Construction of melamine foam–supported WO3/CsPbBr3 S–scheme heterojunction with rich oxygen vacancies for efficient and long–period CO2 photoreduction in liquid–phase H2O environment

Effect of LiCl·H2O on sintering properties of MgO prepared from natural brine from Qarhan Salt Lake, crystalline bischofite and MgCl2·6H2O(AR) was studied. The results showed that LiCl·H2O of addition exceeded 1 wt% had promoting effect on sintering of magnesia prepared from MgCl2·6H2O(AR). While 1.5 wt% LiCl·H2O was added, the bulk density of magnesia was 3.40 g/cm3, and the relative density was 95.0%. With 0.5 wt% LiCl·H2O, the bulk densities of magnesia prepared from crystalline bischofite and brine were 3.04 and 3.10 g/cm3, and the relative densities increased by 8.4% and 14.8%, respectively. The main mechanism for promoting MgO sintering with LiCl·H2O was that Li2O produced by hydrolysis solubilized in MgO to form solid solutions and oxygen vacancies which were favorable to sintering. The main reasons for promoting sintering of brine magnesia with LiCl·H2O were solid solution and liquid phase sintering, while the main reason was solid solution for magnesia from crystalline bischofite and MgCl2·6H2O(AR).

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On the Polytypic Transformations in SiC

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.18-19.89 ◽

2012 ◽

Vol 18-19 ◽

pp. 89-96

Author(s):

Maya Marinova ◽

Alkyoni Mantzari ◽

Ariadne Andreadou ◽

Efstathios K. Polychroniadis

Keyword(s):

Liquid Phase ◽

Liquid Phase Epitaxy ◽

Growth Conditions ◽

Small Energy ◽

Long Period ◽

Stacking Order

In the present work we report on the polytypic transformations taking place in nanoscale dimensions within 6H-SiC crystals. The examined crystals were grown by Liquid Phase Epitaxy using a mixture of Si and Al as solvents. The study concentrated on the differences from the “correct” stacking order of the Si-C bilayers for 6H-SiC leading to the formation of other polytypes. A great variety of sequences was found, which resulted to the appearance of rare short and long period polytypes or individual lamellae having their “own” stacking inside the 6H-SiC matrix. These nanostructured faults which deteriorate the quality of the grown material indicate also their “sensitivity” to any small or even infinitesimal change of the growth conditions, due to the very small energy among them.

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On the Nanostructure of SiC

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.12.99 ◽

2010 ◽

Vol 12 ◽

pp. 99-104

Author(s):

Maya Marinova ◽

Efstathios K. Polychroniadis

Keyword(s):

Silicon Carbide ◽

Liquid Phase ◽

Structural Properties ◽

Liquid Phase Epitaxy ◽

Stacking Faults ◽

Growth Conditions ◽

Small Energy ◽

Long Period ◽

Stacking Order

The present work deals with the structural properties of silicon carbide in nanoscale dimensions. The examined crystals were 6H-SiC grown by Liquid Phase Epitaxy. The study was concentrated on the stacking faults and any other differences from the “correct” stacking order of the Si-C bilayers for this polytype. Three main types of stacking faults were observed: (i) Cubic lamellae with thickness of four and two Si-C bilayers, always occurring in reverse stacking with respect to each other and separated by at least one unit cell of 6H-SiC; (ii) “twinned” 6H-SiC lamellae separated by a two-bilayer thick cubic inclusion. As a result the sequence in the “twinned” 6H-SiC changes from (3+3-) to (3-3+). (iii) Lamellae showing fringes, the interrelated distance of which suggests inclusion with sequence (22). Further, a high variety of sequences was found, leading to the appearance of rare long period polytypes or individual lamellae having their “own” stacking inside the 6H-SiC matrix. These nanostructured faults which deteriorate the quality of the grown material indicate also their “sensitivity” to any small or even infinitesimal change of the growth conditions, due to the very small energy among them.

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