Short-range order, thermal vibration and expansion, and other properties of pseudosymmetric and mixed crystals of small organic molecules - Calculation of dimensions of ordered regions in triclinic and monoclinic pseudosymmetic crystals from the intensity of diffuse scattering

1970 ◽  
Vol 266 (1180) ◽  
pp. 575-582 ◽  
Keyword(s):  
Diffuse Scattering ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Small Organic Molecules ◽  
Thermal Diffuse Scattering ◽  
X Ray Scattering ◽  
Thermal Diffuse ◽  
Mathematical Relations ◽  
Disorder Scattering

Mathematical relations are obtained giving the X-ray scattering for a crystal the unit cell of which contains one or two asymmetric molecules, each of which can adopt either of two centrosymmetrically-related orientations, giving pseudocentrosymmetry. It is shown that measurements of the integral breadth of maxima of the diffuse ‘disorder’ scattering can give the dimensions of the short-range order regions. The temperature variation of intensity of such diffuse scattering is different from that of thermal diffuse scattering.

Short-range order, thermal vibration and expansion, and other properties of pseudosymmetric and mixed crystals of small organic molecules - Short-Range order in n- oxyphenazine and in mixed crystals of phenazine- n -oxyphenazine

1970 ◽  
Vol 266 (1180) ◽  
pp. 635-639 ◽  
Keyword(s):  
Diffuse Scattering ◽  
Short Range ◽  
Short Range Order ◽  
Mixed Crystal ◽  
Range Order ◽  
Mixed Crystals ◽  
Miscibility Gap ◽  
Small Organic Molecules ◽  
Two Phases ◽  
Average Size

Disorder diffuse scattering has been observed for N -oxyphenazine which indicates the existence of domains of short-range order in (100) planes, of average size 13 A (along b) by 50 A (along c). Along a the alternation of centrosymmetrically arranged molecules is random. Mixed crystals with phenazine show diffuse scattering which indicates that up to about 60 mole % of phenazine can occur in the structure without disrupting these short-range-order domains. Mixed crystals of low N -oxyphenazine content have these molecules arranged randomly in the phenazine matrix. Between these two phases there appears to be a miscibility gap. It is probable that two components, one of which is ordered and the other showing only short-range order cannot form a continuous mixed-crystal series.

Short range order in liquid acetic acid as studied by X-ray scattering and DFT calculations

2012 ◽  
Vol 173 ◽  
pp. 164-171 ◽  
Author(s):  
Nourhane Ben Zineb ◽  
Abir Chebaane ◽  
Ferid Hammami ◽  
Mohamed Bahri ◽  
Salah Nasr
Keyword(s):  
Acetic Acid ◽  
Dft Calculations ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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