Thermal changes of the crystal structure and the influence of thermo-chemical annealing on the optical properties of YbAlO₃crystals

Abstract

The paper presents experimental results of investigations on the influence of temperature and thermo-chemical annealing on the structural and optical properties of YbAlO(3) crystals. Thermal behaviour of the crystal structure has been studied in the temperature range of 19-1173 K by means of in situ high-resolution x-ray powder diffraction using synchrotron radiation. Lattice expansion of YbAlO(3) displays a strongly anisotropic character: the relative expansion along the b direction is about two times smaller than that along the a and c axes. The influence of thermo-chemical annealing in oxidizing and reducing atmospheres has been studied by means of in situ optical spectroscopy. The increase of the absorption in the range of 300-600 nm during annealing in an oxidizing atmosphere as well as its bleaching during reduction has been observed in the temperature range 700-1000 K. The oxidation and reduction kinetics have been analysed by means of mathematical models taking into account diffusion and the quasi-chemical reaction of the defect centres.

Multiple fermion scattering in the weakly coupled spin-chain compound YbAlO3

“…A single crystal of YbAlO 3 with a mass of ≈ 0.5 g was prepared by a Czochralski technique, as described elsewhere 28 , 29 . The INS measurements were performed at the time-of-flight spectrometer CNCS 30 , 31 at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory with E i = 1.55 and 3.32 meV.…”

Tomonaga–Luttinger liquid behavior and spinon confinement in YbAlO3

“…YbAlO 3 crystallizes in an orthorhombically distorted perovskite structure 9 , with room temperature lattice constants a = 5.126 Å, b = 5.331 Å, and c = 7.313 Å (in conventional Pbnm notation). The local point-group symmetry of the Yb 3+ ions splits the eight-fold degenerate J = 7/2 ( L = 3, S = 1/2) ground state multiplet (2 J + 1 = 8) into four doublet states.…”

Antiferromagnetic ordering and dipolar interactions of YbAlO3

“…A single crystalline sample of YbAlO 3 with clear orange color was prepared by the Czochralski technique, as described elsewhere [14,15]. Magnetization measurements were performed using a Quantum Designs Magnetic Property Measurement System (MPMS) with a horizontal sample rotator insert and MPMS-3 with 3 He insert for the lowtemperature measurements down to 0.5 K. Neutron scattering measurements of YbAlO 3 were performed at the time-offlight Cold Neutron Chopper Spectrometer (CNCS) [16,17], at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory.…”