Optical Properties of CaNb2O6 Single Crystals Grown by OFZ*

Guanlin Feng,Dapeng Xu,Liang Li

doi:10.3390/cryst11080928

Abstract

CaNb2O6 single crystals with an orthorhombic columbite structure are grown via an optical floating zone (OFZ) method. The as-grown crystals are colorless and free of low-angle grain boundaries and inclusions. They are transparent (up to 62%) in the visible to the infrared region (400–1000 nm) and have a low absorption coefficient (α = 1.56). The bandgap is determined as a direct transition and Eg = 4.28 eV. The wavelength-dependent refractive index and extinction coefficient of the CaNb2O6 crystals are derived from the obtained T and α spectra. Their photoluminescence spectra exhibit a strong and broad emission band centered at 465 nm.

Highlights

The X-ray diffractometer (XRD) pattern of the powder sample was refined via the Rietveld method by using GASA software
CaNb2 O6 single crystals are grown through the optical floating zone (OFZ)
The measured transmission is up to 62% in the visible-to-infrared region (400–1000 nm), and the absorption coefficient of α = 1.56 is low

Summary

Introduction

In 1968, CaNb2 O6 crystals were grown via a chemical transport method [19] (crystal dimension: 1 mm × 0.2 mm × 0.5 mm); in 1998, they were fabricated through a flux method [20] (size: 0.8 mm × 0.8 mm × 0.05 mm). In 2004, R. de Almeida Silva et al [21] grew CaNb2 O6 crystals fiber through laser-heated pedestal growth. By this method, they avoided impurities, but they obtained small-dimension crystal fibers (Ø < 1 mm). Considering the abovementioned factors, we grow CaNb2 O6 single crystals via an OFZ method. Pure CaNb2 O6 single crystals were grown via the OFZ method.

Materials and Methods

Results and Discussion

Conclusions