>Our current dilemma is that our data collected at 400C and below deviates from >a smooth linear trend, >and this is not expected.
In oxide perovskites the oxygen vacancies may be stabilized below the temperature threshold at 400-500C. It can be detected by DSC measurements. ******************************************************* Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660036, Akademgorodok 50/24, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid ******************************************************* ________________________________ From: "Hudish, Grant" <ghud...@coorstek.com> To: "Rietveld_l@ill.fr" <Rietveld_l@ill.fr> Sent: Wednesday, April 2, 2014 3:39 AM Subject: Hot stage data inconsistencies Greetings Rietvelders, We are currently running experiments on BCZY proton conductors. The nature of the runs require us to heat our samples to 1200C, then ramp down to 800C and collect an Xray pattern every 25C between 800 and 400C. We then cool in 100C increments and collect patterns at 300, 200, 100 & RT. We’ve been analyzing the data in TOPAS using a whole powder pattern fitting procedure to obtain a cubic lattice parameter at each temperature. Our current dilemma is that our data collected at 400C and below deviates from a smooth linear trend, and this is not expected. During the fitting process we’re letting the lattice parameter, crystallite size, strain, and sample height refine. All of these values stay consistent between temperatures except the sample height. For the troubled values, we see the sample displacement decrease as well. Currently, we’re not sure if this is a thermal equilibrium issue with the sample (unlikely) or the stage (possible?), a quark of the refinement, something related to our ramp rate/hold time, or loosening of the stage due to the extended time at temperature. We consistently have to re-tension our Pt strip after each 34+hr run. Experimental details: Anton Paar HTK 2000N hot stage Pt heat strip 10C/min ramp rate 10min hold at temp before scan If anyone out there has any thoughts or criticisms on the nature of our issue and/or refinement method they’d be greatly appreciated! Also, does anyone have a preferred resource/reference for hot stage XRD methodologies? Grant Hudish Materials & Ceramic Engineer CoorsTek – Research & Development ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
