| Abstrakt: |
Abstract: Pyrophyllites from Zalamea (Badajoz, Spain) and from Hillsboro (North Carolina USA), were subjected to treatment in ultrasonic liquid processor and studied by BET, SEM and XRD methods in an attempt to reveal changes in structure ordering and particle sizes. Original sample of pyrophyllite from Zalame a is characterized by clay size particles and well organised polytypic structure 1A A-II,1. During 5 hrs of sonication the structure suffered only small destruction, but further sonication for 10 hrs produced significant structure disorder marked by smearing out of all the polytypic 02 l, 11 l reflections. Pyrophyllite from Hillsboro is represented by lath-crystals of macroscopic size, displaying poorly ordered structure classified to subfamily A of polytypes. MDO group and polytype could not be determined and stay unknown. Changes in particle sizes in terms of specific surface area, e.s.d. and best mean thickness of the domains of coherent X-ray scattering were most rapid during first 10 hrs of sonication, similar in the both studied pyrophyllites. Limit of particle division was achieved after 20 hrs - 40 hrs sonication. Irrespective of differences in the initial morphology and structural order the samples finally divided during sonication reached similar particle sizes (e.s.d. around 30 nm), best mean thickness of the domains of coherent scattering (around 12 nm) and showed alike structural disorder. |
