Effects of Ultrahigh Pressures on the Formation and Properties of Organic Semiorganic and Inorganic Materials

Studies on the effect of ultrahigh pressures up to 90,000 atmospheres were carried out on organic polymers and a variety of semiorganic and inorganic materials. The experimental work was done in a Belt-type internally heated high pressure apparatus calibrated by means of electrical-resistance discontinuities in Bi, Tl, and Ba using the fixed pressure points of the new post-1960 absolute pressure scale. With organic polymers results to dat;e indicate that the effect of compression is influenced by: (1) The compression attained, (2) the compression rate, (3) the holding period, and (4) the polymer used. The most influential parameters within the target range of compression appear to be the polymer and the holding period. Results to date do not show any generalized pattern of behavior for polymers. Rather the limited data suggest that each material may well have its individual response to compression. Among the semiorganic compounds studied, dimethyldicyano silane apparently polymerized at 60,000 atmospheres through conversion of the nitrile groups to C =N -. Other semiorganics, alumino-siloxanes, ethyldicyanophosphine arseno-siloxane, phosphonitrilic chloride trimer and diphenylphosphinoborine showed little effect of pressure or decomposed. In the work with inorganic materials, ultrahigh-pressure high-temperature studies of two heteropolynuclear acids (silicotungstic and phosphotungstic acid) and two heteropolynuc1ear salts (ammonium-arseno-vanado tungstate and ammonium.-phospho-vanado tungstate) revealed what appear to be pressure dependent modifications over a broad pressure-temperature range to 75,000 atmospheres and 1300 C. The results of preliminary high-pressure experiments on a group of sulfides, including SbZS3 and AsZS3 , and on apatite [Ca5(P04)3(OH,F)] were negative.