Observation of defects and the incommensurate phase in berlinite crystals by high-temperature X-ray topography

Growth defects and the incommensurate phase have been observed in synthetic berlinite (AlPO₄) samples. This study was performed by high-temperature X-ray topography using synchrotron radiation at LURE (Orsay, France). Some results concerning the defects observed above room temperature are presented. The incommensurate phase was investigated by using a narrow beam which allows the observation and analysis of the satellites around Bragg spots.