Thermoelasticity of SSP Materials: An Integrated Ultrasonic and X-radiation Study

Li, Baosheng

SUNY Stony Brook

关键词: Data Analysis;    Sample Preparation;    Tantalum;    X-Ray Diffraction;    75 Condensed Matter Physics, Superconductivity And Superfluidity;   

DOI  :  10.2172/935213
RP-ID  :  DOE-NA26211-2
RP-ID  :  FG52-06NA26211
RP-ID  :  935213

美国|英语

来源: UNT Digital Library

【 摘 要 】

It has been a very productive year for accomplishing the tasks outlined in the original proposal. Quite a few crystalline materials [tantalum (Ta), molybdenum (Mo), cerium (Ce) beryllium (Be)] and amorphous materials [zirconium tungstate (ZrW2O8), SiO2, and germanium diselenide (GeSe2) glasses] have been assessed at high pressures up to 12 GPa and acoustic velocities and densities have been obtained simultaneously using our unique technique. Major activities include sample preparation, high pressure cell assembly testing, and conducting ultrasonic and X-ray diffraction measurements at BNL as well as resonance ultrasonic spectroscopy (RUS) measurements at UCLA on appropriate samples. Sample preparations for Ce and Be were made at Los Alamos National Lab for which special grades and specialized machining of the sample are required. Pilot experiments for optimizing high pressure cell assemblies were conducted using the 1000-ton multi-anvil press (USCA-1000) in the High Pressure Lab at Stony Brook, and simultaneous ultrasonic and X-ray diffraction experiments were conducted using the DDIA apparatus installed at X17B2 of NSLS at BNL. New data analysis protocols have been developed for deriving density of amorphous materials at high pressure and therefore its equation of state. Following on previous years effort, attempts have been made to derive single crystal elastic constants based on the current measurements on polycrystalline samples at high pressure in conjunction with previous data as well as the current RUS measurements at ambient conditions. Single crystal elastic constants of Tantalum have been measured using RUS techniques at room pressure and high temperature. Educational and training opportunities have been provided for postdoctoral associate researchers, Drs. Wei Liu (project leader for Mo, and ZrW2O8 and SiO2 glass) and Qiong Liu (Ta project leader) and graduate students Mr. Matthew Whitaker (Project Ce and FeSi) and Sytle Antao (GeSe2 glass project). A total of 6 undergraduate students (2 summer students at Stony Brook University, and 4 undergraduates from Azusa Pacific University) participated in the experiments at various stages and benefited from the discussions about the science and research work conducted by our collaborators of the current project at DoE national labs.