X-RAY PHASE MEASUREMENTS USED AS A PROBE OF SMALL STRUCTURAL CHANGES INDUCED BY DOPANTS IN CRYSTALS OF TECHNOLOGICAL RELEVANCE

• Grant number: 12/01367-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2012
• End date: June 30, 2014
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Sérgio Luiz Morelhão
• Grantee: Zohrab Gevorg Amirkhanyan
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The phases of diffracted X-ray waves in crystals carry extra structural information, many of which are lost in intensity measurements of single Bragg reflections. By n-beam diffraction (nBD) experiments it is possible to access phase values. A long ago, there was the hope in solving the phase problem in X-ray crystallography by means of these experiments, but accessing even one phase value with good accuracy was too difficult. Recently, we have shown that phase measurements are useful for studying doped non-linear optic (NLO) materials [J. Appl. Cryst. 44, 82 (2011)]. However, it lead us to another challenge, the one of predicting which nBD are susceptible to small structural changes induced by doping. The presence of foreign ions into the crystal lattice introduces internal stress and rebalancing of charges in the neighboring atoms (of the dopant ions). By structural modeling is possible, in general, to determine a few probable structural changes, but the resolution of the common techniques of structural analysis may not be enough to detect such changes, and thus, to confirm if the changes are in fact occurring. The aim of this work is to create and to validate experimentally systematic procedures capable of predicting the best nBDs to elucidate structural changes feasible to occur in doped NLO crystals. Therefore, we will be providing a new tool of structural analysis for this class of materials and, at the same time, further studying the ion incorporation dynamics into crystalline lattices.

Scientific publications

(6)

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

MORELHAO, SERGIO L.; REMEDIOS, CLAUDIO M. R.; CALLIGARIS, GUILHERME A.; NISBET, GARETH. X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological molecules via physical phase measurements. JOURNAL OF APPLIED CRYSTALLOGRAPHY, v. 50, n. 3, p. 689-700, JUN 2017. (14/21284-0, 14/08819-1, 16/11812-4, 12/01367-2, 12/15858-8)

AMIRKHANYAN, ZOHRAB G.; REMEDIOS, CLAUDIO M. R.; MASCARENHAS, YVONNE P.; MORELHAO, SERGIO L.. Analyzing structure factor phases in pure and doped single crystals by synchrotron X-ray Renninger scanning. JOURNAL OF APPLIED CRYSTALLOGRAPHY, v. 47, p. 6-pg., 2014-01-01. (12/01367-2)

MORELHAO, SERGIO L.; REMEDIOS, CLAUDIO M. R.; CALLIGARIS, GUILHERME A.; NISBET, GARETH. X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological molecules via physical phase measurements. JOURNAL OF APPLIED CRYSTALLOGRAPHY, v. 50, p. 12-pg., 2017-06-01. (12/01367-2, 16/11812-4, 14/08819-1, 14/21284-0, 12/15858-8)

MORELHAO, SERGIO L.; AMIRKHANYAN, ZOHRAB G.; REMEDIOS, CLAUDIO M. R.. Absolute refinement of crystal structures by X-ray phase measurements. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, v. 71, n. 3, p. 291-296, MAY 2015. (12/01367-2, 14/08819-1)

AMIRKHANYAN, ZOHRAB G.; REMEDIOS, CLAUDIO M. R.; MASCARENHAS, YVONNE P.; MORELHAO, SERGIO L.. Analyzing structure factor phases in pure and doped single crystals by synchrotron X-ray Renninger scanning. JOURNAL OF APPLIED CRYSTALLOGRAPHY, v. 47, n. 1, p. 160-165, JAN 2014. (12/01367-2)

MORELHAO, SERGIO L.; AMIRKHANYAN, ZOHRAB G.; REMEDIOS, CLAUDIO M. R.. Absolute refinement of crystal structures by X-ray phase measurements. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, v. 71, p. 6-pg., 2015-05-01. (14/08819-1, 12/01367-2)