scholarly journals Low Temperature Synthesis of Aegirine NaFeSi2O6: Spectroscopy (57Fe Mössbauer, Raman) and Size/Strain Analysis from X-ray Powder Diffraction

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 444 ◽  
Author(s):  
Günther J. Redhammer ◽  
Julian Weber ◽  
Gerold Tippelt ◽  
Gregor A. Zickler ◽  
Andreas Reyer

Using a low temperature synthesis protocol, it was possible to obtain phase-pure synthetic aegirine (NaFeSi2O6) at temperatures as low as 130 °C, albeit only with rather long synthesis times of ~200 h; at 155 °C, a nano-crystallite shaped phase-pure material is formed after 24 h. These are, to the best of our knowledge, the lowest temperatures reported so far for phase-pure aegirine synthesis. Powder X-ray diffraction (PXRD) was used to characterize phase purity, structural state and microstructural properties (size and strain) of the as-synthesized (130–230 °C) and heat treated (300–900 °C) samples, via Rietveld analysis of powder patterns. Melting was observed at 999 °C. With increasing synthesis temperature, crystallite size linearly increased from 10 nm to 30 nm at 230 °C, while unit cell parameters decreased. The microstrain was very small. Additional heat treatment of as synthesized samples showed that the crystallite size remained rather unaffected up to 700 °C. The lattice parameters, however, already changed at low temperatures and successively became smaller, indicating increasing ordering towards more regular arrangements of building units. This was confirmed by 57Fe Mössbauer spectroscopy, where a distinct decrease of the quadrupole splitting with increasing synthesis temperature was found. Finally, Raman spectroscopy showed that some weakly-developed pre-ordering effects were present in the samples, which appeared to be amorphous in PXRD, while well-resolved spectra appeared as soon as the long-range ordered crystalline state could be found with X-ray diffraction.

2021 ◽  
Vol 129 (2) ◽  
pp. 207
Author(s):  
В.А. Кравец ◽  
Е.В. Иванова ◽  
К.Н. Орехова ◽  
Г.А. Гусев ◽  
В.В. Васькевич ◽  
...  

The main purpose of this work was to carry out a low-temperature synthesis of glass ceramics containing YNbO4:Eu3+ crystallites and to study the structural and luminescent properties of the obtained samples. Within the framework of this work, the inclusions that crystallized under the conditions of low-temperature synthesis in the systems of SiO2-Na2O-K2O-Y2O3-Nb2O5-Eu2O3 (SiNaK) and B2O5-Na2O-Y2O3-Nb2O5-Eu2O3 (BNa) were investigated for the first time. It was shown that YNbO4: Eu3+ crystallized in both considered systems. In the SiNaK system the crystallization of SiO2 also occurred (quartz, crisstabolite, and tridymite) under the selected conditions. The BNa system proved to be the most promising for the synthesis of activated glass-ceramics with YNbO4, since the required crystallites crystallized only in ithis system. The luminescent properties of crystalline inclusions were investigated using the local cathodoluminescence technique. The composition and structure of glass ceramics were studied by electron-probe microanalysis and X-ray diffraction phase analysis.


2013 ◽  
Vol 829 ◽  
pp. 737-741 ◽  
Author(s):  
Mohammad Javad Pourhosseini Asl ◽  
Ali Ghasemi ◽  
Gholam Reza Gordani

In this study, the low temperature synthesis of barium-Z type hexaferrite nanoparticles was considered. In this manner, the Z-type hexaferrite with the chemical composition of Ba3 Co1.7 Ni0.1 Cu0.1 Mn0.1 Fe24 O41 was synthesized at different temperatures of 900, 1000 and 1100 0C for 3hr. An X-Ray diffraction, field emission scanning electron microscopy (FE-SEM) and a vibrating sample magnetometer (VSM) analysis were carried out to investigate structural and magnetic properties of samples. XRD results showed that the Z-type ferrite phase was formed in all samples. However, At the low temperature synthesis (T=900 0C), the Ba2Me2Fe12O22 and BaFe2O4 phases were also detected. FE-SEM micrographs showed that with increasing the synthesis temperature, the particle size was increased. It was found that the saturation of magnetization was slightly increased from 54 to 55. 5emugr with an increase in synthesis temperature from 900 to 11000C, while the coercivity increased initially from 670 Oe to 860 Oe and then decreased to 488 Oe. The results also indicated that the temperature of 10000C was the optimum synthesis temperature of Ba-Z type hexaferrite nanoparticles, which was much lower than that of Z-type hexaferrite produced by previous researchers.


2011 ◽  
Vol 309-310 ◽  
pp. 271-274
Author(s):  
Ata Myatiev ◽  
Ilya Krechetov

A method of metalorganic compounds pyrolysis for low-temperature (about 500–600 oC) synthesis of perovskites PbTiO3 and PbZrO3 was tested to obtain films of this structures on sapphire substrates. The qualitative and quantitative X-ray diffraction analysis (XRD) of the films was carried out. The analysis showed that films obtained at 550 oC contain perovskites PbZrO3 and PbTi3O7.


2020 ◽  
Vol 26 (42) ◽  
pp. 9330-9337
Author(s):  
Kenneth P. Marshall ◽  
Anders B. Blichfeld ◽  
Susanne L. Skjærvø ◽  
Ola G. Grendal ◽  
Wouter Beek ◽  
...  

2020 ◽  
Vol 235 (4-5) ◽  
pp. 167-172
Author(s):  
Anastasiia P. Topnikova ◽  
Elena L. Belokoneva ◽  
Olga V. Dimitrova ◽  
Anatoly S. Volkov ◽  
Leokadiya V. Zorina

AbstractA new silicate-germanate K2Y[(Si3Ge)O10(OH)] was synthesized hydrothermally in a system Y2O3:GeO2:SiO2 = 1:1:2 (T = 280 °C; P = 90–100 atm.); K2CO3 was added to the solution as a mineralizer. Single-crystal X-ray diffraction experiment was carried out at low temperature (150 K). The unit cell parameters are a = 10.4975(4), b = 6.9567(2), c = 15.4001(6) Å, β = 104.894(4)°; V = 1086.86(7) Å3; space group is P 21/c. A novel complex anion is presented by corrugated (Si,Ge) tetrahedral layers connected by couples of YO6 octahedra into the mixed microporous framework with the channels along b and a axes, the maximal size of cross-section is ~5.6 Å. This structure has similarity with the two minerals: ring silicate gerenite (Ca,Na)2(Y,REE)3Si6O18 · 2H2O and chain silicate chkalovite Na2BeSi2O6. Six-member rings with 1̅ symmetry as in gerenite are distinguished in the new layer. They are mutually perpendicular to each other and connected by additional tetrahedra. Straight crossing chains in chkalovite change to zigzag four-link chains in the new silicate-germanate layer.


2007 ◽  
Vol 5 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Abdülhadi Baykal ◽  
Yüksel Köseoğlu ◽  
Mehmet Şenel

AbstractHeating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn2+signal with a highly resolved hyperfine structure.


2014 ◽  
Vol 543-547 ◽  
pp. 3741-3744
Author(s):  
Quan Jing Mei ◽  
Cong Ying Li ◽  
Jing Dong Guo ◽  
Gui Wang ◽  
Hai Tao Wu

The ecandrewsite-type ZnTiO3was successfully synthesized by the aqueous sol-gel method using TiO2dioxide and zinc nitrate as starting materials instead of expensive organic solvent and metal alkoxides. The as-prepared nanopowders were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM), respectively. The results showed that the calcination process of gel consisted of a series of oxidation and combustion reactions, accompanied by significantly exothermal effects. Highly reactive nanosized ZnTiO3powders were successfully obtained at 850 °C with particle size ~50 nm. By comparison, the aqueous sol-gel process was the most effective and least expensive technique used for the preparation of ZnTiO3nanopowders.


2010 ◽  
Vol 2010 (9) ◽  
pp. 1343-1347 ◽  
Author(s):  
Duk Kyu Lee ◽  
In-Sun Cho ◽  
SangWook Lee ◽  
Dong Hoe Kim ◽  
Hyun-Woo Shim ◽  
...  

2010 ◽  
Vol 136 ◽  
pp. 14-17 ◽  
Author(s):  
Yu Zhong Li ◽  
Xiao Chun Zhou

A novel red emitting phosphor, Ca2SnO4: Eu3+, was prepared by the low temperature solid state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4: Eu3+. Scanning electron-microscopy (SEM) observation indicated a narrow size distribution of about 500 nm for the particles with spherical shape. Under 396 nm excitation, the Ca2SnO4: Eu3+ phosphor exhibits novel red emission at about 613 nm which is assigned to the 5D0→7F2 electric-dipole transition. Furthermore, the emission transition 5D0→7F2 has been found to be more prominent over the normal orange emission transition 5D0→7F1.


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