Precession Electron Diffraction – a versatile tool for the characterization of Phase Change Materials

Abstract

Precession Electron Diffraction (PED) has become a versatile tool of Transmission Electron Microscopy (TEM) for enhancing its nanoscale characterization abilities. In this contribution the advantages of PED are demonstrated on bulk samples of Phase Change Materials (PCM) with the nominal compositions Ge 8 Sb 2 Te 11 and Ge 8 Bi 2 Te 11 . PED was applied in combination with High Resolution Transmission Electron Microscopy (HRTEM) to determine such homologous structures based on variable sequences of layered building units. The efficiency of PED can be shown by the identification of ordering which is not evident from the projection of the structure in HRTEM or by use of Selected Area Electron Diffraction (SAED). Simulations support the ability of PED for recording 3D structural information. The PED patterns of the PCM can be assigned to superstructures which exhibit specific distances between adjacent Te-Te double layers. PED was also performed to analyze the structural changes after massive irradiation of PCM crystals.

New insights into hard phases of CoCrMo metal-on-metal hip replacements

“…For reference, the PED method is relatively new and has proved to be a very powerful approach to obtaining crystallographic information within a transmission electron microscope, in most cases rather superior to older fixed-beam diffraction techniques. For some recent publications see (Ciston et al, 2008; Gemmi et al, 2010; Gjonnes et al, 1998a; Gjonnes et al, 2004; Gjonnes, 1997; Gjonnes et al, 1998b; Hadermann et al, 2010; Hadermann et al, 2011; Meshi et al, 2011; Moeck and Rouvimov, 2010; Own et al, 2006a; Own et al, 2006b; Rauch et al, 2010; Schurmann et al, 2011; Sinkler and Marks, 2010; Sinkler et al, 2007). …”

From Chalcogenides to Polychalcogenidehalides – First Identification in Mineral Samples

“…Precession electron diffraction (PED) proofs itself as versatile tool for phase identification since the reflection conditions according to the crystal symmetry can be identified. Figures 3a) and b) depict the PED [8] patterns of the monoclinic (space group P2 1 / c; zone axis [100]) and the tetragonal polymorph (space group I4/mcm; zone axis [001]), respectively. Violations of the zonal and serial reflection conditions for the monoclinic crystal are restricted to the first order reflections (Figure 2b).…”

Nanostructure, thermoelectric properties, and transport theory of V2VI3 and V2VI3/IV–VI based superlattices and nanomaterials

“…Such systems like Bi 2 Te 3 /GeTe offer interesting real structure property relationships with high ZT . V 2 VI 3 /IV–VI mixed compounds exhibit a layer like structure with vacancy layers (VL) as reported for many Ge–Sb–Te and Ge–Bi–Te phases . The formation of VL is strongly dependent on chemical composition and thermal treatment and consequently corresponding changes of thermoelectric performance are expected.…”