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A single crystal of LiNa5Mo9O30 of 52 × 44 × 8 mm3 was successfully grown using the top-seed solution growth method. The full width at half maximum of the high-resolution X-ray diffraction rocking curve for the (100) plane is 17′′. The LiNa5Mo9O30 single crystal can transmit well from 0.31–5.35 μm. It was easily processed with a moderate hardness of 5.2. The specific heat curve increases slowly without an inflection point. The thermal expansion coefficients were measured to be αc > αa > αb, and the structure–property relationship was discussed in detail. It exhibits good thermal conductivity with κa = 2.67 W m−1 K−1, κb = 3.61 W m−1 K−1, and κc = 3.22 W m−1 K−1, respectively. As a molybdenum crystal, the spontaneous Raman spectra along the a-axis with different Raman configurations were characterized. There is a strong Raman shift at 946.6 cm−1, which can be used for Raman laser applications. Our results show that the LiNa5Mo9O30 single crystal is not only a second order nonlinear optical crystal but also an excellent candidate for stimulated Raman scattering.

Transition-metal tellurites have motivated growing research interest in both fundamental and applied chemistry, and the corresponding single crystals could serve as rich and fascinating platforms to regulate, explore, and elucidate the intrinsic characteristics of different structures from 0D to 3D architectures. In this context, a zirconium tellurite (namely, ZrTe

The anisotropic properties of a nonlinear optical (NLO) material are of critical importance for comprehending the intrinsic characteristics and evaluating the further applications. However, due to the severe layered growth habits, the anisotropic investigations of the NLO crystal CdTeMoO6 with a quasi-two dimensional structure have been severely hindered. Here, a detailed study of the bulk growth, exhaustive thermal properties and polarized Raman spectra for CdTeMoO6 single crystal are provided and all of them exhibit obvious anisotropic characteristics. Based on high quality crystal CdTeMoO6, the spontaneous Raman spectra along X and Z-axis with different configurations show the strongest Raman shifts at 921.6 and 944.1 cm−1. More importantly, the relationship between structure and the anisotropic physical properties, including thermal expansion, specific heat, thermal diffusion, thermal conductivity and hardness of the CdTeMoO6 crystal have also been systemically discussed, which provide a guidance for the further application of CdTeMoO6.

Controlling polymorphism crystallization can be used to tune the intrinsic properties of a material without introducing any other atoms and is, therefore, of important technological significance. A...

Recent research on cesium tellurium tungstate (Cs2TeW3O12) has demonstrated that it is a promising candidate for use in photoelectric applications. However, further improvement, particularly for the study of the anisotropic properties of Cs2TeW3O12, is hampered by the difficulty of bulk crystal growth. Here, single crystals of the polar compound Cs2TeW3O12 with dimensions reaching 75 mm × 35 mm × 8 mm were grown successfully through a modified top-seeded solution growth (TSSG) method. Laue diffraction and high-resolution X-ray diffraction (HRXRD) measurements indicate that the Cs2TeW3O12 crystals are of high crystalline quality. Optical measurements demonstrate a UV absorption edge near 385 nm, with a transmittance window reaching 5.5 μm. Using a large high-quality crystal, the thermophysical properties including specific heat, thermal diffusion and thermal conductivity were also systematically studied. More importantly, the Raman scattering properties determined using spontaneous Raman spectroscopy show that the Cs2TeW3O12 crystal exhibits an intense Raman shift (910.34 cm−1) and narrow line-width (6.84 cm−1) that are comparable to those of the YVO4 crystal. In addition, first-principles calculations have been performed to better understand the structure–property relationships of the Cs2TeW3O12 crystal. These attributes may establish a foundation for future nonlinear optical applications of Cs2TeW3O12 crystals.

High-quality single crystals of the bismuth ferrite-based material Bi3FeO4(MoO4)2 of size up to 28 × 20 × 12 mm3 were successfully grown via the modified top-seeded solution growth (TSSG) technique by using MoO3–Bi2O3 as the self-flux. Bi3FeO4(MoO4)2 crystallizes into the space group C2/c (no. 15, a = 16.927(12) A, b = 11.672(12) A, c = 5.263(4) A, and Z = 4) with a typical scheelite-type structure. The as-grown crystals exhibit major face forms {100}, {110}, and {111}, which is consistent with the predicted growth morphology on the basis of the BFDH method. The high-resolution X-ray diffraction results demonstrate that the FWHM of the (200) face of the crystal is 31 arcsec, which indicates a high quality. The thermal measurements showed that the crystal melts incongruently and is thermally stable up to 912 °C. The crystal also displays a wide transmission region of 0.64–5.8 μm with a band gap of 2.26 eV. Moreover, the magnetization properties with variations in temperature were measured, and the anti-ferromagnetic ordering is found to occur at 11 K. Notably, the Raman scattering measurements show that the crystal exhibits an intense Raman shift and narrow line-width that are comparable with those of the YVO4 crystal. In addition, the first-principles calculations on the title compound were carried out to analyze the structure–property relationships. These results of the Bi3FeO4(MoO4)2 single crystals may provide a better understanding for further studies of these materials.

With existing and emerging technologies urgently demanding the expansion of the laser wavelengths, high-performance nonlinear optical (NLO) crystals are becoming indispensable. Here, a prospective NLO crystal, Li2ZrTeO6, is rationally designed by the element substitution of Nb for Zr and Te from LiNbO3, which has been recognized as one of the most commercial NLO crystals. Li2ZrTeO6 with R3 symmetry inherits the structural merits of LiNbO3 (space group R3 c) and thus meets the requirements for NLO applications, including noncentrosymmetric crystal structure, moderate birefringence, and phase-matchability. Moreover, it can be exploited to achieve more outstanding optical damage resistant behavior (>1.3 GW cm-2), exceeding 22 times that of LiNbO3, which is more suitable for high-energy laser applications. Notably, this compound displays the widest IR absorption edge (7.4 μm) among all of the noncentrosymmetric tellurates reported so far. These excellent attributes suggest that Li2ZrTeO6 is a promising candidate for providing high NLO performance. The substitution of Nb for Zr and Te from LiNbO3 demonstrates a viable strategy toward the rational design of NLO crystals with anticipated properties.

An interesting phenomenon of two polymorphic heterojunctions is reported in this paper. The selective growth of the individual phases of high-quality α- and β-BaTeMo2O9 (BTM) crystals was successfully achieved using an optimized flux system and growth parameters. A biphasic BTM crystal based on a multiseeding technique used to control the nucleation and subsequent growth was realized in a one-flux system. The formation of a grain boundary, similar to a heterojunction, between the α- and β-BTM crystals emerged as an unavoidable consequence of this process, and the factors that led to the formation of the grain boundaries in the multiseeds were examined. Lattice mismatch and interfacial binding energy calculation verified that the BTM crystals were grown together rather than being physically adhered, and the chains at the grain boundary were linked by O5Mo–O–MoO5 dioctahedrons corner-sharing O atoms at the eutectic boundary. The screw dislocation growth mechanism was confirmed for β-BTM with the growth unit...

Acentric compounds with a layered structure are of current interest owing to their advanced functional properties for technical applications. However, the growth of bulk single crystals of acentric materials with a quasi-two-dimensional structure is challenging, which severely hinders the intrinsic properties investigation and optoelectronic applications of these materials. Herein, we report the controlled growth of bulk CdTeMoO6 single crystals with a layered structure and the investigation of their linear and nonlinear optical properties. High quality CdTeMoO6 single crystals with dimensions of ∼26 × 10 × 9 mm3 were successfully grown through the modified top-seeded solution growth method using TeO2-MoO3 as a flux. The transparent range of CdTeMoO6 single crystals is in the range of 0.345–5.40 μm, and with large birefringence (Δn = no – ne = 0.2868–0.2219 from 514 nm to 1.5467 μm). In addition, the nonlinear optical (NLO) coefficient d36 of CdTeMoO6 single crystals was measured to be 8.5 pm/V using Make...

Large sized crystals of CdTeMoO6 with dimensions up to 30 × 12 × 9 mm3 were successfully grown using the top-seeded solution growth technique with an optimized flux system. High resolution X-ray diffraction rocking curve measurements revealed that the full-width at half-maximum (FWHM) of the rocking curve was 36 arcsec from the (001) reflection, which indicated high crystal quality. A complete set of room temperature elastic, dielectric, and piezoelectric constants of CdTeMoO6 single crystals was obtained using both resonance techniques and impedance analysis. The results demonstrate that the CdTeMoO6 crystals exhibit intriguing piezoelectric and elastic properties. The piezoelectric coefficients d14 and d36 reached 20.14 pC N−1 and 7.58 pC N−1, respectively, and the corresponding electromechanical coupling coefficients k14 and k36 were up to 22.78% and 19.48%, respectively. Furthermore, the relationship between the crystal structure and piezoelectric properties is also investigated. Our observations indicate that CdTeMoO6 crystals are good potential candidates for piezoelectric applications.

Bismuth layered Aurivillius oxides have attracted longstanding research interest due to their unique structural characteristics and outstanding performance in ferroelectric dielectrics. The complex phase evolution process as a function of temperature and pressure in this family also provides fascinating platforms for understanding the chemical origin of their versatility. Herein, high-quality single crystals of a bismuth layered Aurivillius oxide, Bi2W2O9, with dimensions up to 29 × 23 × 11 mm3 were successfully grown via the top-seeded solution growth (TSSG) method using a mixture of WO3 and Li2B4O7 as a flux. The material crystallizes in an unexpected centrosymmetric orthorhombic Pbcn (no. 60) space group with unit cell parameters a = 23.705(2), b = 5.4148(6), and c = 5.4345(6) A. A complete survey of the anisotropic and variable-temperature thermal and dielectric properties was carried out with the aim of gaining detailed insights into their polymorphism evolution process. The results demonstrate that, with increasing temperature, the compound undergoes complicated phase transitions and, by analogy, signatures of the transitions are summarized and compared with those in Bi2WO6 and Bi2MoO6. The phase sequences and transition mechanisms of Bi2W2O9 are proposed by careful inspection and estimation.

A prospective acousto–optic (A/O) crystal TiTe3O8 endowed with superior thermal features and appreciable transparency is rationally developed by a tailored approach, namely TeO2 (a material possessing outstanding A/O performance) in synergistic combination with TiO2. Using the selected Li2CO3–TeO2 fluxes, a high-quality and large-dimension single crystal of cubic TiTe3O8 is extracted through a high temperature top-seeded solution growth (TSSG) technique. Remarkably, TiTe3O8 contains a d0 transition metal cation, Ti4+, which is typically susceptible to second-order Jahn–Teller (SOJT) distortions, but surprisingly in a locally undistorted octahedral geometry. The high symmetry of TiTe3O8 makes it ideal for crystal processing and A/O device design. Notably, the tellurite crystal TiTe3O8 displaying an adequate A/O figure of merit is originally utilized to fabricate an A/O modulator that exhibits a high diffraction efficiency of 77%, which is competitive with the value reported for the TeO2 crystal. Such a tailored design enriches the family of A/O materials and opens up a viable route toward exploiting controlled fabrication of potential A/O materials.

Single crystals of an environmental friendly material LiInSe2 (LISe) with dimensions up to Φ16 mm × 55 mm were grown successfully through a modified vertical Bridgman technique. The quality of the crystal was measured by a high resolution X-ray diffraction rocking curve, and a full width at half-maximum (fwhm) for a, b, and c faces are 47″, 46″, 36″, respectively. It indicates that the as-grown crystal is high quality. The complete sets of dielectric, elastic, and piezoelectric constants of LISe crystals at room temperature were obtained by the resonant technique and impedance analysis for the first time. The piezoelectric constants d24 and d33 reached −13.6 pC/N and 8.5 pC/N, respectively. The corresponding electromechanical coupling coefficient k33 is 21%. In addition, the structural distortions and dipole moments of LISe were analyzed in detail. Our results show that LISe is a promising candidate as an environmental friendly piezoelectric material.

Bulk single crystals of zinc cadmium thiocyanate, ZnCd(SCN) 4 (ZCTC) with dimensions of 51 × 15 × 12 and 28 × 13 × 12 mm 3 have been obtained. Growth habits were investigated, two-dimensional nucleation growth mechanism and crystal twinning defect were observed from the as-grown crystals. The thermal diffusivities were measured, and then thermal conductivities were calculated with values decreasing from 1.3683 to 0.8739 W⋅m −1 ⋅K −1 and 0.8496 to 0.5356 W⋅m −1 ⋅K −1 as the temperature increasing from 303 to 423 K, along the a- and c-directions, respectively. The relative dielectric constants and elastic compliance constants at room temperature were determined. Meanwhile, first-principles calculation was used to calculate elastic constants.

In this study, Cs2TeW3O12 (CTW) single crystals were grown successfully through a top-seeded solution growth (TSSG) method using TeO2 as a self-flux. We identified a complete set of growth process parameters suitable for facilitating the growth of a high-quality CTW crystal. The results indicate that, in the same thermal field and with an appropriate flux ratio, a smaller cooling rate of the melt facilitates the smooth growth of high-quality CTW single crystals. The melt-viscosity versus temperature curves for different flux ratios were measured, and their effects on the crystal quality were discussed. In addition, the morphology of the crystal can be controlled by adjusting the rotation speed and the orientation of the seed. To investigate piezoelectric performance, complete sets of dielectric, elastic, and piezoelectric coefficients of CTW crystals were measured using both resonance and impedance analysis. The piezoelectric coefficients d33 and d15 reached 19.1 pC N−1 and 25.9 pC N−1, respectively. The electromechanical coupling coefficient, k33, was 37.7%, slightly higher than that of Cs2TeMo3O12 (CTM). Furthermore, the extent of dipole moment and polyhedron distortion of the CTW crystal were analysed in detail, and the relationship between the crystal structure and the piezoelectric properties was also discussed.

Organic–inorganic hybrid materials crystallized in noncentrosymmetric (NCS) structures have been receiving considerable attention due to their fascinating physical properties and promising applications. Herein, bulk single crystals of an NCS organometallic compound, MnHg(SCN)4 (MMTC), are grown via a temperature lowering method. The grown crystals present negative uniaxial characteristics with large birefringence, good optical homogeneity and high thermal conductivities. In addition, their Raman scattering properties are measured using spontaneous Raman spectroscopy, which show that the MMTC crystal exhibits a large Raman shift (2148.1 cm−1), narrow line-width (4.468 cm−1) and high Raman gain coefficient (1.753 times higher than that of crystalline YVO4). Moreover, the direct current conductivity, dielectric, and piezoelectric constants of MMTC are also measured, which display that the crystal also possesses a strong piezoelectric response of d15 = 22.7 pC N−1. Furthermore, structure property relationships are discussed on the basis of the structure of the crystal. As a multi-functional crystal, MMTC is a particularly promising candidate for stimulated Raman scattering in the visible and near-infrared regions and piezoelectric applications at room temperature.

Considering their easy growth and doping in bulk crystal growth, and good crystalline quality, ?-Ga2O3 single crystals, a very important wide-bandgap semiconductor, are now also considered to be a promising optical crystal candidate. In this work, a Cr4+:?-Ga2O3 single crystal has been grown successfully by the edge-defined film-fed growth method. The thermal conductivity of Cr4+:?-Ga2O3 has been measured along the a* direction at room temperature obtaining 16.2 W m-1 K-1, and it was much larger than that of the usually used Cr4+-doped crystals, such as Y3Al5O12 (YAG) or YVO4. The Raman spectrum indicated that the cutoff phonon energy of the ?-Ga2O3 crystal was 767.8 cm-1. A passively Q-switched nanosecond pulsed Nd:YAG laser based on a Cr4+:?-Ga2O3 saturable absorber was experimentally demonstrated for the first time to our knowledge and its mechanism is explained by first-principles calculations. By inserting the Cr4+:?-Ga2O3 crystal into the Nd:YAG laser cavity, a Q-switched laser operation was obtained with a maximum average output power of 50 mW. The corresponding pulse repetition rate, pulse width, and pulse energy were determined to be of 421.5 kHz, 235.2 ns and 0.12 ?J, respectively.

Bulk Ca12Al14O33 (C12A7) crystals were successfully grown by the Czochralski (Cz) method. However, the surface exhibited severe cracking to a depth of about 1 mm during cooling of the as-grown crystals to room temperature. To determine the mechanism of the surface cracking we measured powder crystal X-ray diffraction, Raman spectroscopy, thermal gravimetry, and infrared spectroscopy of the OH-stretching band. It was found that the lattice parameters of the cracked crystal surface and the core were different. A weight increase in the TGA curve was observed during the cooling process. Furthermore, the OH– ion content of the crystal increased after annealing experiments. It can be concluded that incorporation of hydroxide ions caused the surface cracking of the as-grown C12A7 crystals.

Large sized crystals of Na2TeW2O9 with dimensions up to 75 × 35 × 25 mm3 were successfully grown using an optimized top-seeded solution growth method. The as-grown Na2TeW2O9 single crystal exhibits well-developed faces with the major forms {200}, {002}, {202}, and {220}, which are in superior accordance with the ideal morphology predicted by the Bravais–Friedel and Donnay–Harker methods. A complete set of room temperature elastic, dielectric, and piezoelectric constants of Na2TeW2O9 single crystals was determined using resonance techniques and impedance analysis. Our results show that Na2TeW2O9 exhibits excellent piezoelectric properties (d15 = −23.93 pC N−1, d24 = −20.34 pC N−1), making the crystal a promising candidate for piezoelectric applications. The relationship between the piezoelectric properties and the crystal structure is also discussed.

Single crystal LiVMoO6, with dimensions up to 20 mm × 15 mm × 12 mm, has been grown successfully for the first time from a high-temperature solution with MoO3 as a flux. LiVMoO6 crystalizes in the monoclinic system with space group C2/m (no. 12) and unit cell parameters of a = 9.3531(9) A, b = 3.6477(4) A, c = 6.647(4) A, β = 111.643° and Z = 2. The crystal structure consists of MO6 (M = Mo and V) and LiO6 octahedrons mutually combined via corner sharing to form a 3D network. The as-grown LiVMoO6 crystal has well-developed faces with major forms {1−11}, {−1−11}, {001}, {100}, {11−1}, and {−11−1}. The crystal exhibits good transmittance from 490 to 4950 nm. High-resolution X-ray diffraction (HRXRD) shows that the full-width at half-maximum (fwhm) of the rocking curve is 47.22′′, indicating high crystal quality. The refractive index coordinate is established using a polarizing microscope. Spontaneous Raman spectra along the Z-axis with different configurations exhibit strong Raman shifts at 963.7 cm−1 and 830.5 cm−1, which are comparable to those of crystalline YVO4. The results indicate that LiVMoO6 should be an excellent Raman crystal.

The optical properties of the α/β-BaTeMo2O9 (α/β-BTM) crystal in the terahertz range were characterized by the terahertz time domain spectroscopy (TDS) system. Frequency-dependent refractive indices and absorption coefficients of two crystals were measured from 0.2 to 2 THz, and discussions and comparisons were made on birefringence, absorption and phonon modes by referring to their structures. The Sellmeier equations for both crystals were also fitted in their transparent ranges. Based on the mode properties and parameters, a feasible scheme for terahertz generation via stimulated polariton scattering (SPS) with β-BTM was proposed and the angle tuning characteristics were calculated. Simulations show that β-BTM has great potential and should be more advantageous than LiNbO3 in generating high-frequency terahertz waves.

The high efficiency acousto-optic modulators become indispensable in photonics and optoelectronics for the pulse generation and signal modulation in optical display and telecommunications. In this paper, the validity and feasibility of the biaxial crystals as acousto-optic mediums have been theoretically analyzed and confirmed by experiments using a biaxial crystal of β-BaTeMo2O9. The diffraction angle and diffraction efficiency of the β-BaTeMo2O9 acousto-optic Q-switch are determined to be 1.420° and 78.1%, which are comparable with that of TeO2 acousto-optic modulator at the identical operating wavelength of 1064 nm and 100 MHz, respectively. The minimum of the modulated pulse width can be achieved to be 6 ns at 5 kHz with Nd:YVO4 as the gain medium. The results not only provide an excellent acousto-optic medium, but also explore the field of biaxial acousto-optic medium for device fabrications.

Mid-infrared (MIR) nonlinear optical crystals of LiInSesub2/sub(LISe) were grown by a modified Bridgman technique on a (001)-seed. A 7-12 μm widely tunable picosecond (ps) MIR optical parametric amplifier (OPA) based on a LISe crystal was demonstrated for the first time, to the best of our knowledge. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser and injected by a KTiOPOsub4/sub(KTP)-based widely tunable near-infrared seed. The idler operating at 7.5 μm with the highest pulse energy of 170 μJ was obtained under a pump energy of 14 mJ. The corresponding energy conversion efficiency is ∼1.21%, and the photon conversion efficiency is 8.6%. The output energies were measured to be ∼121 μJ at 7 μm and ∼21 μJ at 12 μm.

We report the linear and nonlinear optical (NLO) properties of a polar crystal Cs2TeW3O12 (CTW). The second-order NLO coefficients were determined by Maker Fringe (MF) techniques for the first time. CTW belong to hexagonal system with point group P63, the two independent NLO coefficients of d32 and d33 were determined to be 6.2 and 4.3 pm/V, respectively. CTW can realize phase-matching (PM) and in the direction of θ = 39.6° the effective NLO coefficient is 4.0 pm/V at 1064 nm. To illustrate the good NLO properties of CTW, the distortions of polyhedron structures were also discussed in detail.