Physica B 365 (2005) 155–162 Effects of high pressure on stability of the nanocrystalline LiAlSi 2 O 6 phase of a glass–ceramic composite: A synchrotron X-ray diffraction study Kristina E. Lipinska-Kalita a,Ã , Gino Mariotto b , Patricia E. Kalita c , Yoshimichi Ohki d a High Pressure Science and Engineering Center, Department of Physics, University of Nevada Las Vegas, Las Vegas, NV 89154, USA b Dipartimento di Fisica, Universita` di Trento, 38050 Povo (Trento), Italy c Department of Physics, University of Nevada Las Vegas, Las Vegas, NV 89154, USA d Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555, Japan Received 5 January 2005; received in revised form 1 May 2005; accepted 9 May 2005 Abstract Synchrotron X-ray diffraction studies, under pressures up to 50GPa, have been performed on a lithium- aluminosilicate glass–ceramic composite with nanometer-sized LiAlSi 2 O 6 crystals embedded in a host matrix. The pressure-induced evolution of X-ray diffraction patterns was followed in a diamond anvil cell on compression and decompression cycles with the aim of probing the effect of high-pressure compression on the nanocomposite structure. On the compression cycle from ambient pressure up to 20 GPa the unit cell volume of the LiAlSi 2 O 6 phase decreased by about 22%. The diffraction patterns also revealed the presence, at high pressures, of the ZrTiO 4 phase that was nucleated in the matrix prior to the crystallization of the main LiAlSi 2 O 6 phase. After quenching from 50 GPa to close to ambient conditions the diffraction pattern indicated that the high-pressure phase was retained to some extent although the decompressed structure still carried the signature of the initial ambient LiAlSi 2 O 6 phase. A Birch–Murnaghan fit of the unit cell volume as a function of pressure yielded a zero pressure bulk modulus K 0 ¼ 71  2GPa and its pressure derivative K 0 0 ¼ 4:4  0:6GPa for the nanocrystalline phase. r 2005 Elsevier B.V. All rights reserved. PACS: 61.10.I; 61.46.+w; 61.82.Rx; 62.50.+p Keywords: High-pressure; Synchrotron X-ray diffraction; Nanocrystals; Glass–ceramics; Composites ARTICLE IN PRESS www.elsevier.com/locate/physb 0921-4526/$-see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2005.05.010 Ã Corresponding author. Tel.: +17028952536; fax: +17029850804. E-mail address: kristina@physics.unlv.edu (K.E. Lipinska-Kalita).