Microstructural and compositional study of a bulk Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal grown from a BaTiO3 seed

The microstructure, composition and homogeneity of a Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PMNT) single crystal were studied using a combination of electron-microprobe techniques: scanning electron microscopy, orientation analysis and quantitative X-ray microanalysis. A PMNT single crystal was grown from a polycrystalline PMNT matrix using a BaTiO₃ single crystal as a seed. The PMNT crystal retained the same crystallographic orientation as the seed with no interdiffusion at the interface. The average chemical composition, determined with optimized quantitative wavelength-dispersive X-ray microanalysis, was Pb(Mg_1/3Nb_2/3)_1−XTi_XO₃ where x = 0.33. A statistical evaluation of the data using the analysis of variance showed that the achieved experimental uncertainty was below ± 1% relative. The compositional homogeneity of the crystal was verified on the micrometer-scale; however on the macro-scale slight fluctuations of the Mg, Nb and Ti concentrations were observed across the crystal. The measured variations from the average composition were ± 2.3% relative for Ti, ± 1.3% for Nb and ± 1.4% for Mg. In contrast, the Pb concentration was found to be uniform on both the micro- and macro-scale, showing a variation below ± 0.5% relative.