Optical anisotropy of (C3H7NH3)2CuCl4 and (C3H7NH3)2MnCl4 crystals  Order this article O.S.Kushnir, I.M.Bolesta, Yu.M.Furgala, L.P.Lutsiv-Shumski, R.Y.Shopa S.A.Sveleba Using the Senarmont and the universal null-polarimetric techniques, the birefringence, optical indicatrix orientation and the gyration of (001) bis-propylammonium tetra-chloro-cuprate crystal are studied above the room temperature. The indicatrix rotation and the normal light wave ellipticity related to the gyration effect are found to be less than ~   and ~  , respectively, including the temperature region of the incommensurate ? phase. The birefringence of iso-propyl-ammonium tetra-chloromanganate crystal is also measured and the second-order phase transition at 38 oC is found. doi 10.3116/16091833/3/1/12/2002 1. Cummins HZ, 1990. Phys. Rep. 185: 211         doi:10.1016/0370-1573(90)90058-A http://dx.doi.org/10.1016/0370-1573(90)90058-A 2. Etxebarria J, Ruiz-Larrea I, Tello MJ and Lopez-Echarri A, 1988. J. Phys.C 21: 1717.         doi:10.1088/0022-3719/21/9/011 http://dx.doi.org/10.1088/0022-3719/21/9/011 3. Jahn IR, Knorr K and Ihringer J, 1989. J. Phys.: Condens. Matter 1: 6005.         doi:10.1088/0953-8984/1/35/001 http://dx.doi.org/10.1088/0953-8984/1/35/001 4. Doudin B and Chapius G, 1990. Acta Cryst. B 46: 175.         doi:10.1107/S0108768189010281 http://dx.doi.org/10.1107/S0108768189010281 5. Jahn IR, Schwab K, Knorr K and Holocher K, 1994. J. Phys.: Condens. Matter 6: 10839.         doi:10.1088/0953-8984/6/49/024 http://dx.doi.org/10.1088/0953-8984/6/49/024 6. Sveleba SA, Polovinko II, Bublyk MI and Kusto WJ, 1995. Kristallografiya 40: 104. 7. Kapustianik VB, Korchak YuM, Polovinko II and Sveleba SA, 2000. Ukrain. Fiz. Zhurn. 45: 868. 8. Saito K and Kobayashi J, 1991. Japan. J. Appl. Phys. 30: 2416.         doi:10.1143/JJAP.30.2416 http://dx.doi.org/10.1143/JJAP.30.2416 9. Vlokh OG and Kushnir OS, 1996. Pribory i Tekhnika Eksperim. 1: 119. 10. Kushnir OS, Burak VY, Bevz OA and Polovinko II, 1999. J. Phys.: Condens. Matter 11: 8313.         doi:10.1088/0953-8984/11/42/312 http://dx.doi.org/10.1088/0953-8984/11/42/312 11. Kremers M, Dijkstra E and Meekes H, 1996. Phys. Rev. B 54: 3125.         doi:10.1103/PhysRevB.54.3125 http://dx.doi.org/10.1103/PhysRevB.54.3125 12. Kushnir OS, 2001. J. Phys. Studies.