Raman spectroscopy of the LaGaO3 phase transition

✍ Scribed by G. A. Tompsett; N. M. Sammes; R. J. Phillips

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 62 KB
• Volume: 30
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199907)30:7<497::aid-jrs409>3.0.co;2-v

✦ Synopsis

LaGaO 3 is reported to undergo a low-temperature phase transition from Pnma to R3c at 418 K. The phases involved in the low-temperature phase transition of LaGaO 3 were determined using Raman spectroscopy from 77 to 773 K. There is a total of 17 bands observed in the room temperature (294 K) Raman spectrum, namely, 55(A g ), 92(B 1g ), 101(B 3g ), 117(B 2g ), 137(B 1g ), 147(A g ), 173(B 3g ), 255(A g ), 277(A g ), 335(B 3g ), 357(B 1g ), 404(B 3g ), 417(B 2g ), 433(A g ), 451(B 3g ), 584(overtone), 708(overtone) cm -1 (at 294 K) and an extra band observed at 77 K of 331(B 2g ) cm -1 . The Raman spectra of the rhombohedral LaGaO 3 phase showed four distinct bands at 444(E g /E g ), 232(A g ), 159(E g ) and 55(E g ) cm -1 (at 773 K) of a possible five predicted. The spectra of both the low-temperature orthorhombic and high-temperature rhombohedral phases of LaGaO 3 phases were assigned with comparison with assignments of SmAlO 3 and NdAlO 3 , respectively. The phase transition is observed to occur at approximately 418 K.