Space Group I42d Research Articles

Studying the Effect of Composition on the Crystal Structure, Optical Properties, and Photogenerated Current Carriers Lifetimes in AgxCu1 – xGaSe2 (0 ≤ x ≤ 1) Solid Solutions

A set of AgxCu1 – xGaSe2 (0 ≤ x ≤ 1) solid solution powders has been prepared by solid-state synthesis. Using a combination of X-ray diffraction analysis and Raman spectroscopy, it has been found that the samples have a single-phase tetragonal structure (space group I-42d). It has been shown that their crystal lattice parameters do not follow Vegard’s law up to x ≈ 0.4. It has been revealed that the band gap of the samples also changes nonlinearly: initially it decreases and then increases. Studies of the low-temperature luminescence and microwave photoconductivity decay spectra have shown that a set of samples with x of 0 to ~0.4 and further in the region with x > 0.4 is characterized by an increase in the photogenerated current carrier lifetime in AgxCu1 – xGaSe2 powders. The observed effect is apparently attributed to the replacement of deep charge carrier traps, such as selenium vacancies, by shallower cation vacancies.

Investigation of the luminescence properties and temperature dependent luminescence properties of Sm3+ doped NaPbBi2(PO4)3 orthophosphate phosphor: A promising candidate for light and light sensing applications

The red phosphor for light application is in high demand. In this regard, a series of orange-red phosphors, NaPbBi2(PO4)3: Sm3+, with a single phase were obtained by the conventional solid state reaction method. The X-ray diffraction (XRD) confirms that the phosphor belongs to the cubic structure with a space group I-43d (220). The optical property of the phosphor was studied through the diffuse reflectance spectroscopy measurements and the characteristic peaks of the Sm3+ ions were identified. Exciting the phosphors at 404 nm, produced a strong orange-red emission at 601 nm. The optimum concentration of the phosphor was found to be 0.03 mol. In all emission transitions of the Sm3+ ions within the host lattice, the energy transfer (ET) occurs among the nearest neighbour ions. The lifetime values were in the order of milliseconds. The photometric parameters revealed that the emission lies in the orange-red region with color coordinates (0.5863, 0.4129) and a color purity of 99.4 %. The temperature dependent luminescence properties of the phosphor were also investigated and all these results showed that the phosphor could serve as a good candidate for light/light sensing applications.

Phase equilibrium diagram of Y-Cu-Sb system at 870 K

The interaction of the components in the Y-Cu-Sb ternary system was investigated using the methods of X-ray phase analysis, microstructure, and energy-dispersive X-ray spectroscopy in the whole concentration range at 870 K. At the temperature of investigation Y-Cu-Sb system is characterized by the formation of three ternary compounds: Y3Cu22Sb9 (Dy3Cu20+xSb11-x structure type, space group F-43m, a=1.6614(3) nm), Y3Cu3Sb4 (Y3Au3Sb4 structure type, space group I-43d, а=0.95357(5) nm), YCuSb2 (HfCuSi2 structure type, space group P4/nmm, a=0.42580(1), c=0.98932(3) nm). The solubility of copper in the binary compound YSb (NaCl structure type) extends up to 8 at. %.

Ruizhongite, (Ag2☐)Pb3Ge2S8, a thiogermanate mineral from the Wusihe Pb-Zn deposit, Sichuan Province, Southwest China

Abstract Ruizhongite (IMA2022-066), (Ag2☐)Pb3Ge2S8, is a thiogermanate of economic importance discovered in the Wusihe Pb-Zn deposit in Sichuan Province, southwestern China. This mineral occurs as anhedral grains 1–10 μm in size. It is gray and opaque, with a metallic luster and black streak, closely associated with galena and pyrite in a sphalerite matrix. Under reflected light, it displays a greenish-gray color without internal reflection. Its reflectance values in air (R %) based on SiC as the reference material are 30.5, 32.2, 34, and 34.1 for corresponding wavelengths of 650, 589, 470, and 546 nm, respectively. According to the average of 18 electron microprobe analyses, Pb (57.37 wt%), S (21.39 wt%), Ge (11.53 wt%), Ag (7.34 wt%), Zn (1.57 wt%), and Fe (0.27 wt%) constitute 99.46 wt% of ruizhongite. The empirical formula based on the 8 S apfu is (Ag0.82Pb0.32Zn0.28Fe0.06)Σ1.48Pb3Ge1.9S8, and (Ag2☐)Pb3Ge2S8 is its ideal formula. Ruizhongite displays a cubic structure, space group I43d (#220), with the unit-cell parameters a = 14.0559(2), V = 2777.00(7), Z = 8, and the calculated density is 5.706 g/cm3. The strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are 3.755 (100) (123), 3.511 (76) (004), 2.992 (73) (233), 2.574 (21) (125), 2.482 (79) (044), 2.276 (46) (235), 1.784 (39) (237), and 2.075 (24) (136). The structure of ruizhongite was determined using single-crystal XRD and was refined to an R1 of 0.0323 for all 2594 (474 unique) reflections. The structure comprises a non-centrosymmetric arrangement of [GeS4]4− tetrahedra, forming two interstice sites: fully occupied Pb1 and partially occupied Ag1, aligned in the directions of a-, b-, and c-axes. Ruizhongite was named in honor of Ruizhong Hu (1958), an eminent Chinese ore geochemist. The discovery of ruizhongite has significant implications for the occurrence and enrichment mechanism of Ge in sphalerite and other metallic minerals.

Investigation of Physiochemical Impact of Organic Molecule L-Lysine on Ammonium Dihydrogen Phosphate Single Crystal for Optoelectronics Applications

Ammonium dihydrogen phosphate (ADP) single crystals along with the incorporated 0.5 and 1% L-lysine, an organic molecule which possesses a good nonlinear response, were grown with the vision to meet the requirements of the optoelectronic industry. The inclusion of the L-lysine molecule in the crystal was confirmed by the XRD and EDX. The experiment not only confirms the inclusion level of the impurity but also the capability of the amino acid molecule to bond hydrogen within the crystal facet. A minor decrease in lattice parameters was reported for all ADP: L-lysine crystals compared with pure ADP. The structures of the grown crystals were identified as tetragonal with the space group I42d by the single-crystal XRD analysis. Vibrational signatures and functional groups were confirmed using FTIR spectroscopy. The thermal stability and decomposition temperatures of 0.5 and 1% L-lysine-added crystals were measured by TG/DTA and found to be 203 °C and 207 °C, respectively. The UV–visible transmission spectra prove a higher transparency for doped crystals as compared to pure crystals; therefore, these doped crystals can be considered the best option for the frequency doubling process in a broad range of visible and near-IR spectra. The improved hardness of the doped crystals was confirmed by the Vickers hardness data. The nonlinear optical (NLO) behaviour investigated using a second-harmonic generation (SHG) technique, indicating an efficient quadratic nonlinear coefficient of ADP: Lysine crystals at a 1064 nm initial wavelength, shows about 1.5-fold higher efficiency compared with undoped ADP.

Phase evolution, structure, and electrochemical performance of Al-, Ga- and Ta- substituted Li7La3Zr2O12 ceramic electrolytes by a modified wet chemical route

Garnet-type Li7La3Zr2O12 (LLZO) is one of the most promising solid-state electrolytes (SSEs) for advanced solid-state lithium batteries (SSLBs). In this work, Li6.25Al0.25La3Zr2O12, Li6.4Ga0.2La3Zr2O12, and Li6.4La3Zr1.4Ta0.6O12 ceramics are prepared by a modified wet chemical route. The composition of the black mixtures derived from the precursors is ascertained. The phase evolution and structural properties from the ceramic mother powders to the final ceramic electrolytes are discussed in detail. The characteristic of cubic LLZO with the space group I-43d arises in the Li6.4Ga0.2La3Zr2O12 ceramic electrolyte pellet after the secondary higher-temperature (1200 °C) sintering. The Rietveld refinement reveals the roles of Al3+ substitution at the Li+ sites and Ta5+ substitution at the Zr4+ sites to adjust crystal structure. In addition, the electrochemical performance of the ceramic pellets is also investigated. Remarkably, the Li6.4La3Zr1.4Ta0.6O12 ceramic electrolyte has the most outstanding electrochemical performance, showing the high ionic conductivity of 6.88 × 10−4 S cm−1 (25 °C), the low activation energy of 0.42 eV and an extremely low electronic conductivity of 1.77 × 10−8 S cm−1 (25 °C). Overall, it is supposed that this work may help to achieve high-quality modified LLZO ceramic electrolytes, especially using the wet chemical strategy.

A complex mayenite-type strontium oxy-chloride exhibiting three-component site mixing: Sr12Al3.44Fe8.16Ge2.38O32Cl4.34

A new mayenite-type strontium oxy-chloride, Sr12Al3.44Fe8.16Ge2.38O32Cl4.34, was grown from a SrCl2 flux at 1000 ​°C. The compound crystallizes in the complex three-dimensional chloromayenite structure type, a rare calcium aluminum oxide mineral of cubic symmetry, exhibiting nanocages that contain Sr and Cl ions. The lattice framework is composed of corner-sharing, three-component Al/Fe/Ge site-mixed tetrahedra. The compound crystallizes in the cubic space group I-43d with lattice parameter a ​= ​12.6126(3) Å.

Microwave-Assisted Solution Synthesis of Metastable Intergrowth of AgInS2 Polymorphs.

The intergrowth of stable and metastable AgInS2 polymorphs was synthesized using a microwave-assisted synthesis. The samples were synthesized in water and in a deep eutectic solvent (DES) consisting of choline chloride and thiourea. An increase in the metal precursor concentration improved the crystallinity of the synthesized samples and affected the particle size. AgInS2 cannot be synthesized from crystalline binary Ag2S or In2S3 via this route. The solution synthesis reported here results in the intergrowth of the thermodynamically stable polymorph (space group I2d, chalcopyrite structure) and the high-temperature polymorph (space group Pna21, wurtzite-like structure) that is metastable at room temperature. A scanning transmission microscopy (STEM) study revealed the intergrowth of tetragonal and orthorhombic polymorphs in a single particle and unambiguously established that the long-thought hexagonal wurtzite polymorph has pseudo-hexagonal symmetry and is best described with the orthorhombic unit cell. The solution-synthesized AgInS2 polymorphs intergrowth has slightly lower bandgap values in the range of 1.73 eV–1.91 eV compared to the previously reported values for tetragonal I2d (1.86 eV) and orthorhombic Pna21 (1.98 eV) polymorphs.

Structure of a Fe4O6-Heteraadamantane-Type Hexacation Stabilized by Chelating Organophosphine Oxide Ligands.

Metal-containing heteraadamantanes are compounds of interest due to their spectroscopic and magnetic properties, which make them promising materials for non-linear optics and semiconductors. Herein we report the comprehensive structural characterization of a new coordination compound of the formula [(µ-OH′)2(µ-OH″)4(O = P(Ph2)CH2CH2(Ph2)P = O)4{Fe(t-BuOH)}4](PF6)4(Cl)2 with the chelating ligand Ph2P(O)-CH2CH2-P(O)Ph2. The compound crystallizes as a polynuclear metal complex with the adamantane-like core [Fe4O6] in the space group I-43d of a cubic system. The single-crystal XRD analysis showed that the crystal contains one symmetrically independent octahedrally coordinated Fe atom in the oxidation state +3. The adamantine-like scaffold of the Fe complex is formed by hydroxy bridging oxygen atoms only. Hirshfeld surface analysis of the bridging oxygen atoms revealed two types of µ-OH groups, which differ in the degree of exposure and participation in long-range interactions. Additionally, the Hirshfeld surface analysis supported by the enrichment ratio calculations demonstrated the high propensity of the title complex to form C-H…Cl, C-H…F and C-H…O interactions.

Structural and enhanced hydrogen storage properties of the Li12Mg3Si3Al phase.

The multicomponent alumosilicide Li12Mg3Si3Al (cubic, space group I-43d, cI76) belongs to the structural family based on the Cu15Si4 type. The Li atoms are ordered and occupy the site with symmetry 1 and the Mg atoms occupy the site with -4.. symmetry. The Si/Al statistical mixture occupies the site with .3. symmetry. The coordination polyhedra around the Li atoms are 13-vertex distorted pseudo-Frank-Kasper polyhedra. The environments of the Mg and Si/Al atoms are icosahedral. The hydrogen storage characteristics of Li12Mg3Si3Al were investigated. The reversible hydrogen storage capacity of the title compound is excellent and the gravimetric storage capacity of this new material, corresponding to 9.1 wt% H2, is higher compared to Li12Mg3Si4 (8.8 wt%). The enthalpy of hydrogen desorption is 86 kJ mol-1 and is lower compared to known lithium-based hydrides.

Ferromagnesian jeffbenite synthesized at 15 GPa and 1200 °C

Abstract Single crystals of Al-free, ferromagnesian jeffbenite up to 200 µm in size have been synthesized at 15 GPa and 1200 °C in a 1200 tonne multi-anvil press from a starting composition in the forsteritefayalite-magnetite-water system. This phase has the approximate formula Mg2.62Fe0.872+Fe1.633+Si2.88O12 and is observed to coexist with a Ca-free clinopyroxene plus what appears to be quenched melt. The crystal structure has been refined from single-crystal X-ray diffraction data and is similar to that determined for natural Al-bearing jeffbenite, Mg3Al2Si3O12, reported from inclusions in superdeep diamonds. The structure is a tetragonal orthosilicate in space group I42d with a = 6.6449(4) Å, c = 18.4823(14) Å, and is structurally more closely related to zircon than to garnet. The T2 site is larger than T1, shares an edge with the M2 octahedron, and incorporates significant Fe3+. Because of the tetrahedral incorporation of trivalent cations, jeffbenite appears to be compositionally distinct from garnet. Previous speculations that the phase may only occur as a retrograde decompression product from bridgmanite are not supported by its direct synthesis under transition zone conditions. The phase has a calculated density of 3.93 g/cm3, which is indistinguishable from a garnet of comparable composition, and is a possible component in the mantle transition zone under oxidizing conditions or with Al-rich compositions.

Photoluminescence and comparative thermoluminescence studies of UV/γ-irradiated Dy3+ doped bismuth silicate phosphor

A series of Bi4Si3O12:Dy3+ phosphor have been synthesized via conventional solid-state reaction method and its luminescence properties were investigated as near cool white light emitting and long afterglow phosphor. Crystal structure and phase structure characterization is determined using X-ray diffraction (XRD), SEM and EDS. Rietveld structural refinement and XRD confirms that prepared sample exhibit pure cubic structure [space group I-43d]. Photoluminescence spectra of both doped and undoped Bi4Si3O12 phosphor were efficiently excited in the range of 200-450 nm, and prepared phosphor under 272 nm excitation exhibit three emission peaks located at 463 nm(blue), 482 nm(blue) and 576 nm (yellow) corresponding to 3P1 → 1S0, 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions. Characteristic emission peaks of Dy3+ centered at 482 nm and 576 nm were assigned for white light emission. The calculated Commission Internationale de I’Eclairage (CIE) chromaticity confirms that with Dy3+ doping, the luminescence co-ordinates of Bi4Si3O12 phosphor shift to near white(x = 0.316, y = 0.358) region which is close to commercial pc-LED (Blue LED + YAG:Ce3+) (x = 0.320, y = 0.320) co-ordinates. Computation of correlated color temperature 6184 K endorses that prepared phosphor is cool in nature and can be served as white light emitting phosphor. Comparative thermoluminescence study of UV and γ-irradiated Bi4Si3O12:Dy3+ phosphor is performed for the dosimetry application. TL intensity is recorded maximum at 30 min under UV irradiation (256 nm), and for γ irradiation, it was recorded at 10 kGy dose rate. γ-irradiated Bi4Si3O12:Dy3+ phosphor TL study is reported for the first time at different dose rate and concentration for high dosimetry application. The defect characteristic is examined, Trap depths and other kinetic parameters are also evaluated by Chen’s peak shape method. Decay and fading measurement under UV/γ irradiation are performed to examine the long after glow properties of prepared samples. TL emission spectrum studies are also performed.

The Hydrogarnets Sr3[RE(OH)6]2 (RE = Sc, Y, Ho – Lu): Syntheses, Crystal Structures, and their Thermal Decomposition to Ternary Rare‐Earth Metal Oxides

Seven rare‐earth metal hydrogarnets Sr3[RE(OH)6]2 (RE = Sc, Y, Ho‐Lu) were synthesized at about 200 °C starting from the respective RE2O3 and Sr(NO3)2 in a KOH hydroflux with a water‐to‐base ratio of 1.6. All seven hydrogarnets crystallize in the acentric variant (space group I43d) of the cubic garnet structure. The crystal structures of the hydrogarnets Sr3[RE(OH)6]2, the differences between both structural variants including a simple method to distinguish between them, and the crystal‐chemical classification with respect to other known strontium hydrogarnets are discussed. The rare‐earth hydrogarnets can be used as carbon‐free precursors for magnetic oxides. Starting at about 300 °C, the hydrogarnets decompose in a two‐ or three‐step dehydration to SrRE2O4 and SrO. The decomposition of Sr3[Sc(OH)6]2 follows a different mechanism and was studied by in‐situ temperature‐dependent powder X‐ray diffraction up to 1000 °C. The final decomposition products were SrO and an unknown strontium scandium oxide, with an X‐ray pattern similar to BaSc2O4. Magnetic measurements of the erbium and ytterbium hydrogarnets revealed paramagnetic behavior down to 1.8 K.

Phase equilibria in the Gd-Ge-Sb system at 773 K and the magnetic properties of novel compound Gd8Ge13.29Sb1.72

The isothermal section of the phase diagram of the Gd-Ge-Sb ternary system at 773 K has been studied by X-ray powder diffraction (XRPD and S-PXRD), Rietveld method, scanning electron microscopy (SEM) equipped with energy dispersive (EDS), electron probe microanalysis (EPMA) and electron diffraction (ED). The existence of nine binary compounds, Gd5Ge3, Gd5Ge4, GdGe, Gd2Ge3, Gd3Ge5, Gd5Sb3, Gd4Sb3, GdSb, Gd16Sb39, and Mn5Si3-type Gd5Ge3-0Sb0-3 (space group P63/mcm, No. 193, hP16) and Th3P4-type Gd4Ge2-0Sb1-3 (space group I-43d, No. 220, cI28) quasibinary solid solutions and ternary Gd6Ge4.3Sb11.7-type Gd6Ge4.3Sb11.7 (space group Immm, No. 71, oI46) were confirmed, while new GdGe1.69Bi0.21-type Gd8Ge13.29Sb1.72 (space group Cmcm, No. 63, oC23) was found in this work which is air- and moisture-stable over periods of long time. Gd8Ge13.29Sb1.72 exhibits field unsensitive antiferromagnetic ordering at 24 K in fields up to 60 kOe and metallic type of conductivity in the temperature range of 2–400K.

First Principles Investigation of Anomalous Pressure-Dependent Thermal Conductivity of Chalcopyrites.

The effect of compression on the thermal conductivity of CuGaS2, CuInS2, CuInTe2, and AgInTe2 chalcopyrites (space group I-42d) was studied at 300 K using phonon Boltzmann transport equation (BTE) calculations. The thermal conductivity was evaluated by solving the BTE with harmonic and third-order interatomic force constants. The thermal conductivity of CuGaS2 increases with pressure, which is a common behavior. Striking differences occur for the other three compounds. CuInTe2 and AgInTe2 exhibit a drop in the thermal conductivity upon increasing pressure, which is anomalous. AgInTe2 reaches a very low thermal conductivity of 0.2 W·m−1·K−1 at 2.6 GPa, being beneficial for many energy devices, such as thermoelectrics. CuInS2 is an intermediate case. Based on the phonon dispersion data, the phonon frequencies of the acoustic modes for CuInTe2 and AgInTe2 decrease with increasing pressure, thereby driving the anomaly, while there is no significant pressure effect for CuGaS2. This leads to the negative Grüneisen parameter for CuInTe2 and AgInTe2, a decreased phonon relaxation time, and a decreased thermal conductivity. This softening of the acoustic modes upon compression is suggested to be due to a rotational motion of the chalcopyrite building blocks rather than a compressive oscillation. The negative Grüneisen parameters and the anomalous phonon behavior yield a negative thermal expansion coefficient at lower temperatures, based on the Grüneisen vibrational theory.

Hydrothermal Synthesis, Crystal Structure Determination, and Magnetic Properties of a New Calcium Iron Iridium Hydrogarnet Ca3(Ir2–xFex)(FeO4)2–x(O4H4)1+x with 0 ≤ x ≤ 1

The new calcium iron iridium hydrogarnet Ca3(Ir2–xFex)(FeO4)2–x(H4O4)1+x (0 ≤ x ≤ 1) was obtained by hydrothermal synthesis under strongly oxidizing alkaline conditions. The compound adopts a garnet‐like crystal structure and crystallizes in the acentric cubic space group I43d (no. 220) with a = 12.5396(6) Å determined at T = 100 K for a crystal with a refined composition Ca3(Ir1.4Fe0.6)(FeO4)1.4(O4H4)1.6. Iridium and iron statistically occupy the octahedrally coordinated metal position, the two crystallographically independent tetrahedral sites are partially occupied by iron. Hydroxide groups are found to cluster as hydrogarnet defects, i.e. partially substituting oxide anions around the empty tetrahedral metal sites. The presence of hydroxide ions was confirmed by infrared spectroscopy and the hydrogen content was quantified by carrier gas hot extraction; the overall composition was verified by energy dispersive X‐ray spectroscopy. The structure model is supported by 57Fe‐Mössbauer spectroscopic data evidencing different Fe sites and a magnetic ordering of the octahedral iron sublattice at room temperature. The thermal decomposition proceeds via three steps of water loss and results in Ca2Fe2O5, Fe2O3 and Ir. Mössbauer and magnetization data suggest magnetic order at ambient temperature with complex magnetic interactions.

Mixed‐Valent Europium in the Cubic Thiosilicate Li3Eu6[SiS4]4

In an attempt to synthesize LiEu3S3[SiS4] utilizing elemental europium and sulfur as well as SiS2 and an excess of LiCl as flux and lithium source, dark red, platelet‐shaped single crystals of Li3Eu6[SiS4]4 were obtained. This new compound crystallizes in the cubic space group I43d (a = 1369.22(5) pm) with four formula units per unit cell. Both the Li+ and the Si4+ cations are surrounded by four sulfide anions. The [SiS4]4– tetrahedra show merely a slight trigonal distortion, while the [LiS4]7– units are best described as flattened bisphenoids. The europium cations exhibit an eightfold, rather irregular coordination environment by eight S2– anions and have to be regarded mixed‐valent with a +2:+3 charge‐ratio of 5:1 in order to gain electroneutrality. The lack of an inversion center is caused by the [SiS4]4– tetrahedra being stacked exclusively top up along [111] in this acentric crystal structure.

A New Type of 2 × 2 × 2 Superstructure of Clathrate‐I with I43d Symmetry in A8Sn46–x–yTlx⬜y (A = Rb, Cs)

The ternary clathrates Rb8Tl1.70Sn42.80⬜1.5 and Cs8Tl1.03Sn43.64⬜1.33 were prepared by the reaction of the elements in welded niobium ampoules in a resistance furnace. Both compounds crystallize in space group I43d and adopt a new type of 2 × 2 × 2 superstructure of the known clathrate‐I structure with partially ordered framework vacancies (⬜) and a statistical Sn/Tl atom mixing on specific atomic positions. Important crystallographic parameters are a = 24.160(1) Å, wR2 = 0.059 (all data), 3201 F2 values, 84 variable parameters for Rb8Tl1.70Sn42.80⬜1.5 and a = 24.2148(3) Å, wR2 = 0.088 (all data), 2535 F2 values, 85 variable parameters for Cs8Tl1.03Sn43.64⬜1.33.

Investigation of red-emitting Bi4Si3O12:Eu3+ phosphor under the deep UV irradiation as a novel material for white light and color tunable emission

Bi4Si3O12:Eu3+ phosphors are synthesized by a solvothermal reaction method. The structural properties are investigated using the X-ray diffraction patterns, which confirmed the cubic phase with a space group I-43d. The optical properties are studied by the measurement of diffused reflectance, excitation and emission spectra. The photoluminescence (PL) excitation spectra of Bi4Si3O12:Eu3+ phosphor exhibits a broad band between 220 and 350 nm with two peaks occurring around 271 and 297 nm corresponding to the host absorption and charge transfer bands, respectively, and several sharp peaks due to the f–f transitions of Eu3+ ions in the wavelength over 350 nm. The PL spectra exhibit blue emission due to the 1S0 → 3P1 transition of Bi3+ and red emission due to the 5D0 → 7F2 transition of Eu3+. With increase of Eu3+ concentration, blue emission decreased and red emission increased. At the concentration of 3 mol% Eu3+, Bi4Si3O12:Eu3+ phosphors show white emission with the CIE chromaticity coordinates (x = 0.345, y = 0.327). These results suggest that the Bi4Si3O12:Eu3+ phosphors are promising luminescence materials for UV based white light emitting diodes.

Cs3LiZn2(WO4)4 and Rb3Li2Ga(MoO4)4: different filled derivatives of the cation-deficient Cs6Zn5(MoO4)8 structure.

Two new compounds, namely cubic tricaesium lithium dizinc tetrakis(tetraoxotungstate), Cs3LiZn2(WO4)4, and tetragonal trirubidium dilithium gallium tetrakis(tetraoxomolybdate), Rb3Li2Ga(MoO4)4, belong to the structural family of Cs6Zn5(MoO4)8 (space group I-43d, Z = 4), with a partially incomplete (Zn5/6□1/6) position. In Cs3LiZn2(WO4)4, this position is fully statistically occupied by (Zn2/3Li1/3), and in Rb3Li2Ga(MoO4)4, the 2Li + Ga atoms are completely ordered in two distinct sites of the space group I-42d (Z = 4). In the same way, the crystallographically equivalent A+ cations (A = Cs, Rb) in Cs6Zn5(MoO4)8, Cs3LiZn2(WO4)4 and isostructural A3LiZn2(MoO4)4 and Cs3LiCo2(MoO4)4 are divided into two sites in Rb3Li2Ga(MoO4)4, as in other isostructural A3Li2R(MoO4)4 compounds (AR = TlAl, RbAl, CsAl, CsGa, CsFe). In the title structures, the WO4 and (Zn,Li)O4 or LiO4, GaO4 and MoO4 tetrahedra share corners to form open three-dimensional frameworks with the caesium or rubidium ions occupying cuboctahedral cavities. The tetrahedral frameworks are related to that of mayenite 12CaO·7Al2O3 and isotypic compounds. Comparison of isostructural Cs3MZn2(MoO4)4 (M = Li, Na, Ag) and Cs6Zn5(MoO4)8 shows a decrease of the cubic lattice parameter and an increase in thermal stability with the filling of the vacancies by Li+ in the Zn position of the Cs6Zn5(MoO4)8 structure, while filling of the cation vacancies by larger Na+ or Ag+ ions plays a destabilizing role. The series A3Li2R(MoO4)4 shows second harmonic generation effects compatible with that of β'-Gd2(MoO4)3 and may be considered as nonlinear optical materials with a modest nonlinearity.