Family Of Halides Research Articles

Synthesis, Structure, and Electrochemistry of Crystallized Layered Chlorides, LiMCl6 (M = Ta/Nb)

AbstractA suitable solid electrolyte can turn the long‐standing dream of a safe commercial all‐solid‐statebattery into reality in the same way as appropriate liquid electrolytes kickstarted the first commercial lithium‐ion battery. Presently, halide‐based electrolytes despite their reactivity with lithium metal are extensively studied as they offer better processability, malleability, oxidative stability, and safety over sulfide‐based electrolytes. Particularly, LiMCl6 (M = Ta/Nb) chloride‐based amorphous electrolytes are generating widespread interest with their high conductivities, comparable to liquid electrolytes. In this context, with synchrotron X‐ray and neutron powder diffraction techniques, well‐crystallized triclinic layered LiMCl6 (M = Ta/Nb) chlorides with an hcp AB‐type stacking of chloride ions is reported. The hexagonally ordered NbCl6 octahedra share edges with LiCl6 octahedra forming a honeycomb pattern, whereas Li+ is intermixed with M5+ for M = Ta. Furthermore, it is found that crystalline LiTaCl6 has an ionic conductivity of ≈10−5 mS cm−1, six orders of magnitude lower than that reported for superionic amorphous LiTaCl6. Nevertheless, crystalline LiTaCl6 is utilized as an intercalation compound in an all‐solid‐state‐battery, uncovering a solid‐solution/two‐phase/conversion pathway for lithium‐insertion during the three distinct redox plateaus below 3 V versus Li+/Li°. Broadly, the findings give insights into the structure, ionic conduction, and intercalation in a new family of layered halides.

Hybrid metal halide family with color-time-dual-resolved phosphorescence for multiplexed information security applications

Luminescent materials with engineered optical properties play an important role in anti-counterfeiting and information security technology. However, conventional luminescent coding is limited by fluorescence color or intensity, and high-level multi-dimensional luminescent encryption technology remains a critically challenging goal in different scenarios. To improve the encoding capacity, we present an optical multiplexing concept by synchronously manipulating the emission color and decay lifetimes of room-temperature phosphorescence materials at molecular level. Herein, we devise a family of zero-dimensional (0D) hybrid metal halides by combining organic phosphonium cations and metal halide tetrahedral anions as independent luminescent centers, which display blue phosphorescence and green persistent afterglow with the highest quantum yields of 39.9 % and 57.3 %, respectively. Significantly, the luminescence lifetime can be fine-tuned in the range of 0.0968–0.5046 μs and 33.46–125.61 ms as temporary time coding through precisely controlling the heavy atomic effect and inter-molecular interactions. As a consequence, synchronous blue phosphorescence and green afterglow are integrated into one 0D halide platform with adjustable emission lifetime acting as color- and time-resolved dual RTP materials, which realize the multiple applications in high-level anti-counterfeiting and information storage. The color-lifetime-dual-resolved encoding ability greatly broadens the scope of luminescent halide materials for optical multiplexing applications.

Synchronously Improved Multiple Afterglow and Phosphorescence Efficiencies in 0D Hybrid Zinc Halides With Ultrahigh Anti-Water Stabilities.

Zero-dimensional (0D) hybrid metal halides have been emerged as room-temperature phosphorescence (RTP) materials, but synchronous optimization of multiple phosphorescence performance in one structural platform remains less resolved, and stable RTP activity in aqueous medium is also unrealized due to serious instability toward water and oxygen. Herein, we demonstrated a photophysical tuning strategy in a new 0D hybrid zinc halide family of (BTPP)2ZnX4 (BTPP=benzyltriphenylphosphonium, X=Cl and Br). Infrequently, the delicate combination of organic and inorganic species enables this family to display multiple ultralong green afterglow and efficient self-trapped exciton (STE) associated cyan phosphorescence. Compared with inert luminescence of [BTPP]+ cation, incorporation of anionic [ZnX4]2- effectively enhance the spin-orbit coupling effect, which significantly boosts the photoluminescence quantum yield (PLQY) up to 30.66 % and 54.62 % for afterglow and phosphorescence, respectively. Synchronously, the corresponding luminescence lifetime extend to 143.94 ms and 0.308 μs surpassing the indiscernible phosphorescence of [BTPP]X salt. More importantly, this halide family presents robust RTP emission with nearly unattenuated PLQY in water and harsh condition (acid and basic aqueous solution) over half a year. The highly efficient integrated afterglow and STE phosphorescence as well as ultrahigh aqueous state RTP realize multiple anti-counterfeiting applications in wide chemical environments.

A Luminescent Hybrid Bimetallic Halide Family with Solvent‐Coordinated Rare Earth and Alkaline Earth Metals

AbstractHybrid metal halides are an extraordinary class of optoelectronic materials with extensive applications. To further diversify and study the in‐depth structure‐property relations, we report here a new family of 21 zero‐dimensional hybrid bimetallic chlorides with the general formula A(L)n[BClm] (A=rare earth (RE), alkaline earth metals and Mn; L=solvent ligand; and B=Sb, Bi and Te). The RE(DMSO)8[BCl6] (RE=La, Ce, Sm, Eu, Tb, and Dy; DMSO=dimethyl sulfoxide) series shows broadband emission attributed to triplet radiative recombination from Sb and Bi, incorporating the characteristic emission of RE metals, where Eu(DMSO)8[BiCl6] shows a staggering PL quantum yield of 94 %. The pseudo‐octahedral [SbCl5] with Cl vacancy in AII(DMSO)6[SbCl5] (AII=Mg, Ca and Mn) and the square pyramidal [SbCl5] in AII(TMSO)6[SbCl5] (TMSO=tetramethylene sulfoxide) enhance the stereoactive expression of the 5 s2 lone pairs of Sb3+, giving rise to the observation of dual‐band emission of singlet and triplet emission, respectively. A series of Te(IV) analogues have been characterized, showing blue‐light‐excitable single‐band emission. This work expands the materials space for hybrid bimetallic halides with an emphasis on harnessing the RE elements, and provides important insights into designing new emitters and regulating their properties.

A Luminescent Hybrid Bimetallic Halide Family with Solvent-Coordinated Rare Earth and Alkaline Earth Metals.

Hybrid metal halides are an extraordinary class of optoelectronic materials with extensive applications. To further diversify and study the in-depth structure-property relations, we report here a new family of 21 zero-dimensional hybrid bimetallic chlorides with the general formula A(L)n[BClm] (A=rare earth (RE), alkaline earth metals and Mn; L=solvent ligand; and B=Sb, Bi and Te). The RE(DMSO)8[BCl6] (RE=La, Ce, Sm, Eu, Tb, and Dy; DMSO=dimethyl sulfoxide) series shows broadband emission attributed to triplet radiative recombination from Sb and Bi, incorporating the characteristic emission of RE metals, where Eu(DMSO)8[BiCl6] shows a staggering PL quantum yield of 94 %. The pseudo-octahedral [SbCl5] with Cl vacancy in AII(DMSO)6[SbCl5] (AII=Mg, Ca and Mn) and the square pyramidal [SbCl5] in AII(TMSO)6[SbCl5] (TMSO=tetramethylene sulfoxide) enhance the stereoactive expression of the 5 s2 lone pairs of Sb3+, giving rise to the observation of dual-band emission of singlet and triplet emission, respectively. A series of Te(IV) analogues have been characterized, showing blue-light-excitable single-band emission. This work expands the materials space for hybrid bimetallic halides with an emphasis on harnessing the RE elements, and provides important insights into designing new emitters and regulating their properties.

Phonon mode softening and band convergence induced significant enhancement of thermoelectric performance in strained CdI2-type SnI2 monolayer

Monolayer group IVA metal halides have attracted intensive attention for their excellent thermoelectric performance. Recently, the CdI2-type SnI2 monolayer has been successfully fabricated by molecular beam epitaxy for the first time. The universal two-dimensional growth behavior on different substrates, motivates strain engineering on its thermoelectric performance. Herein, the structure stability and thermoelectric properties of SnI2 monolayer under different strains are systematically investigated, based on first-principles calculations combined with Boltzmann transport theory. The investigation shows that the tensile strain can simultaneously induce phonon mode softening and band convergence, resulting in a significant enhancement in thermoelectric performance. The phonon mode softening for ZA and optical branches further enhances lattice anharmonicity and a reduced thermal conductivity of ∼0.14 Wm−1K−1 at 300 K (∼0.05 Wm−1K−1, 800 K) can be obtained. Additionally, band convergence in valence band improves the Seebeck coefficient and increases power factor. Under +2 % tensile strain, the optimal ZT values of SnI2 monolayer for p-type doping are substantially enhanced up to 3.05 (300 K) and 5.06 (800 K), which are increased by ∼98 % and ∼50 % compared to the case without strain. Our results reveal the close relationship between the phonon mode softening and enhanced anharmonicity, and provide the physical insights into the understanding of the modulation of thermoelectric properties of monolayer SnI2, shedding light on substantially optimizing the thermoelectric performance of monolayer group IVA metal halides family.

Empowering Indoor Photovoltaics: Stable Lead‐Free Perovskites and Beyond

Indoor photovoltaics (IPVs) have garnered significant attention in recent years due to their potential to empower small portable electronic devices and the Internet of Things. After silicon solar cells, it is now widely acknowledged that the dominant technology in the field of outdoor photovoltaics/IPVs is hybrid lead (Pb) halide perovskites. Despite the fascinating characteristics of hybrid Pb halide perovskites, the presence of toxic Pb is regarded as one of the major factors that prevent commercialization. Low‐toxic, Pb‐free, and stable perovskites are also being used in outdoor solar cells (ODSCs), but their efficiencies are low due to large bandgap (i.e., ≈2.0 eV). Recently, some of the stable, Pb‐free perovskite materials have drawn great interest due to their initial performance across various fields, including light‐emitting diodes, photodetectors, X‐rays, photocatalysis, ODSCs, and in IPVs. In this perspective, the current status and prospects for Pb‐free halide perovskites, chalcogen perovskites, silver bismuth halide (AaBbXa + 3b) family, and other chalcogen materials are summarized and being explored to speed up the progress of IPVs.

Rational Design of the Alkali Metal Sn-Based Mixed Halides with Large Birefringence and Wide Transparent Range.

Birefringent materials are widely used in various advanced optical systems, owing to their vital role in creating and controlling polarized light. Currently, Sn2+-based compounds containing stereochemically active lone-pair (SCALP) cations are extensively investigated and considered as one class of promising birefringent materials. To solve the problem of relatively narrow bandgap of Sn2+-based compounds, alkali metals and multiple halogens are introduced to widen the bandgap during the research. Based on this strategy, four new Sn2+-based halides, A2Sn2F5Cl and ASnFCl2 (A = Rb and Cs), with large birefringence, short ultraviolet (UV) cutoff edge, and wide transparent rangeare successfully found. The birefringences of A2Sn2F5Cl (A = Rb and Cs) are 0.31 and 0.28 at 532nm, respectively, which are among the largest in Sn-based halide family. Remarkably, A2Sn2F5Cl possess relatively shorter UV cutoff edge (<300nm) and broad infrared (IR) transparent range (up to 16.6µm), so they can become promising candidates as birefringent materials applied in both UV and IR regions. In addition, a comprehensive analysis on crystal structures and structure-property relationship of metal Sn2+-based halides is performed to fully understand this family. Therefore, this work provides insights into designing birefringent materials with balanced optical properties.

Oxidation-Induced Dissolution Recrystallization Structural Transformation Strategy Enhanced Nonlinear Optical Effect of Hybrid Chiral Tin Bromide Single Crystals.

In order to reveal the integrated effect of inorganic lattice structure disturbances and chiral ligands on the structure of tin halide hybrid materials, we show the synthesis, crystal growth, dissolution recrystallization structural transformation (DRST), optical properties, energy band structure, and nonlinear optical properties of a class of chiral tin bromide R/S-2-mpip[SnBr3]Br (2-mpip is 2-methylpiperazinium) and R/S-2-mpipSnBr6 for the first time. The formation of R/S-2-mpipSnBr6 in solution was interestingly caused by irreversible DRST of R/S-2-mpip[SnBr3]Br. The second-harmonic generation response of the new phase R-2-mpipSnBr6 is significantly enhanced compared to that of the initial phase R-2-mpip[SnBr3]Br. These structural transformations of chiral tin bromides reflect, to some extent, the DRST commonality of the tin halide family induced by oxidation and serve as a starting point for investigating the structural chirality and asymmetry of chiral metal hybrid halides.

AIB3 IIC2 IIIQ6 VIXVII: A Thioborate Halide Family for Developing Wide Bandgap Infrared Nonlinear Materials by Coupling Planar [BS3] and Polycations.

Developing high-performance infrared (IR) nonlinear optical (NLO) materials is urgent but challenging due to the competition between NLO coefficient and bandgap in one compound. Herein, by coupling NLO-active [BS3] planar units and halide-centered polycations, six new metal thioborate halides ABa3B2S6X (A = Rb, Cs; X = Cl, Br, I) composed of zero-dimensional [XBamRbn/Csn] polycations and [BS3] units, belonging to a new family, are rationally designed and fabricated. The compounds show an interesting structural transition from Pbcn (ABa3B2S6Cl) to Cmc21 (ABa3B2S6Br and ABa3B2S6I) driven by the clamping effect of polycationic frameworks. ABa3B2S6Br and ABa3B2S6I are the first series metal thioborate halide IR NLO materials, and the introduction of [BS3] unit effectively widens the bandgap of planar unit-constructed chalcogenides. ABa3B2S6Br and ABa3B2S6I, exhibiting wide bandgaps (3.55-3.60 eV), high laser-induced damage thresholds (≈ 6 × AgGaS2), and strong SHG effects (0.5-0.6 × AgGaS2) with phase-matching behaviors, are the promising IR NLO candidates for high-power laser applications. The results enrich the chemical and structural diversity of boron chemistry and give some insights into the design of new IR NLO materials with planar units.

Investigation on broadband emission of two-dimensional melamine lead iodide perovskite (2D-C3H8N6PbI4): An experimental and theoretical approach

Novel two-dimensional melamine lead iodide perovskite (2D-C3H8N6PbI4) is synthesized to investigate its crystallinity, optical band gap and broadband emission properties and to make comparisons with 2D-C3H8N6PbCl4/2D-C3H8N6PbBr4 perovskites. Both experimental and density functional theory (DFT) interrogations on 2D-C3H8N6PbX4 (X = Cl, Br and I) are conducted. The crystal structure, morphology and percentile of Pb and halide elements are confirmed using scanning electron microscope (SEM), and energy dispersive spectrum (EDS), powder/single crystal X-ray diffraction (PXRD/SXRD), DFT and X-ray crystallography simulations. The optical band gaps of 2D-C3H8N6PbX4 perovskites are determined from the Tauc plot fitting of absorbance and DFT studies. Distinct broadband emission of 2D-C3H8N6PbX4 perovskites between 300 and 800 nm is observed, which can be fitted with multiple Gaussian distributions. The fittings of broad PL spectra from 2D-C3H8N6PbCl4/2D-C3H8N6PbBr4 perovskites confirm the involvement of both Dexter energy transfer from melamine cation and self-trapped excitons (STEs). However, the broadband emission of 2D-C3H8N6PbI4 is attributed only to the Dexter energy transfer from melamine cation and the absence of STEs is attributed to the larger lattice deformation of 2D-C3H8N6PbI4. Moreover, the involvement of spin–orbit coupling (SOC) in the energy transfer is clarified to attest that the broadband emission of 2D-C3H8N6PbI4 is distinct among its halide family.

The halide ion replacement effects on the physical properties of Cs2BX6 variant perovskites

Variant perovskites of the halide family have gained great attention in the recent times due to their prominent characteristics favorable for various applications. The variant perovskite Cs2BX6 (B= Hf, Ti, Zr and X = Cl, Br, I) have been the subject of some reports for experimental growth and measurement to computational studies. However, so far no work is available for the comparative study and detail optical properties. Here in this work, the structural, electronic and optical properties of Cs2BX6 determined using FP-LAPW + lo method and compared with the existing literature. The obtained results show improvement to good comparison with the earlier reports. The optimized band structure reveals that the band gap is decreased gradually switching from Cl to Br and I. The band structures show that most of variant perovskite under consideration are pseudo direct band gap with wide energy gaps. The optical properties like dielectric constant, absorption coefficient and optical conductivity peaks are also found up to incident photon energy of 20 eV. The materials show rising peaks in the ultraviolet region showing their great potential for high frequency applications.

Metal halide HgI2 monolayer with auxetic property and photocatalysis application

Recently, two-dimensional (2D) metal halides have shown extraordinary performances as photocatalysts, triggering our enormous interest to explore new 2D metal halides for photocatalysis water splitting. Here, based on an unbiased first-principles swarm intelligence structure search, we identified a thermally and dynamically stable HgI2 monolayer. Interestingly, its atomic configuration forms an unusual in-plane negative Poisson's ratio, resulting in an auxetic property. More importantly, the HgI2 monolayer exhibits excellent optoelectronic properties, including suitable direct bandgap (∼2.45 eV), good carrier mobility (×102 cm2 V−1 s−1), excellent light absorption coefficient (×105 cm−1), and suitable band edges for photocatalytic water splitting. These excellent characteristics make the HgI2 monolayer fulfill the basic criteria of efficient photocatalysts for water splitting, supporting it as a promising candidate for photocatalytic materials. Our findings bloom the 2D metal halides family and offer a new candidate material for photocatalysis water splitting.

A New Zero-Dimensional (CsK2)BiCl6 Metal Halide: Boosting Emission via B-Site Mn-Doping

The A site of zero-dimensional (0D) metal halides A3BiCl6 can be replaced by Cs and/or K, thus, four possible 0D A3BiCl6 forms exist, such as (Cs2K)BiCl6, (CsK2)BiCl6, K3BiCl6 and Cs3BiCl6. It is well known that Cs3BiCl6 has been reported. We predict that both (Cs2K)BiCl6 and K3BiCl6 do not have enough structural and thermodynamic stability, but (CsK2)BiCl6 should be a 0D stable A3BiCl6 candidate based on density functional theory (DFT). Furthermore, 0D (CsK2)BiCl6 metal halide was experimentally prepared by the solvothermal method. Though (CsK2)BiCl6 metal halide exhibits an indirect bandgap and poor luminescence properties, the emission can be boosted by B-site Mn-doping due to the efficient energy transfer from self-trapped excitons (STE) to the d-state of Mn ions. Our results enrich the family of 0D bi-based metal halides and provide guidance for the regulation of the structural and optical properties of metal halides.

J=0 nonmagnetic insulating state in K2OsX6 (X=F,Cl,andBr)

In $4d/5d$ transition-metal systems, many interesting physical properties arise from the interplay of bandwidth, electronic correlations, and spin-orbit interactions. Here, using {\it ab initio} density functional theory, we systematically study the double-perovskite-like system K$_2$Os$X_6$ (X = F, Cl, and Br) with a $5d^4$ electronic configuration. Our main result is that the $J = 0$ nonmagnetic insulating state develops in this system, induced by strong spin-orbital coupling. Specifically, the well-separated Os$X_6$ octahedra lead to the cubic crystal-field limit and result in dramatically decreasing hoppings in nearest neighbor Os-Os sites. In this case, the three degenerate $t_{2g}$ orbitals are reconstructed into two ``effective'' $j_{\rm eff}$ ($j_{\rm eff} = 1/2$ and $j_{\rm eff} = 3/2$ states) states separated by the strong SOC, opening a gap with four electrons occupying the $j_{\rm eff} = 3/2$ orbitals. Furthermore, the hybridization between the Os $5d$ orbitals and the $X$ ($X$ = F, Cl, and Br) $p$ orbitals increases from F to Br, leading the electrons in K$_2$OsF$_6$ to be more localized than in K$_2$OsCl$_6$ and K$_2$OsBr$_6$, resulting in a smaller bandwidth for K$_2$OsF$_6$ than in the Cl- or Br- cases. Our results provide guidance to experimentalists and theorists working on this interesting family of osmium halides.

Symmetry Analysis of the Complex Polytypism of Layered Rare-Earth Tellurites and Related Selenites: The Case of Introducing Transition Metals

Our systematic explorations of the complex rare earth tellurite halide family have added several new [Ln12(TeO3)12][M6X24] (M = Cd, Mn, Co) representatives containing strongly deficient and disordered metal-halide layers based on transition metal cations. The degree of disorder increases sharply with decrease of M2+ radius and the size disagreements between the cationic [Ln12(TeO3)12]+12 and anionic [M6Cl24]−12 layers. From the crystal chemical viewpoint, this indicates that the families of both rare-earth selenites and tellurites can be further extended; one can expect formation of some more complex structure types, particularly among selenites. Analysis of the polytypism of compounds have been performed using the approach of OD (“order–disorder”) theory.

Luminescence from Self‐Trapped Excitons and Energy Transfers in Vacancy‐Ordered Hexagonal Halide Perovskite Cs2HfF6 Doped with Rare Earths for Radiation Detection (Advanced Optical Materials 19/2022)

Cs2HfX6 halides show a vacancy-ordered cubic double perovskite structure when X = Cl, Br, and I. As to the first member of the halide family, Zhiping Luo and co-workers (article number 2201374) identify Cs2HfF6 as a new type of vacancy-ordered hexagonal perovskite. It is composed of single layers of building blocks. Tunable emission is obtained based on self-trapped exciton emissions from the host and energy transfers in the rare-earth-doped material. From energy-dependent cathodoluminescence and time-resolved X-ray radioluminescence, the co-doped material is found to be more sensitive to radiation energy than the singly-doped or pristine host.

Towards Highly Efficient Cesium Titanium Halide Based Lead-Free Double Perovskites Solar Cell by Optimizing the Interface Layers.

Lead halide perovskites are the most promising compared to the other recently discovered photovoltaic materials, but despite their enormous potential, these materials are facing some serious concerns regarding lead-based toxicity. Among many lead-free perovskites, the vacancy-ordered double perovskite cesium titanium halide family (Cs2TiX6, X = Cl, Br, I) is very popular and heavily investigated and reported on. The main objective of this study is to design and compare an efficient cesium titanium halide-based solar cell that can be used as an alternative to lead-based perovskite solar cells. For efficient photovoltaic requirements, the hole-transport layer and electron-transport layer materials such as PEDOT:PSS and Nb2O5 are selected, as these are the commonly reported materials and electronically compatible with the cesium titanium halide family. For the active layer, cesium titanium halide family members such as Cs2TiCl6, Cs2TiBr6, and Cs2TiI6 are reported here for the devices ITO/Nb2O5/Cs2TiI6/PEDOT:PSS/Au, ITO/Nb2O5/Cs2TiBr6/PEDOT:PSS/Au, and ITO/Nb2O5/Cs2TiCl6/PEDOT:PSS/Au, respectively. To determine the most efficient photovoltaic response, all the layers (PEDOT:PSS, Nb2O5, and active perovskite layer) of each device are optimized concerning thickness as well as doping density, and then each optimized device was systematically investigated for its photovoltaic responses through simulation and modeling. It is observed that the device ITO/Nb2O5/Cs2TiI6/PEDOT:PS/Au shows the most efficient photovoltaic response with little above 18.5% for maximum power-conversion efficiency.

Mid-Infrared Nonlinear Optical Halides with Diamond-like Structures: A Theoretical and Experimental Study

As an important family of potential mid-IR nonlinear optical (NLO) crystals, halides exhibit superiority in large optical band gaps and wide IR transparency. However, their second-harmonic generation (SHG) effects are generally small, limiting their frequency conversion efficiency in NLO processes. Diamond-like structures, due to the intrinsic polarization-parallel alignment of tetrahedral frameworks, enable sufficiently large SHG effects while maintaining balanced NLO performance in the mid-IR spectral region. Accordingly, in this study, we focused on the NLO performance mining and assembly of tetrahedral polar motifs in halides with unique diamond-like structures. We screened almost all diamond-like structures in inorganic halide systems and investigated in detail how their balanced NLO performances evolve with ideal and defective diamond-like structures. We predicted that the three existing diamond-like iodides, CuGaI4, Ag2CdI4, and Ag2ZnI4, can satisfy the balanced requirement of strong SHG effects (>3.9 pm/V) and large optical band gaps (>3 eV) by analyzing the microstructural NLO origin. Preliminary experiments also verified our predictions with Ag2CdI4 (1.4 × AgGaS2 and 3.3 eV) and Ag2HgI4 (2.2 × AgGaS2 and 2.4 eV). More importantly, a map with the diamond-like halide family tree was illuminated, unlocking dozens of diamond-like structures with balanced NLO properties, from ternary AgCdI3, Ag2Cd3I8, Ag4CdI6, and AgInI4 to quaternary AgCuCdI4, Ag8HgCd3I16, Ag3HgGaI8, AgCd2InI8, and Ag2CdI2Br2. As long as following this map, one may design and discover potentially promising mid-IR NLO halide crystals with diamond-like structures.

Potassium rare-earth tellurite chlorides: A new branch from the old root

Single crystals of four new potassium rare earth tellurite chlorides, [(Ln,K)1-xLn11(TeO3)12]K6Cl16+y (Ln = Pr, Sm, Gd, and Ho), have been prepared via molten salt synthesis. From the structural viewpoint, they belong to a numerous family of complex rare-earth (and Bi) selenite and tellurite halides featuring complex [(Ln,M)12-x(ChO3)12] building blocks interleaving with various halide or metal-halide slabs. Similar to the formally isostructural Rb- and Cs-containing analogs, in the new series of nearly isostructural compounds, the [Ln12-x(TeO3)12] slabs alternate with [K6Cl16+x] counterparts derived from the CsCl archetype. We discuss the overall trends in the structural chemistry of these layered chalcogenite halides.