TEMPERATURE STUDY OF LATTICE-CONSTANTS AND RAMAN-SCATTERING OF SRLAGAO4 SINGLE-CRYSTAL

The lattice parameters of SrLaGaO4 (SLG) single crystal were measured in the temperature range from 300 to 700 K using X-ray spectroscopy. T he measurements revealed that (i) the thermal coefficient along a and c axes is different and (ii) thermal expansion coefficient in a direct ion depends on temperature, showing the transition temperature at abou t 460 K. To verify this result we have also studied the Raman intensit y I-R and full width at half maximum (FWHM) of the Raman band at 218 c m(-1) ascribed to the librational lattice mode. The above temperature dependences display a characteristic discontinuity at about 460 K whic h coincides with the previous data obtained from X-ray measurements. T he obtained results are discussed in terms of the nature of defects wh ich might arise in the ABCO(4) lattice during the crystal growth proce ss.