Micro Far-Infrared Reflectivity of CaNb₂O₆ Single Crystal Fibers Grown by the Laser-Heated Pedestal Growth Technique

Abstract

The experimental setup used for mid-and far-infrared measurements under microscope.The figure below (Fig. S1) shows a sketch of the detector selection inside the microscope.

Raman and Infrared Phonon Features in a Designed Cubic Polymorph of CaTa2O6

“…First, we note that the ε ∞ value gives us a measurement of the refractive index of the crystal (ε ∞ = n 2 ), as 2.01, which is comparable to the values obtained for a CaNb 2 O 6 orthorhombic columbite crystal (n between 1.97 and 2.22). 17 On the other hand, the intrinsic dielectric properties of an insulator centrosymmetrical material at microwave frequencies is entirely given by the phonon (and electronic) characteristics. 22 The static (microwave, Ω j,TO .…”

“…The obtained (high) dielectric constant and quality factors are adequate for microwave applications, but the quality factors are relatively low compared with values shown by orthorhombic CaNb 2 O 6 with columbite structure. 1,2,17,26 Conversely to tantalite perovskites, which have higher Q u than niobate ones, the AB 2 O 6 tantalites (B = Ta, A = divalent cation) have lower Q u than corresponding niobates (B = Nb). 1,27 The polymorphism presented by members the tantalite family 1 could be at the origin of such behavior, since the ANb 2 O 6 compounds with different A 2+ cations have usually the columbite structure.…”

The Raman scattering of trirutile structure MgTa2O6 single crystals grown by the optical floating zone method

“…The dazzling effect of the lens is another inuencing factor; the strong leakage of the E g modes can be attributed to this. 19 In-site temperature-dependent Raman spectra were measured on a small crystallite sample size of 1 mm 3 , taken from the crushed MgTa 2 O 6 crystals, to obtain a rapid thermal response. A total of 24 temperature-measurement points were observed every 30 K from 89 to 778 K. Raman spectra obtained at selected temperatures are shown in Fig.…”

Optical phonon characteristics of an orthorhombic-transformed polymorph of CaTa2O6single crystal fibre

“…This commercial instrument has been designed for the midinfrared region (550-4000 cm −1 ), where a SiC source, a KBr:Ge beamsplitter and a MCT detector, plus a grid polarizer on a ZnSe substrate constitute the standard accessories for building up the appropriate configuration. In order to reach the far-infrared region (50-700 cm −1 ), we adapted the microscope to receive a Si-bolometer detector [17]. Then, far-infrared measurements could be performed using the following configuration: SiC source, a solid-state Si beamsplitter, the Si-bolometer detector and a wire grid polarizer on a PE substrate.…”