Rubidium‐ und Caesium‐Verbindungen mit dem Isopolyanion [Ta6O19]8– – Synthesen,Kristallstrukturen, thermische und schwingungsspektroskopische Untersuchungen der Oxotantalate A8[Ta6O19] · n H2O (A = Rb,Cs; n = 0, 4, 14)

Rubidium und Caesium Compounds with the Isopolyanion [Ta₆O₁₉]^8– – Synthesis, Crystal Structures, Thermogravimetric and Vibrational Spectrocopic Analysis of the Oxotantalates A₈[Ta₆O₁₉] · n H₂O (A = Rb, Cs; n = 0, 4, 14) The compounds A₈[Ta₆O₁₉] · n H₂O (A = Rb, Cs; n = 0, 4, 14) contain the isopoly anion [Ta₆O₁₉]^8–, which consists of six [TaO₆] octahedra connected via corners to form a large octahedron. They transform into each other by reversible hydratation/dehydratation processes, as shown from thermoanalytic measurements (TG/DSC), and show also structural similarities. Cs₈[Ta₆O₁₉] (tetragonal, I4/m, a = 985.9(1) pm, c = 1403.3(1) pm, Z = 2), the isotypic phases A₈[Ta₆O₁₉] · 14 H₂O (A = Rb/Cs; monoclinic, P2₁/n, a = 1031.30(6)/1055.4(1) pm, b = 1590.72(9)/1614.9(6) pm, c = 1150.43(6)/1171.4(1) pm, β = 100.060(1)/99.97(2)°, Z = 2) and Rb₈[Ta₆O₁₉] · 4 H₂O (monoclinic, C2/c, a = 1216.9(4) pm, b = 1459.2(5) pm, c = 1414.7(4) pm, β = 90.734(6)°, Z = 4) have been characterised on the basis of single crystal x‐ray data. Furthermore the RAMAN spectra allow a detailled comparison of the hexatantalate ions in the four compounds.     

Ternary molybdenum(III) chlorides

The phase diagrams of ACl/MoCl₃ (A=Na, K, Rb, Cs) were elucidated by DTA measurements in sealed quartz ampoules in the range of 0–40 mol% MoCl₃. The samples were prepared from alkali metal chlorides and the compounds A₃MoCl₆ or A₃Mo₂Cl₉. The 31 compounds withA=Na, Rb, Cs were obtained by sintering mixtures of 3ACl+MoCl₃; the enneachlorides A₃Mo₂Cl₉ withA=K, Rb, Cs were precipitated from solutions of MoCl₃·3H₂O and ACl in formic acid. Congruently melting compounds A₃MoCl₆ exist in all four systems, incongruently melting enneachlorides A₃Mo₂Cl₉ in systems withA=K, Rb, Cs. Still unknown structures were determined by analog-indexing powder patterns according to known structure families. Especially Cs₃MoCl₆ is isotypic with the recently found Cs₃CrCl₆ structure. Additionally, the unit cell parameters were determined for the compounds A₃MoCl₅·H₂O (A=K, Rb, Cs) analogous to Cs₂TiCl₅·H₂O, whose structure was determined by single crystal measurements.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthday     

Thermisches Verhalten von Caesiumchloroferraten(III) und Caesiumchloroferrat(III)-Hydraten. II. Die Rehydratation der Zersetzungsprodukte von Cs3[FeCl6] – Eine ramanspektroskopische Untersuchung unter definierter Wasserdampfatmosphäre [1]

The Thermal Behaviour of Caesiumchloroferrates(III) and Caesiumehloroferrate(III) Hydrates. II. The Rehydration of Decomposition Products of Cs₃[FeCl₆] — A Raman Spectroscopic Study under Definite Atmosphere of Water Vapour Cs₃[FeCl₆] formed by dehydration of Cs₃[FeCl₆] · H₂O at about 160°C does not change at normal atmosphere within 3 till 4 hours. Rehydration under the vapour pressure of the eliminated water yields the monohydrate in nearly the same time. In the same manner rehydration of the solid mixture of Cs[FeCl₄] and 2 CsCl formed by thermal decomposition of the metastable Cs₃[FeCl₆] (280°C) produces the intermediates Cs₃[Fe₂Cl₉] and Cs₂[Fe(H₂O)Cl₅] in mixtures with CsCl and, finally, Cs₃[FeCl₆] · H₂O. The formation of Cs₃[Fe₂Cl₉] from Cs[FeCl₄] and CsCl is accelerated by water. The reaction cycle has been studied using Raman and IR spectroscopy. The results will be discussed with respect to thermoanalytical data.     

Carbonat‐Hydrate der schweren Alkalimetalle: Darstellung und Struktur von Rb2CO3 · 1,5 H2O und Cs2CO3 · 3 H2O

Carbonate Hydrates of the Heavy Alkali Metals: Preparation and Structure of Rb₂CO₃ · 1.5 H₂O und Cs₂CO₃ · 3 H₂O Rb₂CO₃ · 1.5 H₂O and Cs₂CO₃ · 3 H₂O were prepared from aqueous solution and by means of the reaction of dialkylcarbonates with RbOH and CsOH resp. in hydrous alcoholes. Based on four‐circle diffractometer data, the crystal structures were determined (Rb₂CO₃ · 1.5 H₂O: C2/c (no. 15), Z = 8, a = 1237.7(2) pm, b = 1385.94(7) pm, c = 747.7(4) pm, β = 120.133(8)°, V_EZ = 1109.3(6) · 10⁶ pm³; Cs₂CO₃ · 3 H₂O: P2/c (no. 13), Z = 2, a = 654.5(2) pm, b = 679.06(6) pm, c = 886.4(2) pm, β = 90.708(14)°, V_EZ = 393.9(2) · 10⁶ pm³). Rb₂CO₃ · 1.5 H₂O is isostructural with K₂CO₃ · 1.5 H₂O. In case of Cs₂CO₃ · 3 H₂O no comparable structure is known. Both structures show [(CO₃^2–)(H₂O)]‐chains, being connected via additional H₂O forming columns (Rb₂CO₃ · 1.5 H₂O) and layers (Cs₂CO₃ · 3 H₂O), respectively.     

Ternäre Halogenide vom Typ A3MX6. I A3YCl6 (A = K,NH4, Rb,Cs): Synthese,Strukturen, Thermisches Verhalten. Über einige analoge Chloride der Lanthanide

Ternary Halides of the A₃MX₆ Type I. A₃YCI₆ (A = K, NH₄, Rb, Cs): Synthesis, Structures, Thermal Behaviour. Some Analogous Chlorides of the Lanthanides Reaction of the trichlorides MCl₃ (M = Y, Tb? Lu) with alkali chlorides AC1 (A = K, Rb, Cs) in evacuated silica ampoules at 850?900°C yields A₃MCl₆-type chlorides. (NH₄)₃YCl₆ is obtained via the ammonium-chloride route. The crystal structure of Rb₃YCl₆ (monoclinic, C2/c (no. 15), Z = 8, a = 2583(1)pm, b = 788.9(4)pm, c = 1283.9(7)pm, p = 99.63(4)°, R = 0.062, R_w = 0.050) is that of Cs₃BiCl₆. The Rb₃YCl₆/Cs₃BiCl₆ structure and the closely related structures of K₃MoCl₆ and In₂CI₃ are derived from the elpasolite-type of structure (K₂NaAlF₆) making use of the model of closest-packed layer structures. Cell parameters for the chlorides Rb₃MCl₆ (M = Y, Tb? Lu) and Cs₃YCl₆ and Cs₃ErCl₆ as well, which are all isostructural with Rb₃YCl₆, are given. The “system” (K, NH₄, Rb, Cs)YCl₆ has been investigated by DTA and high-temperature X-ray powder diffractometry.     

Polysulfonylamine. CLXIII [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 12 [1] Das orthorhombische Doppelsalz Na2Cs2[(CH3SO2)2N]4·3H2O: Ein dreidimensionales Koordinationspolymer aus (Caesium‐Anion‐Wasser)‐Schichten und intercalierten Natriumionen

Polysulfonylamines. CLXIII. Crystal Structures of Metal Di(methanesulfonyl)amides. 12. The Orthorhombic Double Salt Na₂Cs₂[(CH₃SO₂)₂N]₄·3H₂O: A Three‐Dimensional Coordination Polymer Built up from Cesium‐Anion‐Water Layers and Intercalated Sodium Ions The packing arrangement of the three‐dimensional coordination polymer Na₂Cs₂[(MeSO₂)₂N]₄·3H₂O (orthorhombic, space group Pna2₁, Z′ = 1) is in some respects similar to that of the previously reported sodium‐potassium double salt Na₂K₂[(MeSO₂)₂N]₄·4H₂O (tetragonal, P4₃2₁2, Z′ = 1/2). In the present structure, four multidentately coordinating independent anions, three independent aquo ligands and two types of cesium cation form monolayer substructures that are associated in pairs to form double layers via a Cs(1)—H₂O—Cs(2) motif, thus conferring upon each Cs⁺ an irregular O₈N₂ environment drawn from two N, O‐chelating anions, two O, O‐chelating anions and two water molecules. Half of the sodium ions occupy pseudo‐inversion centres situated between the double layers and have an octahedral O₆ coordination built up from four anions and two water molecules, whereas the remaining Na⁺ are intercalated within the double layers in a square‐pyramidal and pseudo‐C₂ symmetric O₅ environment provided by four anions and the water molecule of the Cs—H₂O—Cs motif. The net effect is that each of the four independent anions forms bonds to two Cs⁺ and two Na⁺, two independent water molecules are involved in Cs—H₂O—Na motifs, and the third water molecule acts as a μ₃‐bridging ligand for two Cs⁺ and one Na⁺. The crystal cohesion is reinforced by a three‐dimensional network of conventional O—H···O=S and weak C—H···O=S/N hydrogen bonds.     

Halogenaustausch an Re3-Clustern: Ein neuer Syntheseweg für binäre und ternäre Rhenium(III)-bromide. Kristallstrukturen von Cs2[Re3Br11] und Cs3[Re3Br3Cl9]

Halogen Exchange at Re₃-Clusters: A New Synthetic Route to Binary and Ternary Rhenium(III) Bromides. Crystal Structures of Cs₂[Re₃Br₁₁] and Cs₃[Re₃Br₃Cl₉] The substitution of “inner” ligands in transition metal clusters in aqueous HX solutions is hitherto unknown. For the first time the substitution of bridging and terminal chloride for bromide ions was observed at rhenium clusters, [Re₃(μ-Cl^i,b)₃(Cl)(Cl^i,t)_(3?x)(H₂O^i,t)_x]^(3?x)? (x = 0–3), via the reaction of “ReCl₃ · 2 H₂O” in hot hydrobromic acid solution under an inert gas atmosphere. This establishes a new synthetic route to ternary Re(III) bromides as well as to ReBr₃. However, ternary Re(IV) bromides, A₂ReBr₆ (A = Rb, Cs), are dominating in the presence of oxygen, rhenium(III) bromides are only by-products. Dark brown rods of Cs₂[Re₃Br₁₁] are obtained from argon saturated, hot hydrobromic acid solutions of “ReCl₃ · 2 H₂O” and CsBr. The crystal structure (orthorhombic, Pnma (Nr. 62); a = 955.51(5); b = 1 610.29(10); c = 1 372.70(9); Z = 4; V_m = 318.0(2) cm³mol^?1; R = 0.084, R_w = 0.058) consists of defect clusters [Re₃BrBrBr□^i,t]^2? in which one in plane, terminal position is not occupied. The substitution of “inner” ligands has been observed in the case of chloride for bromide only, the Br^i,b and I^i,b ligands in ReBr₃ and ReI₃, respectively, are not substituted in hydrochloric acid even at temperatures as high as 100°C. Bordeaux red square pyramids of CsReBrCl₃ = Cs₃[Re₃(μ-Br^i,b)₃ClCl] are obtained from hot hydrochloric acid solutions of ReBr₃ · 2/3 H₂O upon evaporation. CsReBrCl₃ (orthorhombic, C2cm (Nr. 40); a = 1 419.0(1); b = 1 419.2(1); c = 1 080.30(8) pm; Z = 4; V_m = 327.6(3) cm³mol^?1; R = 0.033, R_w = 0.028) is isostructural to the corresponding chloride CsReCl₄.     

XPS study of nanorods of doped vanadium oxide MxV2O5 · nH2O (M = Na, K, Rb, Cs)

Nanorods of vanadium oxide doped with alkali metal ions M _x V₂O₅ · nH₂O (M = Na, K, Rb, Cs, x = 0.31–0.44) have been obtained under hydrothermal conditions. The particles are 30–80 nm in diameter and a few micrometers in length. The chemical state of atoms and their concentration ratios have been studied by XPS. It has been shown that vanadium atoms are in two oxidation states V⁵⁺ and V⁴⁺ and the concentration of vanadium(IV) ions directly depends on the alkali metal. The X-ray photoelectron spectra of the valence bands of M _x V₂O₅ · nH₂O (M = Na, K, Rb, Cs) nanorods have been measured and interpreted.     

Caesiumchloropalladat(II)‐hydrate – zwei neue Verbindungen mit kondensierten [Pd2Cl6]‐Baugruppen

Caesiumchloropalladate(II)‐hydrates – Two New Compounds with Condensed [Pd₂Cl₆] Groups We were able to synthesize two caesiumchloropalladate(II)‐hydrates in the CsCl/PdCl₂/H₂O system by hydrothermal methods. Both compounds show combination of monomeric and dimeric Pd–Cl groups. We characterized the crystal structures by single‐crystal X‐ray diffraction. Cs₆Pd₅Cl₁₆ · 2 H₂O ( I ) crystallizes triclinic in space group type P1 (Nr. 2) with a = 8.972(1) Å, b = 11.359(1) Å, c = 18.168(1) Å, α = 83.61(1)°, β = 76.98(1)°, γ = 76.39(1)° and Z = 2, Cs₁₂Pd₉Cl₃₀ · 2 H₂O ( II ) monoclinic, space group type C2/m (No. 12) with a = 19.952(1) Å, b = 14.428(1) Å, c = 14.411(1) Å, β = 125.29(1)°, and Z = 2.     

Synthese,Kristallstruktur und thermischer Abbau von Cs1,5[Re3I3Cl7,5(H2O)1,5]

Synthesis, Crystal Structure and Thermal Behaviour of Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] Dark brown tetrahedra of Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] crystallize on slow cooling of a hot saturated solution of ReI₃ and CsCl in conc. hydrochlorid acid. The crystal structure (cubic, P4 3m (No. 215), a = 1241.06(3)pm, V_m = 287.8(1) cm³mol^?1, Z = 4, R = 0.067, R_w = 0.037) is built up from isolated building units [Re₃I₃Cl_7,5(H₂O)_1,5]^1,5? with statistical distribution of chloride ions and water molecules in the in plane, terminal positions. Consistent with the result based on the X-ray analysis, the IR-spectrum shows one band for the OH stretching frequencies of the water molecules coordinated to the Re₃ triangle at 3240 cm^?1. The anions are arranged in the fashion of a cubic closest packing with the cesium ions occupying all octahedral and one quarter of the tetrahedral interstices. Temperature-dependent Guinier-Simon photographs in connection with DTA/TG investigations reveal that Cs_1,5[Re₃I₃Cl_7,5(H₂O)_1,5] releases water at 190°C accompanied with a structural transition and the dehydration product decomposes at 370°C to Cs₂ReCl_6?xI_x, Re₃I_3+yCl_6?y and rhenium metal.     

Synthesis and crystal structure of tetraethylammonium-μ-trichloro-heptachloro-diaqua-trirhenate(III)-dihydrate,NEt4[Re3Cl10(H2O)2] · 2 H2O

NEt₄[Re₃Cl₁₀(H₂O)₂] · 2 H₂O ( 1 ) was obtained from hydrochloric acid solutions of ReCl₃ and tetraethylammonium chloride, NEt₄Cl, by isothermal evaporation as dark red crystals. 1 crystallizes in the orthorhombic crystal system, space group Pnma, Z = 4, with a = 1838,7(2), b = 1456.9(1), c = 972.08(7) pm, V_m = 391.81(6) cm³ · mol^?l. The crystal structure consists of [Re₃Cl₁₀(H₂O)₂]^? anions that are arranged in the fashion of a hexagonal closest-packing of spheres. These are held together by partially disordered NEt₄⁺ cations and are bound into a hydrogen bonding system with the crystal water.     

Ternäre Chloride in den Systemen ACl/DyCl3 (A = Cs,Rb, K)

Ternary Chlorides in the Systems ACl/DyCl₃ (A = Cs, Rb, K) The phase diagrams of the pseudobinary systems ACl/DyCl₃ (A = Cs, Rb, K) were investigated by DTA. With all alkali metals compounds A₃DyCl₆ (elpasolite family) and Ady₂Cl₇ are formed. Compounds A₂DyCl₅ exist only with Cs (Cs₂DyCl₅-type) and K (K₂PrCl₅-type). By solution calorimetry the formation enthalpies of the ternary chlorides from (nACl + DyCl₃) were measured and ‘synproportionation enthalpies’ for the formation from the compounds, adjacent in the phase diagrams, calculated. K₃DyCl₆ is the only compound, which is formed with a loss in lattice enthalpy. E.m.f. measurements in dependence on the temperature have revealed that, as for the other compounds A₃DyCl₆, a remarkable gain in entropy exists, which stabilizes K₃DyCl₆ at T ≧ 312 K. This entropy gain correlates with the existence of isolated DyCl₆^3? octahedra.     

Crystal structure and proton conductivity of a new Cs3(H2PO4)(HPO4)·2H2O phase in the caesium di‐ and monohydrogen orthophosphate system

The M_x H_y (A O₄)_z acid salts (M = Cs, Rb, K, Na, Li, NH₄; A = S, Se, As, P) exhibit ferroelectric properties. The solid acids have low conductivity values and are of interest with regard to their thermal properties and proton conductivity. The crystal structure of caesium dihydrogen orthophosphate monohydrogen orthophosphate dihydrate, Cs₃(H_1.5PO₄)₂·2H₂O, has been solved. The compound crystallizes in the space group Pbca and forms a structure with strong hydrogen bonds connecting phosphate tetrahedra that agrees well with the IR spectra. The dehydration of Cs₃(H_1.5PO₄)₂·2H₂O with the loss of two water molecules occurs at 348–433 K. Anhydrous Cs₃(H_1.5PO₄)₂ is stable up to 548 K and is then converted completely into caesium pyrophosphate (Cs₄P₂O₇) and CsPO₃. Anhydrous Cs₃(H_1.5PO₄)₂ crystallizes in the monoclinic C 2 space group, with the unit‐cell parameters a = 11.1693 (4), b = 6.4682 (2), c = 7.7442 (3) Å and β = 71.822 (2)°. The conductivities of both compounds have been measured. In contrast to crystal hydrate Cs₃(H_1.5PO₄)₂·2H₂O, the dehydrated form has rather low conductivity values of ∼6 × 10⁻⁶–10⁻⁸ S cm⁻¹ at 373–493 K, with an activation energy of 0.91 eV.     

Über die Pentachlorothallate(III) K2TlCl5 · 2 H2O und M2TlCl5 · H2O (M = Rb,NH4)

On the Pentachlorothallates(III) K₂TlCl₅ · 2 H₂O and M₂TlCl₅ · H₂O (M = Rb, NH₄) The pentachlorothallates(III) K₂TlCl₅ · 2 H₂O and M₂TlCl₅ · H₂O (M = Rb, NH₄) were obtained by crystallization from aqueous solutions of TlCl₃ and MCl. The crystal structure of the monoclinic K₂TlCl₅ · 2 H₂O contains dimeric Tl₂Cl₁₀ anions formed by two edge sharing octahedra. The orthorhombic monohydrates are isotypic with Cs₂[TlCl₅(OH₂)].     

Tetrakis(chloromethyl)phosphonium chloride monohydrate

Tetrakis­(chloro­methyl)­phospho­nium chloride monohydrate, C₄H₈Cl₄P⁺·Cl^?·H₂O or P(CH₂Cl)₄⁺·Cl^?·H₂O, is the first crystal structure determination of a tetrakis­(halogeno­methyl)­phospho­nium compound to date. The only comparable structures known so far are of phospho­nium ions containing just one halogeno­methyl group. The solvent water mol­ecule interacts with the Cl^? anion via hydrogen bonds, with O?Cl distances of 3.230 (2) and 3.309 (2) Å. The structure also contains several C—H?Cl^? and C—H?O contacts, though with longer D?A distances [D?A 3.286 (3)–3.662 (2) Å] or bent D—H?A angles. For these reasons, the C—H?Cl^? and C—H?O interactions should not be considered as strong hydrogen bonds.     

Cesium tetrakis(1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluorobutane-1,3-diono)europiate(III): Synthesis, crystal structure, and luminescence properties

Anionic complex Cs⁺[EuL₄]^? (I) is synthesized by the reaction of Eu(NO₃)₃ · 6H₂O with 1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluorobutane-1,3-dione (HL) and CsOH in an aqueous-alcohol medium. Unstable adduct Cs⁺[EuL₄]^? · 2CH₂Cl₂ (Ia) is obtained from a solution in CH₂Cl₂. The structure of complex Ia is determined by X-ray diffraction analysis. The crystals of complex Ia at 100 K are monoclinic, a = 10.8435(5), b = 20.1353(9), c = 23.355(1) Å, β = 92.548(1)°, V = 5094.3(4) ų, space group P2₁/n, Z = 4, and R = 0.0294. The coordination number of the Cs⁺ ion is 9. The Cs⁺ ion forms shortened (up to 3.3 Å) contacts with the O, N, and F atoms of four diketonate fragments joining the molecules into a three-dimensional structure.     

Darstellung von Alkalichlorowolframaten(V) aus WCl6 in chloridhaltigen Lösungsmitteln

Preparation of Compounds AWCl₆ from WCl₆ in Cl^?-containing Solvents In Glyme, ACN or CH₂Cl₂ WCl₆ is reduced by Cl^? to WCl₆^?. From those solutions compounds AWCl₆ can be isolated with A = Cs (Glyme, ACN), A = Rb, K, NH₄(ACN) and A = N(C₂H₅)₄ (CH₂Cl₂). By concentrating of glyme-solutions a precipitate of A₂WCl₆ is formed by disproportionation. In methanol/HCl also solvolysis to oxo-compounds of W⁶⁺ takes place as function of the H⁺-concentration. With N(C₂H₅)₄Cl not only chlorotungstates but also methoxy- and oxo-spezies of W⁵⁺ can be isolated.     

All-Inorganic Lead-Free 0D Perovskites by a Doping Strategy to Achieve a PLQY Boost from <2 % to 90 %

Zero-dimensional (0D) lead-free perovskites have unique structures and optoelectronic properties. Undoped and Sb-doped all inorganic, lead-free, 0D perovskite single crystals A₂InCl₅(H₂O) (A=Rb, Cs) are presented that exhibit greatly enhanced yellow emission. To study the effect of coordination H₂O, Sb-doped A₃InCl₆ (A=Rb, Cs) are also synthesized and further studied. The photoluminescence (PL) color changes from yellow to green emission. Interestingly, the photoluminescence quantum yield (PLQY) realizes a great boost from <2 % to 85–95 % through doping Sb³⁺. We further explore the effect of Sb³⁺ dopants and the origin of bright emission by ultrafast transient absorption techniques. Furthermore, Sb-doped 0D rubidium indium chloride perovskites show excellent stability. These findings not only provide a way to design a set of new high-performance 0D lead-free perovskites, but also reveal the relationship between structure and PL properties.     

Ternäre Chloride in den Systemen ACl/GdCl3 (A = Na?Cs)

Ternary Chlorides in the Systems ACl/GdCl₃ (A = Na? Cs) The phase diagrams of the pseudobinary systems ACl/GdCl₃ (A = Na? Cs) were investigated by DTA. Their powder diffractograms were indexed in analogy to known structure families. By solution calorimetry and measurements of e.m.f. = f(T) in galvanic cells for solid electrolytes the enthalpies ΔH⁰ and free enthalpies ΔG⁰ for the formation of the ternary chlorides from the compounds adjacent in the systems were determined. The systems with A = K, Rb, Cs are analogous to those with Sm³⁺ and Eu³⁺. There exist compounds A₃GdCl₆, A₂GdCl₅ and AGd₂Cl₇. Cs₂GdCl₅ is crystallysing in the Cs₂DyCl₅ type; the Rb- and K-compounds and also Na₂GdCl₅ have the K₂PrCl₅?structure. In the system NaCl/GdCl₃ additionally the compounds NaGdCl₄ and Na₃GdCl₆ were found. L? Na₃GdCl₆ is metastable compared with (NaCl + Na₂GdCl₅); above 265°C stable H? Na₃GdCl₆ is existing (cryolite-structure).     

Phase Equilibrium System of CsCl-YCl3-（9.5%）HCL-H2O at T=298.15 K and Its Compounds

Introduction In a series of papers the authors reported the spec-troscopy results on upconversion luminescence of the double salts between the alkali metal (Rb,Cs) halide and rare earth metal trihalide (REX3).1-4 Consequently, ex-tensive syntheses of new double salts and studies on optical properties of such species have received much more attention.5-12 Although a number of these double salts have been synthesized, the formation in alkali metal halide/rare earth metal halide double salts s…