multiple sensitive detectors (PSD) Focussing Crystal Diffractometer (FCD) set up by UGC-DAE Consortium for Scientific Research Mumbai centre at the National Facility for Neutron Beam Research (NFNBR), Dhruva reactor, Mumbai (India) at a wavelength of 1.48Å.…”

Hard X-ray studies of stress-induced phase transformations of superelastic NiTi shape memory alloys under uniaxial load

“…Diffraction intensities were extracted with FIT2D into a multicolumn ASCII spread sheet [12], where each column corresponds to an intensity distribution along the azimuth for a particular 2θ value. The peak positions were identified from full profile analysis using the GSAS refinement code [13] and intensity versus azimuth data for particular reflections were extracted. It needs to be considered that the diffraction ring is not circular if the material is under stress [14].…”

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

“…However, the deformed austenite (despite being untextured at the start and finish of the test) develops a reversible texture that correlates with the austenite/martensite ratio [8,9]. This, along with the evolving texture in the martensite, is accommodated in the refinement by a generalized harmonic description of the texture [15,16] within the correction factor K. The other aspect of the refinements that warrants special attention is the strain. Since loading was uniaxial, the 'macroscopic' strain differs parallel and perpendicular to the load direction.…”