Mössbauer and electronic-reflectance spectroscopic studies and resistivity measurements on the systems CsPb_1–xSn_xBr₃, CsPb_1–xSn_xBr₂Cl, M_xCs_1–xSnBr₃, and M_xCs_1–xSnBr₂Cl (M = Na, K, Rb, and NH₄)

Abstract

A series of coloured compounds of general formula CsPb,-,Sn,X, (X, = Br, or Br,CI) has been prepared. X-Ray and Mossbauer data show that the compounds have highly symmetrical tin-lead environments. Their electronic resistivity and optical-reflectance spectra are interpretable in terms of the partial filling of electronic bands produced by the interaction of orbitals of the bromine atoms, As x increases the band population increases, consistent with the lower ionisation energies of the tin 5s electrons compared to those of the lead 6s electrons. Replacement of Cs+ by Naf, K+, Rbf, or [NH,] + shows that these singly charged ions have no effect on band formation. Replacement of Br, by Br,CI raises the energy of the band due to the inclusion of the higher-energy chlorine orbitals.

CH3NH3SnBrxI3-x (x = 0-3), ein Sn(II)-System mit kubischer Perowskitstruktur / CH3NH3SnBrxI3-x(x = 0-3), a Sn(II)-System with Cubic Perovskite Structure

“…Die in den meisten Fällen anzutreffende Liganden Verteilung niederer Symmetrie kann mit der Mischung von s-und p-Valenzzuständen erklärt werden [2], Eines dieser seltenen Beispiele mit stereochemisch inaktiven ns 2 -Elektronen ist das schwarze, im kubischen Perowskitgitter kristallisierende CsSnBr3 [3,4], das sich im Gegensatz zu den übrigen Alkali-Zinn(II)-Halogeniden durch intensive Eigenfarbe und elektrische Leitfähigkeit auszeichnet [5,6], Das Sn(II)-Ion ist hier streng oktaedrisch von den Anionen umgeben.…”

Blue luminescence in yttrium and gadolinium niobates caused by bismuth. The importance of non‐bonding ns2 valence orbital electrons

“…The coating thickness was ca. 5 mg cm 22 . The coated Al stubs were then placed into a chamber, which was evacuated to a pressure of ca.…”

“…For a band model, we turn to recent work by Blasse and coworkers 9 who proposed a model to explain the electronic band structure for b-Bi(Nb/Ta)O 4 justi®ed from known crystal structural data. The reasonable assumption is made that the 6s 2 valence band levels lie just above the 2p(O 22 ) valence band levels. Absorption transitions are determined by the 6s 2 ±4d/5d transition, which takes place at lower energy than the 2p±4d/5d charge-transfer transition.…”

“…Several of our studies examined small amounts of ns 2 dopant ion on colourless or pale coloured lattices, 12,18±22 at very low concentrations (v0.5% of ns 2 active element dopant), little change of colour was observed. 12,22 However it could be inferred that the ns 2 electrons were at the top of the valence band. 22 Such a picture is similar to that of Blasse and coworkers 9 and will be discussed further in the present work to investigate the in¯uence of an ns 2 cation, in this case Bi 3z , on the luminescence properties of the rare-earth element± transition-metal element oxides YNbO 4 and GdNbO 4 .…”

“…12,22 However it could be inferred that the ns 2 electrons were at the top of the valence band. 22 Such a picture is similar to that of Blasse and coworkers 9 and will be discussed further in the present work to investigate the in¯uence of an ns 2 cation, in this case Bi 3z , on the luminescence properties of the rare-earth element± transition-metal element oxides YNbO 4 and GdNbO 4 .…”