A new apparatus design for high temperature (up to 950 °C) quasi-elastic neutron scattering in a controlled gaseous environment

Abstract

Development of a new radiometer for the thermodynamic measurement of high temperature fixed points AIP Conf. Proc. 1552, 65 (2013); 10.1063/1.4821372High-temperature and high-pressure pulsed synthesis apparatus for supercritical production of nanoparticles Rev. Sci. Instrum. 82, 084102 (2011) A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950• C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments. C 2015 AIP Publishing LLC. [http://dx

In Situ X-ray and Neutron Diffraction of the Rare-Earth Phosphate Proton Conductors Sr/Ca-Doped LaPO4 at Elevated Temperatures

“…Acceptor-doped lanthanum orthophosphates have attracted much attention as potential candidate electrolytes for proton conductors in high and intermediate-temperature-range fuel cells. − It is necessary to develop thermally and chemically stable and efficient proton-conducting electrolytes for solid oxide fuel cell (SOFC) applications. LaPO 4 has high temperature stability, low thermal conductivity, a melting point of 2072 °C, and a high thermal expansion coefficient. , Monoclinic P 2 1 / n (No.…”

“…There have been few neutron scattering studies focused on materials containing tetrahedral units that are involved in proton transport such as La 0.958 Ca 0.042 PO 4 and La 0.8 Ba 1.2 GaO 3.9 . ,,, To explore the structure, defect structure, and dynamics of aliovalent (Sr,Ca) doping on LaPO 4 materials, we employed X-ray diffraction (XRD), neutron powder diffraction (NPD), quasi-elastic neutron scattering (QENS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). We investigated the proton conductivity of the phosphate materials La 0.958 Sr 0.042 PO 4 and La 0.958 Ca 0.042 PO 4 with EIS.…”

Quartz Cell for a Backscattering Spectrometer

“…Other low incoherent metals such as molybdenum [5], niobium [6], and platinum [7] are potential candidates as they are anticorrosive materials. Nevertheless, these materials involve machinability and base material cost.…”

Structure and Dynamics Investigations of Sr/Ca-Doped LaPO4 Proton Conductors

“…Proton conduction is a fascinating phenomenon taking place in a broad range of systems from biochemical living organisms to pure solid materials, including ampullae of Lorenzini jelly of sharks, solid biopolymer electrolytes, Nafion ionomers in proton exchange membrane fuel cells (PEMFCs), and acceptor-doped lanthanum orthophosphates electrolytes for solid oxide fuel cells (SOFCs). − As the worldwide demand in energy is growing, PEMFCs and SOFCs stand out as clean renewable energy technologies that have the potential to reduce the environmental impact of energy production. Nafion-based PEMFCs constitute environmentally friendly energy solutions, which could contribute to the world energy demands but still lack stability at high temperature.…”

“…Here we focus on the development of an electrolyte that is thermally and chemically stable, inexpensive, and environmentally friendly, with proton conductivity on the order of 10 –2 S cm –1 around 400 °C. Acceptor-doped lanthanum orthophosphates LaPO 4 have been reported to be promising candidates for intermediate-temperature fuel cell electrolytes − due to good conductivity, thermal stability, and thermal expansion properties. However, their proton conductivity remains lower than ideal, on the order of 10 –4 S cm –1 . ,,− A number of syntheses and crystal growth conditions have been considered such as identifying the optimal heat treatment conditions. ,,− However, the synthesis of the acceptor-doped lanthanum orthophosphates is challenging due to the typical presence of a secondary phase, the limited dopant solubility, and the segregation of Sr which restricts the proton conductivity in the orthophosphates. , …”