Search results for "diffraction"

Single-Element Reflective Digital Holographic Microscopy

2021

Digital holographic microscopy (DHM) is a well-known microscopy technique using an interferometric architecture for quantitative phase imaging (QPI) and it has been already implemented utilizing a large number of interferometers. Among them, single-element interferometers are of particular interest due to its simplicity, stability, and low cost. Here, we present an extremely simple common-path interferometric layout based on the use of a single one-dimensional diffraction grating for both illuminating the sample in reflection and generating the digital holograms. The technique, named single-element reflective digital holographic microscopy (SER-DHM), enables QPI and topography analysis of r…

TEM studies on La2−2xCa1+2xMn2O7 (x=0.5 and 0.25)

2003

The nominal compositions and structures of the compounds La2-2xCa1+2xMn2O7 (x=0.5 and 0.25) prepared by solid-state reaction have been studied by transmission electron microscopy and high-resolution electron microscopy. Besides the observation of the major phase of a two-layer structure in the nominal composition La1.0Ca2.0Mn2O7, the embedded n = 3, n = 4 Ruddlesden-Popper phases and La rich phase in the two-layer structure were observed as defects. No layered structure was observed in the nominal composition La1.5Ca1.5Mn2O7. Instead, a major phase of orthorhombically distorted perovskite, a minor phase of an ideal cubic perovskite, and a small fraction of calcium-oxide were observed in the…

Submicrometer CaCuO2 and Ca2CuO3 particles from bimetallic formate precursors

1992

Abstract CaCuO2 and Ca2CuO3 are readily obtained by thermal decomposition of two new calcium and copper formates, CaCu(HCOO)4 and Ca2Cu(HCOO)6. These chemical-precursor based syntheses, while overcoming problems related to the stoichiometry of the final products, involve very short diffusion path lengths. This, in turn, results in soft treatments yielding pure phases constituted by submicrometer (≈0.4 μm) homogeneous particles.

Quantitative X-Ray Powder Diffraction Analysis of Some Feldspars Used as Raw Material in Ceramics

2001

Synthesis of Nd:YAG nanopowder using the citrate method with microwave irradiation

2010

Abstract Nd:YAG nanopowders were prepared using the Pechini process with microwave irradiation ( MWs ). A reference sample was also prepared using conventional heating. XRD pattern analysis showed that nanopowder obtained by means of conventional heating and calcination for 1 h at 900 °C has a structure made up of the garnet phase together with the hexagonal phase that disappeared after two additional hours of thermal treatment. The MWs powder calcined for 1 h consists of the single garnet phase. SAXS data analysis indicated that nanoparticles are characterized by a sharp interface. TEM investigation showed crystalline particles with remarkable agglomeration in both samples, although a more…

Crystal structures of new ternary compounds in RE–Pt–Pb and RE–Au–Pb systems (RE=rare earth metal)

2012

Abstract The crystal structures of the compounds RE 2 Pt 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Mo 2 FeB 2 structure type, space group P 4/ mbm , Pearson code tP10 ), REPtPb (RE = La, Ce, Pr, Nd, Sm; ZrNiAl structure type, space group P 6 ¯ 2 m , Pearson code hP9 ), RE 2 Au 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Er 2 Au 2 Sn structure type, space group P 4 2 / mnm , Pearson code tP20 ) and REAuPb (RE = Tm, Yb and Lu) were determined using X-ray powder diffraction.

Desummation of Mixed Powder Diffraction Lines

1991

Determination of Molecular Crystal Structures from X-Ray Powder Diffraction Data

1993

Partially Coherent Optical Diffraction Tomography Toward Practical Cell Study

2021

Optical diffraction tomography (ODT) is a computational imaging technique based on refractive index (RI) contrast. Its application for microscopic imaging of weakly absorbing and scattering samples has been demonstrated by using a specially designed holographic microscope with angular scanning of the coherent sample illumination direction. Recently, an alternative low cost technique based on partially coherent sample illumination (PC-ODT), which is compatible with the conventional wide-field transmission microscope, has been established. In this case, the 3D refractive index distribution of the sample is obtained by deconvolution from a single stack of through-focus intensity images. The pe…

“Ab-initio” structure solution of nano-crystalline minerals and synthetic materials by automated electron tomography

2012

Most of the newly discovered mineral phases, as well as many new synthesized industrial materials, appear only in the form of nano crystals, with a size not sufficient for single-crystal x-ray structure analysis. The development of techniques able to investigate the structure of nano crystalline materials is therefore one of the most important frontiers of crystallography. The most widespread technique providing relatively fast and well consolidated routes for structure analysis of bulk materials is x-ray powder diffraction (XRPD). Nevertheless, XRPD suffers from intrinsic 1-dimension reduction of information that greatly limits its applicability in presence of peak broadening and overlappi…