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The paper presents a flux crystal growth technique, studies of the structural peculiarities and the optical absorption spectra of double orthoborate TbCr3(BO3)4 with a huntite structure. The intensities of the phonon modes were used to determine the ratios of the rhombohedral and monoclinic polytypes for this compound, depending on the growth conditions. The broadband absorption spectra of the Tb3+ ions in TbCr3(BO3)4 single crystals were studied in the temperature range from room temperature to 3.0 K. From them, the energies of the crystal-field levels of the Tb3+ ion were determined. The temperature dependence of the absorption spectra of the Er3+ probe ion in TbCr3(BO3)4:Er(1%) shows that there are two phase transitions and agrees with their previously proposed interpretation: at 8.8 K, the chromium subsystem antiferromagnetically orders, and at 5 K, a reorientation of chromium magnetic moments occurs. [ABSTRACT FROM AUTHOR]

In this paper, we report the conditions and results of the synthesis of solid solutions and flux growth of single crystals with the general formula La1 −x–yTbxEuyMgB5O10 from a K2Mo3O10-based high-temperature solution. The structural properties, composition, thermal characteristics, Tb3+ and Eu3+ luminescence spectra, and excitation spectra of the solid solutions have been studied in the ranges 0.2 < x < 0.7 and 0.1 < y < 0.6. We have calculated CIE luminescence spectra of the single crystals and fabricated operating prototype emitters using them. [ABSTRACT FROM AUTHOR]

The paper presents a flux crystal growth technique, studies of the structural peculiarities and the optical absorption spectra of double orthoborate TbCr3(BO3)4 with a huntite structure. The intensities of the phonon modes were used to determine the ratios of the rhombohedral and monoclinic polytypes for this compound, depending on the growth conditions. The broadband absorption spectra of the Tb3+ ions in TbCr3(BO3)4 single crystals were studied in the temperature range from room temperature to 3.0 K. From them, the energies of the crystal-field levels of the Tb3+ ion were determined. The temperature dependence of the absorption spectra of the Er3+ probe ion in TbCr3(BO3)4:Er(1%) shows that there are two phase transitions and agrees with their previously proposed interpretation: at 8.8 K, the chromium subsystem antiferromagnetically orders, and at 5 K, a reorientation of chromium magnetic moments occurs. [ABSTRACT FROM AUTHOR]

We have studied and optimized conditions for spontaneous flux growth of TbCr3(BO3)4 crystals. Phase relations in the pseudoternary system TbCr3(BO3)4–K2Mo3O10–B2O3 have been studied in the temperature range 900–1130°C and the single-phase terbium chromium borate crystallization field has been mapped out. It has been shown that increasing the TbCr3(BO3)4 content of the starting high-temperature solution leads to a rhombohedral-to-monoclinic phase transition. Using K2Mo3O10-based high-temperature solutions, we have grown single-phase TbCr3(BO3)4 single crystals or crystals in which the rhombohedral phase (sp. gr. R32) significantly prevails over the monoclinic phase (sp. gr. C2/c). The grown crystals have been characterized by X-ray diffraction techniques, IR spectroscopy, and magnetic measurements. [ABSTRACT FROM AUTHOR]

The temperature dependence of the magnetic susceptibility χ (T) of the GdCr3(BO3)4 single crystal was studied in the temperature range of 2–300 K for two orientations of the external magnetic field: H ǁ c and H ± c. It was established that gadolinium chromium borate is ordered antiferromagnetically at TN = 7 K. It was found that, at T > 10 K, the magnetic properties of the crystal are isotropic, which is characteristic of the pure spin states of Cr3+ and Gd3+ ions. It was demonstrated that the magnetic susceptibility χ(T) of the GdCr3(BO3)4 compound at T > TN is well described by a one-dimensional spin model for a system of ferromagnetic chains of Cr3+ ions with ferromagnetic exchange 2J/k = −13.6 K and antiferromagnetic interchain interaction of 2J′/k = + 0.72 K. The gadolinium subsystem is antiferromagnetically biased due to the exchange f-d-interaction, which gives θ Gd = − 2.8 K. It was assumed that the GdCr3(BO3)4 compound is an antiferromagnet with “easy-plane” type anisotropy in the magnetically ordered state. [ABSTRACT FROM AUTHOR]

A complex study of the CrBO3 single crystal has been performed by optical and IR spectroscopy methods over a broad temperature range. Factor-group and correlation analyses of the phonon modes are presented. All IR active phonons and their frequencies are experimentally identified by way of attenuated total reflectance. A magnetic phase transition at a temperature of 6K is detected. In the magnetically ordered state, an anisotropy of the optical spectrum was observed during polarization studies in the isotropic ab-plane of the crystal. A study of the temperature dependences of the phonon spectrum did not show any anomalies over the course of magnetic ordering, which indicates that there is an absence of an appreciable spin-lattice interaction in CrBO3. [ABSTRACT FROM AUTHOR]

An experimental study of AFMR in a GdCr3(BO3)4 single crystal within the frequency range of 17–38 GHz, at the temperature 4.2 K, was performed. The determined value of the energy gap in spin-wave spectrum equals (25.5 ± 0.5). It was shown that the high-frequency properties of gadolinium chromium borate are well defined within the framework of a two-sublattice antiferromagnet model with “easy-plane” anisotropy. [ABSTRACT FROM AUTHOR]