Search

A high-quality tetragonal LiY(MoO4)2 single crystal was grown by a top-seeded solution growth method. Based on the quality evaluation, the optical transmission and thermal properties of the LiY(MoO4)2 single crystal were fully characterized.

A high-quality Y2Mo4O15 single crystal was grown by the top-seed solution growth method. The negative thermal expansion mechanism of the Y2Mo4O15 crystal has been explored and the space thermal expansion coefficient curve has been calculated.

The delaminated O-Ti2CTx aqueous solution can be stably stored for 30 days, which is much higher than that of HCl- and LiF-etched Ti2CTx (F-Ti2C) (completely oxidized within 24 hours).

In this work, recent advances in tellurite molybdate/tungstate crystals have been systematically reviewed, including crystal growth, research of physical properties, theoretical analysis, and some electric/optical devices.

Oxide crystals have been widely used in the nonlinear optical (NLO) field in the ultraviolet-visible and near-infrared region. Most of the traditional oxide crystals are restricted in the mid-infrared region due to their narrow transmission window. Hence, attempting to extend infrared cutoff wavelength of oxide has attracted much attention. In our work, we reported two new tellurate Li 2 TiTeO 6 (LTT) and Li 2 SnTeO 6 - (LST) with broad transparent region 0.38-6.72 and 0.38-6.86 μm, respectively, which could be excellent candidates for the mid-infrared NLO application. Both LTT and LST are crystallized in the orthorhombic space group P nn 2. The LTT crystal exhibits intense powder second-order generation efficiency (26×KDP) under the fundamental wavelength of 1064 nm. The first-principles calculations and dipole moments were used to illustrate the results of the powder second-harmonic generations based on the crystal structures. Our results provide a novel oxide NLO crystal with a strong SHG and wide transparency range. It also paves a way to design new oxide mid-IR NLO crystals.

In this Letter, the spontaneous Raman spectra of a novel, to the best of our knowledge, crystal α-BaTeW

In this letter, a novel acousto-optical (AO) Q-switch is designed by using $\alpha $ -BaTeMo $_{\mathbf {2}}~\text{O}_{\mathbf {9}}$ crystal grown by the flux method. The acousto-optical modulator (AOM) exhibits a high polarization extinction ratio of 65 dB with a rise time of 32.8 ns and insertion loss of 3.66 dB. An actively Q-switched ytterbium doped all fiber laser at 1035 nm is successfully realized by using the prepared AOM. Under a pump power of 404.9 mW, a maximum output power of 1.66 W is obtained with pulse width of 167 ns at the modulation rate of 10 kHz. The results show that the $\alpha $ -BaTeMo $_{\mathbf {2}}~\text{O}_{\mathbf {9}}$ AOM is a potential Q-switch for all fiber lasers.

The quasi two-dimensional Ruddlesden–Popper perovskites (RPPs) have drawn unprecedented research attention due to their superior long-term environmental stability, abundant structural diversity, and favorable performance in energy-related application scenarios. Rational molecular design strategies, especially proper selections and modifications on the bulky organic spacer cations, play a vital role in obtaining RPPs with desired properties. Recently, employing fluorinated organic cations for further improving the stability and artificial tuning of the performance of RPP based devices has become a promising strategy. However, the mechanism of how fluorination affects the orientation of the spacer cations and the interactions between the organic slabs and the inorganic frameworks is still controversial and needs further investigations, especially on the structure–property relationship based on well-developed single crystals. Herein, we adopted meta-fluorophenethylamine (3-FPEA) as the spacer cation and successfully synthesized a RPP, (3-FPEA)2PbI4. Centimeter-sized single crystals of this material were grown through the bottom-seeded solution growth (BSSD) method by using hydroiodic acid as the self-solvent. (3-FPEA)2PbI4 exhibits superior thermal stability (from −175 °C to 281 °C), while a reversible phase transition occurs at 212 °C and it remains stable for at least 90 days when exposed to RH 80% at room temperature. Structural refinement and optical characterization indicate that the meta-substitution of fluorine breaks its original symmetry from monoclinic Cc to triclinic P space group accompanying a certain degree of disorder of the Pb2+ ions as well as the equatorial bridging I− ions and leads to a smaller band gap (2.20 eV), blue-shifted photoluminescence peak (516 nm), and longer decay time (τave = 1.36 ns). This work offers further insights into the structure–property relationships of the fluorinated RPPs and provides an effective strategy for designing novel RPPs with superior photoelectric properties.

Li2ZrTeO6 crystals have been proved as a novel nonlinear optical material with a high laser-damage threshold (>1.3 GW cm−2) and wide transparency window. However, investigations of the anisotropic properties of Li2ZrTeO6 are impeded by the difficulty of high-quality crystal growth. Here, centimeter-sized and high-quality Li2ZrTeO6 crystals were grown by a modified top-seed solution growth method. The full-widths at half-maximum of (20) and (001) wafers are 33 and 36 arcsec, respectively. Based on a large high-quality crystal, the thermal properties including thermal expansion, specific heat and thermal conductivity were studied in detail. Our results show that the Li2ZrTeO6 crystal exhibits a moderate anisotropic thermal expansion (αa/αc ≈ 5) from 25 to 500 °C. The specific heat is measured to be 0.77 to 0.902 J g−1 K−1 from 25 to 500 °C. The thermal conductivities along the a and c axes are determined to be 4.14 and 4.86 W m−1 K−1, respectively, which are superior to that of molybdenum-tellurite and tungsten-tellurite crystals. The excellent thermal properties are one of the origins of the high laser-damage threshold. In addition, the relationship between the structure and the anisotropic thermal properties is also discussed. The results indicate that the Li2ZrTeO6 crystal is a promising candidate for high-energy laser applications.

In this work, a novel, to the best of our knowledge

A new multi-functional crystal has been implemented by combining the acousto-optic (A/O) modulation with Raman laser output, which has never reported before. Notably, the α-BTM displaying an adequate A/O figure of merit of 10.18 × 10 -18 s 3 /g using the comparison method is originally tailored to fabricate an A/O modulator that exhibits a high diffraction angle and diffraction efficiency of 1.432° and 82.1% at 1064 nm, respectively, which can be competitive with that of TeO 2 . Pumped by a pulsed laser, sequentially, the self-Q-switch Raman laser working at 1178.1 nm is successfully realized based on α-BTM crystal. A maximum output power of 86 mW operating at 1178.1 nm and the repetition frequency of 15 kHz were obtained with the pump power of 27 W. Our works not only enrich the family of A/O materials, but also opens up a viable route towards exploiting the design of multi-functional crystal.

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.

The anisotropic physical property is the most noteworthy feature of crystals. In this paper, the subscript change method is used to analyze the sign changes of different tensors describing physical properties in uniaxial crystals. The distribution of some physical properties in special point groups exhibits non-symmetry in eight quadrants, which should attract the attention of crystal research. The difference between the crystallographic and physical coordinate systems and the lack of crystal symmetry operations are considered to be the origins of the non-symmetry. To avoid ambiguities and difficulties in characterizing and applying crystal physical properties, eight quadrants in space should be clarified. Hence, we proposed the use of piezoelectric properties to define the positive direction of the optical coordinate axis prior to the research and applications of optical properties.

Oxide crystals have been widely used in nonlinear optics (NLO) in the ultraviolet-visible and near-infrared regions. Most traditional oxide crystals are restricted to the mid-infrared region due to their narrow transmission window. Hence, attempting to extend infrared cutoff wavelength of oxides has attracted much attention. Herein, we report two new tellurates Li

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.

A new crystal Y

A new generation of orthogonally polarized dual-wavelength lasers was demonstrated using a dye mode-locked neodymium-doped yttrium aluminum garnet laser for the first time. With a hexagonal

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.

In this work, a novel, to the best of our knowledge, α − B a T e M o 2 O 9 crystal-based acousto-optical modulator is designed and successfully applied in actively Q -switched and mode-locked Er-doped fiber lasers (EDFLs) and Yb-doped fiber lasers (YDFLs) operating at 1.5 and 1.0 µm. The shortest pulse width of 429 ns and 1.37 µs are obtained in actively Q -switched EDFLs and YDFLs, respectively. For actively mode-locked operation, a pulse width of 11.32 ns at a modulation frequency of 3.19 MHz is obtained in EDFLs, while it is 29.9 ns at 1.036 MHz in YDFLs. The results indicate that the α − B a T e M o 2 O 9 crystal is a promising candidate for all-fiber active modulators.

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.

Theoretical simulations were carried out to evaluate the properties of terahertz (THz) generation in β-BaTeMo2O9 (βBTM) crystal by stimulated polariton scattering (SPS) process. The effects of different polariton modes on THz generation were analyzed, from which we determined the optimal crystal design and polarizations of the coupled waves. The dispersion and absorption characteristics of these vibration modes were also given based on the first-principle calculation and correlation Raman spectrum. Finally, the angle phase matching property and THz-wave gain were calculated. Simulation results showed that β-BTM is a kind of potential material for high-power tunable THz generation.

In eight quadrants, the positive and negative signs of tensor components describing physical properties of biaxial crystals have been given. The distributions of the physical properties described with different order tensors and their space symmetries have been discussed. These results show that the distributions of effective physical constants are symmetrical in the eight quadrants for the orthorhombic system, but there are two and four kinds of distributions for monoclinic and triclinic systems respectively. Thence, to avoid ambiguities and difficulties in characterizing and applying properties of biaxial crystals, we suggest that the really positive directions of the coordinate axes should be defined before the measurements of their physical properties and their device applications.

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.

A new generation of orthogonally polarized dual-wavelength lasers was demonstrated using a dye mode-locked neodymium-doped yttrium aluminum garnet laser for the first time. With a hexagonal C s 2 T e M o 3 O 12 as the Raman medium, efficient dual-wavelength stimulated Raman scattering was obtained at 1175 and 1154 nm with similar output power, corresponding to the stretching vibration of Mo-O and the asymmetric stretching vibrations of Mo-O and Te-O groups, respectively. The power ratio of two Raman components can be flexibly adjusted by tuning the polarization of the incident laser, which can be tuned from 0% to 100%. Laser sources with such a small wavelength separation could prove interesting for the difference-frequency generation of terahertz waves in the 4.6 THz range. Our study provides a simple and flexible method to achieve a promising dual-wavelength laser source in orthogonal polarization by Raman-based nonlinear frequency conversions.

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, Li

Single crystals of the polar material Cs2TeW3O12 (CTW) with dimensions up to 26 × 18 × 4 mm3 were successfully grown using a top-seeded solution growth method. The morphologies of the as-grown crystals have been described and compared with that obtained from the Bravais–Friedel and Donnay–Harker (BFDH) method. The crystal structure of CTW has been solved for the first time using single-crystal X-ray diffraction: the compound crystallizes in polar hexagonal space group P63 (No. 173) with cell parameters a = b = 7.3279(3) A, c = 12.4075(5) A, Z = 2, and V = 577.00(4) A3. Thermal analysis shows that CTW is thermally stable up to 820 °C, at which it melts incongruently. Further high-resolution X-ray diffraction experiments gave a full-width at half-maximum of the rocking curve of 33″, indicating a good crystalline quality for the as-grown crystals. Optical transmittance spectra of CTW show a broad transmission range from 410 to 5310 nm. Powder second-harmonic generation (SHG) measurements with a 1064 nm laser...

A single crystal of TbCa 4 O(BO 3 ) 3 (TbCOB) with diameter of 35 mm and length of 80 mm has been successfully grown using the Czochralski (Cz) method. The polarized Raman spectra were studied to analyze the vibrational structure of TbCOB, especially the modes from [BO 3 ] 3− triangles that are responsible for the nonlinear optical generation. The fluorescence properties of the X -cut, Y -cut, and Z -cut non-centrosymmetric TbCOB crystals were measured for the first time, and both f–d and f–f transitions were identified according to the energy level diagram. Based on the non-radiative energy transfer process, TbCOB crystal shows the characteristic emission of Tb 3+ corresponding to 5 D 4 → 7 F 6,5,4,3 transitions with the green light of 542 nm ( 5 D 4 → 7 F 5 ) being the most prominent group. Additionally, the lifetime decay indicates single exponential character for the excited wavelength at 378 nm, following the result of τ = 2.07 ms at room temperature. The long fluorescence lifetime and good spectra properties of TbCOB single crystal indicate its potential optical prospects.