Abstract
Syntheses of Ln-Si-As compounds (Ln ≡ La, Ce, Pr, Nd, Sm) have been attempted using a temperature-gradient furnace by controlling the arsenic pressure. Several ternary compounds, with the composition LnSiAs 3 (Ln ≡ La — Pr), were formed. In the case of lanthanum, two polymorphs, the LaSiAs 3 type and CeSiP 3 type, were found. By X-ray diffraction structure analysis using the Rietveld method the crystallographic data of the LaSiAs 3 type are obtained as space group Pbca, a = 6.0855(2) A ̊ , b = 5.9837(2) A ̊ , c = 26.2279(6) A ̊ ; and those of the CeSiP 3 type are found to be space group Pn2 1a , a = 6.0498(3) Å, b = 5.9545(3) A ̊ , c = 26.383(1) A ̊ . For Ln ≡ Ce and Pr, only the CeSiP 3 type was found. An apparatus for thermogravimetric experiments in a sealed silica tube under a controlled arsenic pressure using the temperature-gradient furnace was constructed for thermogravimetric measurements of conditions of formation for the Ln-Si-As systems between 700 and 1000°C and arsenic pressures of 10 −2 to 20 atm. From these results, together with other results from differential thermal and X-ray analyses, the conditions for the formation of these ternary compounds were obtained.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
