| The powder X-ray diffraction (XRD) technique is usually used at room temperature forobservation and identification on the crystal structure of some inorganic materials. With thedevelopment of science and technology, variable temperature application of XRD techniquebecomes gradually broadened, such as some studies on reaction kinetics, phase transformationmechanism, crystallization and annealing of amorphous alloys. A growing number ofresearchers are no longer confined to the room temperature XRD measurement.Thus, it isimportant that we must use different temperature correction according to different types ofmaterials (such as metal, ceramic materials, as well as powder) owing to their differentthermal conductivity in temperature XRD techniques testing.Therefore, in this paper, the BaTiO3ceramic was employed to make a temperaturecorrection with the aid of its obvious phase transition temperature and structure as thecorrective sample in XRD measurement at a higher temperature and the BaTiO3modified bylanthanum as the corrective sample at a lower temperature, thus we achieved a calibrationcurve of inorganic ceramic in temperature XRD techniques testing. So we used the calibrationcurve to probe the structure of BaTiO3doped with rare-earth (such as lanthanum, cerium, iron,erbium, magnesium) ceramic at different temperature. Moreover solder alloy with a fixedmelting point was elected to verify the accuracy of specimen chamber in temperature XRDmeasurement.The aim and novelty of this master’s thesis:(1) On the basis of BaTiO3ceramic’s phase transition temperature, we got linear relationTa-T as a temperature correction line between25and170℃and according to the BaTiO3modified by lanthanum, we proved that the specimen chamber in low temperature XRDmeasurement had a good veracity;(2) Using temperature-dependent X-ray diffraction (XRD), we found the link between thedielectric peak with DPT and the lattice change of a high-k BL3TC5[(Ba1-xLax)(Ti1-x/4-yCey)O3(x=0.03, y=0.05)] ceramic with cubic structure at roomtemperature.The structural transition of the hexagonal BaTiO3dielectric ceramic did not occurat the Curie temperature of BaTiO3(TC=130℃) had been clarified.In(Ba1-xErx)(Ti1-x/2Mgx/2)O3（x=0.01~0.05）ceramics with a fixed ratio of Er/Mg(2/1), thesolubility of Er in the Ba sites was3.0mol%~4.0mol%. With the increasing of temperature,the ceramics had a tetragonal-cubic phase transition and with the increase of doping content,the temperature of phase transition moved to low temperature. Therefore, this study provides technical reference for application of monitoring the structure of inorganic powder materialsin industry production via the temperature-dependent X-yay diffraction technique.(3)Indicated that the real formula of BET is expressed by (Ba1-xEr3x/4)(Ti1-x/4Erx/4)O3, thegreatly enhanced and abnormal Raman spectra originated from resonance Ramanspectroscopy of Ba-site Er3+ionsand the tetragonal-cubic phase transition temperature of BEToccurred at between120~150℃;(4) Tin-lead solder (Sn63/Pb37) with a fixed melting point was used as a standard samplefor the confirmation of temperature accuracy of metal XRD measurements at varioustemperatures via domestic X-ray diffractometer. The results indicated that the differencebetween the monitoring temperature detected by a thermal couple in the temperature camera(To) and the actual temperature of ceramic powders surface (Ta) was less than5℃. Thisconclusion directly demonstrates that the temperature camera developed has highertemperature accuracy. |
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