* Corresponding author. Tel.: #301-6503977; fax: #301- 6511766. E-mail address: stefan@cyclades.nrcps.ariadne-t.gr (K.L. Stefanopoulos) Physica B 276}278 (2000) 479}480 Study on the entrapment of mercury in porous glasses by neutron scattering in conjunction with mercury porosimetry P.K Makri, K.L. Stefanopoulos*, A.Ch. Mitropoulos, N.K. Kanellopoulos, W. Treimer N.C.S.R. DEMOKRITOS, Institute of Physical Chemistry, 15310 Ag. Paraskevi Attikis, Athens, Greece Cavala+s Institute of Technology, Department of Petroleum Technology, 65404 St. Lucas, Cavala, Greece Hahn Meitner Institut, BENSC, Glienicker Strasse 100, D-14109 Berlin, Germany Abstract A series of controlled porous glasses (CPGs) with pore sizes from 17 to 300 nm has been examined by very-small-angle neutron scattering (VSANS). The scattering curves show a peak in a range of Q values, depending on the particle size to the average pore size ratio. The entrapment of mercury in CPGs having undergone a complete intrusion}extrusion cycle has also been examined by VSANS. The peak positions do not vary for the mercury-loaded samples suggesting no structural changes due to the high intrusion pressures involved (60,000 psi). It was concluded that an amount of mercury blobs is trapped within the cavities of the glasses.  2000 Elsevier Science B.V. All rights reserved. Keywords: Small-angle neutron scattering; Glasses; Porosity 1. Main text Controlled porous glasses (CPGs) have the unique feature of having narrow pore size distribution and are widely used in chromatography. SAXS measurements from CPGs of various average pore sizes (APS) in the range 7.5}200 nm suggest that their surfaces are fractally rough with a fractal dimension D"2.20$0.02 [1]. In this work we report results on a series of CPGs with APS between 17 and 300 nm obtained by very-small- angle neutron scattering (VSANS). Porous glasses, par- tially loaded with mercury, after a complete mercury intrusion}extrusion cycle, were also examined by VSANS. The experiment was performed on the double- crystal di!ractometer V12a, at HMI, Berlin, Germany. The wavelength was 0.478 nm and the Q range was between 0.0017 and 0.13 nm. All samples supplied by CPG Inc. were available in powdered form with a grain size varying between 37 and 74 m. The spectra from dry and mercury-loaded CPGs are shown in Fig. 1. The scattering curves exhibit a shoulder which is characteristic of structural units much larger than the respective APS values. Ho K hr et al. [1] modeled the CPG microstructure by a random-packed assembly of spheres of equal size. They concluded that the ratio of the particle diameter, ¸, to the APS is about 2.7. How- ever, they did not con"rm this result experimentally for the case of glasses having large APS since the shoulder was not expected within the instrumental accessible range of Q values. The shoulder positions measured from VSANS data are in excellent agreement with the above prediction. Another interesting result is that the position of the shoulders does not vary for the samples partially loaded with mercury suggesting that the glass matrices have not undergone structural changes due to the high pressures involved during mercury porosimetry measure- ments (60,000 psi). Towards lower scattering angles, the spectra show a rather extended #at part beyond the shoulder vicinity. Let us assume a genuine #at region of the scattering curves extending up to Q  "0.0063 and Q  "0.0052 nm Physb1=16215=Jolly=Venkatachala=BG 0921-4526/00/$ - see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 3 4 8 - 4