Electron processes in ionic-covalent compounds with a natural crystal-chemical state of disorder (taking lead oxides as examples)

1976 ◽  
Vol 19 (2) ◽  
pp. 251-262
Author(s):  
V. A. Izvozchikov
Keyword(s):  
Chemical State ◽  
Crystal Chemical ◽  
Natural Crystal ◽  
Lead Oxides

First Refinement of the Sinoite Structure of a Natural Crystal from the Neuschwanstein (EL6) Meteorite

2005 ◽  
Vol 60 (12) ◽  
pp. 1231-1234 ◽  
Author(s):  
Addi Bischoff ◽  
Thorsten Grund ◽  
Thomas Jording ◽  
Birgit Heying ◽  
Rolf-Dieter Hoffmann ◽  
...  
Keyword(s):  
Single Crystal ◽  
Thin Section ◽  
Three Dimensional ◽  
Crystal Chemical ◽  
Variable Parameters ◽  
X Ray ◽  
Polished Thin Section ◽  
Natural Crystal ◽  
Dimensional Network

A well-shaped sinoite crystal was milled out of a polished thin section of the Neuschwanstein (EL6) chondrite. The structure was refined on the basis of X-ray single crystal data:Cmc21, a=885.66(18), b = 549.61(11), c = 484.23(10) pm, R1 = 0.0282, 491 F2 values, 26 variable parameters. The structure consists of a complex three-dimensional network of corner-sharing SiN3O tetrahedra (Si-O 161.9, Si-N 171.9-172.8 pm). The crystal chemical peculiarities of Si2N2O are briefly discussed.

Use of a Method of Small X-Ray Line Shifts to Investigate the Electronic Structure of Crystal Chemical Bonds

1974 ◽  
Vol 113 (6) ◽  
pp. 360 ◽  
Author(s):  
O.M. Sumbaev ◽  
E.V. Petrovich ◽  
Yu.P. Smirnov ◽  
I.M. Band ◽  
Aleksandr I. Smirnov
Keyword(s):  
Electronic Structure ◽  
Crystal Chemical ◽  
Chemical Bonds ◽  
X Ray ◽  
Small X

The pseudomalachite-ludjibaite-reichenbachite conundrum: OD description

2019 ◽  
Vol 57 (5) ◽  
pp. 571-581
Author(s):  
Emil Makovicky
Keyword(s):  
Crystal Structures ◽  
Current Knowledge ◽  
The Other ◽  
Crystal Chemical ◽  
Layer System ◽  
Coordination Polyhedra

Abstract Crystal structures of the three polymorphs of Cu5(PO4)2(OH)4, namely pseudomalachite, ludjibaite, and reichenbachite, can be described as being composed of rods perpendicular to their crystal-chemical layering. Two different sorts of rods can be defined. Type 1 rods share rows of Cu coordination polyhedra, forming a series of slabs. Slab boundaries and slab interiors represent alternating geometric OD layers of two kinds, with layer symmetries close to P21/m and , which make up two different stacking schemes of geometric OD layers in the structures of ludjibaite and pseudomalachite. Such OD layers, however, are not developed in reichenbachite. Type 2 rods are defined as having columns of PO4 tetrahedra in the corners of the rods. In the Type 2 slabs composed of these rods, geometric Pg OD layers of glide-arrayed tetrahedra alternate with more complex OD layers; in ludjibaite this system of layers is oriented diagonally with respect to the Type 1 OD layer system. Two different OD stackings of Type 2 OD layers form the ludjibaite and reichenbachite structures but not that of pseudomalachite. Thus, ludjibaite might form disordered intergrowths with either of the other two members of the triplet but reichenbachite and pseudomalachite should not form oriented intergrowths. Current knowledge concerning formation of the three polymorphs is considered.

Cordylite-(Ce); a crystal chemical investigation of material from four localities, including type material

1998 ◽  
Vol 83 (1-2) ◽  
pp. 178-184 ◽  
Author(s):  
Gerald Giester ◽  
Yunxiang Ni ◽  
Dietmar Jarosch ◽  
John M. Hughes ◽  
Jorn G. Ronsbo ◽  
...  
Keyword(s):  
Chemical Investigation ◽  
Type Material ◽  
Crystal Chemical
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