ayers were less well-ordered with more variations of struc- [5]J. Bill, F Aldinger, Adv Mater. 7(1995)775 tural elements. These differences may be correlated to the [6]D Seyferth, H Am Ceram. Soc. 73(1990)2131 different polymer structures which in turn govern decom- U Bassie teret p p W.S. Rees Jr.. K. Buchner. in: A R (Eds ) Frontiers of position processes during thermolysis. Early formation ry, Royal Society of Chemistry, Cambridge, 1991, p. 15. and/or separation of the matrix phase in polysilazanes [8]E. Butchereit, K G. Nickel, A. Moller, J. Am. Ceram Soc. 84(2001) favors the development of well-ordered structures inducing crystallization during annealing experiments. By contrast, 9]R. Riedel, L M. Ruwisch, L. An, R. Raj, J. Am. Ceram. Soc. 81 the thermal stability of the carbodimide group most prob- (1998)3341 [OJR. Riedel, A. Kienzle, w. Dressler, L.M. Ruwisch, ably shifts BN formation to higher temperatures. As a J. Bill. F Aldinger, Nature 382(1996)796 result the matrix phase is less well-ordered. The observa- [11]H.. Baldus. M. Jansen, Angew. Chem. 109(1997)338 tion that even after 5 h at 2000C polymer-derived ceram Angew. Chem., Int. Ed. Engl. 36(1997)328 cs are not fully crystalline i.e. not thermodynamically [2JA Jalowiecki, J. Bill, F. Aldinger, J. Mayer, Composites 27A(1996) stable, and'remember'structural features of the polymeric state points to the fact that the stability of the amorphous 13]A. Jalowiecki, PhD thesis, Universitat Stuttgart, 1997(in German) state in these materials is essentially based on chemical [14]J. Bill. T.w. Kamphowe, A. Miller, T.Wichmann, A. Zern,A Jalowiecki, J. Mayer, M. Weinmann, J. Schuhmacher, K. Muller, J Peng, H.J. Seifert, F. Aldinger, Appl. Organomet. Chem. 15(2001) Acknowledgements [5]A. Moller, P. Gerstel, M. Weinmann, J. Bill, F. Aldinger, Chem. Mater.14(2002)3398 [6]A. Muller, J. Peng, H.J. Seifert, J. Bill, F. Aldinger, Chem. Mater. 14 The authors would like to thank horst Kummer(high (2002)3406. temperature annealing), Maria Sycha and Ute Bader for [7]H. J Seifert, F. Aldinger, Z. Metallkd 87(1996)84 the help with sample preparation, Rainer Hoschen for [18]H Schmidt, G Borchardt,AMiller,J.Bill,JNon-Cryst.Solids 341 assistance with the high-voltage microsco (2004)13 [9]H. Schmidt, w. Gruber, G. Borchardt, P. Gerstel, A. Muller, N Bunjes, J. Eur. Ceram Soc. 25(2005)227. References [20]A. Muller, A. Zern, P. Gerstel, J. Bill, F. Aldinger, J. Eur. Ceram. Soc.22(2002)1631. []W German Patent DE 2 218 960.1973 21]J Schuhmacher, PhD thesis, Universitat Stuttgart, 2000 (in German). [2]W G. winter. German Patent DE 2 236 068. 1974 [22]P. Gerstel, A. Muller, J. Bill, F. Aldinger, Chem. Mater. 15(26) [3]M T. Aahs. M. Bruck, Adv Mater. 2(1990)398. (2003)4980 [4]M p pillot H. Dunogues, Chem. rev 95 (1995)1443layers were less well-ordered with more variations of struc￾tural elements. These differences may be correlated to the different polymer structures which in turn govern decom￾position processes during thermolysis. Early formation and/or separation of the matrix phase in polysilazanes favors the development of well-ordered structures inducing crystallization during annealing experiments. By contrast, the thermal stability of the carbodiimide group most prob￾ably shifts BN formation to higher temperatures. As a result the matrix phase is less well-ordered. The observa￾tion that even after 5 h at 2000 C polymer-derived ceram￾ics are not fully crystalline i.e. not thermodynamically stable, and ‘remember’ structural features of the polymeric state points to the fact that the stability of the amorphous state in these materials is essentially based on chemical design. Acknowledgements The authors would like to thank Horst Kummer (high￾temperature annealing), Maria Sycha and Ute Ba¨der for the help with sample preparation, Rainer Ho¨schen for assistance with the high-voltage microscope. References [1] W. Verbeek, German Patent DE 2 218 960, 1973. [2] W. Verbeek, G. Winter, German Patent DE 2 236 068, 1974. [3] M. Peuckert, T. Vaahs, M. Bru¨ck, Adv. Mater. 2 (1990) 398. [4] M. Birot, J.-P. Pillot, H. Dunogue`s, Chem. Rev. 95 (1995) 1443. [5] J. Bill, F. Aldinger, Adv. Mater. 7 (1995) 775. [6] D. Seyferth, H. Plenio, J. Am. Ceram. Soc. 73 (1990) 2131. [7] D. Seyferth, H. Plenio, W.S. Rees Jr., K. Bu¨chner, in: A.R. Bassindale, P.P. Gaspar (Eds.), Frontiers of Organosilicon Chemis￾try, Royal Society of Chemistry, Cambridge, 1991, p. 15. [8] E. Butchereit, K.G. Nickel, A. Mu¨ller, J. Am. Ceram. Soc. 84 (2001) 2184. [9] R. Riedel, L.M. Ruwisch, L. An, R. Raj, J. Am. Ceram. Soc. 81 (1998) 3341. [10] R. Riedel, A. Kienzle, W. Dressler, L.M. Ruwisch, J. Bill, F. Aldinger, Nature 382 (1996) 796. [11] H.-P. Baldus, M. Jansen, Angew. Chem. 109 (1997) 338; Angew. Chem., Int. Ed. Engl. 36 (1997) 328. [12] A. Jalowiecki, J. Bill, F. Aldinger, J. Mayer, Composites 27A (1996) 717. [13] A. Jalowiecki, PhD thesis, Universita¨t Stuttgart, 1997 (in German). [14] J. Bill, T.W. Kamphowe, A. Mu¨ller, T. Wichmann, A. Zern, A. Jalowiecki, J. Mayer, M. Weinmann, J. Schuhmacher, K. Mu¨ller, J. Peng, H.J. Seifert, F. Aldinger, Appl. Organomet. Chem. 15 (2001) 777. [15] A. Mu¨ller, P. Gerstel, M. Weinmann, J. Bill, F. Aldinger, Chem. Mater. 14 (2002) 3398. [16] A. Mu¨ller, J. Peng, H.-J. Seifert, J. Bill, F. Aldinger, Chem. Mater. 14 (2002) 3406. [17] H.-J. Seifert, F. Aldinger, Z. Metallkd. 87 (1996) 841. [18] H. Schmidt, G. Borchardt, A. Mu¨ller, J. Bill, J. Non-Cryst. Solids 341 (2004) 133. [19] H. Schmidt, W. Gruber, G. Borchardt, P. Gerstel, A. Mu¨ller, N. Bunjes, J. Eur. Ceram. Soc. 25 (2005) 227. [20] A. Mu¨ller, A. Zern, P. Gerstel, J. Bill, F. Aldinger, J. Eur. Ceram. Soc. 22 (2002) 1631. [21] J. Schuhmacher, PhD thesis, Universita¨t Stuttgart, 2000 (in German). [22] P. Gerstel, A. Mu¨ller, J. Bill, F. Aldinger, Chem. Mater. 15 (26) (2003) 4980. 1576 N. Bunjes et al. / Journal of Non-Crystalline Solids 353 (2007) 1567–1576