Ag₂Te₂O₇, ein neues Silbertellurat mit Weberit‐Struktur

Abstract

Ag2Te2O7, a Novel Silver Tellurate of Weberite Structure Type Ag2Te2O7 has been synthesized by solid state reaction of Ag2O and TeO2 under elevated oxygen pressure. The compound is diamagnetic and insulating, and decomposes at 560 °C in an Ar atmosphere into oxygen, Ag2TeO3 and TeO2. Ag2Te2O7 crystallizes orthorhombic in space group Imma with a = 7.266(2), b = 10.1430(9), c = 7.6021(17) Å, V = 560.3(2) Å3, Z = 4, 410 independent reflections, R1 = 4.65 %, wR2 = 11.13 %. The crystal structure consists of a three‐dimensional framework of TeO6 octahedra which are linked by common vertices. Voids of the framework accommodate silver atoms which are coordinated by eight oxygen atoms. The structure derives from that one of naturally occurring Weberite, Na2MgAlF7. The relationship to the pyrochlore structure type is discussed.

Crystal Structure of Silver Chromate Silicate, Ag6(CrO4)(SiO4)

“…Dark-red crystals of Ag 6 (CrO 4 )(SiO 4 ) were obtained as a by-product of preparations originally aiming at silver silicates [10,16], when elevated oxygen pressures with water added as mineralizer were applied in stainless-steel autoclaves [17]. While silver(I) oxide and silicon dioxide were given as the reaction mixture, the chromium is part of the autoclave steel and was dissolved from the autoclave wall under the reaction conditions.…”

“…Ag 6 (CrO 4 )(SiO 4 ) was obtained as a by-product during experiments at elevated oxygen pressures and temperatures in stainless-steel autoclaves [17]. Ag 2 O and SiO 2 were used as the reaction mixture in molar ratios around 2 : 1, water was added as a mineralizer, while chromium was dissolved from the autoclave wall under the reaction conditions.…”

Synthesis, Crystal Structure, and Properties of Ag3SbO4

“…During our systematic investigations of ternary silver oxides we were able to identify a considerable number of silver bismuthates [1][2][3][4][5][6][7] and silver tellurates [8][9][10][11]. One of the reasons behind this wealth in individual phases is the ability of bismuth and tellurium to adopt more than one oxidation state in these compounds.…”

New Silver Tellurates – The Crystal Structures of a Third Modification of Ag2Te2O6 and of Ag4TeO5

“…In search of representatives with similar silver-mercury cluster cations in the system Ag-Hg-Te-O-(H), systematic phase formation studies were undertaken under hydrother-(C2/c, Z ϭ 8, a ϭ 16.271 (2), b ϭ 6.0874 (10), c ϭ 11.4373(16) Å , β ϭ 106.730(10)°, 2372 independent reflections, R[F 2 > 2σ(F 2 )] ϭ 0.0288, wR2(F 2 all) ϭ 0.0737) is made up of a layer-like arrangement of isolated [Te VI 2 O 10 ] double octahedra and of Ag ϩ cations situated both in layers parallel and inside the layers of the anionic moieties.…”

“…The latter is the third known polymorph (denoted as Ag 2 Te 2 O 6 ϪIII in the following) of a compound with the composition "AgTeO 3 ". Up to now, in the system Ag-Te-O the tellurate(IV) Ag 2 TeO 3 [7], the mixed-valent tellurates(IV,VI) Ag 2 Te 2 O 6 ϪI, Ag 2 Te 2 O 6 ϪII, Ag 2 Te 4 O 11 [8], and the tellurates(VI) Ag 2-TeO 4 [9] and Ag 2 Te 2 O 7 [10] have been crystallographically well characterized, whereas for the orthotellurate(VI) Ag 6-TeO 6 only the synthesis [11] and dubious powder X-ray diffraction data [12] have been reported. In this communication the crystal structures of the new phases Ag 4 TeO 5 and Ag 2 Te 2 O 6 ϪIII are discussed including a comparative description with the other Ag 2 Te 2 O 6 polymorphs.…”