Crystal growth,structure, infrared spectroscopy,and luminescent properties of rare-earth gallium borates RGa3(BO3)4, R = Nd,Sm–Er,Y

Crystals of the rare-earth gallium borates RGa₃(BO₃)₄, where R = Nd, Sm–Er, or Y, were grown by the flux method. The crystal structures of RGa₃(BO₃)₄ (R = Eu, Ho) were studied on the basis of single-crystal X-ray diffraction measurements. The hexagonal unit-cell parameters are a = 9.4657(1) Å, c = 7.4667(1) Å and a = 9.4394(2) Å, c = 7.4322(1) Å for EuGa₃(BO₃)₄ and HoGa₃(BO₃)₄, respectively, space group R32. Structure model was determined by “charge flipping” method and refined to R = 1.93% [EuGa₃(BO₃)₄] and R = 1.89% [HoGa₃(BO₃)₄] in anisotropic approximation. All grown gallium borates were investigated by infrared (IR) spectroscopy technique in a middle and far IR region. IR spectra of rare-earth gallium borates correspond to a pure rhombohedral (R32) polytype structure. Small inclusions of a monoclinic phase were detected only in Eu and Nd compounds. Luminescence of Eu and Ho gallium borates was studied at room temperature. The measured decay times for the most intensive emission lines of EuGa₃(BO₃)₄ (∼614 nm) and HoGa₃(BO₃)₄ (434 nm) are 940 μs and 140 μs, respectively. The scheme of crystal-field energy levels of Eu³⁺ in EuGa₃(BO₃)₄ was built on the basis of the temperature-dependent optical transmission measurements combined with the luminescence data. The measured UV absorption edge for RGa₃(BO₃)₄ is at about 300 nm.     

Single-crystal oxoborate (Pb3O)2(BO3)2WO4: Growth and characterization

An oxoborate, (Pb₃O)₂(BO₃)₂WO₄, has been prepared by solid-state reaction methods below 620 °C. Single-crystal XRD analysis shows that it crystallizes in the orthorhombic group Cmcm with a = 18.480(4) Å, b = 6.3567(13) Å, c = 11.672(2) Å, Z = 4. The crystal structure is composed of one-dimensional 1/∞ [Pb₃O]⁴⁺ chains formed by corner-sharing OPb₄ tetrahedra. BO₃ and WO₄ groups are located around the chains to hold them together via PbO bonds. The IR spectra further confirmed the presence of BO₃ groups. Furthermore we have performed theoretical calculations by employing the all-electron full potential linearized augmented plane wave (FP-LAPW) method to solve the Kohn Sham equations. Starting from our XRD data we have optimized the atomic positions by minimizing the forces. These are used to calculate the electronic band structure, the atomic site-decomposed density of states, electron charge density and the chemical bonding features. The calculated electronic band structure and densities of states suggest that this oxoborate possesses a wide energy band gap. The valence band maxima and the conduction band minima are located at Y point in the Brillouin zone resulting in a direct energy band gap of 2.3 eV using the local density approximation and 2.6 eV for the Engel–Vosko generalized gradient approximation. This compares well with our experimentally measured energy band gap of 2.9 eV. From our calculated electron charge density distribution, we obtain an image of the electron clouds that surround the molecules in the unit cell of the crystal. The chemical bonding features were analyzed and the substantial covalent interactions are observed between Pb and O, B and O and W and O atoms.     

Synthesis,crystal structure and properties of a new lead fluoride borate,Pb3OBO3F

A new compound, Pb₃OBO₃F, has been grown by the high temperature solution method from the PbO–PbF₂–B₂O₃ system. It crystallizes in the orthorhombic system, space group Pbcm with unit-cell parameters a = 7.6313(14) Å, b = 6.5229(12) Å, c = 11.906(2) Å, Z = 4, volume = 592.66(19) Å³. The structure of the compound is solved by the direct methods and refined to R₁ = 0.0528 and wR₂ = 0.1400. Pb₃OBO₃F consists of Pb(1)O₃F tetrahedra, Pb(2)O₄ tetrahedra and BO₃ triangles which build up the symmetrical chains extended along the c-axis. The powder X-ray diffraction pattern of the Pb₃OBO₃F has been measured. Functional groups presented in the sample were identified by Fourier transform infrared spectrum.     

Synthesis and characterization of a new p-phenylenediammonium dihydrogenmonophosphate [p-NH3C6H4NH3][H2PO4]2

Chemical preparation, crystal structure and NMR spectroscopy of a new organic cation p-phenylenediammonium monophosphate [p-NH₃C₆H₄NH₃][H₂PO₄]₂ are presented. This new compound crystallizes in the orthorhombic system, with the space group Pnma and the following parameters: a = 7.970 (2) Å; b = 22.770 (7) Å; c = 7.000 (7) Å, V = 1270.3 (11) Å³, Z = 4 and D_x = 1.590 g cm⁻³. The crystal structure has been determined and refined to R = 0.043 and R_(w) = 0.057 using 2623 independent reflections. The structural arrangement can be described as inorganic layers of (H₈P₄O₁₆)⁴⁻ units, parallel to (a, c) planes. The organic groups (p-H₃NC₆H₄NH₃)²⁺are anchored between the phosphoric layers to form a three-dimensional infinite network. This compound is also investigated by IR and solid-state ¹H, ¹³C and ³¹P MAS NMR spectroscopies. The ab initio method is used in the calculation of chemical shifts.     

Two 2-D 36 tessellated metal–organic frameworks constructed from trimetallic clusters and dicarboxylate ditopic links

Two metal–organic framework compounds, [Zn₃(1,4-BDC)₃(Py)₂]·2(1,4-dioxane) (MOF-CJ6) and [Cd₃(bpdc)₃(H₂O)₂] (MOF-CJ7), have been solvothermally synthesized and characterized by single crystal X-ray diffraction, X-ray powder diffraction, ICP, IR and photoluminescence spectroscopy analyses, respectively. MOF-CJ6 crystallizes in monoclinic, space group P2(1)/n (no. 14) with a = 14.6886(14) Å, b = 9.6194(6) Å, c = 15.9161(16) Å and β = 105.687(6)°. Its framework can be described as a 2-D 3⁶ tessellated net based on the assembly of trimeric Zn₃(CO₂)₆ clusters and 1,4-benzenedicarboxylates ditopic links. The 2-D nets can be further linked into a novel 3-D supramolecular hexagonal lattice (hex) network through π–π packing interaction. MOF-CJ7 crystallizes in trigonal, space group R-3 (no. 148) with a = 14.1129(8) Å, b = 14.1129(8) Å, c = 20.1168(13) Å and γ = 120°. MOF-CJ7 exhibits analogous framework topology with that of MOF-CJ6, consisting of trimeric Cd₃(CO₂)₆ clusters and 4,4′-biphenyldicarboxylate links.     

(C2N2H10)[FexV1−x(HPO3)F3] (x = 0.44, 0.72): Two new organically templated phosphites: Solvothermal synthesis and structural,thermal, spectroscopic and magnetic studies

(C₂N₂H₁₀)[Fe_xV_1−x(HPO₃)F₃] (x = 0.44, 0.72) have been synthesized using mild solvothermal conditions under autogenous pressure and the ethylenediamine molecule as templating agent. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds crystallize in the orthorhombic P2₁2₁2₁ space group with Z = 4 and unit-cell parameters a = 12.8494(9), b = 9.5430(6), c = 6.4372(5) Å, and a = 12.8578(1), b = 9.5342(1), c = 6.4370(7) Å for (C₂N₂H₁₀)[Fe_0.44V_0.56(HPO₃)F₃] and (C₂N₂H₁₀)[Fe_0.72V_0.28(HPO₃)F₃], (1) and (2), respectively. These isostructural compounds exhibit a monodimensional crystal structure formed by pillared double anionic chains with the formula [M(HPO₃)F₃]²⁻, extended along the [0 0 1] direction. These doubled ionic chains are the result of the linking of two simple chains in which there are alternating octahedral [MO₃F₃] and tetrahedral groups [HPO₃]. The ethylendiammonium cations are placed in the space delimited by three different chains. The metallic ions are interconnected by the pseudo-pyramidal (HPO₃)²⁻ phosphite oxoanions, adopting a slightly distorted octahedral geometry. The IR spectra show bands corresponding to the phosphite oxoanion and the ethylendiamonium cation at 2400 and 1600 cm⁻¹, respectively. The thermogravimetric analyses show that these phases are stable up to ca. 280 °C, at higher temperatures, the decomposition of the crystal structure begins by calcination of the organic cation and the elimination of the fluoride anions. The diffuse reflectance spectra show bands of the V³⁺ ion (d²) in octahedral symmetry. The values of the Dq (1540, 1540 cm⁻¹), and Racah parameters, B (560, 535 cm⁻¹) and C (3055, 3140 cm⁻¹) for (1) and (2), respectively, correspond with those usually found for octahedrically coordinated V(III) compounds. Magnetic measurements, performed on a powered sample from 5.0 to 300 K at 1000 G, in the ZFC and FC modes, indicate the existence of antiferromagnetic interactions.     

Structural,thermal, spectroscopic and magnetic studies of the (C2N2H10)0.5[FexV1−x(HPO3)2] (x = 0.26, 0.52, 0.74) solid solution

The (C₂N₂H₁₀)_0.5[Fe_xV_1−x(HPO₃)₂] (x = 0.26, 0.52 0.74) compounds have been obtained by mild solvothermal conditions in the form of micro-crystalline powder with brown color. The crystal structures were refined by X-ray powder diffraction data using the Rietveld method. The compounds crystallize in the monoclinic system, space group P2/c with the unit-cell parameters, a = 9.262(5) Å, b = 8.823(5) Å, c = 9.714(6) Å, β = 120.84(3)°; a = 9.245(1) Å, b = 8.823(1) Å, c = 9.698(1)Å, β = 120.80(1)° and, a = 9.254(4)Å, b = 8.822(4)Å, c = 9.702(4)Å, β = 120.73(3)° for (C₂N₂H₁₀)_0.5[Fe_0.26V_0.74 (HPO₃)₂] (1), (C₂N₂H₁₀)_0.5[Fe_0.52V_0.48(HPO₃)₂] (2), and (C₂N₂H₁₀)_0.5[Fe_0.74V_0.26(HPO₃)₂] (3). The compounds show an open crystalline structure with three-dimensional character, whose formula for the anionic inorganic skeleton is [M(HPO₃)₂]²⁻. The inorganic framework is formed by [MO₆] octahedra inter-connected by phosphite groups. The structure of the compounds exhibits channels extended along the [1 0 0] and [0 0 1] directions and the ethylendiammonium cations are located inside these channels, linked through hydrogen bonds and ionic interactions. The infrared spectra show the bands corresponding to the stretching (P–H) vibration of the phosphite group and the band corresponding to the deformation mode of the ethylendiammonium cation, δ(NH₃⁺). The thermal and thermodiffractometric behavior show that the compounds are stable up to approximately 300 °C, at higher temperatures the decomposition of the crystal structure by calcination of the organic cation starts. The diffuse reflectance spectra show bands of the V³⁺ ion (d²), and a band of the Fe³⁺ ion (d⁵), in a slightly distorted octahedral symmetry. The values of the Dq and Racah parameters (B and C) have been calculated for the V(III) cation. Magnetic measurements were performed on a powdered sample from 5 to 300 K at magnetic fields 1000, 500 and 100 G, in the ZFC and FC modes. At the magnetic field of 1000 G antiferromagnetic interactions were observed, but at 100 G have been detected higher values of the χ_m in the FC mode than those observed in the ZFC one, indicating the existence of a dominant ferromagnetic component at low temperature. The magnetization measurements show hystheresis loops at 5 K, with values of the remanent magnetization and coercive field of 1.91 emu/mol and 23 Gauss for (1), 25 emu/mol and 300 Gauss for (2), and 3 emu/mol and 50 Gauss for the compound (3).     

Spectroscopic properties of Er3+ ions in La2(WO4)3 crystal

Er³⁺-doped La₂(WO₄)₃ single crystals were grown by the Czochralski technique. The absorption spectra, fluorescence spectra and fluorescence decay curves of the crystals were measured at room temperature. The spectroscopic parameters, including intensity parameters Ω_t (t = 2, 4, 6), spontaneous emission probability, fluorescence branching ratio, radiative lifetime, and stimulated emission cross-section were estimated. The fluorescence decay curves of fluorescence manifolds ⁴I_13/2, ⁴I_11/2, and ⁴S_3/2 were measured for crystal and powder samples, respectively. The effect of radiation trapping on the spectroscopic parameters was discussed. Green up-conversion fluorescence bands centered at wavelengths of 530 nm and 550 nm were observed when the crystal was excited at 977 nm. The possible up-conversion mechanisms were proposed.     

Flux growth and thermal properties of LiBaB9O15 single crystal

A large LiBaB₉O₁₅ single crystal has been grown by the top-seeded solution growth (TSSG) method using a Li₂Mo₃O₁₀ flux system. The crystal obtained exhibits (1 1 0), (1 1 3) and (1 0 2) faces. For the first time, thermal properties of the as-grown crystal, including thermal expansion, specific heat and thermal conductivity, have been investigated as a function of temperature. The specific heat of the LiBaB₉O₁₅ crystal was measured to be 0.663–1.110 J g^?1 K^?1 over the temperature range of 20–400 °C. The crystal exhibits thermal expansion along the a- and b-axis, coupled with thermal contraction along the c-axis, over the measured temperature range of 25–500 °C. The average thermal expansion coefficients along the a- and c-axis of the LiBaB₉O₁₅ crystal from 25 to 500 °C are calculated to be α_a = 6.56 × 10^?6 K^?1 and α_c = ?4.82 × 10^?6 K^?1, respectively.     

Second-order optical nonlinearities of metastable BiBO3 phases in crystallized glasses

Metastable BiBO₃ and rare-earth (RE)-doped RE_xBi_1−xBO₃ crystals were prepared through the crystallization of 50Bi₂O₃ · 50B₂O₃ and xRE₂O₃ · (50−x)Bi₂O₃ · 50B₂O₃ glasses (RE = Y, La, Gd, Yb), and their second harmonic (SH) intensities were examined using the Kurtz powder method. It was confirmed that BiBO₃ has two different crystalline forms, i.e., BiBO₃(I) and BiBO₃(II), and that BiBO₃(I) transforms into BiBO₃(II) at temperatures around 500 °C. Both phases were found to be nonlinear optical crystals with a phase matchable character, and the SH intensity of BiBO₃(II) powders was approximately 110 times as large as α-quartz powders. The incorporation of RE³⁺ into BiBO₃(II) was confirmed from X-ray diffraction analysis, and in particular, Gd_xBi_1−xBO₃(II) showed an enhanced SH intensity of approximately 145 times as large as α-quartz.     

Polarized spectral properties and 1.5–1.6 μm laser operation of Er:Sr3Yb2(BO3)4 crystal

Undoped and Er³⁺-doped Sr₃Yb₂(BO₃)₄ crystals were grown by the Czochralski method. Room temperature polarized spectral properties of the Er:Sr₃Yb₂(BO₃)₄ crystal were investigated. The efficiency of the energy transfer from Yb³⁺ to Er³⁺ ions in this crystal was calculated to be about 95%. End-pumped by a diode laser at 970 nm in a hemispherical cavity, a 0.75 W quasi-CW laser at 1.5–1.6 μm with a slope efficiency of 7% and an absorbed pump threshold of 3.8 W was achieved in a 0.5-mm-thick Z-cut crystal glued on a 5-mm-thick pure YAG crystal with UV-curable adhesive.     

Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X=P,As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H₂XO₄)_n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic–organic NLO crystals with general formula (2,3-(CH₃)₂C₆H₃NH₃)H₂XO₄ (X=P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a=8.866(3) Å, b=5.909(6) Å, c=10.644(5) Å, β=112.44(1)°, V=515.5(5) Å³ and D_X=1.412 g cm⁻³. The space group is P2₁ with Z=2. The structure was refined with R=0.041 (R_w=0.057) for 1652 reflections with I≥3σ(I). It exhibits infinite (H₂PO₄)_nⁿ⁻ chains. The organic groups (2,3-(CH₃)₂C₆H₃NH₃)⁺ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.     

Synthesis and structure determination of new open-framework chromium carboxylate MIL-105 or CrIII(OH)·{O2C–C6(CH3)4–CO2}·nH2O

Two new three-dimensional chromium(III) dicarboxylate, MIL-105 or Cr^III(OH)·{O₂C-C₆(CH₃)₄-CO₂}·nH₂O, have been obtained under hydrothermal conditions, and their structures solved using X-ray powder diffraction data. Both solids are structural analogs of the known Cr benzenedicarboxylate compound (MIL-53). Both contain trans corner-sharing CrO₄(OH)₂ octahedral chains connected by tetramethylterephthalate di-anions. Each chain is linked by the ligands to four other chains to form a three-dimensional framework with an array of 1D pores channels. The pores of the high temperature form of the solid, MIL-105ht, are empty. However, MIL-105ht re-hydrates at room temperature to finally give MIL-105lt with pores channels filled with free water molecules (lt: low temperature form; ht: high temperature form). The thermal behaviour of the two solids has been investigated using TGA. Crystal data for MIL-105ht: monoclinic space group C2/c with a = 19.653(1) Å, b = 9.984(1) Å, c = 6.970(1) Å, β = 110.67(1)° and Z = 4. Crystal data for MIL-105lt: orthorhombic space group Pnam with a = 17.892(1) Å, b = 11.165(1) Å, c = 6.916(1) Å and Z = 4.     

Spectroscopic properties of HoAl3(BO3)4 single crystal

The Judd–Ofelt theory has been applied to analyze absorption spectra of Ho³⁺ ion in HoAl₃(BO₃)₄ measured in spectral range 300–700 nm at room temperature. The Judd–Ofelt spectroscopic parameters have been determined as: Ω₂ = 18.87 × 10⁻²⁰ cm², Ω₄ = 17.04 × 10⁻²⁰ cm², Ω₆ = 9.21 × 10⁻²⁰ cm². These parameters have been used to calculate radiative lifetimes and branching ratios of the luminescence manifolds. Three luminescent bands were found in the spectral range 450–700 nm ascribed to transitions from the ⁵F₅, (⁵F₄, ⁵S₂) and ³K₈ states to the ground state ⁵I₈. Experimental intensities of these luminescence transitions were compared with those calculated by using Judd–Ofelt theory and the system of kinetic equations for populations of starting luminescing states. Probabilities of radiativeless transitions were evaluated from this comparison.     

Crystal structure of a new organic dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C₆H₈N₃O)₂(H₂PO₄)₂ (denoted IAHP) in the solid state. This compound crystallizes in the orthorhombic space group P2₁2₁2₁. The unit cell dimensions are: a = 7.422(3) Å, b = 12.568(5) Å, c = 20.059(8) Å with V = 1871.1(13) Å³ and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.029. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions between which are located the organic groups (C₆H₈N₃O)⁺ through multiple hydrogen bonds.     

Novel two-dimensional metal-organic framework with unprecedented trimeric building unit constructed from bridging water molecules

A novel two-dimensional nickel trimesate (1,3,5-benzenetricarboxylate), Ni₃(C₉O₆H₃)₂(H₂O)₈, has been obtained by solvothermal route. Its structure is built up from linear trimers of nickel, {Ni₃O₈(μ₂–OH₂)₂(H₂O)₆}, connected by trimesate anions. It crystallizes in the triclinic system, space group P-1, with a = 6.6960(3), b = 9.6446(3), c = 10.1114(3) Å, α = 112.638(1)°, β = 94.008(1)°, γ = 106.476(1)°, V = 565.99(4) Å³. Synthesis, X-ray structure determination, thermogravimetric analysis and magnetic properties are presented.     

First observation of the reversible O3 ↔ P2 phase transition: Crystal structure of the quenched high-temperature phase Na0.74Ni0.58Sb0.42O2

According to thermal expansion data, O3-type phase Na_xNi_(1+x)/3Sb_(2−x)/3O₂ (x ≈ 0.8) undergoes at ca. 1270 K a reversible transition to a less dense form. The high-temperature phase quenched to liquid nitrogen belongs to P2 type, space group P6₃/mmc (no. 194), a = 3.0123 Å(2), c = 11.2264 Å(7) for x ≈ 0.74 at 298 K. The stabilisation of P2 versus O3-type structure at high temperatures seems to be due to alkali distribution over greater number of sites thus increasing entropy and decreasing Na⁺–Na⁺ repulsion.     

X-ray powder diffraction,vibration and thermal studies of [A0.92(NH4)0.08]2TeCl4Br2 with A = Cs,Rb: Influence of mixed cationic and anionic substitutions

The crystal structures of [A_0.92(NH₄)_0.08]₂TeCl₄Br₂ with A = Cs, Rb have been determined using X-ray powder diffraction techniques. The two compounds crystallize in the tetragonal space group P4/mnc, with the unit cell parameters: a = 7.452(1) Å, c = 10.544(3) Å, Z = 2 and a = 7.315(2) Å, c = 10.354(4) Å, Z = 2 in the presence of Cs and Rb, respectively. These two compounds have an antifluorite-type arrangement of NH₄⁺/Rb⁺/Cs⁺ and octahedral TeCl₄Br₂^2? anions. The stability of these structure is by ionic and hydrogen bonding contacts: A?Cl, A?Br and N–H?Cl, N–H?Br. The different vibrational modes of these powders were analysed by FTIR and Raman spectroscopic studies. A DTA/TGA experiment reveals one endothermic peak at 780 K implicating the decomposition of the sample. At low temperature, one endothermic peak in thermal behavior is detected at around 213 K by DSC experiment. This transition was confirmed by dielectric measurements.     

Synthesis and tunable luminescence of RbCaGd(PO4)2:Ce3+, Mn2+ phosphors

RbCaGd(PO₄)₂ doped with Ce³⁺, Mn²⁺ was synthesized by the sol-gel method. The crystal structure and crystallographic location of Ce³⁺ in RbCaGd(PO₄)₂ were identified by Rietveld refinement. Powder X-ray diffraction (XRD) revealed that the structure of RbCaGd(PO₄)₂:Ce³⁺ compounds is hexagonal structure which is similar to that of hexagonal LnPO₄ with the lattice constant of a = b = 7.005(57) Å, c = 6.352(05) Å, and V (cell volume) = 269.980 Å³. The photoluminescence behavior and emission mechanism were studied systematically by doping activators in the RbCaGd(PO₄)₂ host. The Mn²⁺ incorporated RbCaGd(PO₄)₂:Ce³⁺, Mn²⁺ compounds exhibited blue emission from the parity- and spin-allowed f-d transition of Ce³⁺ and orange-to-red emission from the forbidden ⁴T₁ → ⁶A₁ transition of Mn²⁺. The emission chromaticity coordinates of RbCaGd(PO₄)₂:0.10Ce³⁺, xMn²⁺ (x = 0.16, 0.25) are close to the white region due to an energy transfer process and the energy transfer mechanism from Ce³⁺ to Mn²⁺ in the RbCaGd(PO₄)₂ host was dominated by dipole-dipole interactions.     

Temperature-dependence of Raman spectroscopy on the phase transition in LuBO3

Temperature-dependence of Raman spectroscopy on LuBO₃ structure was performed in order to obtain information on structural changes induced by temperature evolution. The stability of the calcite phase and low-temperature vaterite phase of LuBO₃ were both evaluated. For the sample with low-temperature vaterite phase, a strong first-order phase transition occurred during 1000–1200 °C, as indicated by the behavior of the Raman modes: the Raman bands split and new bands appear. The transition was associated with the B–O bond being broken in the cyclic B₃O₉ groups at high temperature, forming an open B₃O₉ group consisting of BO₄ and BO₃. Moreover, the influence of In³⁺ content on the structural characteristics of LuBO₃ was investigated. It was found that the calcite phase of LuBO₃ can be stabilized up to 1550 °C at least when the n(In)/n(Lu + In) ratio was more than 20 at%. The crystal growth and characterizations of Lu_1?xIn_xBO₃:Ce materials deserve further investigation.