Recently, several excellent SO4-based polyanion cathodes for Na-ion batteries (NIBs) were exploited, e.g. Na2+2xM2−x(SO4)3 (M = Fe and Mn), which can make NIBs competitive with state-of-the-art Li-ion batteries (LIBs). To search for more excellent SO4-based materials for NIBs, we studied the Na2SO4–MnSO4 system and isolated a new compound Na2Mn3(SO4)4, which crystallizes in the orthorhombic space group Cmc21 with a = 14.8307(18) Å, b = 9.9107(18) Å, c = 8.6845(12) Å, and Z = 4. The structure has tunnels for the migration of Na+ ions, which can be confirmed by using BVS maps. The impedance studies further demonstrated the mobility of Na+ ions. A high redox potential with a value of 4.48 V was obtained using the density functional theory (DFT) method based on ab initio calculations. Additionally, magnetic tests, infrared spectroscopy (IR), and differential scanning calorimetry (DSC) were also employed for the characterization of the material.

The crystals of the title compound have been grown in molten salt media. Single-crystal X-ray diffraction experiment revealed that the compound crystallizes in an orthorhombic space group Pbcn (no. 60) with cell parameters: a = 5.1023(10) Å, b = 19.717(4) Å, c = 12.557(3) Å, and Z = 4. The structure of Li5CsMn(P2O7)2 consists of one-dimensional manganese pyrophosphate chains [MnP4O14]∞ interleaved with Cs+ and Li+ cations. A pseudo-two-dimensional layer [CsMnP4O14]∞ parallel to the ab plane is made up of [MnP4O14]∞ chains and Cs–O polyhedra through sharing the oxygen atoms. The three crystallographically distinct Li atoms are all located in the interlayered space to form a ‘lithium hamburger’ structure. Magnetic studies demonstrated that the compound shows paramagnetic behavior. DSC and XRD investigations revealed that the compound melts congruently. AC impedance studies show that the conductivity is 1.3 × 10−5 S cm−1 at 573 K and the activation energy is 0.42 eV. In addition, Li ion diffusional pathways were obtained using the bond valence map.

•A new halophosphate crystal Sr3P3O10Cl was prepared by salt molten method.•There are flexible [P3O10]5− trimers in Sr3P3O10Cl.•The calculations of DFT reveal that Sr3P3O10Cl has a direct band gad of 5.14 eV.A new halophosphate crystal Sr3P3O10Cl was grown in molten chloride flux media. It crystallizes in the centrosymmetric orthorhombic space group Pnma (No. 62) with a = 10.617(2) Å, b = 10.736(2) Å, and c = 8.7354(17) Å. In the structure, the basic building unit is the [P3O10]5− anion, which is consist of three PO4 tetrahedra by sharing the corner oxygen atoms. The two Sr atoms and the Cl atom are linked to construct an infinite [Sr3Cl]5+ chain. The [P3O10]5− anions are interconnected with the [Sr3Cl]5+ chains to form a three-dimensional frameworks. Additionally, the first-principle calculation was employed to obtain the band structures and densities of states.

Single crystals of K3Y3(BO3)4 were grown using the KBO2, LiF, and Li2CO3 as the fluxes by the top-seed solution method. The K3Y3(BO3)4 can be an excellent host for doping of Yb3+, because there are six low-symmetric yttrium atoms in one unit-cell of K3Y3(BO3)4. The growth of K3Y3(BO3)4 was studied in detail, and a good crystal with sizes of 24 mm × 15 mm × 8 mm was grown successfully below 900 °C. Some characteristics, such as the X-ray diffraction, infrared spectroscopy, and thermal analysis, were also performed.

•A new lithium zinc iodate, LiZnO(IO3), has been prepared by hydrothermal reactions.•LiZnO(IO3) crystallizes in a noncentrosymmetric structure.•SHG measurement shows a response of 2 × KH2PO4.•LiZnO(IO3) is stable up to 490 °C.A new lithium zinc iodate, LiZnO(IO3), has been prepared by hydrothermal reactions at 200 °C. Single-crystal X-ray diffraction experiment revealed that the compound crystallizes in a noncentrosymmetric orthorhombic space group Ama2 with cell parameters: a = 6.3386(6) Å, b = 11.2613(11) Å, c = 4.6840(5) Å, Z = 4. In the structure, the basic building units are the distorted ZnO6 octahedron, LiO4 tetrahedron and the IO3 group. These groups are linked together to form a three-dimensional structure by sharing the oxygen atoms. The DSC measurement demonstrates that the compound is stable up to 490 °C. Powder second-harmonic generation (SHG) test shows that the SHG effect is about 2 × KH2PO4.

The synthesis, crystal structure, crystal growth, and characterization of a new noncentrosymmetric rare-earth borate BiSr3(YO)3(BO3)4 are reported. BiSr3(YO)3(BO3)4 belongs to gaudefroyite type of structure and crystallizes in the polar hexagonal space group P63 (no. 173) with a = 10.6975(16) Å and c = 6.7222(12) Å. In the structure, the YO7 polyhedra share edges to form an one-dimensional chain along the [001] direction. These chains are interconnected by the BO3 group to construct a three-dimensional framework, leaving two kinds of channels for Bi atoms and Sr atoms together with BO3 groups, respectively. On the basis of the powder second-harmonic generation (SHG) measurement, BiSr3(YO)3(BO3)4 belongs to the phase-matchable class with a SHG response of about 3 × KDP.

The title compound was firstly synthesized by solid state reaction and its single crystals were successfully obtained using a selected flux. It is isotypic with the mineral buetschliite, K2Ca(CO3)2, and crystallizes in the trigonal space group R-3m with a = 5.4526(12) Å, c = 17.781(8) Å, Z = 3. In the structure, Ba and K atoms are disordered on a same site in the proportion of 0.492(4):0.508(4). The fundamental building units are YO6 octahedra and BO3 triangles. The structure consists of [YB2O6]∞ double layers constructed by corner-sharing YO6 and BO3 groups. Ba/K atoms occupy the spaces between these two layers and play the role of bridges. In addition, the luminescence properties of Eu3+ doped KBaY(BO3)2 were also studied.

•Three new pyrophosphates crystals LiCsFeP2O7, LiCsCoP2O7 and NaCsCoP2O7 have been grown in the molten media.•LiCsFeP2O7 and LiCsCoP2O7 crystallize in space group Pnma.•NaCsCoP2O7 crystallize in space group P21/n.•Both Co and Fe atoms exhibit tetrahedral geometry in the three compounds.Three new pyrophosphates crystals, LiCsFeP2O7 (1), LiCsCoP2O7 (2) and NaCsCoP2O7 (3), have been grown in molten salt media. Their crystal structures have been determined by single crystal X-ray diffraction. 1 and 2 crystallize in orthorhombic space group Pnma, and 3 in monoclinic space group P21/n. In the three compounds, Co and Fe atoms are all coordinated with four oxygen atoms to form tetrahedral MO4 geometry. The three-dimensional frameworks, constructed by MO4 tetrahedra and P2O7 groups through shared corners, exhibit multi-channels structures. In 1 and 2, Li and Fe/Co atoms disorder in a same site with the proportion of 0.5:0.5. While in 3, Na and Co atoms locate on independent site. The IR spectrum further proves the presence of P2O7 groups. The impedance studies also were employed to evaluate the conductivities of 2 and 3.

The crystals of the title compound have been grown in molten salt media. Single-crystal X-ray diffraction experiment revealed that the compound crystallizes in an orthorhombic space group Pbcn (no. 60) with cell parameters: a = 5.1023(10) Å, b = 19.717(4) Å, c = 12.557(3) Å, and Z = 4. The structure of Li5CsMn(P2O7)2 consists of one-dimensional manganese pyrophosphate chains [MnP4O14]∞ interleaved with Cs+ and Li+ cations. A pseudo-two-dimensional layer [CsMnP4O14]∞ parallel to the ab plane is made up of [MnP4O14]∞ chains and Cs–O polyhedra through sharing the oxygen atoms. The three crystallographically distinct Li atoms are all located in the interlayered space to form a ‘lithium hamburger’ structure. Magnetic studies demonstrated that the compound shows paramagnetic behavior. DSC and XRD investigations revealed that the compound melts congruently. AC impedance studies show that the conductivity is 1.3 × 10−5 S cm−1 at 573 K and the activation energy is 0.42 eV. In addition, Li ion diffusional pathways were obtained using the bond valence map.

Recently, several excellent SO4-based polyanion cathodes for Na-ion batteries (NIBs) were exploited, e.g. Na2+2xM2−x(SO4)3 (M = Fe and Mn), which can make NIBs competitive with state-of-the-art Li-ion batteries (LIBs). To search for more excellent SO4-based materials for NIBs, we studied the Na2SO4–MnSO4 system and isolated a new compound Na2Mn3(SO4)4, which crystallizes in the orthorhombic space group Cmc21 with a = 14.8307(18) Å, b = 9.9107(18) Å, c = 8.6845(12) Å, and Z = 4. The structure has tunnels for the migration of Na+ ions, which can be confirmed by using BVS maps. The impedance studies further demonstrated the mobility of Na+ ions. A high redox potential with a value of 4.48 V was obtained using the density functional theory (DFT) method based on ab initio calculations. Additionally, magnetic tests, infrared spectroscopy (IR), and differential scanning calorimetry (DSC) were also employed for the characterization of the material.